Posting with HttpClient

HttpClient是Java中经常使用的Http Client，总结下HttpClient4中经常使用的post请求用法。

1 Basic Post

使用2个参数进行post请求：

@Test
public void whenPostRequestUsingHttpClient_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();
}

2 POST with Authorization

使用Post进行Basic Authentication credentials验证：

@Test
public void whenPostRequestWithAuthorizationUsingHttpClient_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();
}

3 Post with JSON

使用JSON body进行post请求：

@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();
}

4 Post with HttpClient Fluent API

使用Request进行post请求：

@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));
}

5 Post Multipart Request

Post一个Multipart Request：

@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();
}

6 Upload a File using HttpClient

使用一个Post请求上传一个文件：

@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();
}

7 Get File Upload Progress

使用HttpClient获取文件上传的进度。扩展HttpEntityWrapper 获取进度。

上传代码：

@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 =
     new ProgressEntityWrapper.ProgressListener() {
        @Override
        public void progress(float 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();
}

观察上传进度接口：

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

扩展了HttpEntityWrapper的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()));
    }
}

扩展了FilterOutputStream的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;
    }
}

总结

简单举例说明如何使用Apache HttpClient 4进行各种post请求。做个笔记。