HADOOP-9044. add FindClass main class to provide classpath checking of installations (Steve Loughran via aw)
This commit is contained in:
Allen Wittenauer
parent
69c8a7f45b
commit
276485e1de
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@ -0,0 +1,388 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.hadoop.util;
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import com.google.common.annotations.VisibleForTesting;
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import org.apache.hadoop.conf.Configuration;
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import org.apache.hadoop.conf.Configured;
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import org.apache.hadoop.util.StringUtils;
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import org.apache.hadoop.util.Tool;
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import org.apache.hadoop.util.ToolRunner;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.PrintStream;
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import java.net.URL;
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import java.security.CodeSource;
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/**
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* This entry point exists for diagnosing classloader problems:
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* is a class or resource present -and if so, where?
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*
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* <p/>
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* Actions
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* <p/>
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* <ul>
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* <li><pre>load</pre>: load a class but do not attempt to create it </li>
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* <li><pre>create</pre>: load and create a class, print its string value</li>
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* <li><pre>printresource</pre>: load a resource then print it to stdout</li>
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* <li><pre>resource</pre>: load a resource then print the URL of that
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* resource</li>
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* </ul>
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*
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* It returns an error code if a class/resource cannot be loaded/found
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* -and optionally a class may be requested as being loaded.
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* The latter action will call the class's constructor -it must support an
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* empty constructor); any side effects from the
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* constructor or static initializers will take place.
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*
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* All error messages are printed to {@link System#out}; errors
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* to {@link System#err}.
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*
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*/
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@SuppressWarnings("UseOfSystemOutOrSystemErr")
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public final class FindClass extends Configured implements Tool {
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/**
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* create command: {@value}
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*/
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public static final String A_CREATE = "create";
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/**
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* Load command: {@value}
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*/
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public static final String A_LOAD = "load";
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/**
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* Command to locate a resource: {@value}
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*/
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public static final String A_RESOURCE = "locate";
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/**
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* Command to locate and print a resource: {@value}
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*/
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public static final String A_PRINTRESOURCE = "print";
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/**
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* Exit code when the operation succeeded: {@value}
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*/
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public static final int SUCCESS = 0;
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/**
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* generic error {@value}
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*/
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protected static final int E_GENERIC = 1;
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/**
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* usage error -bad arguments or similar {@value}
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*/
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protected static final int E_USAGE = 2;
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/**
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* class or resource not found {@value}
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*/
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protected static final int E_NOT_FOUND = 3;
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/**
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* class load failed {@value}
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*/
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protected static final int E_LOAD_FAILED = 4;
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/**
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* class creation failed {@value}
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*/
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protected static final int E_CREATE_FAILED = 5;
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/**
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* Output stream. Defaults to {@link System#out}
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*/
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private static PrintStream stdout = System.out;
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/**
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* Error stream. Defaults to {@link System#err}
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*/
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private static PrintStream stderr = System.err;
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/**
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* Empty constructor; passes a new Configuration
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* object instance to its superclass's constructor
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*/
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public FindClass() {
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super(new Configuration());
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}
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/**
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* Create a class with a specified configuration
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* @param conf configuration
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*/
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public FindClass(Configuration conf) {
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super(conf);
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}
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/**
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* Change the output streams to be something other than the
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* System.out and System.err streams
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* @param out new stdout stream
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* @param err new stderr stream
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*/
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@VisibleForTesting
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public static void setOutputStreams(PrintStream out, PrintStream err) {
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stdout = out;
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stderr = err;
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}
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/**
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* Get a class fromt the configuration
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* @param name the class name
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* @return the class
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* @throws ClassNotFoundException if the class was not found
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* @throws Error on other classloading problems
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*/
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private Class getClass(String name) throws ClassNotFoundException {
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return getConf().getClassByName(name);
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}
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/**
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* Get the resource
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* @param name resource name
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* @return URL or null for not found
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*/
