上文分析了Heritrix3.1.0系统是怎么扩展HttpClient组件的ProtocolSocketFactory接口用于创建HTTP和HTTPS连接的SOCKET对象的
接下来我们分析Heritrix3.1.0系统是怎么扩展HttpClient组件的HttpConnection对象的（创建SOCKET连接）
先看一下HttpConnection类的成员变量
// ----------------------------------------------------- Instance Variables /** My host. */ private String hostName = null; /** My port. */ private int portNumber = -1; /** My proxy host. */ private String proxyHostName = null; /** My proxy port. */ private int proxyPortNumber = -1; /** My client Socket. */ private Socket socket = null; /** My InputStream. */ private InputStream inputStream = null; /** My OutputStream. */ private OutputStream outputStream = null; /** An {@link InputStream} for the response to an individual request. */ private InputStream lastResponseInputStream = null; /** Whether or not the connection is connected. */ protected boolean isOpen = false; /** the protocol being used */ private Protocol protocolInUse; /** Collection of HTTP parameters associated with this HTTP connection*/ private HttpConnectionParams params = new HttpConnectionParams(); /** flag to indicate if this connection can be released, if locked the connection cannot be * released */ private boolean locked = false; /** Whether or not the socket is a secure one. */ private boolean usingSecureSocket = false; /** Whether the connection is open via a secure tunnel or not */ private boolean tunnelEstablished = false; /** the connection manager that created this connection or null */ private HttpConnectionManager httpConnectionManager; /** The local interface on which the connection is created, or null for the default */ private InetAddress localAddress;
这些成员变量都是创建SOCKET对象需要用到的参数或对象以及SOCKET的输入流输出流等，Heritrix3.1.0系统是怎么创建HttpConnection对象的呢
SingleHttpConnectionManager类的HttpConnection getConnectionWithTimeout(HostConfiguration hostConfiguration, long timeout)方法
public HttpConnection getConnectionWithTimeout( HostConfiguration hostConfiguration, long timeout) { HttpConnection conn = new HttpConnection(hostConfiguration); conn.setHttpConnectionManager(this); conn.getParams().setDefaults(this.getParams()); return conn; }
我们再来看一下HttpConnection类的构造方法
/** * Creates a new HTTP connection for the given host configuration. * * @param hostConfiguration the host/proxy/protocol to use */ public HttpConnection(HostConfiguration hostConfiguration) { this(hostConfiguration.getProxyHost(), hostConfiguration.getProxyPort(), hostConfiguration.getHost(), hostConfiguration.getPort(), hostConfiguration.getProtocol()); this.localAddress = hostConfiguration.getLocalAddress(); } /** * Creates a new HTTP connection for the given host with the virtual * alias and port via the given proxy host and port using the given * protocol. * * @param proxyHost the host to proxy via * @param proxyPort the port to proxy via * @param host the host to connect to. Parameter value must be non-null. * @param port the port to connect to * @param protocol The protocol to use. Parameter value must be non-null. */ public HttpConnection( String proxyHost, int proxyPort, String host, int port, Protocol protocol) { if (host == null) { throw new IllegalArgumentException("host parameter is null"); } if (protocol == null) { throw new IllegalArgumentException("protocol is null"); } proxyHostName = proxyHost; proxyPortNumber = proxyPort; hostName = host; portNumber = protocol.resolvePort(port); protocolInUse = protocol; }
HttpConnection类的构造方法里面基本上就是初始化成员变量，我们注意到里面的初始化Protocol protocolInUse成员对象，接下来的获取SocketFactory工厂就是通过Protocol protocolInUse成员对象获取的（上文中提到Protocol类中注册了HTTP和HTTPS的SocketFactory工厂）
下面的void open()方法首先通过Protocol protocolInUse成员对象获取SOCKET对象，接着设置相关参数，得到SOCKET对象的InputStream和OutStream等
/** * Establishes a connection to the specified host and port * (via a proxy if specified). * The underlying socket is created from the {@link ProtocolSocketFactory}. * * @throws IOException if an attempt to establish the connection results in an * I/O error. */ public void open() throws IOException { LOG.trace("enter HttpConnection.open()"); final String host = (proxyHostName == null) ? hostName : proxyHostName; final int port = (proxyHostName == null) ? portNumber : proxyPortNumber; assertNotOpen(); if (LOG.isDebugEnabled()) { LOG.debug("Open connection to " + host + ":" + port); } try { if (this.socket == null) { usingSecureSocket = isSecure() && !isProxied(); // use the protocol's socket factory unless this is a secure // proxied connection ProtocolSocketFactory socketFactory = null; if (isSecure() && isProxied()) { Protocol defaultprotocol = Protocol.getProtocol("http"); socketFactory = defaultprotocol.getSocketFactory(); } else { socketFactory = this.protocolInUse.getSocketFactory(); } this.socket = socketFactory.createSocket( host, port, localAddress, 0, this.params); } /* "Nagling has been broadly implemented across networks, including the Internet, and is generally performed by default - although it is sometimes considered to be undesirable in highly interactive environments, such as some client/server situations. In such cases, nagling may be turned off through use of the TCP_NODELAY sockets option." */ socket.setTcpNoDelay(this.params.getTcpNoDelay()); socket.setSoTimeout(this.params.getSoTimeout()); int linger = this.params.getLinger(); if (linger >= 0) { socket.setSoLinger(linger > 0, linger); } int sndBufSize = this.params.getSendBufferSize(); if (sndBufSize >= 0) { socket.setSendBufferSize(sndBufSize); } int rcvBufSize = this.params.getReceiveBufferSize(); if (rcvBufSize >= 0) { socket.setReceiveBufferSize(rcvBufSize); } int outbuffersize = socket.getSendBufferSize(); if ((outbuffersize > 2048) || (outbuffersize <= 0)) { outbuffersize = 2048; } int inbuffersize = socket.getReceiveBufferSize(); if ((inbuffersize > 2048) || (inbuffersize <= 0)) { inbuffersize = 2048; } // START IA/HERITRIX change Recorder httpRecorder = Recorder.getHttpRecorder(); if (httpRecorder == null || (isSecure() && isProxied())) { // no recorder, OR defer recording for pre-tunnel leg inputStream = new BufferedInputStream( socket.getInputStream(), inbuffersize); outputStream = new BufferedOutputStream( socket.getOutputStream(), outbuffersize); } else { inputStream = httpRecorder.inputWrap((InputStream) (new BufferedInputStream(socket.getInputStream(), inbuffersize))); outputStream = httpRecorder.outputWrap((OutputStream) (new BufferedOutputStream(socket.getOutputStream(), outbuffersize))); } // END IA/HERITRIX change isOpen = true; } catch (IOException e) { // Connection wasn't opened properly // so close everything out closeSocketAndStreams(); throw e; } }
我们注意到，Heritrix3.1.0系统用Recorder httpRecorder = Recorder.getHttpRecorder()对象封装了SOCKET连接的输出流和输入流，这样系统可以通过Recorder httpRecorder = Recorder.getHttpRecorder()对象得到SOCKET连接的输入流和输出流了
在Heritrix3.1.1系统里面同时封装了获取上述HttpConnection对象的构建类，它是通过扩展HttpCllient组件的SimpleHttpConnectionManager类来实现的
SimpleHttpConnectionManager类本身实现了HttpConnectionManager接口，HttpConnectionManager接口定义了构建HttpConnection连接对象的方法声明
public interface HttpConnectionManager { HttpConnection getConnection(HostConfiguration hostConfiguration); HttpConnection getConnection(HostConfiguration hostConfiguration, long timeout) throws HttpException; HttpConnection getConnectionWithTimeout(HostConfiguration hostConfiguration, long timeout) throws ConnectionPoolTimeoutException; void releaseConnection(HttpConnection conn); void closeIdleConnections(long idleTimeout); HttpConnectionManagerParams getParams(); void setParams(final HttpConnectionManagerParams params); }
Heritrix3.1.0系统扩展的SingleHttpConnectionManager类如下
public class SingleHttpConnectionManager extends SimpleHttpConnectionManager { public SingleHttpConnectionManager() { super(); } @Override public HttpConnection getConnectionWithTimeout( HostConfiguration hostConfiguration, long timeout) { HttpConnection conn = new HttpConnection(hostConfiguration); conn.setHttpConnectionManager(this); conn.getParams().setDefaults(this.getParams()); return conn; } @Override public void releaseConnection(HttpConnection conn) { // ensure connection is closed conn.close(); finishLast(conn); } static void finishLast(HttpConnection conn) { // copied from superclass because it wasn't made available to subclasses InputStream lastResponse = conn.getLastResponseInputStream(); if (lastResponse != null) { conn.setLastResponseInputStream(null); try { lastResponse.close(); } catch (IOException ioe) { //FIXME: badness - close to force reconnect. conn.close(); } } } }
扩展了获取HttpConnection连接对象和释放HttpConnection连接对象资源的方法
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本系列Heritrix 3.1.0 源码解析系本人原创
转载请注明出处 博客园 刺猬的温驯
本文链接 http://www.cnblogs.com/chenying99/archive/2013/04/27/3047510.html
