通过POST方法轻松发送HTTP参数

我成功地使用这段代码通过GET方法发送带有一些参数的HTTP请求

void sendRequest(String request)
{
    // i.e.: request = "http://example.com/index.php?param1=a&param2=b&param3=c";
    URL url = new URL(request); 
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();           
    connection.setDoOutput(true); 
    connection.setInstanceFollowRedirects(false); 
    connection.setRequestMethod("GET"); 
    connection.setRequestProperty("Content-Type", "text/plain"); 
    connection.setRequestProperty("charset", "utf-8");
    connection.connect();
}

现在我可能需要通过POST方法发送参数(即param1, param2, param3)，因为它们非常长。我想添加一个额外的参数，该方法(即字符串httpMethod)。

我怎样才能尽可能少地更改上面的代码，以便能够通过GET或POST发送参数?

我希望情况会有所改变

connection.setRequestMethod("GET");

connection.setRequestMethod("POST");

可以完成这个任务，但是参数仍然通过GET方法发送。

HttpURLConnection有任何方法可以帮助吗? 有什么有用的Java构造吗?

任何帮助都将不胜感激。

当前回答

我已经阅读了上面的答案，并创建了一个实用工具类来简化HTTP请求。我希望它能帮助你。

方法调用

  // send params with Hash Map
    HashMap<String, String> params = new HashMap<String, String>();
    params.put("email","me@example.com");
    params.put("password","12345");

    //server url
    String url = "http://www.example.com";

    // static class "HttpUtility" with static method "newRequest(url,method,callback)"
    HttpUtility.newRequest(url,HttpUtility.METHOD_POST,params, new HttpUtility.Callback() {
        @Override
        public void OnSuccess(String response) {
        // on success
           System.out.println("Server OnSuccess response="+response);
        }
        @Override
        public void OnError(int status_code, String message) {
        // on error
              System.out.println("Server OnError status_code="+status_code+" message="+message);
        }
    });

实用程序类

import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Map;
import static java.net.HttpURLConnection.HTTP_OK;

public class HttpUtility {

 public static final int METHOD_GET = 0; // METHOD GET
 public static final int METHOD_POST = 1; // METHOD POST

 // Callback interface
 public interface Callback {
  // abstract methods
  public void OnSuccess(String response);
  public void OnError(int status_code, String message);
 }
 // static method
 public static void newRequest(String web_url, int method, HashMap < String, String > params, Callback callback) {

  // thread for handling async task
  new Thread(new Runnable() {
   @Override
   public void run() {
    try {
     String url = web_url;
     // write GET params,append with url
     if (method == METHOD_GET && params != null) {
      for (Map.Entry < String, String > item: params.entrySet()) {
       String key = URLEncoder.encode(item.getKey(), "UTF-8");
       String value = URLEncoder.encode(item.getValue(), "UTF-8");
       if (!url.contains("?")) {
        url += "?" + key + "=" + value;
       } else {
        url += "&" + key + "=" + value;
       }
      }
     }

     HttpURLConnection urlConnection = (HttpURLConnection) new URL(url).openConnection();
     urlConnection.setUseCaches(false);
     urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // handle url encoded form data
     urlConnection.setRequestProperty("charset", "utf-8");
     if (method == METHOD_GET) {
      urlConnection.setRequestMethod("GET");
     } else if (method == METHOD_POST) {
      urlConnection.setDoOutput(true); // write POST params
      urlConnection.setRequestMethod("POST");
     }

     //write POST data 
     if (method == METHOD_POST && params != null) {
      StringBuilder postData = new StringBuilder();
      for (Map.Entry < String, String > item: params.entrySet()) {
       if (postData.length() != 0) postData.append('&');
       postData.append(URLEncoder.encode(item.getKey(), "UTF-8"));
       postData.append('=');
       postData.append(URLEncoder.encode(String.valueOf(item.getValue()), "UTF-8"));
      }
      byte[] postDataBytes = postData.toString().getBytes("UTF-8");
      urlConnection.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
      urlConnection.getOutputStream().write(postDataBytes);

