Java Socket简例

Socket IO工具类：

package com.test.util;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class SocketIO{
	public static DataInputStream getInput(Socket socket) throws IOException{
		//接收缓存区大小，socket获取输入流之前设置
		socket.setReceiveBufferSize(10);
		InputStream input = socket.getInputStream();
		return new DataInputStream(input);
	}

	public static DataOutputStream getOutput(Socket socket) throws IOException{
		//发送缓存区大小，socket获取输出流之前设置
		socket.setSendBufferSize(10);
		OutputStream output = socket.getOutputStream();
		return new DataOutputStream(output);
	}
}

如果传输数据量较大，则应配置较大缓存区，以减少数据传输次数，提高数据传输效率

如果传输数据量较小并且比较频繁，则应配置较小缓存，以提高通信速度

Socket Client客户端：

package com.test.client;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;

import org.apache.log4j.Logger;

import com.test.util.SocketIO;

public class Client {
	static Logger logger = Logger.getLogger(Client.class);
	private int port = 10000;
	private String host = "127.0.0.1";
	private Socket socket;

	public Client(){
		try {
			socket = new Socket();
			//关闭socket时，立即释放socket绑定端口以便端口重用，默认为false
			socket.setReuseAddress(true);
			//关闭传输缓存，默认为false
			socket.setTcpNoDelay(true);
			//如果输入流等待1000毫秒还未获得服务端发送数据，则提示超时，0为永不超时
			socket.setSoTimeout(10000);
			//关闭socket时，底层socket不会直接关闭，会延迟一会，直到发送完所有数据
			//等待10秒再关闭底层socket连接，0为立即关闭底层socket连接
			socket.setSoLinger(true, 10);
			//设置性能参数，可设置任意整数，数值越大，相应的参数重要性越高（连接时间，延迟，带宽）
			socket.setPerformancePreferences(3, 2, 1);
			SocketAddress address = new InetSocketAddress(host, port);
			//socket创建超时时间为1000毫秒
			socket.connect(address, 10000);

			logger.info("client ip:"+socket.getLocalAddress());
			logger.info("client port:"+socket.getLocalPort());
			logger.info("servetr ip:"+socket.getInetAddress());
			logger.info("servetr port:"+socket.getPort());
		} catch (IOException e) {
			e.printStackTrace();
			logger.error("Cilent socket establish failed!");
		}
		logger.info("Client socket establish success!");
	}

	public void request(){
		try{
			DataOutputStream output = SocketIO.getOutput(socket);
			DataInputStream input = SocketIO.getInput(socket);

			String question = "your name?";
			byte[] bytes = question.getBytes("utf-8");
			int len = bytes.length;
			output.writeInt(len);
			output.write(bytes);

			len = input.readInt();
			bytes = new byte[len];
			input.read(bytes);

			logger.info("server answer:"+new String(bytes,"utf-8"));
		}catch(Exception e){
			e.printStackTrace();
			logger.error("client request error");
		}finally{
			if(null != socket){
				try{
					socket.close();
				}catch(Exception e){
					e.printStackTrace();
					logger.error("socket close error");
				}
			}
		}
	}

	public static void main(String[] args){
		Client client = new Client();
		client.request();
	}
}

Socket Server服务端:

package com.test.server;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;

import org.apache.log4j.Logger;

import com.test.util.SocketIO;

public class Server {
	static Logger logger = Logger.getLogger(Server.class);
	private int queueSize = 10;
	private int port = 10000;
	private ServerSocket serverSocket;

	public Server(){
		try{
			serverSocket = new ServerSocket();
			//关闭serverSocket时，立即释放serverSocket绑定端口以便端口重用，默认为false
			serverSocket.setReuseAddress(true);
			//accept等待连接超时时间为1000毫秒，默认为0，永不超时
			//serverSocket.setSoTimeout(10000);
			//为所有accept方法返回的socket对象设置接收缓存区大小，单位为字节，默认值和操作系统有关
			serverSocket.setReceiveBufferSize(128*1024);
			//设置性能参数，可设置任意整数，数值越大，相应的参数重要性越高（连接时间，延迟，带宽）
			serverSocket.setPerformancePreferences(3, 2, 1);
			//服务端绑定至端口，10为服务端连接请求队列长度
			serverSocket.bind(new InetSocketAddress(port), queueSize);
		}catch(Exception e){
			e.printStackTrace();
			logger.error("Server establish error!");
		}
		logger.info("Server start up!");
	}

	public void service(){
		while(true){
			Socket socket = null;
			try{
				//从连接请求队列中取出一个客户连接请求，创建与客户连接的socket对象
				//如果队列中没有请求，accept方法就会一直等待
				socket = serverSocket.accept();

				DataOutputStream output = SocketIO.getOutput(socket);
				DataInputStream input = SocketIO.getInput(socket);

				int len = input.readInt();
				byte[] bytes = new byte[len];
				input.read(bytes);

				String request = new String(bytes, "utf-8");

				logger.info("client request:"+request);

				String answer = "not supported";
				if(request.equals("your name?")){
					answer = "server";
				}
				bytes = answer.getBytes("utf-8");
				len = bytes.length;
				output.writeInt(len);
				output.write(bytes);
			}catch(Exception e){
				e.printStackTrace();
				logger.error("Server run exception!");
			}
		}
	}

	public static void main(String[] args) {
		Server server = new Server();
		server.service();
	}
}

log4j.properties日志设置：

log4j.rootLogger=info,logOutput

#log console out put
log4j.appender.logOutput=org.apache.log4j.ConsoleAppender
log4j.appender.logOutput.layout=org.apache.log4j.PatternLayout
log4j.appender.logOutput.layout.ConversionPattern=%p%d{[yy-MM-dd HH:mm:ss]}[%c] -> %m%n

Client端日志：

INFO[13-10-10 10:04:23][com.test.client.Client] -> client ip:/127.0.0.1
INFO[13-10-10 10:04:23][com.test.client.Client] -> client port:52362
INFO[13-10-10 10:04:23][com.test.client.Client] -> servetr ip:/127.0.0.1
INFO[13-10-10 10:04:23][com.test.client.Client] -> servetr port:10000
INFO[13-10-10 10:04:23][com.test.client.Client] -> Client socket establish success!
INFO[13-10-10 10:04:23][com.test.client.Client] -> server answer:server

Server端日志：

INFO[13-10-10 10:04:19][com.test.server.Server] -> Server start up!
INFO[13-10-10 10:04:23][com.test.server.Server] -> client request:your name?

PS:

这里要特别说明一下DataInputStream这个类的readShort方法：

public final short readShort() throws IOException {
        int ch1 = in.read();
        int ch2 = in.read();
        if ((ch1 | ch2) < 0)
            throw new EOFException();
        return (short)((ch1 << 8) + (ch2 << 0));
    }

可以看到是先读高位，再读低位

再来看下DataOutputStream这个类的writeShort方法：

public final void writeShort(int v) throws IOException {
        out.write((v >>> 8) & 0xFF);
        out.write((v >>> 0) & 0xFF);
        incCount(2);
}

可以看到是先写高位，再写低位

如果传输Short类型数据（其它类型数据相同）时，要求先传低位，再传高位，则不能使用自带的方法

将数据转为低位在前高位在后的字节数组，然后传输整个数组即可

public void write(byte b[]) throws IOException {
	write(b, 0, b.length);
}

public void write(byte b[], int off, int len) throws IOException {
	if ((off | len | (b.length - (len + off)) | (off + len)) < 0)
	    throw new IndexOutOfBoundsException();

	for (int i = 0 ; i < len ; i++) {
	    write(b[off + i]);
	}
}