本文共 4928 字，大约阅读时间需要 16 分钟。

1、获取文件目录大小

package IOTest_12;import java.io.File;/* * 读取大小 */import org.apache.commons.io.FileUtils;public class CommonsIOTest_1 {
   	public static void main(String[] args) {
   		//文件大小		long len = FileUtils.sizeOf(new File("测试.mp4"));		System.out.println(len);		//目录大小		len = FileUtils.sizeOf(new File("F:/eclipse-workspace/Java300集_8"));		System.out.println(len);			}}

2、列出子孙级目录

package IOTest_12;import java.io.File;import java.util.Collection;/* * 读取大小 */import org.apache.commons.io.FileUtils;import org.apache.commons.io.filefilter.DirectoryFileFilter;import org.apache.commons.io.filefilter.EmptyFileFilter;import org.apache.commons.io.filefilter.FileFilterUtils;import org.apache.commons.io.filefilter.SuffixFileFilter;/** * 列出子孙级目录 * @author Root * */public class CommonsIOTest_2 {
   	public static void main(String[] args) {
   		//只显示一层		Collection
   
     files = FileUtils.listFiles(				new File("F:\\eclipse-workspace\\Java300集_8"), 				EmptyFileFilter.NOT_EMPTY, null);		for (File file : files) {
   			System.out.println(file.getAbsolutePath());		}		System.out.println("------------------");		//子孙级		files = FileUtils.listFiles(				new File("F:\\eclipse-workspace\\Java300集_8"), 				EmptyFileFilter.NOT_EMPTY, DirectoryFileFilter.INSTANCE);		for (File file : files) {
   			System.out.println(file.getAbsolutePath());		}		System.out.println("------------------");		//子孙级——指定过滤		files = FileUtils.listFiles(				new File("F:\\eclipse-workspace\\Java300集_8"), 				new SuffixFileFilter("class"), DirectoryFileFilter.INSTANCE);		for (File file : files) {
   			System.out.println(file.getAbsolutePath());		}		System.out.println("------------------");		//子孙级——指定过滤		files = FileUtils.listFiles(				new File("F:\\eclipse-workspace\\Java300集_8"), 				new SuffixFileFilter("class"), DirectoryFileFilter.INSTANCE);		for (File file : files) {
   			System.out.println(file.getAbsolutePath());		}		System.out.println("------------------");		//子孙级——指定过滤		files = FileUtils.listFiles(				new File("F:\\eclipse-workspace\\Java300集_8"), 				FileFilterUtils.or(new SuffixFileFilter("class"),new SuffixFileFilter("java")), DirectoryFileFilter.INSTANCE);		for (File file : files) {
   			System.out.println(file.getAbsolutePath());		}	}}
   

3、读取文件

package IOTest_12;import java.io.File;import java.io.IOException;import java.util.List;import javax.sound.sampled.LineListener;/* * 读取大小 */import org.apache.commons.io.FileUtils;import org.apache.commons.io.LineIterator;/** * 读取文件 * @author Root * */public class CommonsIOTest_3 {
   	public static void main(String[] args) throws IOException {
   		//读取文件		String msg = FileUtils.readFileToString(new File("abc.txt"),"GBK");		System.out.println(msg);		byte[] datas = FileUtils.readFileToByteArray(new File("abc.txt"));		System.out.println(datas.length);		//逐行读取		List
   
     msgs = FileUtils.readLines(new File("abc.txt"),"GBK");		for (String string : msgs) {
   			System.out.println(string);		}		System.out.println("----------");		LineIterator it = FileUtils.lineIterator(new File("abc.txt"),"GBK");		while(it.hasNext()) {
   			System.out.println(it.nextLine());		}	}}
   

4、写出文件

package IOTest_12;import java.io.File;import java.io.IOException;import java.util.ArrayList;import java.util.List;import javax.sound.sampled.LineListener;/* * 读取大小 */import org.apache.commons.io.FileUtils;/** *  * @author Root * */public class CommonsIOTest_4 {
   	public static void main(String[] args) throws IOException {
   		//写出文件		FileUtils.write(new File("CIO.txt"), "测试写出文件\r\n","GBK");		FileUtils.writeStringToFile(new File("CIO.txt"), "测试写出文件\r\n","GBK",true);		FileUtils.writeByteArrayToFile(new File("CIO.txt"), "测试写出文件\r\n".getBytes("GBK"),true);		//写出列表		List
   
     datas = new ArrayList
    
     ();		datas.add("测试1");		datas.add("测试2");		datas.add("测试3");		FileUtils.writeLines(new File("CIO.txt"), datas,"...",true);	}}
    
   

5、文件拷贝

package IOTest_12;import java.io.File;import java.io.IOException;import java.net.URL;import java.util.ArrayList;import java.util.List;import javax.sound.sampled.LineListener;/* * 读取大小 */import org.apache.commons.io.FileUtils;import org.apache.commons.io.IOUtils;/** * * @author Root * */public class CommonsIOTest_5 {
   	public static void main(String[] args) throws IOException {
   		//复制文件		FileUtils.copyFile(new File("情人.mp4"),new File("qr.mp4"));		//复制文件到目录		FileUtils.copyFileToDirectory(new File("img.png"), new File("lib"));		//复制目录到目录		FileUtils.copyDirectory(new File("lib"), new File("mkdir/lib"));		//拷贝URL		String url = "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1551899826700&di=6a078c018ed37648f5c0d1b171560c66&imgtype=0&src=http%3A%2F%2Fimg1.xiazaizhijia.com%2Fwalls%2F20151109%2F1024x768_ee5b2db1b4789b4.jpg";		FileUtils.copyURLToFile(new URL(url), new File("aaa.jpg"));		//获取网页源码		String datas = IOUtils.toString(				new URL("https://www.yanghuisen.cn"), "UTF-8");		System.out.println(datas);	}}

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