Java基于Socket文件传输示例
原文:http://www.blogjava.net/sterning/archive/2007/10/13/152508.html
数据丢失:http://topic.csdn.net/u/20100523/21/5a1a055f-af64-4e01-b669-7ff46f20b4ed.html
解决数据丢失的一个办法:当发送端发完数据之后，就应该让接收端告诉发送端“接收完成”，然后接收端先关闭，发送端才关闭，顺序很重要。
最近需要进行网络传输大文件，于是对基于socket的文件传输作了一个初步的了解。在一位网友提供的程序基础上，俺进行了一些加工，采用了缓冲输入/输出流来包装输出流，再采用数据输入/输出输出流进行包装，加快传输的速度。废话少说，先来看服务器端的程序。
1.服务器端
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Java代码 package sterning; import java.io.BufferedInputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.net.ServerSocket; import java.net.Socket; public class ServerTest { int port = 8821; void start() { Socket s = null; try { ServerSocket ss = new ServerSocket(port); while (true) { // 选择进行传输的文件 String filePath = "D:\\lib.rar"; File fi = new File(filePath); System.out.println("文件长度:" + (int) fi.length()); // public Socket accept() throws // IOException侦听并接受到此套接字的连接。此方法在进行连接之前一直阻塞。 s = ss.accept(); System.out.println("建立socket链接"); DataInputStream dis = new DataInputStream(new BufferedInputStream(s.getInputStream())); dis.readByte(); DataInputStream fis = new DataInputStream(new BufferedInputStream(new FileInputStream(filePath))); DataOutputStream ps = new DataOutputStream(s.getOutputStream()); //将文件名及长度传给客户端。这里要真正适用所有平台，例如中文名的处理，还需要加工，具体可以参见Think In Java 4th里有现成的代码。 ps.writeUTF(fi.getName()); ps.flush(); ps.writeLong((long) fi.length()); ps.flush(); int bufferSize = 8192; byte[] buf = new byte[bufferSize]; while (true) { int read = 0; if (fis != null) { read = fis.read(buf); } if (read == -1) { break; } ps.write(buf, 0, read); } ps.flush(); // 注意关闭socket链接哦，不然客户端会等待server的数据过来， // 直到socket超时，导致数据不完整。 fis.close(); s.close(); System.out.println("文件传输完成"); } } catch (Exception e) { e.printStackTrace(); } } public static void main(String arg[]) { new ServerTest().start(); } } |
2.socket的Util辅助类
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Java代码 package sterning; import java.net.*; import java.io.*; public class ClientSocket { private String ip; private int port; private Socket socket = null; DataOutputStream out = null; DataInputStream getMessageStream = null; public ClientSocket(String ip, int port) { this.ip = ip; this.port = port; } /** * 创建socket连接 * * @throws Exception * exception */ public void CreateConnection() throws Exception { try { socket = new Socket(ip, port); } catch (Exception e) { e.printStackTrace(); if (socket != null) socket.close(); throw e; } finally { } } public void sendMessage(String sendMessage) throws Exception { try { out = new DataOutputStream(socket.getOutputStream()); if (sendMessage.equals("Windows")) { out.writeByte(0x1); out.flush(); return; } if (sendMessage.equals("Unix")) { out.writeByte(0x2); out.flush(); return; } if (sendMessage.equals("Linux")) { out.writeByte(0x3); out.flush(); } else { out.writeUTF(sendMessage); out.flush(); } } catch (Exception e) { e.printStackTrace(); if (out != null) out.close(); throw e; } finally { } } public DataInputStream getMessageStream() throws Exception { try { getMessageStream = new DataInputStream(new BufferedInputStream(socket.getInputStream())); return getMessageStream; } catch (Exception e) { e.printStackTrace(); if (getMessageStream != null) getMessageStream.close(); throw e; } finally { } } public void shutDownConnection() { try { if (out != null) out.close(); if (getMessageStream != null) getMessageStream.close(); if (socket != null) socket.close(); } catch (Exception e) { } } } |
3.客户端
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Java代码 package sterning; import java.io.BufferedOutputStream; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileOutputStream; public class ClientTest { private ClientSocket cs = null; private String ip = "localhost";// 设置成服务器IP private int port = 8821; private String sendMessage = "Windwos"; public ClientTest() { try { if (createConnection()) { sendMessage(); getMessage(); } } catch (Exception ex) { ex.printStackTrace(); } } private boolean createConnection() { cs = new ClientSocket(ip, port); try { cs.CreateConnection(); System.out.print("连接服务器成功!" + "\n"); return true; } catch (Exception e) { System.out.print("连接服务器失败!" + "\n"); return false; } } private void sendMessage() { if (cs == null) return; try { cs.sendMessage(sendMessage); } catch (Exception e) { System.out.print("发送消息失败!" + "\n"); } } private void getMessage() { if (cs == null) return; DataInputStream inputStream = null; try { inputStream = cs.getMessageStream(); } catch (Exception e) { System.out.print("接收消息缓存错误\n"); return; } try { //本地保存路径，文件名会自动从服务器端继承而来。 String savePath = "E:\\"; int bufferSize = 8192; byte[] buf = new byte[bufferSize]; int passedlen = 0; long len=0; savePath += inputStream.readUTF(); DataOutputStream fileOut = new DataOutputStream(new BufferedOutputStream(new BufferedOutputStream(new FileOutputStream(savePath)))); len = inputStream.readLong(); System.out.println("文件的长度为:" + len + "\n"); System.out.println("开始接收文件!" + "\n"); while (true) { int read = 0; if (inputStream != null) { read = inputStream.read(buf); } passedlen += read; if (read == -1) { break; } //下面进度条本为图形界面的prograssBar做的，这里如果是打文件，可能会重复打印出一些相同的百分比 System.out.println("文件接收了" + (passedlen * 100/ len) + "%\n"); fileOut.write(buf, 0, read); } System.out.println("接收完成，文件存为" + savePath + "\n"); fileOut.close(); } catch (Exception e) { System.out.println("接收消息错误" + "\n"); return; } } public static void main(String arg[]) { new ClientTest(); } } |
这就实现了从服务器端向客户端发送文件的过程,当然,反过来,也一样.稍有不同.代码中对跨平台的细节没有实现,有时间或兴趣的朋友可以提供一下.
