示例代码：
https://github.com/gordonklg/study，socket module
A. Socket 编程简单例子
最简单的 Socket 编程是通过回车/换行符，整行读取字符串。网上代码随便抄抄便是。
gordon.study.socket.basic.LineSeparateEchoServer.java
代码略
B. 简单的自定义协议
对于传输内容包含回车/换行符的通讯需求，可以使用自定义协议。
此处演示一个很简单的协议：
- 第一个字节代表类型，1表示为文本，0表示结束通讯，可扩展其它类型，如 jpeg、png、wav
- 第2-3个字节代表整个报文段长度
- 后面为消息内容
gordon.study.socket.basic.CustomProtocolPrintServer.java
public class CustomProtocolPrintServer {
@SuppressWarnings("resource")
public static void main(String[] args) throws Exception {
for (int i = 0; i < 3; i++) {
new Thread(new CustomProtocolPrintClient()).start();
}
ServerSocket serverSocket = new ServerSocket(8888);
while (true) {
Socket socket = serverSocket.accept();
new Thread(new PrintServerHandler(socket)).start();
}
}
private static class PrintServerHandler implements Runnable {
private Socket socket;
public PrintServerHandler(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
DataInputStream dis = new DataInputStream(socket.getInputStream());
while (true) {
int type = dis.read();
if (type == 0) {
break;
}
int length = (dis.readByte() & 0xFF) << 8 | dis.readByte() & 0xFF;
byte[] content = new byte[length - 3];
dis.readFully(content);
System.out.println("server received: " + new String(content));
}
dis.close();
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
gordon.study.socket.basic.CustomProtocolPrintClient.java
public class CustomProtocolPrintClient implements Runnable {
private String[] msgArray = { "ni hao", "hello", "chi le ma?", "你瞅啥？", "hi dude" };
@Override
public void run() {
try (Socket socket = new Socket()) {
socket.connect(new InetSocketAddress(8888));
DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
for (int i = 0; i < 3; i++) {
int pos = ThreadLocalRandom.current().nextInt(msgArray.length);
long sleepTime = ThreadLocalRandom.current().nextLong(1500) + 250;
sendMsg(msgArray[pos], dos);
Thread.sleep(sleepTime);
}
dos.writeByte(0);
dos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
private void sendMsg(String msg, DataOutputStream dos) throws Exception {
byte[] bytes = msg.getBytes();
int totalLength = 3 + bytes.length;
dos.writeByte(1);
dos.write((byte) (totalLength >> 8 & 0xFF));
dos.write((byte) (totalLength & 0xFF));
dos.write(bytes);
}
}