mkdirs与createNewFile区别，Java复制文件工具类

mkdirs 与 createNewFile

mkdirs: 创建【多级目录文件夹】
mkdir：创建【单级目录文件夹】，如果上级文件夹不存在则报错
createNewFile：创建【文件】（如.txt）

例：桌面新建file1/file2/file3文件夹，并在里面新建test1.txt文件

String separator = File.separator;//分割符
System.out.println("separator==========" + separator);//桌面新建file1/file2/file3文件夹，并在里面新建test1.txt文件
String dir = "C:\\Users\\Administrator\\Desktop\\file1\\file2\\file3";
String fileName = "test1.txt";
File dirFile = new File(dir);
if (!dirFile.exists()) {System.out.println("创建文件夹");dirFile.mkdirs();//父级目录不存在可以创建,且只能创建文件夹
//            dirFile.mkdir();//父级目录不存在异常
} else {System.out.println("文件夹已存在");
}File file = new File(dir, fileName);
if (!file.exists()) {System.out.println("创建文件");try {file.createNewFile();} catch (IOException e) {e.printStackTrace();}
} else {System.out.println("文件已存在");
}boolean isDirectory = dirFile.isDirectory();
boolean isFile = file.isFile();
System.out.println("isDirectory========" + isDirectory);
System.out.println("isFile==========" + isFile);

复制文件工具类(四种方法)

import org.apache.commons.io.FileUtils;import java.io.*;
import java.nio.channels.FileChannel;
import java.nio.file.Files;public class CopyUtil {/** 1. 使用FileStreams复制* 这是最经典的方式将一个文件的内容复制到另一个文件中。* 使用FileInputStream读取文件A的字节，使用FileOutputStream写入到文件B。* */public static void copyFileUsingFileStreams(File source, File dest)throws IOException {InputStream input = null;OutputStream output = null;try {input = new FileInputStream(source);output = new FileOutputStream(dest);byte[] buf = new byte[1024];int bytesRead;while ((bytesRead = input.read(buf)) > 0) {output.write(buf, 0, bytesRead);}} finally {if (input != null) {input.close();}if (output != null) {output.close();}}}/** 2. 使用FileChannel复制* Java NIO包括transferFrom方法,根据文档应该比文件流复制的速度更快。* */public static void copyFileUsingFileChannels(File source, File dest) throws IOException {FileChannel inputChannel = null;FileChannel outputChannel = null;try {inputChannel = new FileInputStream(source).getChannel();outputChannel = new FileOutputStream(dest).getChannel();outputChannel.transferFrom(inputChannel, 0, inputChannel.size());} finally {if (inputChannel != null) {inputChannel.close();}if (outputChannel != null) {outputChannel.close();}}}/** 3. 使用Commons IO复制* //<!-- https://mvnrepository.com/artifact/commons-io/commons-io -->*   //<dependency>*    //    <groupId>commons-io</groupId>*   //    <artifactId>commons-io</artifactId>*   //    <version>2.6</version>*  //</dependency>* */public static void copyFileUsingApacheCommonsIO(File source, File dest)throws IOException {FileUtils.copyFile(source, dest);}/** 4. 使用Java7的Files类复制* */public static void copyFileUsingJava7Files(File source, File dest)throws IOException {Files.copy(source.toPath(), dest.toPath());}
}

例：将jar和aar拷贝到指定文件夹中

public class TestFile {private static String source = "C:\\Users\\Administrator\\.gradle\\caches\\modules-2\\files-2.1";private static String targer = "C:\\Users\\Administrator\\Desktop\\libss2222";public static void main(String[] args) {check(targer);copy(source, targer);}private static void check(String targer) {File dirFile = new File(targer);if (!dirFile.exists()) {System.out.println("创建文件夹");dirFile.mkdirs();//父级目录不存在可以创建
//            dirFile.mkdir();//父级目录不存在异常} else {System.out.println("文件夹已存在");}}public static void copy(String source, String targer) {File dir = new File(source);File[] files = dir.listFiles(); // 该文件目录下文件全部放入数组if (files != null) {for (File file : files) {if (file.isDirectory()) { // 判断是文件还是文件夹copy(file.getAbsolutePath(), targer); // 获取文件绝对路径} else {if (file.getAbsolutePath().endsWith(".jar")  || file.getAbsolutePath().endsWith(".aar")) {try {//java.io.FileNotFoundException: //C:\Users\Administrator\Desktop\libss2222 (拒绝访问。)//需要在目标文件夹指定要复制的文件名System.out.println("name==============================" + file.getName());CopyUtil.copyFileUsingFileStreams(file, new File(targer, file.getName()));} catch (IOException e) {e.printStackTrace();}}}}}}
}