niuqinghua/httpclient-failover

An extension to apache httpclient that adds support for failover on multiple http hosts.

httpclient-failover

An extension to apache httpclient that adds support for failover on multiple http hosts.

Using from maven

<repositories>
    <repository>
        <id>mcaprari-releases</id>
        <url>https://github.com/mcaprari/mcaprari-maven-repo/raw/master/releases</url>
    </repository>
    <repository>
        <id>mcaprari-snapshots</id>
        <url>https://github.com/mcaprari/mcaprari-maven-repo/raw/master/snapshots</url>
    </repository>
</repositories>

<dependency>
    <groupId>httpfailover</groupId>
    <artifactId>httpclient-failover</artifactId>
    <version>1.0</version>
</dependency>

FailoverHttpClient extends DefaultHttpClient adding few methods:

/**
 * Tries to execute the request on all targets.
 * Each target failure is evaluated using the multiTargetRetryHandler.
 *
 * In case of non-retriable failure, the last exception is thrown.
 *
 * @param targets   the candidate target hosts for the request.
 *                  The request is executed on each hosts until one succeeds.
 * @param request   the request to execute
 * @param context the request-specific execution context,
 *                  or <code>null</code> to use a default context
 * @return
 * @throws IOException
 * @throws ClientProtocolException
 */
public HttpResponse execute(List<HttpHost> targets, HttpRequest request, HttpContext context)
public HttpResponse execute(List<HttpHost> targets, HttpRequest request)

/**
 * Executes a request using the default context and processes the
 * response using the given response handler.
 *
 * @param targets   the candidate target hosts for the request.
 *                  The request is executed on each hosts until one succeeds.
 * @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(List<HttpHost> targets, HttpRequest request, ResponseHandler<? extends T> responseHandler, HttpContext context)
public <T> T execute(List<HttpHost> targets, HttpRequest request, ResponseHandler<? extends T> responseHandler)

/**
 * Set a for determining if an HttpRequest should fail over a different host
 * @param handler the handler
 */
void setMultiTargetRetryHandler(FailoverRetryHandler handler)

Example Usage

// create a client instance
FailoverHttpClient failoverHttpClient = new FailoverHttpClient();

// the list of hosts
List<HttpHost> hosts = Arrays.asList(
    new HttpHost("localhost", 9090),
    new HttpHost("localhost", 9191)
);

// the request
HttpGet request = new HttpGet(URI.create("/file.txt"));

HttpResponse response = failoverHttpClient.execute(hosts, request);