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private URL getResource(String name) {
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return getConf().getResource(name);
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}
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/**
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* Load a resource
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* @param name resource name
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* @return the status code
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*/
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private int loadResource(String name) {
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URL url = getResource(name);
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if (url == null) {
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err("Resource not found: %s", name);
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return E_NOT_FOUND;
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}
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out("%s: %s", name, url);
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return SUCCESS;
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}
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/**
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* Dump a resource to out
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* @param name resource name
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* @return the status code
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*/
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@SuppressWarnings("NestedAssignment")
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private int dumpResource(String name) {
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URL url = getResource(name);
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if (url == null) {
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err("Resource not found:" + name);
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return E_NOT_FOUND;
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}
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try {
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//open the resource
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InputStream instream = url.openStream();
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//read it in and print
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int data;
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while (-1 != (data = instream.read())) {
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stdout.print((char) data);
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}
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//end of file
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stdout.print('\n');
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return SUCCESS;
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} catch (IOException e) {
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printStack(e, "Failed to read resource %s at URL %s", name, url);
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return E_LOAD_FAILED;
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}
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}
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/**
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* print something to stderr
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* @param s string to print
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*/
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private static void err(String s, Object... args) {
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stderr.format(s, args);
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stderr.print('\n');
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}
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/**
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* print something to stdout
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* @param s string to print
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*/
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private static void out(String s, Object... args) {
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stdout.format(s, args);
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stdout.print('\n');
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}
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/**
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* print a stack trace with text
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* @param e the exception to print
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* @param text text to print
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*/
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private static void printStack(Throwable e, String text, Object... args) {
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err(text, args);
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e.printStackTrace(stderr);
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}
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/**
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* Loads the class of the given name
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* @param name classname
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* @return outcome code
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*/
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private int loadClass(String name) {
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try {
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Class clazz = getClass(name);
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loadedClass(name, clazz);
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return SUCCESS;
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} catch (ClassNotFoundException e) {
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printStack(e, "Class not found " + name);
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return E_NOT_FOUND;
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} catch (Exception e) {
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printStack(e, "Exception while loading class " + name);
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return E_LOAD_FAILED;
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} catch (Error e) {
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printStack(e, "Error while loading class " + name);
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return E_LOAD_FAILED;
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}
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}
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/**
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* Log that a class has been loaded, and where from.
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* @param name classname
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* @param clazz class
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*/
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private void loadedClass(String name, Class clazz) {
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out("Loaded %s as %s", name, clazz);
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CodeSource source = clazz.getProtectionDomain().getCodeSource();
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URL url = source.getLocation();
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out("%s: %s", name, url);
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}
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/**
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* Create an instance of a class
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* @param name classname
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* @return the outcome
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*/
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private int createClassInstance(String name) {
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try {
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Class clazz = getClass(name);
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loadedClass(name, clazz);
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Object instance = clazz.newInstance();
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try {
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//stringify
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out("Created instance " + instance.toString());
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} catch (Exception e) {
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//catch those classes whose toString() method is brittle, but don't fail the probe
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printStack(e,
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"Created class instance but the toString() operator failed");
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}
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return SUCCESS;
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} catch (ClassNotFoundException e) {
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printStack(e, "Class not found " + name);
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return E_NOT_FOUND;
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} catch (Exception e) {
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printStack(e, "Exception while creating class " + name);
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return E_CREATE_FAILED;
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} catch (Error e) {
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printStack(e, "Exception while creating class " + name);
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return E_CREATE_FAILED;
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}
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}
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/**
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* Run the class/resource find or load operation
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* @param args command specific arguments.