     }
     // server response code
     int responseCode = urlConnection.getResponseCode();
     if (responseCode == HTTP_OK && callback != null) {
      BufferedReader reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
      StringBuilder response = new StringBuilder();
      String line;
      while ((line = reader.readLine()) != null) {
       response.append(line);
      }
      // callback success
      callback.OnSuccess(response.toString());
      reader.close(); // close BufferReader
     } else if (callback != null) {
      // callback error
      callback.OnError(responseCode, urlConnection.getResponseMessage());
     }

     urlConnection.disconnect(); // disconnect connection
    } catch (IOException e) {
     e.printStackTrace();
     if (callback != null) {
      // callback error
      callback.OnError(500, e.getLocalizedMessage());
     }
    }
   }
  }).start(); // start thread
 }
}

2017-01-29 12:03:10

其他回答

在GET请求中，参数作为URL的一部分发送。

在POST请求中，参数作为请求体发送，位于请求头之后。

要使用HttpURLConnection进行POST，需要在打开连接后将参数写入连接。

这段代码应该让你开始:

String urlParameters  = "param1=a&param2=b&param3=c";
byte[] postData       = urlParameters.getBytes( StandardCharsets.UTF_8 );
int    postDataLength = postData.length;
String request        = "http://example.com/index.php";
URL    url            = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnection();           
conn.setDoOutput( true );
conn.setInstanceFollowRedirects( false );
conn.setRequestMethod( "POST" );
conn.setRequestProperty( "Content-Type", "application/x-www-form-urlencoded"); 
conn.setRequestProperty( "charset", "utf-8");
conn.setRequestProperty( "Content-Length", Integer.toString( postDataLength ));
conn.setUseCaches( false );
try( DataOutputStream wr = new DataOutputStream( conn.getOutputStream())) {
   wr.write( postData );
}

2010-11-17 15:40:04

我强烈推荐构建在apache http api上的http-request。

对于你的案例，你可以看到例子:

private static final HttpRequest<String.class> HTTP_REQUEST = 
      HttpRequestBuilder.createPost("http://example.com/index.php", String.class)
           .responseDeserializer(ResponseDeserializer.ignorableDeserializer())
           .build();

public void sendRequest(String request){
     String parameters = request.split("\\?")[1];
     ResponseHandler<String> responseHandler = 
            HTTP_REQUEST.executeWithQuery(parameters);

   System.out.println(responseHandler.getStatusCode());
   System.out.println(responseHandler.get()); //prints response body
}

如果您对响应体不感兴趣

private static final HttpRequest<?> HTTP_REQUEST = 
     HttpRequestBuilder.createPost("http://example.com/index.php").build();

public void sendRequest(String request){
     ResponseHandler<String> responseHandler = 
           HTTP_REQUEST.executeWithQuery(parameters);
}

对于一般发送post请求与HTTP -request:阅读文档，看到我的答案HTTP post请求与JSON字符串在JAVA，发送HTTP post请求在JAVA, HTTP post使用JSON在JAVA

2017-09-24 22:23:30

我发现HttpURLConnection使用起来非常麻烦。你必须写大量样板，容易出错的代码。我需要一个轻量级的包装为我的Android项目，并提出了一个库，你可以使用:DavidWebb。

上面的例子可以这样写:

Webb webb = Webb.create();
webb.post("http://example.com/index.php")
        .param("param1", "a")
        .param("param2", "b")
        .param("param3", "c")
        .ensureSuccess()
        .asVoid();

您可以在提供的链接上找到备选库的列表。

2014-01-08 09:13:20

下面是一个简单的示例，它提交了一个表单，然后将结果页面转储到System.out。当然，要适当地更改URL和POST参数:

import java.io.*;
import java.net.*;
import java.util.*;

class Test {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://example.net/new-message.php");
        Map<String,Object> params = new LinkedHashMap<>();
        params.put("name", "Freddie the Fish");
        params.put("email", "fishie@seamail.example.com");
        params.put("reply_to_thread", 10394);
        params.put("message", "Shark attacks in Botany Bay have gotten out of control. We need more defensive dolphins to protect the schools here, but Mayor Porpoise is too busy stuffing his snout with lobsters. He's so shellfish.");

        StringBuilder postData = new StringBuilder();
        for (Map.Entry<String,Object> param : params.entrySet()) {
            if (postData.length() != 0) postData.append('&');
            postData.append(URLEncoder.encode(param.getKey(), "UTF-8"));
            postData.append('=');
            postData.append(URLEncoder.encode(String.valueOf(param.getValue()), "UTF-8"));
        }
        byte[] postDataBytes = postData.toString().getBytes("UTF-8");

