CloseableHttpClient 源码

public abstract class CloseableHttpClient implements HttpClient, Closeable {



    private final Log log = LogFactory.getLog(getClass());



    protected abstract CloseableHttpResponse doExecute(HttpHost target, HttpRequest request,

            HttpContext context) throws IOException, ClientProtocolException;



    /**

     * {@inheritDoc}

     */

    public CloseableHttpResponse execute(

            final HttpHost target,

            final HttpRequest request,

            final HttpContext context) throws IOException, ClientProtocolException {

        return doExecute(target, request, context);

    }



    /**

     * {@inheritDoc}

     */

    public CloseableHttpResponse execute(

            final HttpUriRequest request,

            final HttpContext context) throws IOException, ClientProtocolException {

        Args.notNull(request, "HTTP request");

        return doExecute(determineTarget(request), request, context);

    }



    private static HttpHost determineTarget(final HttpUriRequest request) throws ClientProtocolException {

        // A null target may be acceptable if there is a default target.

        // Otherwise, the null target is detected in the director.

        HttpHost target = null;



        final URI requestURI = request.getURI();

        if (requestURI.isAbsolute()) {

            target = URIUtils.extractHost(requestURI);

            if (target == null) {

                throw new ClientProtocolException("URI does not specify a valid host name: "

                        + requestURI);

            }

        }

        return target;

    }



    /**

     * {@inheritDoc}

     */

    public CloseableHttpResponse execute(

            final HttpUriRequest request) throws IOException, ClientProtocolException {

        return execute(request, (HttpContext) null);

    }



    /**

     * {@inheritDoc}

     */

    public CloseableHttpResponse execute(

            final HttpHost target,

            final HttpRequest request) throws IOException, ClientProtocolException {

        return doExecute(target, request, (HttpContext) null);

    }



    /**

     * Executes a request using the default context and processes the

     * response using the given response handler. The content entity associated

     * with the response is fully consumed and the underlying connection is

     * released back to the connection manager automatically in all cases

     * relieving individual {@link ResponseHandler}s from having to manage

     * resource deallocation internally.

     *

     * @param request   the request to execute

     * @param responseHandler the response handler

     *

     * @return  the response object as generated by the response handler.

     * @throws IOException in case of a problem or the connection was aborted

     * @throws ClientProtocolException in case of an http protocol error

     */

    public <T> T execute(final HttpUriRequest request,

            final ResponseHandler<? extends T> responseHandler) throws IOException,

            ClientProtocolException {

        return execute(request, responseHandler, null);

    }



    /**

     * Executes a request using the default context and processes the

     * response using the given response handler. The content entity associated

     * with the response is fully consumed and the underlying connection is

     * released back to the connection manager automatically in all cases

     * relieving individual {@link ResponseHandler}s from having to manage

     * resource deallocation internally.

     *

     * @param request   the request to execute

     * @param responseHandler the response handler

     * @param context   the context to use for the execution, or

     *                  <code>null</code> to use the default context

     *

     * @return  the response object as generated by the response handler.

     * @throws IOException in case of a problem or the connection was aborted

     * @throws ClientProtocolException in case of an http protocol error

     */

    public <T> T execute(final HttpUriRequest request,

            final ResponseHandler<? extends T> responseHandler, final HttpContext context)

            throws IOException, ClientProtocolException {

        final HttpHost target = determineTarget(request);

        return execute(target, request, responseHandler, context);

    }



    /**

     * Executes a request using the default context and processes the

     * response using the given response handler. The content entity associated

     * with the response is fully consumed and the underlying connection is

     * released back to the connection manager automatically in all cases

     * relieving individual {@link ResponseHandler}s from having to manage

     * resource deallocation internally.

     *

     * @param target    the target host for the request.

     *                  Implementations may accept <code>null</code>

     *                  if they can still determine a route, for example

     *                  to a default target or by inspecting the request.

     * @param request   the request to execute

     * @param responseHandler the response handler

     *

     * @return  the response object as generated by the response handler.

     * @throws IOException in case of a problem or the connection was aborted

     * @throws ClientProtocolException in case of an http protocol error

     */

    public <T> T execute(final HttpHost target, final HttpRequest request,

            final ResponseHandler<? extends T> responseHandler) throws IOException,

            ClientProtocolException {

        return execute(target, request, responseHandler, null);

    }



    /**

     * Executes a request using the default context and processes the

     * response using the given response handler. The content entity associated

     * with the response is fully consumed and the underlying connection is

     * released back to the connection manager automatically in all cases

     * relieving individual {@link ResponseHandler}s from having to manage

     * resource deallocation internally.

     *

     * @param target    the target host for the request.

     *                  Implementations may accept <code>null</code>

     *                  if they can still determine a route, for example

     *                  to a default target or by inspecting the request.

     * @param request   the request to execute

     * @param responseHandler the response handler

     * @param context   the context to use for the execution, or

     *                  <code>null</code> to use the default context

     *

     * @return  the response object as generated by the response handler.

     * @throws IOException in case of a problem or the connection was aborted

     * @throws ClientProtocolException in case of an http protocol error

     */

    public <T> T execute(final HttpHost target, final HttpRequest request,

            final ResponseHandler<? extends T> responseHandler, final HttpContext context)

            throws IOException, ClientProtocolException {

        Args.notNull(responseHandler, "Response handler");



        final HttpResponse response = execute(target, request, context);



        final T result;

        try {

            result = responseHandler.handleResponse(response);

        } catch (final Exception t) {

            final HttpEntity entity = response.getEntity();

            try {

                EntityUtils.consume(entity);

            } catch (final Exception t2) {

                // Log this exception. The original exception is more

                // important and will be thrown to the caller.

                this.log.warn("Error consuming content after an exception.", t2);

            }

            if (t instanceof RuntimeException) {

                throw (RuntimeException) t;

            }

            if (t instanceof IOException) {

                throw (IOException) t;

            }

            throw new UndeclaredThrowableException(t);

        }



        // Handling the response was successful. Ensure that the content has

        // been fully consumed.

        final HttpEntity entity = response.getEntity();

        EntityUtils.consume(entity);

        return result;

    }



}

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