SocketChannel 例子

这几天在看mina 
mina 基于socketChannel 和 DatagramChannel 建立的无阻塞链接。

所以就看了看socket channel 的使用方式，做一份备忘吧。
socketChannel 的使用方式

server端

package com.jimmy.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;

public class TestServerSocketChannel {
    public static void main(String[] args) throws IOException {
        int port=37;

        ByteBuffer in=ByteBuffer.allocate(4);
        ByteBuffer out=ByteBuffer.allocate(8);
       
        //设置绑定端口
        SocketAddress address=new InetSocketAddress(port);

        //Opens a server-socket channel.
        ServerSocketChannel serverSocketChannel=ServerSocketChannel.open();

        //Binds the ServerSocket to a specific address (IP address and port number).
        serverSocketChannel.socket().bind(address);

        System.err.println("bound to " + address);
       
        //Accepts a connection made to this channel's socket
        SocketChannel channel=serverSocketChannel.accept();
        if(channel == null) {
            return;
        }
        //clear byte buffer
        in.clear();
        //read byte to "in" buffer
        channel.read(in);
        //Flips this buffer
        in.flip();
        int a=in.getInt();
        System.out.println("a:" + a);

        //get remote socket address
        SocketAddress client=channel.socket().getRemoteSocketAddress();
        System.err.println(client);
        long secondsSince1970=System.currentTimeMillis();

        //clear "out" byte buffer
        out.clear();
        //put currentTimeMillis value into "out" byte buffer
        out.putLong(secondsSince1970);
        //Flips this buffer
        out.flip();

        //Writes a sequence of bytes to this channel from the given buffer
        //write data from position to limit of buffer
        //so before write ,buffer need call flip method
        channel.write(out);

        channel.close();

        serverSocketChannel.close();
    }
}



client 端

package com.jimmy.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.util.Date;

public class TestClientSocketChannel {

    public static void main(String[] args) throws IOException {
        int port=37;
        SocketChannel channel=SocketChannel.open();
        SocketAddress server=new InetSocketAddress("192.168.1.79", port);
        channel.connect(server);

        ByteBuffer buffer=ByteBuffer.allocate(4);
        ByteBuffer readBuffer=ByteBuffer.allocate(8);
       
        // send a byte of data to the server
        buffer.putInt(100);
        buffer.flip();
        channel.write(buffer);

        // get the buffer ready to receive data
        channel.read(readBuffer);
        readBuffer.flip();

        // convert seconds since 1900 to a java.util.Date
        long currentTimeMillis=readBuffer.getLong();

        Date time=new Date(currentTimeMillis);

        System.out.println(time);

        channel.close();
    }
}



socket channel 操作的对象是ByteBuffer
在read的时候如果byte length 超过了 byteBuffer分配的空间 会抛出java.nio.BufferUnderflowException 异常。
在设置 bytebuffer 空间的时候建议设置大一些。