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 [e-mail]
 */
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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