使用HttpURLConnection发送POST请求并携带请求参数

Bertha 。 2023-09-25 21:38 52阅读 0赞

###    1、先创建URL对象，指定请求的URL地址。 ###

URL url = new URL("http://example.com/api");

### 2、调用URL对象的openConnection()方法创建HttpURLConnection对象。 ###

HttpURLConnection connection = (HttpURLConnection) url.openConnection();

### 3、设置请求方法为POST。 ###

connection.setRequestMethod("POST");

### 4、设置请求头，包括Content-Type、Content-Length等。其中Content-Type表示请求体的格式，Content-Length表示请求体的长度。 ###

connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    connection.setRequestProperty("Content-Length", String.valueOf(param.getBytes().length));

### 5、设置连接超时和读取超时时间。 ###

connection.setConnectTimeout(5000);
    connection.setReadTimeout(5000);

### 6、允许向服务器写入写出数据。 ###

connection.setDoOutput(true);
    
    connection.setDoInput(true);

### 7、获取输出流，向服务器写入数据。 ###

OutputStream outputStream = connection.getOutputStream();
    outputStream.write(param.getBytes());
    outputStream.flush();
    outputStream.close();

这里的param是请求参数，需要将其转换为字节数组后写入输出流。

### 8、获取响应码，判断请求是否成功。 ###

int statusCode = connection.getResponseCode();

### 9、读取响应数据。 ###

InputStream inputStream = statusCode == 200 ? connection.getInputStream() : connection.getErrorStream();
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    StringBuilder response = new StringBuilder();
    String line;
    while ((line = reader.readLine()) != null) {
        response.append(line);
    }
    reader.close();
    inputStream.close();

这里的response是响应数据，需要将其读取为字符串后使用。  
完整的示例代码如下所示：

String param = "name=张三&age=18";
    URL url = new URL("http://example.com/api");
    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    connection.setRequestProperty("Content-Length", String.valueOf(param.getBytes().length));
    connection.setConnectTimeout(5000);
    connection.setReadTimeout(5000);
    connection.setDoOutput(true);
    OutputStream outputStream = connection.getOutputStream();
    outputStream.write(param.getBytes());
    outputStream.flush();
    outputStream.close();
    int statusCode = connection.getResponseCode();
    
    InputStream inputStream = statusCode == 200 ? connection.getInputStream() : connection.getErrorStream();
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
    StringBuilder response = new StringBuilder();
    String line;
    while ((line = reader.readLine()) != null) {
       response.append(line);
    }
    reader.close();
    inputStream.close();
    connection.disconnect();
    System.out.println(response.toString());

需要注意的是，以上示例代码中的请求参数是以字符串形式传递的，如果需要传递复杂的请求参数，可以考虑使用JSON等格式。同时，如果请求的URL需要携带查询参数，可以在URL中添加查询参数。

下面使用HttpURLConnection 发送POST 请求 参数类型是json

下面是使用HttpURLConnection微信小程序发送订阅消息的一个例子

POST请求

json组装成了一个JSONObject

json类似是这样的

{
      "touser": "OPENID",
      "template_id": "TEMPLATE_ID",
      "page": "index",
      "data": {
          "name01": {
              "value": "某某"
          },
          "amount01": {
              "value": "￥100"
          },
          "thing01": {
              "value": "广州至北京"
          } ,
          "date01": {
              "value": "2018-01-01"
          }
      }
    }

try {
    
                URL url = new URL(" https://api.weixin.qq.com/cgi-bin/message/subscribe/send?" +
                        "access_token=" +
                        "自己的小程序token");
    
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                connection.setRequestMethod("POST");
                connection.setRequestProperty("Content-Type", "application/json");
    
                connection.setDoOutput(true);
                connection.setDoInput(true);
    
    //构造发送给用户的订阅消息内容
                Map messageContent = new HashMap<String, Object>();
                messageContent.put("character_string1", new HashMap<String, Object>() {
       {
                    put("value", "a123456789");
                }});
                messageContent.put("amount2", new HashMap<String, Object>() {
       {
                    put("value", "1元");
                }});
                messageContent.put("thing3", new HashMap<String, Object>() {
       {
                    put("value", "西安大学长安学区");
                }});
                messageContent.put("time4", new HashMap<String, Object>() {
       {
                    put("value", "2021年10月20日");
                }});
                messageContent.put("thing5", new HashMap<String, Object>() {
       {
                    put("value", "这是备注");
                }});
                JSONObject messageContentJson = new JSONObject(messageContent);
    
                //构造订阅消息
                Map subscribeMessage = new HashMap<String, Object>();
                subscribeMessage.put("touser", " 。。。");//填写你的接收者openid
                subscribeMessage.put("template_id", " 填写你的模板ID");//填写你的模板ID
                subscribeMessage.put("data", messageContentJson);
                JSONObject subscribeMessageJson = new JSONObject(subscribeMessage);
    /*
                String s = subscribeMessageJson.toJSONString();
                System.out.println("JSONString:" + s);
    */
                String s1 = subscribeMessageJson.toString();
                System.out.println("String:" + s1);
                byte[] bytes = s1.getBytes();
    
                DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
                wr.write(bytes);
                wr.close();
    
                int statusCode = connection.getResponseCode();
    
                InputStream inputStream = statusCode == 200 ? connection.getInputStream() : connection.getErrorStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
                StringBuilder response = new StringBuilder();
                String line;
                while ((line = reader.readLine()) != null) {
                    response.append(line);
                }
                reader.close();
                inputStream.close();
                connection.disconnect();
                System.out.println(response.toString());
    
                connection.disconnect();
    
            } catch (Exception e) {
                e.printStackTrace();
            }