ServerSocketChannel监听问题

今天遇到一个问题，就是推出了监听界面之后，再进来界面还能监听客户端连接服务端。

做法:

1.关闭界面的时候要把服务端线程停止。

2.先关闭跟客户端连接的socket

3.关闭服务端的socket.

4.关闭select选择器.

做完这些，以后再进这个界面就可以重新监听了。

这样可以修复下面这个问题了 W/System.err:     at com.example.tcplibrary.tcpserver.TcpServer.a(Unknown Source)

 W/System.err:     at com.example.tcplibrary.tcpserver.TcpServer.run(Unknown Source)

有这个问题是因为端口资源被暂用了。

如果发现，服务端起来了，但是客户端连接不上，有可能是之前没清掉客户端跟服务端的连接。得清掉之后才能自动连接上。

下面是一个测试的小代码：

socket类的代码：

package gateway.demo.com.gatewaydemo.tcpserver;

import android.util.Log;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

/**
 * Created by caifeng on 2018/7/11.
 */

public class TcpServer implements Runnable {
    private static final String TAG = "TcpServer";
    private static TcpServer mTcpServer = null;
    private Selector mSelector;
    private SocketChannel mSocketChannel;
    private ServerSocketChannel server;
    private boolean work;

    public static TcpServer getInstance() {
        if (mTcpServer == null) {
            synchronized (TcpServer.class) {
                if (mTcpServer == null) {
                    mTcpServer = new TcpServer();
                }
            }
        }
        return mTcpServer;
    }

    private TcpServer() {

    }

    @Override
    public void run() {
        buildServerSocketChannel(); //建立服务端通道
        iterationSelector(); //迭代选择器

    }

    /**
     * 创建ServerSocketChannel
     *
     * @throws IOException
     */
    private void buildServerSocketChannel() {
        try {
            mSelector = Selector.open();
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            server = ServerSocketChannel.open();
        } catch (IOException e) {
            e.printStackTrace();
        }
        Log.d("TcpServer", "打开成功");
        try {
            server.configureBlocking(false);
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            server.socket().bind(new InetSocketAddress(9190), 1024);
        } catch (IOException e) {
            e.printStackTrace();
        }
        Log.d("TcpServer", "绑定成功");
        try {
            server.register(mSelector, SelectionKey.OP_ACCEPT);
        } catch (ClosedChannelException e) {
            e.printStackTrace();
        }
        Log.d("TcpServer", "注册成功");
    }

    /**
     * 循环遍历SelectionKey
     */
    private void iterationSelector() {
        while (work) {
            try {
                mSelector.select(1000);
            } catch (IOException e) {
                e.printStackTrace();
            }
            Set selectionKeys = mSelector.selectedKeys();
            Iterator iterator = selectionKeys.iterator();
            SelectionKey selectionKey = null;

            while (iterator.hasNext()) {
                selectionKey = iterator.next();
                iterator.remove();
                if (selectionKey.isAcceptable()) {
                    ServerSocketChannel serverSocketChannel = (ServerSocketChannel) selectionKey.channel();
                    try {
                        mSocketChannel = serverSocketChannel.accept();
                        mSocketChannel.configureBlocking(false);
                        mSocketChannel.register(mSelector, SelectionKey.OP_READ);
                        Log.d(TAG, "连接成功");
                    } catch (IOException e) {
                        e.printStackTrace();
                        selectionKey.cancel();
                        if (selectionKey.channel() != null) {
                            try {
                                selectionKey.channel().close();
                            } catch (IOException e1) {
                                e1.printStackTrace();
                            }
                        }
                    }
                }

                if (selectionKey.isReadable()) {
                    mSocketChannel = (SocketChannel) selectionKey.channel();
                    //获取t2时间
                    ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                    String content = "";
                    try {
                        int readBytes = mSocketChannel.read(byteBuffer);
                        // 写完就把状态关注去掉，否则会一直触发写事件(改变自身关注事件)
                        selectionKey.interestOps(SelectionKey.OP_READ);
                    } catch (IOException i) {
                        //如果捕获到该SelectionKey对应的Channel时出现了异常,即表明该Channel对于的Client出现了问题
                        //所以从Selector中取消该SelectionKey的注册
                        selectionKey.cancel();
                        if (selectionKey.channel() != null) {
                            try {
                                selectionKey.channel().close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            }
        }
        closeSocket();
    }

    private void closeSocket() {
        if (server != null) {
            try {
                server.socket().close();
                Log.d(TAG, "关闭成功1");
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            if (mSocketChannel != null) {
                mSocketChannel.close();
                Log.d(TAG, "关闭成功2");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            if (mSelector != null) {
                mSelector.close();
                Log.d(TAG, "关闭成功3");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public boolean isWork() {
        return work;
    }

    public void setWork(boolean work) {
        this.work = work;
    }
}

Activity的代码：

package gateway.demo.com.gatewaydemo.activity;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import gateway.demo.com.gatewaydemo.R;
import gateway.demo.com.gatewaydemo.tcpserver.TcpServer;

public class MainActivity extends AppCompatActivity {
    private TcpServer mTcpServer = TcpServer.getInstance();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTcpServer.setWork(true);
        new Thread(mTcpServer).start();
    }

    @Override
    protected void onDestroy() {
        mTcpServer.setWork(false);
        super.onDestroy();
    }
}

我是推出activity停止的线程，具体需求你们可以自己设计。

希望能帮助有这个问题的人。