在Java中发送HTTP POST请求

问题描述 投票：0回答：13

让我们假设这个 URL...

http://www.example.com/page.php?id=10

（这里需要在POST请求中发送id）

我想将 

id = 10
发送到服务器的 
page.php
，服务器以 POST 方法接受它。

我如何在 Java 中执行此操作？

我试过这个：

URL aaa = new URL("http://www.example.com/page.php");
URLConnection ccc = aaa.openConnection();

但我还是不知道如何通过 POST 发送

java http post
13个回答
385
投票

更新答案

由于原始答案中的某些类在较新版本的 Apache HTTP Components 中已弃用，因此我发布此更新。

顺便说一句，您可以在此处访问完整文档以获取更多示例。

HttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("http://www.a-domain.example/foo/");

// Request parameters and other properties.
List<NameValuePair> params = new ArrayList<NameValuePair>(2);
params.add(new BasicNameValuePair("param-1", "12345"));
params.add(new BasicNameValuePair("param-2", "Hello!"));
httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

//Execute and get the response.
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();

if (entity != null) {
    try (InputStream instream = entity.getContent()) {
        // do something useful
    }
}

原答案

我建议使用 Apache HttpClient。它更快、更容易实施。

HttpPost post = new HttpPost("http://jakarata.apache.org/");
NameValuePair[] data = {
    new NameValuePair("user", "joe"),
    new NameValuePair("password", "bloggs")
};
post.setRequestBody(data);
// execute method and handle any error responses.
...
InputStream in = post.getResponseBodyAsStream();
// handle response.

有关更多信息，请检查此 URL：http://hc.apache.org/

254
投票

在普通 Java 中发送 POST 请求很容易。从 

URL
开始，我们需要使用 
URLConnection
将其转换为 
url.openConnection();
。之后，我们需要将其转换为 
HttpURLConnection
，这样我们就可以访问它的 
setRequestMethod()
方法来设置我们的方法。我们最后说我们将通过连接发送数据。

URL url = new URL("https://www.example.com/login");
URLConnection con = url.openConnection();
HttpURLConnection http = (HttpURLConnection)con;
http.setRequestMethod("POST"); // PUT is another valid option
http.setDoOutput(true);

然后我们需要说明我们要发送的内容：

发送简单表格

来自 http 表单的普通 POST 具有“定义良好”的格式。我们需要将输入转换为这种格式： Map<String,String> arguments = new HashMap<>(); arguments.put("username", "root"); arguments.put("password", "sjh76HSn!"); // This is a fake password obviously StringJoiner sj = new StringJoiner("&"); for(Map.Entry<String,String> entry : arguments.entrySet()) sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + URLEncoder.encode(entry.getValue(), "UTF-8")); byte[] out = sj.toString().getBytes(StandardCharsets.UTF_8); int length = out.length; 

然后我们可以将表单内容附加到具有正确标头的 http 请求中并发送。

http.setFixedLengthStreamingMode(length); http.setRequestProperty("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8"); http.connect(); try(OutputStream os = http.getOutputStream()) { os.write(out); } // Do something with http.getInputStream() 

发送 JSON


我们也可以使用java发送json，这也很简单：


byte[] out = "{\"username\":\"root\",\"password\":\"password\"}" .getBytes(StandardCharsets.UTF_8);
int length = out.length;

http.setFixedLengthStreamingMode(length);
http.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
http.connect();
try(OutputStream os = http.getOutputStream()) {
    os.write(out);
}
// Do something with http.getInputStream()



请记住，不同的服务器接受不同的 json 内容类型，请参阅
this
问题。


使用java post发送文件


由于格式更复杂，发送文件可能更难处理。我们还将添加对以字符串形式发送文件的支持，因为我们不想将文件完全缓冲到内存中。


为此，我们定义了一些辅助方法：


private void sendFile(OutputStream out, String name, InputStream in, String fileName) {
    String o = "Content-Disposition: form-data; name=\"" + URLEncoder.encode(name,"UTF-8") 
             + "\"; filename=\"" + URLEncoder.encode(filename,"UTF-8") + "\"\r\n\r\n";
    out.write(o.getBytes(StandardCharsets.UTF_8));
    byte[] buffer = new byte[2048];
    for (int n = 0; n >= 0; n = in.read(buffer))
        out.write(buffer, 0, n);
    out.write("\r\n".getBytes(StandardCharsets.UTF_8));
}

private void sendField(OutputStream out, String name, String field) {
    String o = "Content-Disposition: form-data; name=\"" 
             + URLEncoder.encode(name,"UTF-8") + "\"\r\n\r\n";
    out.write(o.getBytes(StandardCharsets.UTF_8));
    out.write(URLEncoder.encode(field,"UTF-8").getBytes(StandardCharsets.UTF_8));
    out.write("\r\n".getBytes(StandardCharsets.UTF_8));
}



