Question

我成功使用此代码通过HTTP方法

发送带有一些参数的GET个请求

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），因为它们很长。我想在该方法中添加一个额外的参数（即String httpMethod）。

如何通过GET或POST尽可能少地更改上述代码，以便能够发送参数？

我希望改变

connection.setRequestMethod("GET");

到

connection.setRequestMethod("POST");

会完成这个技巧，但参数仍然是通过GET方法发送的。

HttpURLConnection有任何方法可以提供帮助吗？有没有有用的Java构造？

非常感谢任何帮助。

Answer 1

在GET请求中，参数作为URL的一部分发送。

在POST请求中，参数在标题之后作为请求的主体发送。

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

此代码可以帮助您入门：

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 );
}

Answer 2

这是一个提交表单然后将结果页面转储到System.out的简单示例。当然，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);
    }
}

如果您希望结果为String而不是直接打印出来：

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

Answer 3

我无法让Alan's example真正做到这一点，所以我最终得到了这个：

String urlParameters = "param1=a&param2=b&param3=c";
URL url = new URL("http://example.com/index.php");
URLConnection conn = url.openConnection();

conn.setDoOutput(true);

OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());

writer.write(urlParameters);
writer.flush();

String line;
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

while ((line = reader.readLine()) != null) {
    System.out.println(line);
}
writer.close();
reader.close();

Answer 4

我觉得HttpURLConnection真的很麻烦。而且你必须编写很多样板，容易出错的代码。我的Android项目需要一个轻量级的包装器，并且还提供了一个可以使用的库： DavidWebb 。

上面的例子可以写成：

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替代库的列表。

Answer 5

我看到其他一些答案已经给出了替代方案，我个人认为直觉上你做的是正确的事情;）。对不起，在devoxx，有几位发言者一直在咆哮这种事情。

这就是我个人使用Apache的HTTPClient / HttpCore库来完成这项工作的原因，我发现他们的API比Java的本机HTTP支持更容易使用。 YMMV当然！

Answer 6

import java.net.*;

public class Demo{

  public static void main(){

       String data = "data=Hello+World!";
       URL url = new URL("http://localhost:8084/WebListenerServer/webListener");
       HttpURLConnection con = (HttpURLConnection) url.openConnection();
       con.setRequestMethod("POST");
       con.setDoOutput(true);
       con.getOutputStream().write(data.getBytes("UTF-8"));
       con.getInputStream();

    }

}

Answer 7

我已经阅读了上述答案并创建了一个实用程序类来简化HTTP请求。我希望它会对你有所帮助。

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);
        }
    });

公用事业类

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
 }
}

Answer 8

GET和POST方法设置如下... api调用的两种类型：1）get（）和2）post（）。 get（）方法可从api json数组中获取值以获取值，而post（）方法可用于我们在url中的数据发布中并获取响应。

 public class HttpClientForExample {

    private final String USER_AGENT = "Mozilla/5.0";

    public static void main(String[] args) throws Exception {

        HttpClientExample http = new HttpClientExample();

        System.out.println("Testing 1 - Send Http GET request");
        http.sendGet();

        System.out.println("\nTesting 2 - Send Http POST request");
        http.sendPost();

    }

    // HTTP GET request
    private void sendGet() throws Exception {

        String url = "http://www.google.com/search?q=developer";

        HttpClient client = new DefaultHttpClient();
        HttpGet request = new HttpGet(url);

        // add request header
        request.addHeader("User-Agent", USER_AGENT);

        HttpResponse response = client.execute(request);

        System.out.println("\nSending 'GET' request to URL : " + url);
        System.out.println("Response Code : " + 
                       response.getStatusLine().getStatusCode());

        BufferedReader rd = new BufferedReader(
                       new InputStreamReader(response.getEntity().getContent()));

        StringBuffer result = new StringBuffer();
        String line = "";
        while ((line = rd.readLine()) != null) {
            result.append(line);
        }

        System.out.println(result.toString());

