java的socket粘包和半包问题记录

我就是我 2022-11-29 11:59 139阅读 0赞

以下是例子：  
服务端：

package com.zy.callrecord.socket;
    
    
    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 MyServerSocket { 
        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 block
                e.printStackTrace();
            }
        }
    
        static class ReceiveThread extends Thread { 
            public static final int PACKET_HEAD_LENGTH = 3;//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;
            }
    
            @Override
            public 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；要对应编码gbk是2，utf8是3
                        byte[] temp = new byte[0];
                        temp = mergebyte(temp, bytes, 0, PACKET_HEAD_LENGTH);
                        String templength = new String(temp,"UTF8");
                        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,"UTF8"));
                        bytes = new byte[0];
                    } catch (Exception e) { 
                        e.printStackTrace();
                    }
                }
            }
        }
    }

以下是客户端：

package com.zy.callrecord.socket;
    
    
    import java.io.*;
    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 block
                    e.printStackTrace();
                }
            }
    
            @Override
            public void run() { 
                String reqMessage = "HelloWorld！ from clientsocket this is test half packages!流量的点点滴滴的嘎嘎嘎我们中国来来来";
                String reqMessage2="2012年11月7日 - Java Socket TCP粘包和拆包问题 服务端读取这次消息,可能由于socket缓冲区较大,继续等待客户端的发送,如果未收到则读取完成,如果收到则将新读取的内...";
                String reqMessage3="{\n" +
                        " \"employees\": [\n" +
                        " {\n" +
                        " \"firstName\": \"Bill\",\n" +
                        " \"lastName\": \"Gates\"\n" +
                        " },\n" +
                        " {\n" +
                        " \"firstName\": \"George\",\n" +
                        " \"lastName\": \"Bush\"\n" +
                        " },\n" +
                        " {\n" +
                        " \"firstName\": \"Thomas\",\n" +
                        " \"lastName\": \"Carter\"\n" +
                        " }\n" +
                        " ]\n" +
                        "}";
                for (int i = 0; i < 100; i++) { 
                    try { 
                        sendPacket(reqMessage);
                        sendPacket(reqMessage2);
                        sendPacket(reqMessage3);
                    } catch (UnsupportedEncodingException e) { 
                        e.printStackTrace();
                    }
                }
                if (socket != null) { 
                    try { 
                        socket.close();
                    } catch (IOException e) { 
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
    
            }
    
            public void sendPacket(String message) throws UnsupportedEncodingException { 
    			byte[] contentBytes = message.getBytes("UTF8");// 包体内容,如果不指名是utf8编码的话就是默认gbk，那就是一个汉字代表2个字节，utf8是一个汉字3个字节
    		int contentlength = contentBytes.length;// 包体长度
    		String head = String.valueOf(contentlength);// 头部内容
    			byte[] headbytes = head.getBytes("UTF8");// 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 block
                    e.printStackTrace();
                }
            }
        }
    
    }

运行结果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxNjg3MTIz_size_16_color_FFFFFF_t_70_pic_center]

说明：  
注意点：注意编码，因为包含中文所以用utf8编码；而utf8编码是一个汉字3个字节；如果不知道编码是gbk，gbk是一个汉字代表2个字节而且又写汉字不识别；  
以上如有不对请指正；因为对socket也是一知半解

参考博客：  
原博客：  
[https://blog.csdn.net/nongfuyumin/article/details/78298380?utm\_medium=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel\_param&depth\_1-utm\_source=distribute.pc\_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel\_param][https_blog.csdn.net_nongfuyumin_article_details_78298380_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzIxNjg3MTIz_size_16_color_FFFFFF_t_70_pic_center]: /images/20221124/428ea997708c44e1af00ca241e4cad8a.png
[https_blog.csdn.net_nongfuyumin_article_details_78298380_utm_medium_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param_depth_1-utm_source_distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param]: https://blog.csdn.net/nongfuyumin/article/details/78298380?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-1.channel_param