使用DirectoryWalker和FileFilterUtils进行搜索

Apache commons IO包中提供了一个可以遍历目录下资源的DirectoryWalker，还有很多的IOFileFilter用于过滤文件目录。下面的例子分别演示了这个功能。

这两个搜索类都是以内部类的方式嵌入客户端的，客户端接收客户的参数，然后通过一个后台线程来进行搜索，等待子线程完成搜索后(join方法)，再打印搜索结果。

注意这个过程是可以被cancel的。cancel主要有2种情况。外部cancel：外部线程通过调用内部类的cancel()方法。内部cancel：在handleDirectory、handleFile中主动抛出CancelException。

walk方法在每次执行前、后都会检查当前是否有cancel指令发出(checkIfCancelled ---> handleIsCancelled)，如果有那么默认立刻抛出CancelException，然后调用handleCancelled方法。

这里搜索实现类被实现为一个内部类，目的是不想暴露内部的搜索过程逻辑，只对外暴露客户端接口。其次内部采用线程实现，方便充当客户端的外部类可以在必要时cancel这个内部线程操作，而且当搜索过程漫长时不会造成界面假死(GUI界面)。

在搜索过程中，我们可以对搜索到文件、资源进行处理，例如：删除，重命名，移动等。最常见的一个应用就是批量删除搜索到的文件。例如.svn目录或日志文件

/** *//** * Main recursive method to examine the directory hierarchy. * * @param directory the directory to examine, not null * @param depth the directory level (starting directory = 0) * @param results the collection of result objects, may be updated * @throws IOException if an I/O Error occurs */ private void walk(File directory, int depth, Collection results) throws IOException { checkIfCancelled(directory, depth, results); if (handleDirectory(directory, depth, results)) { handleDirectoryStart(directory, depth, results); int childDepth = depth + 1; if (depthLimit < 0 || childDepth <= depthLimit) { checkIfCancelled(directory, depth, results); File[] childFiles = (filter == null ? directory.listFiles() : directory.listFiles(filter)); if (childFiles == null) { handleRestricted(directory, childDepth, results); } else { for (int i = 0; i < childFiles.length; i++) { File childFile = childFiles[i]; if (childFile.isDirectory()) { walk(childFile, childDepth, results); } else { checkIfCancelled(childFile, childDepth, results); handleFile(childFile, childDepth, results); checkIfCancelled(childFile, childDepth, results); } } } } handleDirectoryEnd(directory, depth, results); } checkIfCancelled(directory, depth, results); }