    }

    // HTTP POST request
    private void sendPost() throws Exception {

        String url = "https://selfsolve.apple.com/wcResults.do";

        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost(url);

        // add header
        post.setHeader("User-Agent", USER_AGENT);

        List<NameValuePair> urlParameters = new ArrayList<NameValuePair>();
        urlParameters.add(new BasicNameValuePair("sn", "C02G8416DRJM"));
        urlParameters.add(new BasicNameValuePair("cn", ""));
        urlParameters.add(new BasicNameValuePair("locale", ""));
        urlParameters.add(new BasicNameValuePair("caller", ""));
        urlParameters.add(new BasicNameValuePair("num", "12345"));

        post.setEntity(new UrlEncodedFormEntity(urlParameters));

        HttpResponse response = client.execute(post);
        System.out.println("\nSending 'POST' request to URL : " + url);
        System.out.println("Post parameters : " + post.getEntity());
        System.out.println("Response Code : " + 
                                    response.getStatusLine().getStatusCode());

        BufferedReader rd = new BufferedReader(
                        new InputStreamReader(response.getEntity().getContent()));

        StringBuffer result = new StringBuffer();
        String line = "";
        while ((line = rd.readLine()) != null) {
            result.append(line);
        }

        System.out.println(result.toString());

    }

}

Answer 9

我有同样的问题。我想通过POST发送数据。我使用了以下代码：

    Document doc = Jsoup.parseBodyFragment(value);
    Iterator<Element> opts = doc.select("option").iterator();
    for (;opts.hasNext();) {
        Element item = opts.next();
        if (item.hasAttr("value")) {
            System.out.println(item.attr("value"));
        }
    }

我使用Jsoup进行解析：

gl_VertexID

Answer 10

尝试这种模式：

public static PricesResponse getResponse(EventRequestRaw request) {

    // String urlParameters  = "param1=a&param2=b&param3=c";
    String urlParameters = Piping.serialize(request);

    HttpURLConnection conn = RestClient.getPOSTConnection(endPoint, urlParameters);

    PricesResponse response = null;

    try {
        // POST
        OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
        writer.write(urlParameters);
        writer.flush();

        // RESPONSE
        BufferedReader reader = new BufferedReader(new InputStreamReader((conn.getInputStream()), StandardCharsets.UTF_8));
        String json = Buffering.getString(reader);
        response = (PricesResponse) Piping.deserialize(json, PricesResponse.class);

        writer.close();
        reader.close();

    } catch (Exception e) {
        e.printStackTrace();
    }

    conn.disconnect();

    System.out.println("PricesClient: " + response.toString());

    return response;
}

public static HttpURLConnection getPOSTConnection(String endPoint, String urlParameters) {

    return RestClient.getConnection(endPoint, "POST", urlParameters);

}


public static HttpURLConnection getConnection(String endPoint, String method, String urlParameters) {

    System.out.println("ENDPOINT " + endPoint + " METHOD " + method);
    HttpURLConnection conn = null;

    try {
        URL url = new URL(endPoint);
        conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod(method);
        conn.setDoOutput(true);
        conn.setRequestProperty("Content-Type", "text/plain");

    } catch (IOException e) {
        e.printStackTrace();
    }

    return conn;
}

Answer 11

这里我发送了jsonobject作为参数// jsonobject = {“name”：“lucifer”，“pass”：“abc”} // serverUrl =“http://192.168.100.12/testing”//host=192.168.100.12

  public static String getJson(String serverUrl,String host,String jsonobject){

    StringBuilder sb = new StringBuilder();

    String http = serverUrl;

