Java-WebSocket 项目的研究(三) WebSocketClient 类 详解

通过之前两篇文章

Java-WebSocket 项目的研究(一) Java-WebSocket类图描述

Java-WebSocket 项目的研究(二) 小试身手：客户端连接服务器并发送消息实例

的介绍我们大概了解到了整个项目的类结构，其中有一个重要的类：WebSocketClient，下面就让我们详细了解一下这个类

首先看一下我们之前的类图关于WebSocketClient的描述，可以看出：

1.继承自WebSocketAdapter

2.依赖于类WebSocketImpl（实际上关于WebSocket核心代码都在类WebSocketImpl里）

3.实现了WebSocket接口（实际上通过类WebSocketImpl实现的）

很简单的，从字面意思我们就大概能猜到WebSocketAdapter是适配器类，架起了WebSocketImpl与WebSocketClient之间的桥梁，WebSocketImpl是web implementation的缩写，意思就是真正实现了websocket里主要的功能。

然后我们看一下WebSocketClient的几个主要方法：

首先是connect方法

/**
     * Initiates the websocket connection. This method does not block.
     */
    public void connect() {
        if( writeThread != null )
            throw new IllegalStateException( "WebSocketClient objects are not reuseable" );
        writeThread = new Thread( this );
        writeThread.start();
    }

/**
	 * Initiates the websocket connection. This method does not block.
	 */
	public void connect() {
		if( writeThread != null )
			throw new IllegalStateException( "WebSocketClient objects are not reuseable" );
		writeThread = new Thread( this );
		writeThread.start();
	}

我们可以发现：

他其实是起了一个线程，由于WebSocketClient类实现了Runnable接口，因此他会自动去调用run方法，然后我们进一步到run方法里去一探究竟

public void run() {
        try {
            if( socket == null ) {
                socket = new Socket( proxy );
            } else if( socket.isClosed() ) {
                throw new IOException();
            }
            System.out.println("---->  "+uri.toString()+"   port: "+getPort() );
            if( !socket.isBound() )
                socket.connect( new InetSocketAddress( uri.getHost(), getPort() ), connectTimeout );
            istream = socket.getInputStream();
            ostream = socket.getOutputStream();

            sendHandshake();
        } catch ( /*IOException | SecurityException | UnresolvedAddressException | InvalidHandshakeException | ClosedByInterruptException | SocketTimeoutException */Exception e ) {
            onWebsocketError( engine, e );
            engine.closeConnection( CloseFrame.NEVER_CONNECTED, e.getMessage() );
            return;
        }

        writeThread = new Thread( new WebsocketWriteThread() );
        writeThread.start();

        byte[] rawbuffer = new byte[ WebSocketImpl.RCVBUF ];
        int readBytes;

        try {
            while ( !isClosed() && ( readBytes = istream.read( rawbuffer ) ) != -1 ) {
                engine.decode( ByteBuffer.wrap( rawbuffer, 0, readBytes ) );
            }
            engine.eot();
        } catch ( IOException e ) {
            engine.eot();
        } catch ( RuntimeException e ) {
            // this catch case covers internal errors only and indicates a bug in this websocket implementation
            onError( e );
            engine.closeConnection( CloseFrame.ABNORMAL_CLOSE, e.getMessage() );
        }
        assert ( socket.isClosed() );
    }

public void run() {
		try {
			if( socket == null ) {
				socket = new Socket( proxy );
			} else if( socket.isClosed() ) {
				throw new IOException();
			}
			System.out.println("---->  "+uri.toString()+"   port: "+getPort() );
			if( !socket.isBound() )
				socket.connect( new InetSocketAddress( uri.getHost(), getPort() ), connectTimeout );
			istream = socket.getInputStream();
			ostream = socket.getOutputStream();

			sendHandshake();
		} catch ( /*IOException | SecurityException | UnresolvedAddressException | InvalidHandshakeException | ClosedByInterruptException | SocketTimeoutException */Exception e ) {
			onWebsocketError( engine, e );
			engine.closeConnection( CloseFrame.NEVER_CONNECTED, e.getMessage() );
			return;
		}

		writeThread = new Thread( new WebsocketWriteThread() );
		writeThread.start();

		byte[] rawbuffer = new byte[ WebSocketImpl.RCVBUF ];
		int readBytes;

		try {
			while ( !isClosed() && ( readBytes = istream.read( rawbuffer ) ) != -1 ) {
				engine.decode( ByteBuffer.wrap( rawbuffer, 0, readBytes ) );
			}
			engine.eot();
		} catch ( IOException e ) {
			engine.eot();
		} catch ( RuntimeException e ) {
			// this catch case covers internal errors only and indicates a bug in this websocket implementation
			onError( e );
			engine.closeConnection( CloseFrame.ABNORMAL_CLOSE, e.getMessage() );
		}
		assert ( socket.isClosed() );
	}

下面我们对上面的代码进行详细研究：

socket = new Socket( proxy );

				socket = new Socket( proxy );

这句显而易见，是创建了一个socket套接字。

socket.connect( new InetSocketAddress( uri.getHost(), getPort() ), connectTimeout );

				socket.connect( new InetSocketAddress( uri.getHost(), getPort() ), connectTimeout );

这句的意思是创建连接，参数就是服务器地址，端口号，超时时间。

istream = socket.getInputStream();

			istream = socket.getInputStream();

是接受服务器端的数据，关于接受的详细过程，我会在后期的博客中阐述，敬请期待。

ostream = socket.getOutputStream();

			ostream = socket.getOutputStream();

是发送数据用的。

其他的先不解释，我们继续之前的流程------connect之后就要发送信息，也就是调用send方法，send方法如下：

/**
     * Sends text to the connected websocket server.
     *
     * @param text
     *            The string which will be transmitted.
     */
    public void send( String text ) throws NotYetConnectedException {
        engine.send( text );
    }

/**
	 * Sends text to the connected websocket server.
	 * 
	 * @param text
	 *            The string which will be transmitted.
	 */
	public void send( String text ) throws NotYetConnectedException {
		engine.send( text );
	}

它调用了engine的send方法，那么engine是啥东东呢，在类的声明处有这么一句话：

private WebSocketImpl engine = null;

	private WebSocketImpl engine = null;

说明了 WebSocketImpl类实现了send的操作。

转自：http://blog.csdn.net/zjh171/article/details/24800493