Apache HttpClient 4发送 POST HTTP 请求

codingman included in HTTP Client-Side

2019-09-09 1374 words 3 minutes

Contents

1. 概述

在本教程中，我们将使用HttpClient 4进行 POST ，首先使用授权，然后使用流利的 HttpClient API。

最后，我们将讨论如何使用 HttpClient 上传文件。

2. 基本 POST

首先，让我们看一个简单的例子，并使用HttpClient发送一个 POST 请求。

我们将使用两个参数“username”和“password”进行 POST：

@Test
public void whenSendPostRequestUsingHttpClient_thenCorrect() 
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    List<NameValuePair> params = new ArrayList<NameValuePair>();
    params.add(new BasicNameValuePair("username", "John"));
    params.add(new BasicNameValuePair("password", "pass"));
    httpPost.setEntity(new UrlEncodedFormEntity(params));
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

请注意我们如何使用NameValuePair列表在POST 请求中包含参数。

3. POST 授权

接下来，让我们看看如何使用HttpClient使用身份验证凭据进行 POST 。

在以下示例中，我们将通过添加授权标头向使用基本身份验证保护的 URL 发送 POST 请求：

@Test
public void whenSendPostRequestWithAuthorizationUsingHttpClient_thenCorrect()
  throws ClientProtocolException, IOException, AuthenticationException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    httpPost.setEntity(new StringEntity("test post"));
    UsernamePasswordCredentials creds
      = new UsernamePasswordCredentials("John", "pass");
    httpPost.addHeader(new BasicScheme().authenticate(creds, httpPost, null));
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

4. 使用 JSON 发布

现在让我们看看如何使用HttpClient发送带有 JSON 正文的 POST 请求。

在以下示例中，我们将以JSON 格式发送一些人员信息（id、name ）：

@Test
public void whenPostJsonUsingHttpClient_thenCorrect() 
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    String json = "{"id":1,"name":"John"}";
    StringEntity entity = new StringEntity(json);
    httpPost.setEntity(entity);
    httpPost.setHeader("Accept", "application/json");
    httpPost.setHeader("Content-type", "application/json");
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

请注意我们如何使用StringEntity来设置请求的正文。

我们还将ContentType标头设置为application/json 以向服务器提供有关我们正在发送的内容表示的必要信息。

5. 使用HttpClient Fluent API POST

接下来，让我们使用HttpClient Fluent API 进行 POST。

我们将发送一个带有两个参数的请求，“username”和“password”：

@Test
public void whenPostFormUsingHttpClientFluentAPI_thenCorrect() 
  throws ClientProtocolException, IOException {
    HttpResponse response = Request.Post("http://www.example.com").bodyForm(
      Form.form().add("username", "John").add("password", "pass").build())
      .execute().returnResponse();
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
}

6. POST 多部分请求

现在让我们发布一个多部分请求。

我们将使用MultipartEntityBuilder发布file、username和password：

@Test
public void whenSendMultipartRequestUsingHttpClient_thenCorrect() 
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    builder.addTextBody("username", "John");
    builder.addTextBody("password", "pass");
    builder.addBinaryBody(
      "file", new File("test.txt"), ContentType.APPLICATION_OCTET_STREAM, "file.ext");
    HttpEntity multipart = builder.build();
    httpPost.setEntity(multipart);
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

7. 使用HttpClient上传文件

接下来，让我们看看如何使用HttpClient上传文件。

我们将使用MultipartEntityBuilder上传“ test.txt ”文件：

@Test
public void whenUploadFileUsingHttpClient_thenCorrect() 
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    builder.addBinaryBody(
      "file", new File("test.txt"), ContentType.APPLICATION_OCTET_STREAM, "file.ext");
    HttpEntity multipart = builder.build();
    httpPost.setEntity(multipart);
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

8. 获取file上传进度

最后，让我们看看如何使用HttpClient获取file上传的进度。

在以下示例中，我们将扩展HttpEntityWrapper以了解上传过程。首先，这是上传方法：

@Test
public void whenGetUploadFileProgressUsingHttpClient_thenCorrect()
  throws ClientProtocolException, IOException {
    CloseableHttpClient client = HttpClients.createDefault();
    HttpPost httpPost = new HttpPost("http://www.example.com");
    MultipartEntityBuilder builder = MultipartEntityBuilder.create();
    builder.addBinaryBody(
      "file", new File("test.txt"), ContentType.APPLICATION_OCTET_STREAM, "file.ext");
    HttpEntity multipart = builder.build();
    ProgressEntityWrapper.ProgressListener pListener = 
      percentage -> assertFalse(Float.compare(percentage, 100) > 0);
    httpPost.setEntity(new ProgressEntityWrapper(multipart, pListener));
    CloseableHttpResponse response = client.execute(httpPost);
    assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
    client.close();
}

我们还将添加接口ProgressListener使我们能够观察上传进度：

public static interface ProgressListener {
    void progress(float percentage);
}

这是我们的HttpEntityWrapper的扩展版本， “ ProgressEntityWrapper ”：

public class ProgressEntityWrapper extends HttpEntityWrapper {
    private ProgressListener listener;
    public ProgressEntityWrapper(HttpEntity entity, ProgressListener listener) {
        super(entity);
        this.listener = listener;
    }
    @Override
    public void writeTo(OutputStream outstream) throws IOException {
        super.writeTo(new CountingOutputStream(outstream, listener, getContentLength()));
    }
}

这是FilterOutputStream 的扩展版本，“ CountingOutputStream ”：

public static class CountingOutputStream extends FilterOutputStream {
    private ProgressListener listener;
    private long transferred;
    private long totalBytes;
    public CountingOutputStream(
      OutputStream out, ProgressListener listener, long totalBytes) {
        super(out);
        this.listener = listener;
        transferred = 0;
        this.totalBytes = totalBytes;
    }
    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        out.write(b, off, len);
        transferred += len;
        listener.progress(getCurrentProgress());
    }
    @Override
    public void write(int b) throws IOException {
        out.write(b);
        transferred++;
        listener.progress(getCurrentProgress());
    }
    private float getCurrentProgress() {
        return ((float) transferred / totalBytes) * 100;
    }
}

注意：

当将FilterOutputStream扩展为“ CountingOutputStream ”时，我们重写了*write()*方法来计算写入（传输）的字节数
当将HttpEntityWrapper扩展为“ ProgressEntityWrapper ”时，我们将覆盖writeTo()方法以使用我们的“CountingOutputStream”