    HttpURLConnection urlConnection = null;
    try {
        URL url = new URL(http);
        urlConnection = (HttpURLConnection) url.openConnection();
        urlConnection.setDoOutput(true);
        urlConnection.setRequestMethod("POST");
        urlConnection.setUseCaches(false);
        urlConnection.setConnectTimeout(50000);
        urlConnection.setReadTimeout(50000);
        urlConnection.setRequestProperty("Content-Type", "application/json");
        urlConnection.setRequestProperty("Host", host);
        urlConnection.connect();
        //You Can also Create JSONObject here 
        OutputStreamWriter out = new OutputStreamWriter(urlConnection.getOutputStream());
        out.write(jsonobject);// here i sent the parameter
        out.close();
        int HttpResult = urlConnection.getResponseCode();
        if (HttpResult == HttpURLConnection.HTTP_OK) {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    urlConnection.getInputStream(), "utf-8"));
            String line = null;
            while ((line = br.readLine()) != null) {
                sb.append(line + "\n");
            }
            br.close();
            Log.e("new Test", "" + sb.toString());
            return sb.toString();
        } else {
            Log.e(" ", "" + urlConnection.getResponseMessage());
        }
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    } finally {
        if (urlConnection != null)
            urlConnection.disconnect();
    }
    return null;
}

Answer 12

我非常推荐建立在apache http api上的http-request。

对于您的情况，您可以看到示例：

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
}

如果您对回复正文不感兴趣

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http-request的一般发送邮件请求：阅读文档并查看我的答案HTTP POST request with JSON String in JAVA，Sending HTTP POST Request In Java，HTTP POST using JSON in Java

Answer 13

您好请使用此类来改进您的帖子方法

public static JSONObject doPostRequest(HashMap<String, String> data, String url) {

    try {
        RequestBody requestBody;
        MultipartBuilder mBuilder = new MultipartBuilder().type(MultipartBuilder.FORM);

        if (data != null) {


            for (String key : data.keySet()) {
                String value = data.get(key);
                Utility.printLog("Key Values", key + "-----------------" + value);

                mBuilder.addFormDataPart(key, value);

            }
        } else {
            mBuilder.addFormDataPart("temp", "temp");
        }
        requestBody = mBuilder.build();


        Request request = new Request.Builder()
                .url(url)
                .post(requestBody)
                .build();

        OkHttpClient client = new OkHttpClient();
        Response response = client.newCall(request).execute();
        String responseBody = response.body().string();
        Utility.printLog("URL", url);
        Utility.printLog("Response", responseBody);
        return new JSONObject(responseBody);

    } catch (UnknownHostException | UnsupportedEncodingException e) {

        JSONObject jsonObject=new JSONObject();

        try {
            jsonObject.put("status","false");
            jsonObject.put("message",e.getLocalizedMessage());
        } catch (JSONException e1) {
            e1.printStackTrace();
        }
        Log.e(TAG, "Error: " + e.getLocalizedMessage());
    } catch (Exception e) {
        e.printStackTrace();
        JSONObject jsonObject=new JSONObject();

        try {
            jsonObject.put("status","false");
            jsonObject.put("message",e.getLocalizedMessage());
        } catch (JSONException e1) {
            e1.printStackTrace();
        }
        Log.e(TAG, "Other Error: " + e.getLocalizedMessage());
    }
    return null;
}

Answer 14

此答案涵盖了使用自定义Java POJO进行POST调用的特定情况。

使用Gson的maven依赖关系将Java对象序列化为JSON。

使用以下依赖项安装Gson。

<dependency>
  <groupId>com.google.code.gson</groupId>
  <artifactId>gson</artifactId>
  <version>2.8.5</version>
  <scope>compile</scope>
</dependency>

对于使用gradle的用户可以使用以下内容

dependencies {
implementation 'com.google.code.gson:gson:2.8.5'
}

使用的其他进口商品：

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.*;
import org.apache.http.impl.client.CloseableHttpClient;
import com.google.gson.Gson;

现在，我们可以继续使用Apache

提供的HttpPost

private CloseableHttpClient httpclient = HttpClients.createDefault();
HttpPost httppost = new HttpPost("https://example.com");

