Java实现文件的下载

￡神魔★判官ぃ 2022-02-15 11:27 227阅读 0赞

**一、技术点：IO流、套接字**

**二、代码案例**

1、客户端

package com.mollen.download;
    
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.net.Socket;
    
    /**
    * @ClassName:  Client
    * @Auther:     Mollen
    * @CreateTime: 2018-09-11  11:29:47
    * @Description:
    *              文件下载客户端
    */
    public class Client {
       public static void main(String[] args) throws IOException {
           //1.创建socket对象
           Socket client = new Socket("127.0.0.1",6666);
           //2.获取读入流
           InputStream is = client.getInputStream();
           //3.创建写出流
           FileOutputStream fos = new FileOutputStream("E:\\download\\" + System.currentTimeMillis() + ".avi");
           //4.读入流数据，写出到客户端磁盘
           int len =0;
           byte[] bytes = new byte[10240];
           while((len=is.read(bytes))!=-1){
               fos.write(bytes,0,len);
           }
           //发送回执信息
           client.getOutputStream().write("文件下载完成！".getBytes());
           
           //释放资源
           is.close();
           fos.close();
           client.close();
       }
    }

2、服务端

package com.mollen.download;
    
    import java.io.*;
    import java.net.ServerSocket;
    import java.net.Socket;
    
    /**
    * @ClassName: Server
    * @Auther: Mollen
    * @CreateTime: 2018-09-11  11:29:39
    * @Description:
    */
    public class Server {
       public static void main(String[] args)throws IOException{
           //1.创建serversocket
           ServerSocket server = new ServerSocket(6666);
           
    	   while(true) {
    	       //2.创建读取流对象
    	       FileInputStream fis = new FileInputStream("H:\\1002.avi");            
               //3.监听客户端
               Socket client = server.accept();
               //4.获取写出流
               OutputStream os = client.getOutputStream();
               //5.读入服务端文件，写入到数据流
               int len = 0;
               byte[] bytes = new byte[10240];
               while ((len = fis.read(bytes)) != -1) {
                   os.write(bytes, 0, len);
               }
    
               //写出结束标志
               client.shutdownOutput();
    
               //读取回执信息
               BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));
               System.out.println(br.readLine());
               
                //释放资源
                fis.close();
                os.close();
                client.close();
           }
       }
    }

三、注意事项

1、数据运输路径：服务端磁盘–>(读入)–>(写出)–>数据流–>(读入)–>(写出)–>客户端磁盘。  
2、案例不考虑多线程、缓存、解析等技术的应用。  
3、写出完毕必须有结束标志。  
4、测试先启动服务端再启动客户端。

摘自：[https://blog.csdn.net/mollen/article/details/82624551][https_blog.csdn.net_mollen_article_details_82624551]

[https_blog.csdn.net_mollen_article_details_82624551]: https://blog.csdn.net/mollen/article/details/82624551