socket解决半包粘包问题

Posted 2020-11-08 喻雨晨

  最近项目遇到socket服务端接收报文不全的问题，与其客户端约定的是报文长度+报文体。然而当客户端数据量大的时候，用分包发送，导致服务端报文日志接收不完整，于是想着先读出包体长度，再读出包体，不够就一直读，部分代码如下：

                    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;  
                        }  
                    }  
                    // 取7长度的字节子数组作为报文长度 
                    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];  

mergebyte方法如下：

        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;  
        }

 

这样server端接收到的都是完整的包。