Product product = new Product(); //custom java object to be posted as Request Body
    Gson gson = new Gson();
    String client = gson.toJson(product);

    httppost.setEntity(new StringEntity(client, ContentType.APPLICATION_JSON));
    httppost.setHeader("RANDOM-HEADER", "headervalue");
    //Execute and get the response.
    HttpResponse response = null;
    try {
        response = httpclient.execute(httppost);
    } catch (IOException e) {
        throw new InternalServerErrorException("Post fails");
    }
    Response.Status responseStatus = Response.Status.fromStatusCode(response.getStatusLine().getStatusCode());
    return Response.status(responseStatus).build();

上面的代码将与从POST呼叫收到的响应代码一起返回

Answer 15

我接受了Boann的回答并用它来创建一个更灵活的查询字符串构建器，它支持列表和数组，就像php的http_build_query方法一样：

CodecRegistry codecRegistry = CodecRegistries.fromRegistries(MongoClient.getDefaultCodecRegistry(),
            CodecRegistries.fromCodecs(new ParamCodec()));

MongoClientOptions clientOptions = new MongoClientOptions.Builder()
    ....
    .codecRegistry(codecRegistry)
    .build();

MongoClient(addresses, clientOptions);

Answer 16

对于那些由于希望使用键值对而无法使用$ _POST在php页面上接收请求的人：

尽管所有答案都非常有帮助，但我对实际要发布的字符串缺乏基本的了解，因为在旧的apache HttpClient中，我使用了

new UrlEncodedFormEntity(nameValuePairs); (Java)

然后可以在php中使用$ _POST来获取键值对。

据我所知，现在已经有人在发布之前手动构建了该字符串。所以字符串应该看起来像

val data = "key1=val1&key2=val2"

，而是将其添加到发布的网址中（在标题中）。

替代方法是改用json-string：

val data = "{\"key1\":\"val1\",\"key2\":\"val2\"}" // {"key1":"val1","key2":"val2"}

并在没有$ _POST的情况下将其拉入php：

$json_params = file_get_contents('php://input');
// echo_p("Data: $json_params");
$data = json_decode($json_params, true);

在这里您可以找到Kotlin中的示例代码：

class TaskDownloadTest : AsyncTask<Void, Void, Void>() {
    override fun doInBackground(vararg params: Void): Void? {
        var urlConnection: HttpURLConnection? = null

        try {

            val postData = JsonObject()
            postData.addProperty("key1", "val1")
            postData.addProperty("key2", "val2")

            // reformat json to key1=value1&key2=value2
            // keeping json because I may change the php part to interpret json requests, could be a HashMap instead
            val keys = postData.keySet()
            var request = ""
            keys.forEach { key ->
                // Log.i("data", key)
                request += "$key=${postData.get(key)}&"
            }
            request = request.replace("\"", "").removeSuffix("&")
            val requestLength = request.toByteArray().size
            // Warning in Android 9 you need to add a line in the application part of the manifest: android:usesCleartextTraffic="true"
            // https://stackoverflow.com/questions/45940861/android-8-cleartext-http-traffic-not-permitted
            val url = URL("http://10.0.2.2/getdata.php")
            urlConnection = url.openConnection() as HttpURLConnection
            // urlConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded") // apparently default
            // Not sure what these are for, I do not use them
            // urlConnection.setRequestProperty("Content-Type", "application/json")
            // urlConnection.setRequestProperty("Key","Value")
            urlConnection.readTimeout = 5000
            urlConnection.connectTimeout = 5000
            urlConnection.requestMethod = "POST"
            urlConnection.doOutput = true
            // urlConnection.doInput = true
            urlConnection.useCaches = false
            urlConnection.setFixedLengthStreamingMode(requestLength)
            // urlConnection.setChunkedStreamingMode(0) // if you do not want to handle request length which is fine for small requests

            val out = urlConnection.outputStream
            val writer = BufferedWriter(
                OutputStreamWriter(
                    out, "UTF-8"
                )
            )
            writer.write(request)
            // writer.write("{\"key1\":\"val1\",\"key2\":\"val2\"}") // {"key1":"val1","key2":"val2"} JsonFormat or just postData.toString() for $json_params=file_get_contents('php://input'); json_decode($json_params, true); in php
            // writer.write("key1=val1&key2=val2") // key=value format for $_POST in php
            writer.flush()
            writer.close()
            out.close()

