HttpURLConnection 使用 & MissingServletRequestParameterException异常处理

怼烎@ 2023-02-21 04:47 47阅读 0赞

## http请求处理工具类 ##

### HttpURLConnection 概述 ###

public abstract class HttpURLConnection extends URLConnection

A URLConnection with support for HTTP-specific features. See the spec for details.
    
    Each HttpURLConnection instance is used to make a single request but the underlying network connection to the HTTP 
    server may be transparently shared by other instances. Calling the close() methods on the InputStream or OutputStream 
    of an HttpURLConnection after a request may free network resources associated with this instance but has no effect on 
    any shared persistent connection. Calling the disconnect() method may close the underlying socket if a persistent connection is otherwise idle at that time.
    
    The HTTP protocol handler has a few settings that can be accessed through System Properties. This covers Proxy settings as well as various other settings.

*  支持 HTTP 特定功能的 URL 连接。有关详细信息，请参阅规格。
 *  每个 HttpURLConnection 实例都用于发出单个请求，但与 HTTP 服务器的基础网络连接可能由其他实例透明地共享。在请求后在 HttpURLConnection 的输入流或输出流上调用 close（） 方法可能会释放与此实例关联的网络资源，但对任何共享持久连接没有任何影响。如果持久连接在当时处于空闲状态，则调用断开连接（） 方法可能会关闭基础套接字。
 *  HTTP 协议处理程序有几个可以通过系统属性访问的设置。这包括代理设置以及各种其他设置。

### HttpURLConnection 使用案例 ###

#### GET 请求 ####

public static void main(String[] args) throws IOException { 
         
         // request url
         String URL = "https://xxx.xxxxxxxx.com/xxxx/xxxxx";
    
         // test get
         initGetParams();
         String getRet = testGet(URL);
         System.out.println(getRet);
     }
    
    /** * get 请求处理方法 * @param path * @return * @throws IOException */
     private static String testGet(String path) throws IOException { 
    
         BufferedReader in = null;
         StringBuilder sb = new StringBuilder();
         try { 
    
             // get
             String mPath = path + "?";
             for (String key : getParams.keySet()) { 
                 mPath += key + "=" + getParams.get(key) + "&";
             }
             URL url = new URL(mPath);
             HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    
             // set connection params
             conn.setRequestMethod("GET");
             conn.setDoOutput(false);
             conn.setDoInput(true);
             conn.setConnectTimeout(10000);
             conn.setReadTimeout(10000);
             conn.setRequestProperty("accept", "*/*");
             conn.setRequestProperty("connection", "Keep-Alive");
             conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
             conn.setRequestProperty("Accept", "application/json, text/javascript, */*; q=0.01");
             conn.setRequestProperty("Accept-Language", "zh-CN,zh;q=0.9");
             conn.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36");
             conn.setRequestProperty("Cookie", "xxx-xxxx-xxxxx-xxxx");
             conn.setRequestProperty("X-Requested-With", "XMLHttpRequest");
    
             // connect
             conn.connect();
    
             // reader
             in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
    
             String line;
             while ((line = in.readLine()) != null) { 
                 sb.append(line);
             }
         } catch (Exception e) { 
             System.err.println("调用异常：" + e);
         } finally { 
    
             // close stream
             if (in != null) { 
                 in.close();
             }
         }
         return sb.toString();
     }
    
     /** * 初始化 get 请求参数 */
     private static void initGetParams() { 
    
         getParams.put("param1", "value1");
         getParams.put("param2", "value2");
         getParams.put("param3", "value3");
         getParams.put("param4", "value4");
     }

#### POST请求 ####

public static void main(String[] args) throws IOException { 
         
         // request url
         String URL = "https://xxx.xxxxxxxx.com/xxxx/xxxxx";
    
         // test post
         initPostParams();
         String postRet = testPost(URL, postParams);
         System.out.println(postRet);
     }
    
    /** * post 请求处理方法 * @param requestUrl * @param params * @return * @throws IOException */
     public static String testPost(String requestUrl, String params) throws IOException { 
    
         OutputStreamWriter out = null;
         BufferedReader in = null;
         StringBuilder sb = new StringBuilder();
         try { 
             URL url = new URL(requestUrl);
             HttpURLConnection conn = (HttpURLConnection) url
                     .openConnection();
    
             // set connection params
             conn.setDoOutput(true);
             conn.setDoInput(true);
             conn.setUseCaches(false);
             conn.setInstanceFollowRedirects(true);
             conn.setRequestMethod("POST");
             conn.setRequestProperty("Accept", "*/*");
             conn.setRequestProperty("connection", "Keep-Alive");
             conn.setRequestProperty("Accept-Language", "zh-CN,zh;q=0.9");
             // conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
             // conn.setRequestProperty("Accept", "application/json, text/javascript, */*; q=0.01");
             conn.setRequestProperty("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.97 Safari/537.36");
             conn.setRequestProperty("X-Requested-With", "XMLHttpRequest");
             conn.setRequestProperty("Cookie", "xxx-xxxx-xxxxx-xxxx");
    
             // connect
             conn.connect();
             out = new OutputStreamWriter(
                     conn.getOutputStream(), "UTF-8");
             out.append(params);
             out.flush();
             out.close();
             if (conn != null) { 
    
                 // reader
                 in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
                 String line = null;
                 while ((line = in.readLine()) != null) { 
                     sb.append(line);
                     sb.append("\r\n");
                 }
             }
    
             // connection disconnect
             conn.disconnect();
         } catch (IOException e) { 
             System.err.println("调用异常：" + e);
         } finally { 
    
             // close stream
             if (out != null) { 
                 out.close();
             }
             if (in != null) { 
                 in.close();
             }
         }
         return sb.toString();
     }
    
    /** * 初始化 post 请求参数 */
     private static void initPostParams() { 
         StringBuffer sb=new StringBuffer();
         sb.append("param1=").append("value1&").append("param2=").append("value2&").append("param3=").append("value3&").append("param4=").append("value4");
         postParams =  sb.toString();
     }

### 总结 ###

#### MissingServletRequestParameterException ####

测试`HttpURLConnection`如上所述，期间`POST`请求出现问题

{ 
    	"@type": "org.springframework.web.bind.MissingServletRequestParameterException",
    	"cause": null,
    	"localizedMessage": "Required String parameter 'order_type' is not present",
    	"message": "Required String parameter 'order_type' is not present",
    	"parameterName": "order_type",
    	"parameterType": "String",
    	"rootCause": null,
    	"stackTrace": ...
    }

经检查参数个数，参数名称均无误，怀疑是请求头、响应头类型解析不一致解决方案如下：

// conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
    // conn.setRequestProperty("Accept", "application/json, text/javascript, */*; q=0.01");