Android长连接

关于长连接socket，相信很多朋友都不陌生，和很多朋友一样，都喜欢去网上找一些第三方框架来用

不过在年底面试的时候，被问到这一块的时候，信口而来的第三方遭到了面试官的鄙视

新项目需要做到长连相关，所以就主动提议手写一个第三方

当然很多人会觉得很简单，不过基于最近也是被基友给问到了，所以给出如下的代码

1.建立socket连接：

socket = new Socket(ApiConst.SOCKET_MYAPP, ApiConst.SOCKET_MYAPP_DK);

2.发送socket：

public class SendSocket {
    public static void sendSocket(final String socketData) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    try {
                        String base64Token = CodeUtils.encode( socketData);
//                        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(
//                                ApiConst.SOCKET.getOutputStream()));
                        OutputStream outputStream = ApiConst.SOCKET.getOutputStream();
                        byte[] data1 = base64Token.getBytes();
                        byte[] data2 = new byte[data1.length];
                        byte[] data3 = new byte[data1.length + data2.length];                        
                        System.arraycopy(data2, 0, data3, 0, data2.length);                        
                        System.arraycopy(data1, 0, data3, data2.length, data1.length); 
                       outputStream.write(data3); 
                       outputStream.flush();//               
                       writer.flush();               
                       } catch (Exception e) {                
                         e.printStackTrace();             
                       }       
                   }        
               }).start();  
          }
     }

3.接收socket，关于粘包和半包的处理，代码中都已经处理好了：

InputStream is = null;
byte[] Alldata = new byte[0];
try {
    is = ApiConst.SOCKET.getInputStream();
    byte[] data = new byte[1024];
    int temp = -1;
    while ((temp = is.read(data)) != -1) {  //没收到数据会暂停在这里的.
        byte[] tmpdata = new byte[Alldata.length + temp];
        if (Alldata.length > 0) {
            System.arraycopy(Alldata, 0, tmpdata, 0, Alldata.length);
        }
        System.arraycopy(data, 0, tmpdata, Alldata.length, temp);
        Alldata = tmpdata;
        while (Alldata.length >= 4) {
        int packegLenth = Alldata.lenth;
            if (packetLength > 10 * 1024 * 1024) {//最大Buffer异常保护
                Alldata = new byte[0];
                break;
            }
            if (Alldata.length - 4 < packetLength) break;
            if (Alldata.length - 4 >= packetLength) { //收到的数据达到包长度
                byte[] packet = new byte[packetLength];
                System.arraycopy(Alldata, 4, packet, 0, packetLength);
                packetLength = Alldata.length - 4 - packetLength;
                if (packetLength > 0) {
                    tmpdata = Alldata;
                    Alldata = new byte[packetLength];
                    System.arraycopy(tmpdata, packet.length + 4, Alldata, 0, packetLength);
                } else {
                    Alldata = new byte[0];
                }
                String message = new String(packet);

4.接下来就是保持长连的心跳包了：

    OutputStreamWriter outputStreamWriter = new OutputStreamWriter(ApiConst.SOCKET.getOutputStream());
    BufferedWriter writer = new BufferedWriter(outputStreamWriter);
    writer.write("longConnect");//这个关键字和服务端协商，一些博客里会写Socket.sendUrgentData(0xff)这个方法，当然建议不要用，具体原因在前几篇博文里已经提到
    writer.flush();

代码很简单，如果还有不清楚的，这段时间会整理成demo传到下载区