java递归和非递归方式遍历所有文件和目录

本是古典何须时尚 2022-01-07 05:55 372阅读 0赞

java遍历指定目录的所有文件，可采用递归和非递归的方式。

定义了接口FileOpera，由具体的实现指定对目录及文件执行的操作。

import java.io.File;
    import java.io.FileNotFoundException;
    import java.util.Queue;
    import java.util.concurrent.LinkedBlockingDeque;
    
    public class FileUtil {
        
    
    	/**
    	 * 对目录及文件的制定操作接口封装
    	 * 
    	 * @author jsword
    	 *
    	 */
    	public interface FileOpera {
        
    		void doFile(File file);
    
    		void doFileDir(File file);
    	}
    
    	private static FileOpera fileOpera;
    
    	/**
    	 * 是否输出测试信息的标志 对于条件表达式中永远为false的语句，编译器将不对条件覆盖的代码段生成字节码。
    	 */
    	public static final boolean TEST_FLAG = false;
    
    	/**
    	 * 非递归遍历文件夹,依据树的层次遍历的原理,借助队列queue实现
    	 * 
    	 * @param path
    	 * @param visit : 对每个文件进行操作的接口，如果为null，空操作
    	 * @return int[] : 长度为2的数组，第1个为文件夹数量，第2个为文件数量
    	 * @throws IllegalArgumentException
    	 * @throws FileNotFoundException
    	 */
    	public static int[] traverseFolder(String path, FileUtil.FileOpera visit)
    			throws FileNotFoundException, IllegalArgumentException {
        
    		checktraverseFolderParams(path);
    		
    		fileOpera = visit;
    		int[] params = new int[] {
         0, 0 }; // save folder num(params[0]) and file num(params[1])
    		File file = new File(path);
    		Queue<File> queue = new LinkedBlockingDeque<>();
    
    		queue.add(file);
    
    		File temp_file;
    		while (!queue.isEmpty()) {
        
    			temp_file = queue.remove();
    			File[] files = temp_file.listFiles();
    			for (File tmpFile : files) {
        
    				if (tmpFile.isDirectory()) {
        
    					if (TEST_FLAG)
    						System.out.println("folder :" + tmpFile.getAbsolutePath());
    					if (null != fileOpera)
    						fileOpera.doFileDir(tmpFile);
    					queue.add(tmpFile);
    					params[0]++;
    				} else {
        
    					if (TEST_FLAG)
    						System.out.println("file: " + tmpFile.getAbsolutePath());
    					if (null != fileOpera)
    						fileOpera.doFile(tmpFile);
    					params[1]++;
    				}
    			}
    		}
    		return params;
    	}
    
    	/**
    	 * 递归遍历所有的文件和文件夹
    	 * 
    	 * @param path ： 必须为目录
    	 * @throws IllegalArgumentException
    	 * @throws FileNotFoundException
    	 */
    	public static int[] traverseFolderResusion(String path, FileUtil.FileOpera visit)
    			throws FileNotFoundException, IllegalArgumentException {
        
    
    		checktraverseFolderParams(path);
    
    		fileOpera = visit;
    		int[] params = new int[] {
         0, 0 }; // save folder num(params[0]) and file num(params[1])
    		traverseFolderResusion(new File(path), params);
    		return params;
    	}
    
    	/**
    	 * @param dirFile
    	 * @param params
    	 */
    	private static void traverseFolderResusion(File dirFile, int params[]) {
        
    		File[] files = dirFile.listFiles();
    		if (files.length == 0) {
         // empty folder
    			if (TEST_FLAG)
    				System.out.println("folder is empty!");
    			if (null != fileOpera)
    				fileOpera.doFileDir(dirFile);
    			return;
    		} else {
        
    			for (File tmpFile : files) {
        
    				if (tmpFile.isDirectory()) {
        
    					if (TEST_FLAG)
    						System.out.println("folder " + tmpFile.getAbsolutePath());
    					if (null != fileOpera)
    						fileOpera.doFileDir(tmpFile);
    					++params[0];
    					traverseFolderResusion(new File(tmpFile.getAbsolutePath()), params);
    				} else {
        
    					if (TEST_FLAG)
    						System.out.println("file " + tmpFile.getAbsolutePath());
    					if (null != fileOpera)
    						fileOpera.doFile(tmpFile);
    					++params[1];
    				}
    			}
    		}
    	}
    
    	private static boolean checktraverseFolderParams(String path)
    			throws FileNotFoundException, IllegalArgumentException {
        
    		File scfile = new File(path);
    		if (!scfile.exists())
    			throw new FileNotFoundException("path :" + path + " is not exist.");
    		if (scfile.isFile())
    			throw new IllegalArgumentException("path :" + path + " is not directory.");
    		return true;
    	}
    
    }