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* @return the outcome
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* @throws Exception if something went very wrong
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*/
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@Override
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public int run(String[] args) throws Exception {
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if (args.length != 2) {
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return usage(args);
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}
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String action = args[0];
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String name = args[1];
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int result;
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if (A_LOAD.equals(action)) {
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result = loadClass(name);
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} else if (A_CREATE.equals(action)) {
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//first load to separate load errors from create
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result = loadClass(name);
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if (result == SUCCESS) {
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//class loads, so instantiate it
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result = createClassInstance(name);
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}
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} else if (A_RESOURCE.equals(action)) {
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result = loadResource(name);
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} else if (A_PRINTRESOURCE.equals(action)) {
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result = dumpResource(name);
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} else {
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result = usage(args);
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}
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return result;
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}
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/**
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* Print a usage message
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* @param args the command line arguments
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* @return an exit code
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*/
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private int usage(String[] args) {
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err(
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"Usage : [load | create] <classname>");
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err(
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" [locate | print] <resourcename>]");
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err("The return codes are:");
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explainResult(SUCCESS,
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"The operation was successful");
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explainResult(E_GENERIC,
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"Something went wrong");
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explainResult(E_USAGE,
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"This usage message was printed");
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explainResult(E_NOT_FOUND,
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"The class or resource was not found");
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explainResult(E_LOAD_FAILED,
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"The class was found but could not be loaded");
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explainResult(E_CREATE_FAILED,
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"The class was loaded, but an instance of it could not be created");
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return E_USAGE;
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}
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/**
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* Explain an error code as part of the usage
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* @param errorcode error code returned
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* @param text error text
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*/
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private void explainResult(int errorcode, String text) {
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err(" %2d -- %s ", errorcode , text);
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}
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/**
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* Main entry point.
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* Runs the class via the {@link ToolRunner}, then
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* exits with an appropriate exit code.
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* @param args argument list
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*/
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public static void main(String[] args) {
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try {
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int result = ToolRunner.run(new FindClass(), args);
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System.exit(result);
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} catch (Exception e) {
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printStack(e, "Running FindClass");
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System.exit(E_GENERIC);
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}
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}
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}
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@ -0,0 +1,218 @@
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/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.hadoop.util;
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import java.io.ByteArrayOutputStream;
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import java.io.PrintStream;
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import junit.framework.Assert;
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import org.apache.commons.logging.Log;
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import org.apache.commons.logging.LogFactory;
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import org.apache.hadoop.util.FindClass;
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import org.apache.hadoop.util.ToolRunner;
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import org.junit.Test;
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/**
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* Test the find class logic
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*/
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public class TestFindClass extends Assert {
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private static final Log LOG = LogFactory.getLog(TestFindClass.class);
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public static final String LOG4J_PROPERTIES = "log4j.properties";
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/**
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* Run the tool runner instance
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* @param expected expected return code
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* @param args a list of arguments
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* @throws Exception on any falure that is not handled earlier
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*/
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private void run(int expected, String... args) throws Exception {
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int result = ToolRunner.run(new FindClass(), args);
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assertEquals(expected, result);
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}
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@Test
