CloseableHttpClient与 CloseableHttpResponse应用

最近在使用Apache的httpclient的时候，maven引用了最新版本4.3,发现Idea提示DefaultHttpClient等常用的类已经不推荐使用了，之前在使用4.2.3版本的时候，还没有被deprecated。去看了下官方文档，确实不推荐使用了，点击此处详情。

• DefaultHttpClient —> CloseableHttpClient
• HttpResponse —> CloseableHttpResponse

官方给出了新api的样例，如下。

Get方法：

    CloseableHttpClient httpclient = HttpClients.createDefault();
    HttpGet httpGet = new HttpGet("http://targethost/homepage");
    CloseableHttpResponse response1 = httpclient.execute(httpGet);
    // The underlying HTTP connection is still held by the response object
    // to allow the response content to be streamed directly from the network socket.
    // In order to ensure correct deallocation of system resources
    // the user MUST either fully consume the response content  or abort request
    // execution by calling CloseableHttpResponse#close().
    //建立的http连接，仍旧被response1保持着，允许我们从网络socket中获取返回的数据
    //为了释放资源，我们必须手动消耗掉response1或者取消连接（使用CloseableHttpResponse类的close方法）

    try {
        System.out.println(response1.getStatusLine());
        HttpEntity entity1 = response1.getEntity();
        // do something useful with the response body
        // and ensure it is fully consumed
        EntityUtils.consume(entity1);
    } finally {
        response1.close();
    }

Post方法：

    HttpPost httpPost = new HttpPost("http://targethost/login");
    //拼接参数
    List <NameValuePair> nvps = new ArrayList <NameValuePair>();
    nvps.add(new BasicNameValuePair("username", "vip"));
    nvps.add(new BasicNameValuePair("password", "secret"));
    httpPost.setEntity(new UrlEncodedFormEntity(nvps));
    CloseableHttpResponse response2 = httpclient.execute(httpPost);

    try {
        System.out.println(response2.getStatusLine());
        HttpEntity entity2 = response2.getEntity();
        // do something useful with the response body
        // and ensure it is fully consumed
        //消耗掉response
        EntityUtils.consume(entity2);
    } finally {
        response2.close();
    }

再往下看HttpClients的源码，具体的实现都在HttpClientBuilder的build方法中，有兴趣的可以去apache看源码。

    /**
    * Creates {@link CloseableHttpClient} instance with default
    * configuration.
    */
    public static CloseableHttpClient createDefault() {
        return HttpClientBuilder.create().build();
    }

参考：http://www.yeetrack.com/?p=760