简述
本文学习如何简单的使用POST,如何上传文件等等场景
基础POST
首先,让我们来看一个简单的例子,并使用 HttpClient 发送POST请求。
我们将使用两个参数 – “username”和“password” 进行POST :
@Test
public void test()
throws ClientProtocolException, IOException {
close ableHttpClient client = HttpClients.createDefault();
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("username", "John"));
params.add(new BasicNameValuePair("password", "pass"));
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpPost httpPost = new HttpPost("");
CloseableHttpResponse response = client.execute(httpPost);
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
client.close();
}
请注意我们如何使用List<NameValuePair>在POST请求中包含参数。
使用授权进行POST
接下来,让我们看看如何使用HttpClient对身份验证凭据进行POST 。
在以下示例中 – 我们通过添加Authorization在Header向使用基本身份验证保护的URL发送POST请求:
@Test public void test() throws ClientProtocolException, IOException, AuthenticationException { CloseableHttpClient client = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(""); 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(); }
使用 json POST
现在 – 让我们看看如何使用HttpClient向JSON主体发送POST请求。
在以下示例中 – 我们将一些Person(id,name)作为JSON发送:
@Test
public void test()
throws ClientProtocolException, IOException {
CloseableHttpClient client = HttpClients.createDefault();
HttpPost httpPost = new HttpPost("");
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();
}
注意我们如何使用StringEntity来设置请求的主体。
我们还将 ContentType 标头设置为application / json ,以便为服务器提供有关我们发送的内容表示的必要信息。
使用HttpClient Form进行 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“ username ”和“ password ” 的请求:
@Test
public void test()
throws ClientProtocolException, IOException {
HttpResponse response = Request.Post("").bodyForm(
Form.form().add("username", "John").add("password", "pass"). build ())
.execute().returnResponse();
assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
}
POST多参数请求
现在,让我们发一个多参数请求。
我们将使用MultipartEntityBuilder发布文件,useranme和password:
@Test
public void whenSendMultipartRequestUsingHttpClient_thenCorrect()
throws ClientProtocolException, IOException {
CloseableHttpClient client = HttpClients.createDefault();
HttpPost httpPost = new HttpPost(“”);
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();
}
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 test() throws ClientProtocolException, IOException { CloseableHttpClient client = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(""); 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(); }
获取文件上传 进度
最后 – 让我们看看如何使用HttpClient获取文件上传的进度。
在下面的示例中,我们将扩展HttpEntityWrapper以获得对上载过程的可见性。
首先 – 这是上传方法:
@Test public void test() throws ClientProtocolException, IOException { CloseableHttpClient client = HttpClients.createDefault(); HttpPost httpPost = new HttpPost(""); 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); }
这是我们的扩展版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())); } }
而FilterOutputStream的扩展版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:
- 将FilterOutputStream扩展为CountingOutputStream时 -我们重写write()方法来计算写入(传输)的字节数
- 将HttpEntityWrapper扩展为ProgressEntityWrapper时 -我们重写writeTo()方法以使用我们的CountingOutputStream
小结
HttpClient的基础知识到本文就已经介绍结束,希望对你有所收获。