然后我们可以使用这些方法来创建多部分发布请求，如下所示：


String boundary = UUID.randomUUID().toString();
byte[] boundaryBytes = 
           ("--" + boundary + "\r\n").getBytes(StandardCharsets.UTF_8);
byte[] finishBoundaryBytes = 
           ("--" + boundary + "--").getBytes(StandardCharsets.UTF_8);
http.setRequestProperty("Content-Type", 
           "multipart/form-data; charset=UTF-8; boundary=" + boundary);

// Enable streaming mode with default settings
http.setChunkedStreamingMode(0); 

// Send our fields:
try(OutputStream out = http.getOutputStream()) {
    // Send our header (thx Algoman)
    out.write(boundaryBytes);

    // Send our first field
    sendField(out, "username", "root");

    // Send a seperator
    out.write(boundaryBytes);

    // Send our second field
    sendField(out, "password", "toor");

    // Send another seperator
    out.write(boundaryBytes);

    // Send our file
    try(InputStream file = new FileInputStream("test.txt")) {
        sendFile(out, "identification", file, "text.txt");
    }

    // Finish the request
    out.write(finishBoundaryBytes);
}


// Do something with http.getInputStream()


    



      

      
      
      

      

        

          

            

              
114
投票

              
            

          

        

        

    



      

      
      
      

      

        

          

            

              
30
投票

              
            

          

        

        

另外，我也很难弄清楚如何使用 Java 库读取 
HttpResponse
。 


这是更完整的代码：



/*
 * Create the POST request
 */
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost("http://example.com/");
// Request parameters and other properties.
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("user", "Bob"));
try {
    httpPost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));
} catch (UnsupportedEncodingException e) {
    // writing error to Log
    e.printStackTrace();
}
/*
 * Execute the HTTP Request
 */
try {
    HttpResponse response = httpClient.execute(httpPost);
    HttpEntity respEntity = response.getEntity();

    if (respEntity != null) {
        // EntityUtils to get the response content
        String content =  EntityUtils.toString(respEntity);
    }
} catch (ClientProtocolException e) {
    // writing exception to log
    e.printStackTrace();
} catch (IOException e) {
    // writing exception to log
    e.printStackTrace();
}


    



      

      
      
      

      

        

          

            

              
17
投票

              
            

          

        

        


Request.Post("http://www.example.com/page.php")
            .bodyForm(Form.form().add("id", "10").build())
            .execute()
            .returnContent();



看看
Fluent API

    




      

      
      
      

      

        

          

            

              
11
投票

              
            

          

        

        



然后您将看到以下窗口来选择您希望请求代码使用的语言：


    




      

      
      
      

      

        

          

            

              
5
投票

              
            

          

        

        



String postURL = "http://www.example.com/page.php";

HttpPost post = new HttpPost(postURL);

List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("id", "10"));

UrlEncodedFormEntity ent = new UrlEncodedFormEntity(params, "UTF-8");
post.setEntity(ent);

HttpClient client = new DefaultHttpClient();
HttpResponse responsePOST = client.execute(post);




你已经完成了。现在您可以使用
responsePOST
。
获取字符串形式的响应内容：


BufferedReader reader = new BufferedReader(new  InputStreamReader(responsePOST.getEntity().getContent()), 2048);

if (responsePOST != null) {
    StringBuilder sb = new StringBuilder();
    String line;
    while ((line = reader.readLine()) != null) {
        System.out.println(" line : " + line);
        sb.append(line);
    }
    String getResponseString = "";
    getResponseString = sb.toString();
//use server output getResponseString as string value.
}


    



      

      
      
      

      

        

          

            

