java socket解决半包、粘包问题

java socket解决半包、粘包问题

一、java socket出现半包、粘包问题原因及解决见博客：

http://www.cnblogs.com/solq/p/4315763.html

http://bbs.csdn.net/topics/250027309?page=2

http://blog.csdn.net/pi9nc/article/details/17165171

二、java socket半包、粘包问题解决方案

1、以特殊字符串比如/r、/n作为数据的结尾，这样就可以区分数据包了。

2、发送请求包的时候只发送固定长度的数据包，这样在服务端接收数据也只接收固定长度的数据，这种方法效率太低，不太合适频繁的数据包请求。

3、在tcp协议的基础上封装一层数据请求协议，既数据包=数据包长度+数据包内容，这样在服务端就可以知道每个数据包的长度，也就可以解决半包、粘包问题

三、java socket半包、粘包问题重现，代码如下

package org.weir.socket.socketPackage;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.InetSocketAddress;import java.net.ServerSocket;import java.net.Socket;public class SocketTest {public static void main(String[] args) throws IOException, InterruptedException{new SocketServer().start();new SocketClient().start();}static class SocketClient extends Thread{Socket clientSocket = new Socket();public SocketClient() throws IOException{clientSocket.connect(new InetSocketAddress(8089));}public void run(){String reqMessage = "HelloWorld！ from clientsocket this is test half packages!";try {for( int i=0;i<10;i++){OutputStream os = clientSocket.getOutputStream();os.write(reqMessage.getBytes());System.out.println("send message "+i+" "+reqMessage);}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if (clientSocket != null) {try {clientSocket.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}static class SocketServer extends Thread{ServerSocket serverSocket;public SocketServer(){try {serverSocket = new ServerSocket();serverSocket.bind(new InetSocketAddress(8089));} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void run(){int count = 0;Socket socket = null;try {socket = serverSocket.accept();} catch (IOException e1) {// TODO Auto-generated catch blocke1.printStackTrace();}while(true){try {byte[] byteBuffer = new byte[50];StringBuffer receivBuffer = new StringBuffer();InputStream reader = socket.getInputStream();count = reader.read(byteBuffer);if(count>0){receivBuffer.append(new String(byteBuffer,0,count));System.out.println("receive data from client:"+receivBuffer.toString());}count = 0;} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}

执行结果如下：

一共发送了10个包，因为接收的缓冲区是50个字节，所以会出现无法接收到一个完整包的情况，也即出现半包与粘包的情况。

四、java socket解决半包、粘包的问题。

package org.weir.socket.socketPackage;import java.io.IOException;import java.io.OutputStream;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.net.InetSocketAddress;import java.net.Socket;/** * socket解决半包问题  采用包体长度(两字节)+包体内容来拆包 * @author weir * 2017年9月19日下午4:31:36 */public class ClientSocket {public static void main(String args[]) throws IOException {Socket clientSocket = new Socket();clientSocket.connect(new InetSocketAddress(8089));new SendThread(clientSocket).start();}static class SendThread extends Thread {Socket socket;PrintWriter printWriter = null;public SendThread(Socket socket) {this.socket = socket;try {printWriter = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}@Overridepublic void run() {String reqMessage = "HelloWorld！ from clientsocket this is test half packages!";for (int i = 0; i < 100; i++) {sendPacket(reqMessage);}if (socket != null) {try {socket.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}public void sendPacket(String message) {//byte[] contentBytes = message.getBytes();// 包体内容//int contentlength = contentBytes.length;// 包体长度//String head = String.valueOf(contentlength);// 头部内容//byte[] headbytes = head.getBytes();// 头部内容字节数组//byte[] bytes = new byte[headbytes.length + contentlength];// 包=包头+包体//int i = 0;//for (i = 0; i < headbytes.length; i++) {// 包头//bytes[i] = headbytes[i];//}//for (int j = i, k = 0; k < contentlength; k++, j++) {// 包体//bytes[j] = contentBytes[k];//}try {OutputStream writer = socket.getOutputStream();//writer.write(bytes);writer.write(message.getBytes());writer.flush();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}

package org.weir.socket.socketPackage;import java.io.IOException;import java.io.InputStream;import java.net.InetSocketAddress;import java.net.ServerSocket;import java.net.Socket;/* * packet=packetHead+content * 先读出包体长度，再读出包体，不够就一直读 */public class SocketServer {public static void main(String args[]) {ServerSocket serverSocket;try {serverSocket = new ServerSocket();serverSocket.bind(new InetSocketAddress(8089));while (true) {Socket socket = serverSocket.accept();new ReceiveThread(socket).start();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}static class ReceiveThread extends Thread {public static final int PACKET_HEAD_LENGTH=2;//包头长度private Socket socket;private volatile byte[] bytes = new byte[0];public ReceiveThread(Socket socket) {this.socket = socket;}public byte[] mergebyte(byte[] a, byte[] b, int begin, int end) {byte[] add = new byte[a.length + end - begin];int i = 0;for (i = 0; i < a.length; i++) {add[i] = a[i];}for (int k = begin; k < end; k++, i++) {add[i] = b[k];}return add;}@Overridepublic void run() {int count =0;while (true) {try {InputStream reader = socket.getInputStream();if (bytes.length < PACKET_HEAD_LENGTH) {byte[] head = new byte[PACKET_HEAD_LENGTH - bytes.length];int couter = reader.read(head);if (couter < 0) {continue;}bytes = mergebyte(bytes, head, 0, couter);if (couter < PACKET_HEAD_LENGTH) {continue;}}// 下面这个值请注意，一定要取2长度的字节子数组作为报文长度，你懂得byte[] temp = new byte[0];temp = mergebyte(temp, bytes, 0, PACKET_HEAD_LENGTH);String templength = new String(temp);int bodylength = Integer.parseInt(templength);//包体长度if (bytes.length - PACKET_HEAD_LENGTH < bodylength) {//不够一个包byte[] body = new byte[bodylength + PACKET_HEAD_LENGTH - bytes.length];//剩下应该读的字节(凑一个包)int couter = reader.read(body);if (couter < 0) {continue;}bytes = mergebyte(bytes, body, 0, couter);if (couter < body.length) {continue;}}byte[] body = new byte[0];body = mergebyte(body, bytes, PACKET_HEAD_LENGTH, bytes.length);count++;System.out.println("server receive body:  " + count+new String(body));bytes = new byte[0];} catch (Exception e) {e.printStackTrace();}}}}}

结果如下：

client一共发送了100条数据，server端接收到的都是完整的包。