BAEL-973 Apache Commons Commons IO (#2262)

* BAEL-973 Apache Commons Commons IO

* BAEL-973 : fix up formatting

* BAEL-973 : review comments.

* BAEL-973 : review comments.

* BAEL-973 : review comments.

* BAEL-973 : review comments.

* BAEL-973 : review comments.

* BAEL-973 : review comments.

libraries/src/main/java/com/baeldung/commons/io/FileMonitor.java

@@ -0,0 +1,43 @@
+package com.baeldung.commons.io;
+
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.monitor.FileAlterationListener;
+import org.apache.commons.io.monitor.FileAlterationListenerAdaptor;
+import org.apache.commons.io.monitor.FileAlterationMonitor;
+import org.apache.commons.io.monitor.FileAlterationObserver;
+
+import java.io.File;
+
+public class FileMonitor {
+
+    public static void main(String[] args) throws Exception {
+        File folder = FileUtils.getTempDirectory();
+        startFileMonitor(folder);
+    }
+
+    /**
+     * @param folder
+     * @throws Exception
+     */
+    public static void startFileMonitor(File folder) throws Exception {
+        FileAlterationObserver observer = new FileAlterationObserver(folder);
+        FileAlterationMonitor monitor = new FileAlterationMonitor(5000);
+
+        FileAlterationListener fal = new FileAlterationListenerAdaptor() {
+
+            @Override
+            public void onFileCreate(File file) {
+                // on create action
+            }
+
+            @Override
+            public void onFileDelete(File file) {
+                // on delete action
+            }
+        };
+
+        observer.addListener(fal);
+        monitor.addObserver(observer);
+        monitor.start();
+    }
+}

libraries/src/test/java/com/baeldung/commons/io/CommonsIOUnitTest.java

@@ -0,0 +1,151 @@
+package com.baeldung.commons.io;
+
+import org.apache.commons.io.FileSystemUtils;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.FilenameUtils;
+import org.apache.commons.io.IOCase;
+import org.apache.commons.io.comparator.PathFileComparator;
+import org.apache.commons.io.comparator.SizeFileComparator;
+import org.apache.commons.io.filefilter.AndFileFilter;
+import org.apache.commons.io.filefilter.NameFileFilter;
+import org.apache.commons.io.filefilter.SuffixFileFilter;
+import org.apache.commons.io.filefilter.WildcardFileFilter;
+import org.apache.commons.io.input.TeeInputStream;
+import org.apache.commons.io.output.TeeOutputStream;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.nio.charset.Charset;
+
+public class CommonsIOUnitTest {
+
+    @Test
+    public void whenCopyANDReadFileTesttxt_thenMatchExpectedData()
+        throws IOException {
+
+        String expectedData = "Hello World from fileTest.txt!!!";
+
+        File file = FileUtils.getFile(getClass().getClassLoader()
+            .getResource("fileTest.txt")
+            .getPath());
+        File tempDir = FileUtils.getTempDirectory();
+        FileUtils.copyFileToDirectory(file, tempDir);
+        File newTempFile = FileUtils.getFile(tempDir, file.getName());
+        String data = FileUtils.readFileToString(newTempFile,
+            Charset.defaultCharset());
+
+        Assert.assertEquals(expectedData, data.trim());
+    }
+
+    @Test
+    public void whenUsingFileNameUtils_thenshowdifferentFileOperations()
+        throws IOException {
+
+        String path = getClass().getClassLoader()
+            .getResource("fileTest.txt")
+            .getPath();
+
+        String fullPath = FilenameUtils.getFullPath(path);
+        String extension = FilenameUtils.getExtension(path);
+        String baseName = FilenameUtils.getBaseName(path);
+
+        System.out.println("full path" + fullPath);
+        System.out.println("Extension" + extension);
+        System.out.println("Base name" + baseName);
+    }
+
+    @Test
+    public void whenUsingFileSystemUtils_thenDriveFreeSpace()
+        throws IOException {
+
+        long freeSpace = FileSystemUtils.freeSpaceKb("/");
+    }
+
+    @SuppressWarnings("resource")
+    @Test
+    public void whenUsingTeeInputOutputStream_thenWriteto2OutputStreams()
+        throws IOException {
+
+        final String str = "Hello World.";
+        ByteArrayInputStream inputStream = new ByteArrayInputStream(str.getBytes());
+        ByteArrayOutputStream outputStream1 = new ByteArrayOutputStream();
+        ByteArrayOutputStream outputStream2 = new ByteArrayOutputStream();
+        
+        FilterOutputStream teeOutputStream = new TeeOutputStream(outputStream1,outputStream2);
+        new TeeInputStream(inputStream, teeOutputStream, true).read(new byte[str.length()]);
+        
+        Assert.assertEquals(str, String.valueOf(outputStream1));
+        Assert.assertEquals(str, String.valueOf(outputStream2));
+     }
+
+    @Test
+    public void whenGetFilewithNameFileFilter_thenFindfileTesttxt()
+        throws IOException {
+
+        final String testFile = "fileTest.txt";
+
+        String path = getClass().getClassLoader()
+            .getResource(testFile)
+            .getPath();
+        File dir = FileUtils.getFile(FilenameUtils.getFullPath(path));
+
+        String[] possibleNames = { "NotThisOne", testFile };
+
+        Assert.assertEquals(testFile,
+            dir.list(new NameFileFilter(possibleNames, IOCase.INSENSITIVE))[0]);
+    }
+
+    @Test
+    public void whenGetFilewith_ANDFileFilter_thenFindsampletxt()
+        throws IOException {
+
+        String path = getClass().getClassLoader()
+            .getResource("fileTest.txt")
+            .getPath();
+        File dir = FileUtils.getFile(FilenameUtils.getFullPath(path));
+
+        Assert.assertEquals("sample.txt",
+            dir.list(new AndFileFilter(
+                new WildcardFileFilter("*ple*", IOCase.INSENSITIVE),
+                new SuffixFileFilter("txt")))[0]);
+    }
+
+    @Test
+    public void whenSortDirWithPathFileComparator_thenFirstFileaaatxt()
+        throws IOException {
+
+        PathFileComparator pathFileComparator = new PathFileComparator(
+            IOCase.INSENSITIVE);
+        String path = FilenameUtils.getFullPath(getClass().getClassLoader()
+            .getResource("fileTest.txt")
+            .getPath());
+        File dir = new File(path);
+        File[] files = dir.listFiles();
+
+        pathFileComparator.sort(files);
+
+        Assert.assertEquals("aaa.txt", files[0].getName());
+    }
+
+    @Test
+    public void whenSizeFileComparator_thenLargerFile()
+        throws IOException {
+
+        SizeFileComparator sizeFileComparator = new SizeFileComparator();
+        File largerFile = FileUtils.getFile(getClass().getClassLoader()
+            .getResource("fileTest.txt")
+            .getPath());
+        File smallerFile = FileUtils.getFile(getClass().getClassLoader()
+            .getResource("sample.txt")
+            .getPath());
+
+        int i = sizeFileComparator.compare(largerFile, smallerFile);
+
+        Assert.assertTrue(i > 0);
+    }
+}

libraries/src/test/resources/ABC.txt

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+Hello World from ABC.txt!!!

libraries/src/test/resources/aaa.txt

@@ -0,0 +1 @@
+Hello World from aaa.txt!!!

libraries/src/test/resources/fileTest.txt

@@ -0,0 +1 @@
+Hello World from fileTest.txt!!!

libraries/src/test/resources/sample.txt

@@ -0,0 +1,2 @@
+line 1
+a second line