              
5
投票

              
            

          

        

        


public void post(String uri, String data) throws Exception {
HttpClient client = HttpClient.newBuilder().build();
HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create(uri))
        .POST(BodyPublishers.ofString(data))
        .build();

HttpResponse<?> response = client.send(request, BodyHandlers.discarding());
System.out.println(response.statusCode());



这里有更多信息：

https://openjdk.java.net/groups/net/httpclient/recipes.html#post

    




      

      
      
      

      

        

          

            

              
4
投票

              
            

          

        

        


okhttp 的源代码可以在这里找到 
https://github.com/square/okhttp
.
如果您正在编写 pom 项目，请添加此依赖项


<dependency>
        <groupId>com.squareup.okhttp3</groupId>
        <artifactId>okhttp</artifactId>
        <version>4.2.2</version>
    </dependency>



如果不是，只需在互联网上搜索“download okhttp”即可。将出现几个结果，您可以在其中下载 jar。


你的代码：


import okhttp3.*;
        
import java.io.IOException;

public class ClassName{
        private void sendPost() throws IOException {
        
                // form parameters
                RequestBody formBody = new FormBody.Builder()
                        .add("id", 10)
                        .build();
        
                Request request = new Request.Builder()
                        .url("http://www.example.com/page.php")
                        .post(formBody)
                        .build();


                OkHttpClient httpClient = new OkHttpClient();
        
                try (Response response = httpClient.newCall(request).execute()) {
        
                    if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
        
                    // Get response body
                    System.out.println(response.body().string());
                }
        }
    }


    



      

      
      
      

      

        

          

            

              
4
投票

              
            

          

        

        
java.net.http.HttpClient
 以更少的代码发出 HTTP 请求。
    var values = new HashMap<String, Integer>() {{
        put("id", 10);
    }};
    
    var objectMapper = new ObjectMapper();
    String requestBody = objectMapper
            .writeValueAsString(values);
    
    HttpClient client = HttpClient.newHttpClient();
    HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("http://www.example.com/abc"))
            .POST(HttpRequest.BodyPublishers.ofString(requestBody))
            .build();
    
    HttpResponse<String> response = client.send(request,
            HttpResponse.BodyHandlers.ofString());
    
    System.out.println(response.body());


    



      

      
      
      

      

        

          

            

              
1
投票

              
            

          

        

        
HttpURLConnection.setRequestMethod("POST")
 和 
HttpURLConnection.setDoOutput(true);
 实际上只需要后者，因为 POST 就成为默认方法。
    





      

      
      
      

      

        

          

            

              
1
投票

              
            

          

        

        
http-request
 构建在 apache http api 上。

HttpRequest<String> httpRequest = HttpRequestBuilder.createPost("http://www.example.com/page.php", String.class)
.responseDeserializer(ResponseDeserializer.ignorableDeserializer()).build();

public void send(){
   String response = httpRequest.execute("id", "10").get();
}


    



      

      
      
      

      

        

          

            

              
0
投票

              
            

          

        

        
11
 或更高版本（Android 上除外）具有新的 HTTP 客户端 API。
var uri = URI.create("https://httpbin.org/get?age=26&isHappy=true");
var client = HttpClient.newHttpClient();
var request = HttpRequest
        .newBuilder()
        .uri(uri)
        .version(HttpClient.Version.HTTP_2)
        .timeout(Duration.ofMinutes(1))
        .header("Content-Type", "application/json")
        .header("Authorization", "Bearer fake")
        .POST(BodyPublishers.ofString("{ title: 'This is cool' }"))
        .build();
var response = client.send(request, HttpResponse.BodyHandlers.ofString());



同一个请求异步执行：


var responseAsync = client
        .sendAsync(request, HttpResponse.BodyHandlers.ofString())
        .thenApply(HttpResponse::body)
        .thenAccept(System.out::println);
// responseAsync.join(); // Wait for completion



要以多部分 (
multipart/form-data
) 或 url 编码 (
application/x-www-form-urlencoded
) 格式发送表单数据，请参阅
此解决方案
。
请参阅
本文
，了解有关 HTTP 客户端 API 的示例和更多信息。
对于 Java 标准库 HTTP 
server
，请参阅 这篇文章。
    


      

      
    

  

  

    
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