UrgentData可以理解为紧急发送数据方式，如果我们客户端先用write方法写入数据，再用UrgentData发送数据，再去执行flush操作，我们可以得到服务端先打印UrgentData发送的数据，然后再打印write写入的数据。
客户端代码实现：
package com.chenyu.string.cn; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.net.Socket; public class ClientTest { public static Socket socket; public static final String LocalHOST = "127.0.0.1"; public static final int PORT = 1234; public static void main(String[] args) { Client(LocalHOST, PORT); } public static void Client(String address, int port) { try { socket = new Socket(address, port); } catch (Exception e) { System.out.println("connection reset"); return; } if (socket != null && socket.isConnected()) { try { socket.setOOBInline(true); OutputStream out = socket.getOutputStream(); OutputStreamWriter outWriter = new OutputStreamWriter(out); outWriter.write(67); // 向服务器发送字符"C" outWriter.write("hello world\r\n"); socket.sendUrgentData(65); // 向服务器发送字符"A" socket.sendUrgentData(322); // 向服务器发送字符"B" outWriter.flush(); socket.sendUrgentData(214); // 向服务器发送汉字”中” socket.sendUrgentData(208); socket.sendUrgentData(185); // 向服务器发送汉字”国” socket.sendUrgentData(250); socket.close(); } catch (Exception e) { System.out.println("has throw exception"); e.printStackTrace(); } finally { try { if (socket != null) { socket.close(); } } catch (IOException e) { System.out.println("socket close fail"); } } } else { System.out.println("socket is null or socket connect fail"); } } }
服务端代码实现：
package com.chenyu.string.cn; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket; public class TestInline { public static ServerSocket serverSocket; public static Socket socket; public static void main(String[] args) { try { serverSocket = new ServerSocket(1234); } catch (IOException e1) { System.out.println("serverSocket is fail"); return; } System.out.println("服务器已经启动，端口号：1234"); while (true) { try { socket = serverSocket.accept(); socket.setOOBInline(true); InputStream in = socket.getInputStream(); InputStreamReader inReader = new InputStreamReader(in); BufferedReader bReader = new BufferedReader(inReader); String result; while ((result = bReader.readLine()) != null) { System.out.println(result); } // char [] cha = new char[1024]; // int len = inReader.read(cha); // System.out.println(new String(cha,0,len)); socket.close(); } catch (Exception e){ System.out.println("read data fail"); } finally { if (socket != null) { try { socket.close(); } catch (IOException e) { System.out.println("socket close fail"); } } } } } } socket = serverSocket.accept(); socket.setOOBInline(true); InputStream in = socket.getInputStream(); InputStreamReader inReader = new InputStreamReader(in); BufferedReader bReader = new BufferedReader(inReader); String result; while ((result = bReader.readLine()) != null) { System.out.println(result); } // char [] cha = new char[1024]; // int len = inReader.read(cha); // System.out.println(new String(cha,0,len)); socket.close(); } catch (Exception e){ System.out.println("read data fail"); } finally { if (socket != null) { try { socket.close(); } catch (IOException e) { System.out.println("socket close fail"); } } } } } }
socket = serverSocket.accept();
socket.setOOBInline(true);
InputStream in = socket.getInputStream();
InputStreamReader inReader = new InputStreamReader(in);
BufferedReader bReader = new BufferedReader(inReader);
String result;
while ((result = bReader.readLine()) != null) {
System.out.println(result);
}
// char [] cha = new char[1024];
// int len = inReader.read(cha);
// System.out.println(new String(cha,0,len));
socket.close();
} catch (Exception e){
System.out.println("read data fail");
} finally {
if (socket != null) {
try {
socket.close();
} catch (IOException e) {
System.out.println("socket close fail");
}
}
}
}
}
}
运行结果（先运行服务端，后运行客户端）：
服务器已经启动，端口号：1234 ABChello world 中国
说明使用sendUrgentData方法发送数据后，系统会立即将这些数据发送出去；而使用write发送数据，必须要使用flush方法才会真正发送数据。
在使用setOOBInline方法打开SO_OOBINLINE选项时要注意是必须在客户端和服务端程序同时使用setOOBInline方法打开这个选项，否则无法命名用sendUrgentData来发送数据。
总结：
我们还可以通过socket.sendUrgentData(0xff);来检测是否与服务端连通，和ping IP 效果差不多，其它的socket.isConnected() socket.isOutputShutdown()都是本地检测，我们上面socket发送数据，如果在安卓客户端，我们可以用这个来发送心跳包，
类似上面客户端的代码，通过后台下发的IP和端口配置，开启线程，out.write(data),通过handler.postDelay(Runable, delayTime)发送心跳包给服务端。
