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Review - II Kevin Gilmore Changes

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root 2020-07-25 18:28:28 +00:00
parent c1a9c42194
commit 1299a22eb5
2 changed files with 12 additions and 51 deletions
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39
core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/Launcher.java
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@ -1,48 +1,19 @@
package com.baeldung.loadedclasslisting; package com.baeldung.loadedclasslisting;
import java.lang.reflect.Method;
import java.util.Arrays; import java.util.Arrays;
import com.baeldung.loadedclasslisting.ListLoadedClassesAgent.ClassLoaderType;
import com.baeldung.loadedclasslisting.customLoader.ClassLoaderInfo;
import com.baeldung.loadedclasslisting.customLoader.CustomClassLoader;
public class Launcher { public class Launcher {
private static ClassLoader customClassLoader;
public static void main(String[] args) { public static void main(String[] args) {
printClassesLoadedBy(ClassLoaderType.BOOTSTRAP); printClassesLoadedBy("BOOTSTRAP");
printClassesLoadedBy(ClassLoaderType.SYSTEM); printClassesLoadedBy("SYSTEM");
printClassesLoadedBy(ClassLoaderType.EXTENSION); printClassesLoadedBy("EXTENSION");
printClassesLoadedBy(ClassLoaderType.CUSTOM);
} }
private static void printClassesLoadedBy(ClassLoaderType classLoaderType) { private static void printClassesLoadedBy(String classLoaderType) {
Class<?>[] classes; Class<?>[] classes = ListLoadedClassesAgent.listLoadedClasses(classLoaderType);
if (classLoaderType.equals(ClassLoaderType.CUSTOM)) {
customClassLoader = customClassLoading();
classes = ListLoadedClassesAgent.listLoadedClasses(customClassLoader);
} else {
classes = ListLoadedClassesAgent.listLoadedClasses(classLoaderType);
}
Arrays.asList(classes) Arrays.asList(classes)
.forEach(clazz -> System.out.println( .forEach(clazz -> System.out.println(
classLoaderType + " ClassLoader : " + clazz.getCanonicalName())); classLoaderType + " ClassLoader : " + clazz.getCanonicalName()));
} }
private static CustomClassLoader customClassLoading() {
CustomClassLoader customClassLoader = new CustomClassLoader();
Class<?> c;
try {
c = customClassLoader.findClass(ClassLoaderInfo.class.getName());
Object ob = c.getDeclaredConstructor()
.newInstance();
Method md = c.getMethod("printClassLoaders");
md.invoke(ob);
} catch (Exception e) {
e.printStackTrace();
}
return customClassLoader;
}
} }

24
core-java-modules/core-java-jvm-2/src/main/java/com/baeldung/loadedclasslisting/ListLoadedClassesAgent.java
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@ -4,17 +4,13 @@ import java.lang.instrument.Instrumentation;
public class ListLoadedClassesAgent { public class ListLoadedClassesAgent {
public enum ClassLoaderType {
SYSTEM, EXTENSION, BOOTSTRAP, CUSTOM , PLATFORM
}
private static Instrumentation instrumentation; private static Instrumentation instrumentation;
public static void premain(String agentArgs, Instrumentation instrumentation) { public static void premain(String agentArgs, Instrumentation instrumentation) {
ListLoadedClassesAgent.instrumentation = instrumentation; ListLoadedClassesAgent.instrumentation = instrumentation;
} }
public static Class<?>[] listLoadedClasses(ClassLoaderType classLoaderType) { public static Class<?>[] listLoadedClasses(String classLoaderType) {
if (instrumentation == null) { if (instrumentation == null) {
throw new IllegalStateException( throw new IllegalStateException(
"ListLoadedClassesAgent is not initialized."); "ListLoadedClassesAgent is not initialized.");
@ -23,24 +19,18 @@ public class ListLoadedClassesAgent {
getClassLoader(classLoaderType)); getClassLoader(classLoaderType));
} }
public static Class<?>[] listLoadedClasses(ClassLoader classLoader) { private static ClassLoader getClassLoader(String classLoaderType) {
if (instrumentation == null) {
throw new IllegalStateException(
"ListLoadedClassesAgent is not initialized.");
}
return instrumentation.getInitiatedClasses(classLoader);
}
private static ClassLoader getClassLoader(ClassLoaderType classLoaderType) {
ClassLoader classLoader = null; ClassLoader classLoader = null;
switch (classLoaderType) { switch (classLoaderType) {
case SYSTEM: case "SYSTEM":
classLoader = ClassLoader.getSystemClassLoader(); classLoader = ClassLoader.getSystemClassLoader();
break; break;
case EXTENSION: case "EXTENSION":
classLoader = ClassLoader.getSystemClassLoader().getParent(); classLoader = ClassLoader.getSystemClassLoader().getParent();
break; break;
case BOOTSTRAP: // passing a null value to the Instrumentation : getInitiatedClasses method
// defaults to the bootstrap class loader
case "BOOTSTRAP":
break; break;
default: default:
break; break;