httpclient的池化

我们经常在应用系统中使用httpclient来发送http请求，我们通常会new httpclient创建对象，这样，当请求并发量很大的时候，频繁的创建、销毁httpclient会导致不必要的性能开销，所以有必要对httpclient这个重量级对象进行池化。
在此，我们使用apache提供的common-pool包做相应的事情。
重要代码如下：

public class HttpClientPool extends GenericObjectPool{
     //构造方法接受一个PoolableObjectFactory，来定义对象的创建
    public HttpClientPool(PoolableObjectFactory factory) {
        super(factory);
    }

    //自定义
    public  T doPost(HttpMethod method, HttpClientDataCallback callback) {
        HttpClient toUse = null;
        try {
            toUse = borrowObject();
            toUse.executeMethod(method);
            T rel = callback.handleResponse(method.getResponseBodyAsString());
            return rel;
        } catch (Exception e) {
            logger.error(\"failed to execute http request.\", e);
            return null;
        } finally {
            try {
                method.releaseConnection();
            } catch (Exception e) {
                //in case fail, ignore and return object
            }
            if (toUse != null) {
                try {
                    returnObject(toUse);
                } catch (Exception e) {
                    logger.warn(\"failed to return http client\", e);
                }
            }
        }
    }
}

PoolableHttpClientFactory：该类实现对池化对象的初始创建动作

public class PoolableHttpClientFactory implements PoolableObjectFactory {
    private int contimeout; //Connection time out
    private int sotimeout; //so time out

    public PoolableHttpClientFactory(int contimeout, int sotimeout) {
        this.contimeout = contimeout;
        this.sotimeout = sotimeout;
    }

    /*对象的生成在此定义 
     *(non-Javadoc)
     * @see org.apache.commons.pool.PoolableObjectFactory#makeObject()
     */
    @Override
    public HttpClient makeObject() throws Exception {
        HttpClient httpClient = new HttpClient();
        HttpConnectionManagerParams configParams = httpClient.getHttpConnectionManager().getParams();
        configParams.setConnectionTimeout(contimeout);
        configParams.setSoTimeout(sotimeout);
        httpClient.getParams().setConnectionManagerTimeout(contimeout);
        httpClient.getParams().setParameter(HttpMethodParams.HTTP_CONTENT_CHARSET, \"UTF-8\");
        return httpClient;
    }
}