【一】从根目录开始，查询(指定目录下)指定的文件

Java代码

import java.io.File;import java.io.IOException;import java.util.ArrayList;import java.util.Collection;import java.util.List;import org.apache.commons.io.DirectoryWalker;import org.apache.commons.io.FilenameUtils;import org.apache.commons.io.filefilter.FileFilterUtils;/** * The Class FileSearcher. */public class FileSearcher {/** * The main method. * * @param args * the arguments */public static void main(String[] args) {String baseDir = null;String targetDir = null;String targetFile = null;if (args == null || args.length == 0) {System.err.println("Error: Missing start directory name");System.exit(-1);}if (args == null || args.length == 1) {System.err.println("Error: Missing target file name");System.exit(-1);}FileSearcher searcher = new FileSearcher();// Only base directory and file name are givenif (args != null && args.length == 2) {baseDir = args[0];targetFile = args[1];searcher.search(baseDir, targetFile);}// Both base and parent directories name and file name are givenif (args != null && args.length >= 3) {baseDir = args[0];targetDir = args[1];targetFile = args[2];searcher.search(baseDir, targetDir, targetFile);}}/** * Search by file name * * @param baseDir * the base dir * @param targetFile * the target file */public void search(String baseDir, String targetFile) {search(baseDir, null, targetFile);}/** * Search by file name and parent directory name * * @param baseDir * the base dir * @param targetDir * the target dir * @param targetFile * the target file */public void search(String baseDir, String targetDir, String targetFile) {// File existence checkif ((baseDir == null || baseDir.trim().length() == 0)|| (targetFile == null || (targetFile.trim().length() == 0))) {System.err.println("Error: Missing base directory or file name");System.exit(-1);}File startDirectory = new File(baseDir);if (!startDirectory.exists()) {System.err.println("Error: Couldn't find path by given parameter");System.exit(-1);}// Create a new thread and start to searchSearchFileWalker walker = new SearchFileWalker(startDirectory,targetDir, targetFile);Thread searchThread = new Thread(walker);searchThread.start();System.out.println("Start to search ");try {searchThread.join(); // child thread join to main thread} catch (InterruptedException e) {e.printStackTrace();}walker.displaySearchResult();}class SearchFileWalker extends DirectoryWalker implements Runnable {private volatile boolean cancelled = false;private boolean matchByFileNameOnly = true;private File baseDir;private String targetDirName;private String targetFileName;private List<File> finalResult = new ArrayList<File>();/** * Instantiates a new search directory walker. * * @param startDir * the start dir * @param targetFile * the target file */public SearchFileWalker(File startDir, String targetFile) {this(startDir, null, targetFile);}/** * Instantiates a new search directory walker. * * @param startDir * the start dir * @param targetDir * the target dir * @param targetFile * the target file */public SearchFileWalker(File startDir, String targetDir,String targetFile) {super();baseDir = startDir;targetDirName = targetDir;targetFileName = targetFile;matchByFileNameOnly = (targetDirName == null) ? true : false;}/** * (non-Javadoc) * * @see java.lang.Runnable#run() */public void run() {search();}/** * Search. */public void search() {List<File> searchResult = new ArrayList<File>();try {walk(baseDir, searchResult);} catch (IOException e) {e.printStackTrace();}finalResult = searchResult;}/** * Gets the result. * * @return the result */public List<File> getResult() {return finalResult;}/** * Display search result. */public void displaySearchResult() {File f = null;System.out.println("/n=======================================");for (int i = 0; i < finalResult.size(); i++) {f = (File) finalResult.get(i);System.out.println(" File found: " + f.getAbsolutePath());}System.out.println("=======================================/n");}/** * (non-Javadoc) * * @see org.apache.commons.io.DirectoryWalker#handleDirectory(java.io.File, * int, java.util.Collection) */protected boolean handleDirectory(File directory, int depth,Collection results) throws IOException {System.out.println("/nSearching under directory: "+ directory.getAbsolutePath());if (matchByFileNameOnly) {return true; // Match by file name only} else if (FilenameUtils.equalsNormalizedOnSystem(targetDirName,directory.getName())) {return true; // Parent directory name matched} else if (directory.list(FileFilterUtils.directoryFileFilter()).length > 0) {return true; // Has child directory} else {return false; // Empty directory or file name doesn't match}}/** * (non-Javadoc) * * @see org.apache.commons.io.DirectoryWalker#handleFile(java.io.File, * int, java.util.Collection) */protected void handleFile(File file, int depth, Collection results)throws IOException {// Matches by file name onlyif (targetFileName.equals(file.getName()) && matchByFileNameOnly) {results.add(file);}// Matches by directory name and file nameif (FilenameUtils.equalsNormalizedOnSystem(targetFileName,file.getName())&& (!matchByFileNameOnly)) {String fullPath = FilenameUtils.getFullPathNoEndSeparator(file.getAbsolutePath());String fileParentDir = fullPath.substring(FilenameUtils.indexOfLastSeparator(fullPath) + 1);if (FilenameUtils.equalsOnSystem(targetDirName, fileParentDir)) {results.add(file);}}}/** * Cancel. */public void cancel() {cancelled = true;}/** * (non-Javadoc) * * @see org.apache.commons.io.DirectoryWalker#handleIsCancelled(java.io.File, * int, java.util.Collection) */protected boolean handleIsCancelled(File file, int depth,Collection results) {return cancelled;}/** * (non-Javadoc) * * @see org.apache.commons.io.DirectoryWalker#handleCancelled(java.io.File, * java.util.Collection, * org.apache.commons.io.DirectoryWalker.CancelException) */protected void handleCancelled(File startDirectory, Collection results,CancelException cancel) {if (cancelled) {cancel();}System.out.println("/nCancelled by external or interal thread");finalResult = (List<File>) results;}}}