        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
        conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
        conn.setDoOutput(true);
        conn.getOutputStream().write(postDataBytes);

        Reader in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));

        for (int c; (c = in.read()) >= 0;)
            System.out.print((char)c);
    }
}

如果你想将结果作为字符串而不是直接打印出来，请:

        StringBuilder sb = new StringBuilder();
        for (int c; (c = in.read()) >= 0;)
            sb.append((char)c);
        String response = sb.toString();

2014-02-09 09:41:50

我已经阅读了上面的答案，并创建了一个实用工具类来简化HTTP请求。我希望它能帮助你。

方法调用

  // send params with Hash Map
    HashMap<String, String> params = new HashMap<String, String>();
    params.put("email","me@example.com");
    params.put("password","12345");

    //server url
    String url = "http://www.example.com";

    // static class "HttpUtility" with static method "newRequest(url,method,callback)"
    HttpUtility.newRequest(url,HttpUtility.METHOD_POST,params, new HttpUtility.Callback() {
        @Override
        public void OnSuccess(String response) {
        // on success
           System.out.println("Server OnSuccess response="+response);
        }
        @Override
        public void OnError(int status_code, String message) {
        // on error
              System.out.println("Server OnError status_code="+status_code+" message="+message);
        }
    });

实用程序类

import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Map;
import static java.net.HttpURLConnection.HTTP_OK;

public class HttpUtility {

 public static final int METHOD_GET = 0; // METHOD GET
 public static final int METHOD_POST = 1; // METHOD POST

 // Callback interface
 public interface Callback {
  // abstract methods
  public void OnSuccess(String response);
  public void OnError(int status_code, String message);
 }
 // static method
 public static void newRequest(String web_url, int method, HashMap < String, String > params, Callback callback) {

  // thread for handling async task
  new Thread(new Runnable() {
   @Override
   public void run() {
    try {
     String url = web_url;
     // write GET params,append with url
     if (method == METHOD_GET && params != null) {
      for (Map.Entry < String, String > item: params.entrySet()) {
       String key = URLEncoder.encode(item.getKey(), "UTF-8");
       String value = URLEncoder.encode(item.getValue(), "UTF-8");
       if (!url.contains("?")) {
        url += "?" + key + "=" + value;
       } else {
        url += "&" + key + "=" + value;
       }
      }
     }

     HttpURLConnection urlConnection = (HttpURLConnection) new URL(url).openConnection();
     urlConnection.setUseCaches(false);
     urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); // handle url encoded form data
     urlConnection.setRequestProperty("charset", "utf-8");
     if (method == METHOD_GET) {
      urlConnection.setRequestMethod("GET");
     } else if (method == METHOD_POST) {
      urlConnection.setDoOutput(true); // write POST params
      urlConnection.setRequestMethod("POST");
     }

     //write POST data 
     if (method == METHOD_POST && params != null) {
      StringBuilder postData = new StringBuilder();
      for (Map.Entry < String, String > item: params.entrySet()) {
       if (postData.length() != 0) postData.append('&');
       postData.append(URLEncoder.encode(item.getKey(), "UTF-8"));
       postData.append('=');
       postData.append(URLEncoder.encode(String.valueOf(item.getValue()), "UTF-8"));
      }
      byte[] postDataBytes = postData.toString().getBytes("UTF-8");
      urlConnection.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
      urlConnection.getOutputStream().write(postDataBytes);

     }
     // server response code
     int responseCode = urlConnection.getResponseCode();
     if (responseCode == HTTP_OK && callback != null) {
      BufferedReader reader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
      StringBuilder response = new StringBuilder();
      String line;
      while ((line = reader.readLine()) != null) {
       response.append(line);
      }
      // callback success
      callback.OnSuccess(response.toString());
      reader.close(); // close BufferReader
     } else if (callback != null) {
      // callback error
      callback.OnError(responseCode, urlConnection.getResponseMessage());
     }

     urlConnection.disconnect(); // disconnect connection
    } catch (IOException e) {
     e.printStackTrace();
     if (callback != null) {
      // callback error
      callback.OnError(500, e.getLocalizedMessage());
     }
    }
   }
  }).start(); // start thread
 }
}

2017-01-29 12:03:10

通过POST方法轻松发送HTTP参数

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