Java7's File [turn]

 

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; 

 In the previous operations, a file was mainly constructed through File, and then the File was used as an input parameter to obtain the input stream and other operations. The operation of Api is not very smooth. In the new file IO, Path is used instead of File, Files is used as an operation class, and many very practical APIs are encapsulated. After reading the following example, you will have a new understanding.

 

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 [email protected]
 */
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。
 }