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public void testUsage() throws Throwable {
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run(FindClass.E_USAGE, "org.apache.hadoop.util.TestFindClass");
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}
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@Test
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public void testFindsResource() throws Throwable {
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run(FindClass.SUCCESS,
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FindClass.A_RESOURCE, "org/apache/hadoop/util/TestFindClass.class");
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}
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@Test
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public void testFailsNoSuchResource() throws Throwable {
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run(FindClass.E_NOT_FOUND,
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FindClass.A_RESOURCE,
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"org/apache/hadoop/util/ThereIsNoSuchClass.class");
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}
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@Test
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public void testLoadFindsSelf() throws Throwable {
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run(FindClass.SUCCESS,
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FindClass.A_LOAD, "org.apache.hadoop.util.TestFindClass");
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}
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@Test
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public void testLoadFailsNoSuchClass() throws Throwable {
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run(FindClass.E_NOT_FOUND,
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FindClass.A_LOAD, "org.apache.hadoop.util.ThereIsNoSuchClass");
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}
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@Test
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public void testLoadWithErrorInStaticInit() throws Throwable {
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run(FindClass.E_LOAD_FAILED,
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FindClass.A_LOAD,
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"org.apache.hadoop.util.TestFindClass$FailInStaticInit");
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}
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@Test
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public void testCreateHandlesBadToString() throws Throwable {
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run(FindClass.SUCCESS,
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FindClass.A_CREATE,
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"org.apache.hadoop.util.TestFindClass$BadToStringClass");
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}
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@Test
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public void testCreatesClass() throws Throwable {
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run(FindClass.SUCCESS,
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FindClass.A_CREATE, "org.apache.hadoop.util.TestFindClass");
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}
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@Test
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public void testCreateFailsInStaticInit() throws Throwable {
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run(FindClass.E_LOAD_FAILED,
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FindClass.A_CREATE,
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"org.apache.hadoop.util.TestFindClass$FailInStaticInit");
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}
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@Test
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public void testCreateFailsInConstructor() throws Throwable {
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run(FindClass.E_CREATE_FAILED,
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FindClass.A_CREATE,
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"org.apache.hadoop.util.TestFindClass$FailInConstructor");
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}
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@Test
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public void testCreateFailsNoEmptyConstructor() throws Throwable {
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run(FindClass.E_CREATE_FAILED,
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FindClass.A_CREATE,
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"org.apache.hadoop.util.TestFindClass$NoEmptyConstructor");
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}
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@Test
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public void testLoadPrivateClass() throws Throwable {
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run(FindClass.SUCCESS,
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FindClass.A_LOAD, "org.apache.hadoop.util.TestFindClass$PrivateClass");
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}
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@Test
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public void testCreateFailsPrivateClass() throws Throwable {
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run(FindClass.E_CREATE_FAILED,
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FindClass.A_CREATE,
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"org.apache.hadoop.util.TestFindClass$PrivateClass");
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}
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@Test
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public void testCreateFailsInPrivateConstructor() throws Throwable {
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run(FindClass.E_CREATE_FAILED,
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FindClass.A_CREATE,
|
||||
"org.apache.hadoop.util.TestFindClass$PrivateConstructor");
|
||||
}
|
||||
|
||||
@Test
|
||||
public void testLoadFindsLog4J() throws Throwable {
|
||||
run(FindClass.SUCCESS, FindClass.A_RESOURCE, LOG4J_PROPERTIES);
|
||||
}
|
||||
|
||||
@SuppressWarnings("UseOfSystemOutOrSystemErr")
|
||||
@Test
|
||||
public void testPrintLog4J() throws Throwable {
|
||||
ByteArrayOutputStream baos = new ByteArrayOutputStream();
|
||||
PrintStream out = new PrintStream(baos);
|
||||
FindClass.setOutputStreams(out, System.err);
|
||||
run(FindClass.SUCCESS, FindClass.A_PRINTRESOURCE, LOG4J_PROPERTIES);
|
||||
//here the content should be done
|
||||
out.flush();
|
||||
String body = baos.toString("UTF8");
|
||||
LOG.info(LOG4J_PROPERTIES + " =\n" + body);
|
||||
assertTrue(body.contains("Apache"));
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* trigger a divide by zero fault in the static init
|
||||
*/
|
||||
public static class FailInStaticInit {
|
||||
static {
|
||||
int x = 0;
|
||||
int y = 1 / x;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* trigger a divide by zero fault in the constructor
|
||||
*/
|
||||
public static class FailInConstructor {
|
||||
public FailInConstructor() {
|
||||
int x = 0;
|
||||
int y = 1 / x;
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* A class with no parameterless constructor -expect creation to fail
|
||||
*/
|
||||
public static class NoEmptyConstructor {
|
||||
public NoEmptyConstructor(String text) {
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* This has triggers an NPE in the toString() method; checks the logging
|
||||
* code handles this.
|
||||
*/
|
||||
public static class BadToStringClass {
|
||||
public BadToStringClass() {
|
||||
}
|
||||
|
||||
@Override
|
||||
public String toString() {
|
||||
throw new NullPointerException("oops");
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* This has a private constructor
|
||||
* -creating it will trigger an IllegalAccessException
|
||||
*/
|
||||
public static class PrivateClass {
|
||||
private PrivateClass() {
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* This has a private constructor
|
||||
* -creating it will trigger an IllegalAccessException
|
||||
*/
|
||||
public static class PrivateConstructor {
|
||||
private PrivateConstructor() {
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue