java文件操作之Path,Paths,Files

Java7中文件IO发生了很大的变化，专门引入了很多新的类：

import java.nio.file.DirectoryStream;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.attribute.FileAttribute;

import java.nio.file.attribute.PosixFilePermission;

import java.nio.file.attribute.PosixFilePermissions; 

在以前的操作中，主要通过File构造一个文件，然后将File作为入参，获取输入流等操作。Api的操作不是很流畅。在新的文件IO中，用Path取代了File，用Files作为一个操作类，并且封装了很多非常实用的Api,看完下面的示例，就会有一个新的理解。

package filespaths;
import org.junit.Test;
import java.io.*;
import java.net.URI;
import java.nio.charset.StandardCharsets;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.PosixFilePermission;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.stream.Stream;
/**
 * @Author kingboy
 * @Date 2017/4/13 11:05
 * @Description Path is used to Path Sample
 * @email kingboyworld@163.com
 */
public class PathTest {
  private static String separator = File.separator;
  /**
   * 构建Path
   */
  @Test
  public void constructon(){
    //1.Paths
    Path path = Paths.get("/Users/kingboy/Desktop/");
    Path path1 = Paths.get(URI.create("/Users/kingboy/Desktop/"));
    //2.FileSystems
    Path path2 = FileSystems.getDefault().getPath("/Users/kingboy/Desktop/");
    //3.File
    Path path3 = new File("/Users/kingboy/Desktop/").toPath();
  }
  /**
   * 创建一个空文件/文件夹
   * @throws IOException
   */
  @Test
  public void create() throws IOException {
    //文件夹
    Path path = Paths.get("/Users/kingboy/Desktop/hello");
    if(!Files.exists(path)){
      Files.createDirectory(path);
      //创建多个目录
      //Files.createDirectories(path);
    }
    //文件
    Path path1 = Paths.get("/Users/kingboy/Desktop/helloFile");
    if(Files.exists(path1)){
      Files.createFile(path1);
    }
  }
  /**
   * 文件属性
   */
  @Test
  public void getFileProperties() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/text.txt");
    System.out.println(Files.getLastModifiedTime(path));//最后修改时间
    System.out.println(Files.getOwner(path));//拥有者
    System.out.println(Files.getPosixFilePermissions(path));//权限
    System.out.println(Files.size(path));//文件大小
  }
  /**
   * 读取一个文本文件
   */
  @Test
  public void readText() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/text.txt");
    //通过bufferedReader读取
    BufferedReader bufferedReader = Files.newBufferedReader(path, StandardCharsets.UTF_8);//文件编码
    StringBuilder sb = new StringBuilder();
    String tempString = null;
    while ((tempString = bufferedReader.readLine())!=null){
      sb = sb.append(tempString);
    }
    System.out.println(sb);
    //通过Files方法readAllLines
    List<String> strings = Files.readAllLines(path);
    strings.forEach(s -> System.out.print(s));
    //输出结果
    //adsfasdfasdfadsfasdfgsdfsdffsdfsdf
    //adsfasdfasdfadsfasdfgsdfsdffsdfsdf
  }
  /**
   * 拿到文件输入流
   * @throws IOException
   */
  @Test
  public void getInputStream() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/text.txt");
    InputStream inputStream = Files.newInputStream(path);
  }
  /**
   * 文件写操作
   */
  @Test
  public void writeFile() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/writeFile");
    BufferedWriter bufferedWriter = Files.newBufferedWriter(path);
    String str = "write file test";
    bufferedWriter.write(str);
    bufferedWriter.flush();
    bufferedWriter.close();
  }
  /**
   * 遍历一个文件夹
   */
  @Test
  public void traverseDirectory() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/");
    Stream<Path> list = Files.list(path);
    list.forEach(p -> {
      System.out.println(p.getFileName());
    });
  }
  /**
   * 遍历文件树
   */
  @Test
  public void traverseTree() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/");
    Stream<Path> walk = Files.walk(path);
    walk.forEach(path1 -> {
//      System.out.println(path1.getRoot());//根目录
      System.out.println(path1.getFileName());//文件名
//      System.out.println(path1.getParent());//上级目录
//      System.out.println(path1.getFileSystem());//文件系统
    });
    //还有种方式Files.walkFileTree()
  }
  /**
   * 文件复制
   */
  @Test
  public void copyFile() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/text.txt");
    Path path2 = Paths.get("/Users/kingboy/Desktop/hello.txt");
    Files.copy(path,path2);
  }
  /**
   * 读取权限见上面示例，设置权限
   */
  @Test
  public void writePermission() throws IOException {
    Path path = Paths.get("/Users/kingboy/Desktop/text.txt");
    Set<PosixFilePermission> permissionSet = new HashSet<>();
    permissionSet.add(PosixFilePermission.GROUP_WRITE);
    permissionSet.add(PosixFilePermission.OWNER_EXECUTE);
    Files.setPosixFilePermissions(path,permissionSet);
  }
  //还有很多其他操作Api,自己查看方法名，很容易就能分辨出功能。
 }

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