httpclient 4.0.1 learning

最新推荐文章于 2025-11-25 11:17:27 发布

原创最新推荐文章于 2025-11-25 11:17:27 发布 · 211 阅读

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本文介绍了使用HttpClient进行HTTP请求的方法，包括POST和GET请求的具体实现方式，并对比了关闭响应内容流和关闭响应对象的区别，最后展示了如何通过ResponseHandler接口简化响应处理。

HttpClient client = new DefaultHttpClient ();
        HttpPost post = new HttpPost(url);
        List<NameValuePair> data = Lists.newArrayList();
        data.add(new BasicNameValuePair("sign","sign+md5"));
        try {
            post.setEntity(new UrlEncodedFormEntity(data));
            client.execute(post);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

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4.5

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpget = new HttpGet("http://localhost/");
CloseableHttpResponse response = httpclient.execute(httpget);
try {
    HttpEntity entity = response.getEntity();
    if (entity != null) {
        InputStream instream = entity.getContent();
        try {
            // do something useful
        } finally {
            instream.close();//保持连接
        }
    }
} finally {
    response.close(); //直接shutdown这个连接
}

The difference between closing the content stream and closing the response is that the former will attempt to keep the underlying connection alive by consuming the entity content while the latter immediately shuts down and discards the connection.

Response Handler

The simplest and the most convenient way to handle responses is by using the ResponseHandler interface, which includes the handleResponse(HttpResponse response) method. This method completely relieves the user from having to worry about connection management.

When using a ResponseHandler, HttpClient will automatically take care of ensuring release of the connection back to the connection manager regardless whether the request execution succeeds or causes an exception.

CloseableHttpClient httpclient = HttpClients.createDefault();
HttpGet httpget = new HttpGet("http://localhost/json");

ResponseHandler<MyJsonObject> rh = new ResponseHandler<MyJsonObject>() {

    @Override
    public JsonObject handleResponse(
            final HttpResponse response) throws IOException {
        StatusLine statusLine = response.getStatusLine();
        HttpEntity entity = response.getEntity();
        if (statusLine.getStatusCode() >= 300) {
            throw new HttpResponseException(
                    statusLine.getStatusCode(),
                    statusLine.getReasonPhrase());
        }
        if (entity == null) {
            throw new ClientProtocolException("Response contains no content");
        }
        Gson gson = new GsonBuilder().create();
        ContentType contentType = ContentType.getOrDefault(entity);
        Charset charset = contentType.getCharset();
        Reader reader = new InputStreamReader(entity.getContent(), charset);
        return gson.fromJson(reader, MyJsonObject.class);
    }
};
MyJsonObject myjson = client.execute(httpget, rh);