Apache HTTP 客户端，POST 请求。如何正确设置请求参数？答案

【问题标题】：Apache HTTP Client, POST request. How to correctly set request parameters?Apache HTTP 客户端，POST 请求。如何正确设置请求参数？
【发布时间】：2011-08-15 17:30:44
【问题描述】：

我正在使用 Apache HTTP 客户端，我需要向我的 servlet 发送一个 POST 请求。发送请求时，我的 servlet 没有收到任何参数（在 HttpServletRequest 中）。

这是客户端程序代码：

// Engage the HTTP client
DefaultHttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
try {
    HttpPost httpPost = new HttpPost("http://localhost:8080/test-json-web/JSONReceiverServlet");

    // Setup the request parameters
    HttpParams params = new BasicHttpParams();
    params.setParameter("taskdef", task1JsonString);
    httpPost.setParams(params);

    // Make the request
    response = httpclient.execute(httpPost);

    HttpEntity responseEntity = response.getEntity();

    System.out.println("----------------------------------------");
    System.out.println(response.getStatusLine());
    if(responseEntity != null) {
        System.out.println("Response content length: " + responseEntity.getContentLength());
    }

    String jsonResultString = EntityUtils.toString(responseEntity);
    EntityUtils.consume(responseEntity);
    System.out.println("----------------------------------------");
    System.out.println("result:");
    System.out.println();
} catch (ClientProtocolException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
} finally {
    httpclient.getConnectionManager().shutdown();
}

如何正确设置POST请求参数，让servlet真正接收到？

【问题讨论】：

标签： post httpclient

【解决方案1】：

试试这个：

        List <NameValuePair> nvps = new ArrayList <NameValuePair>();
        nvps.add(new BasicNameValuePair("IDToken1", "username"));
        nvps.add(new BasicNameValuePair("IDToken2", "password"));

        httPost.setEntity(new UrlEncodedFormEntity(nvps, Consts.UTF_8));

【讨论】：

这行得通！但不明白为什么另一个（ BasicHttpParams ）不起作用。任何想法/
Works :) 唯一需要注意的是，当我没有为UrlEncodedFormEntity 指定编码时，Spring Controller 没有收到参数。所以看起来编码实际上是强制性的。

【解决方案2】：

将“Content-Type”标头设置为“application/x-www-form-urlencoded”

【讨论】：

【解决方案3】：

如果你想传递一些http参数并发送一个json请求，你也可以使用这种方法：

（注意：我添加了一些额外的代码，以防它帮助任何其他未来的读者）

注意：导入来自 org.apache.http 库

public void postJsonWithHttpParams() throws URISyntaxException, UnsupportedEncodingException, IOException {

    //add the http parameters you wish to pass
    List<NameValuePair> postParameters = new ArrayList<>();
    postParameters.add(new BasicNameValuePair("param1", "param1_value"));
    postParameters.add(new BasicNameValuePair("param2", "param2_value"));

    //Build the server URI together with the parameters you wish to pass
    URIBuilder uriBuilder = new URIBuilder("http://google.ug");
    uriBuilder.addParameters(postParameters);

    HttpPost postRequest = new HttpPost(uriBuilder.build());
    postRequest.setHeader("Content-Type", "application/json");

    //this is your JSON string you are sending as a request
    String yourJsonString = "{\"str1\":\"a value\",\"str2\":\"another value\"} ";

    //pass the json string request in the entity
    HttpEntity entity = new ByteArrayEntity(yourJsonString.getBytes("UTF-8"));
    postRequest.setEntity(entity);

    //create a socketfactory in order to use an http connection manager
    PlainConnectionSocketFactory plainSocketFactory = PlainConnectionSocketFactory.getSocketFactory();
    Registry<ConnectionSocketFactory> connSocketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
            .register("http", plainSocketFactory)
            .build();

    PoolingHttpClientConnectionManager connManager = new PoolingHttpClientConnectionManager(connSocketFactoryRegistry);

    connManager.setMaxTotal(20);
    connManager.setDefaultMaxPerRoute(20);

    RequestConfig defaultRequestConfig = RequestConfig.custom()
            .setSocketTimeout(HttpClientPool.connTimeout)
            .setConnectTimeout(HttpClientPool.connTimeout)
            .setConnectionRequestTimeout(HttpClientPool.readTimeout)
            .build();

    // Build the http client.
    CloseableHttpClient httpclient = HttpClients.custom()
            .setConnectionManager(connManager)
            .setDefaultRequestConfig(defaultRequestConfig)
            .build();

    CloseableHttpResponse response = httpclient.execute(postRequest);

    //Read the response
    String responseString = "";

    int statusCode = response.getStatusLine().getStatusCode();
    String message = response.getStatusLine().getReasonPhrase();

    HttpEntity responseHttpEntity = response.getEntity();

    InputStream content = responseHttpEntity.getContent();

    BufferedReader buffer = new BufferedReader(new InputStreamReader(content));
    String line;

    while ((line = buffer.readLine()) != null) {
        responseString += line;
    }

    //release all resources held by the responseHttpEntity
    EntityUtils.consume(responseHttpEntity);

    //close the stream
    response.close();

    // Close the connection manager.
    connManager.close();
}

【讨论】：