            val code = urlConnection.responseCode
            if (code != 200) {
                throw IOException("Invalid response from server: $code")
            }

            val rd = BufferedReader(
                InputStreamReader(
                    urlConnection.inputStream
                )
            )
            var line = rd.readLine()
            while (line != null) {
                Log.i("data", line)
                line = rd.readLine()
            }
        } catch (e: Exception) {
            e.printStackTrace()
        } finally {
            urlConnection?.disconnect()
        }

        return null
    }
}

Answer 17

现在我不得不做一个 HTTP 请求类，它可能不是最有效的类，但它可以工作。我从这个页面收集了一些代码，让它更加动态。

任何需要完整代码的人，我在下面附上了它。有关如何使用它的示例，您可以查看 main 方法。

此外，如果您愿意改进在线课程，我们非常欢迎您帮助我改进这门课程。

import java.net.*;
import java.util.*;
import java.nio.charset.*;
import java.io.*;
  
public class HttpRequest {
    
    
    String result = "";
    
    HttpRequest(String _url, String _method, Map<String, String> _postData, String _contentType) {
        
        try {
            URL url = new URL( _url );
            URLConnection con = url.openConnection();
            HttpURLConnection http = (HttpURLConnection)con;
            http.setRequestMethod(_method); // PUT is another valid option
            http.setDoOutput(true);         
            
            StringJoiner sj = new StringJoiner("&");
            for(Map.Entry<String,String> entry : _postData.entrySet())
                sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + entry.getValue());
                //sj.add(URLEncoder.encode(entry.getKey(), "UTF-8") + "=" + URLEncoder.encode(entry.getValue()));
            byte[] out = sj.toString().getBytes(StandardCharsets.UTF_8);
            int length = out.length;
            http.setFixedLengthStreamingMode(length);
            http.setRequestProperty("Content-Type", _contentType);
            http.setRequestProperty( "charset", "utf-8");
            http.setRequestProperty( "Content-Length", Integer.toString( length ));
            http.setInstanceFollowRedirects( false );
            http.setUseCaches( false );
            http.connect();
            try(OutputStream os = http.getOutputStream()) {
                os.write(out);
            }
            if (http.getResponseCode() == HttpURLConnection.HTTP_OK) {
                try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(http.getInputStream()))) {
                String line;
                while ((line = bufferedReader.readLine()) != null) {
                  result = result + line;
                }
            }
          } else {
            System.out.println("Bad response!");
          }
        }catch (IOException e) {
            // writing exception to log
            e.printStackTrace();
        }
        
    }
    
    
    HttpRequest(String _url, String _method, Map<String, String> _postData) {
        this(_url, _method, _postData, "text/html");
    }
    
    HttpRequest(String _url, String _method) {
        this(_url, _method, new HashMap<String, String>());
    }
    
    HttpRequest(String _url) {
        this(_url, "GET");
    }
    
    
    public String toString() {
        return result;
    }
    
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Map<String, String> postData = new HashMap<String, String>();
        postData.putIfAbsent("email", "test@test.com");
        postData.putIfAbsent("password", "test");
        
        HttpRequest result = new HttpRequest("https://httpbin.org/anything", "POST", postData, "application/x-www-form-urlencoded");
        System.out.println(result.toString());
    }
}

Answer 18

似乎您还必须至少调用一次connection.getOutputStream()“（以及setDoOutput(true)）才能将其视为POST。

所以最低要求的代码是：

    URL url = new URL(urlString);
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    //connection.setRequestMethod("POST"); this doesn't seem to do anything at all..so not useful
    connection.setDoOutput(true); // set it to POST...not enough by itself however, also need the getOutputStream call...
    connection.connect();
    connection.getOutputStream().close();

令人惊讶的是，您甚至可以在urlString中使用“GET”样式参数。虽然这可能会让事情变得混乱。

您显然也可以使用NameValuePair。

Java - 通过POST方法轻松发送HTTP参数

18 个答案: