HttpServlet：表单提交HTTP方法此URL不支持GET

素颜马尾好姑娘i 2021-11-12 00:12 405阅读 0赞

表单提交页面405问题描述：HttpServlet：此URL不支持HTTP方法GET

@WebServlet(urlPatterns = "/demo3")
    public class ServletDemo3 extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      **super.doPost(req, resp);**     ----把这个去掉即可
            System.out.println("doGet,,,,,");
    
        }
    
    }

当使用下面的代码访问demo3的时候，浏览器会返回如下信息：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NoaVhpblhpbl9IYXJib3Vy_size_16_color_FFFFFF_t_70]  
问题原因  
我们查看一下HttpServlet的部分源码：

protected void doGet(HttpServletRequest req, HttpServletResponse resp)  
throws ServletException, IOException  
\{  
String protocol = req.getProtocol();  
String msg = lStrings.getString(“http.method\_get\_not\_supported”);  
if (protocol.endsWith(“1.1”)) \{  
resp.sendError(HttpServletResponse.SC\_METHOD\_NOT\_ALLOWED, msg);  
\} else \{  
resp.sendError(HttpServletResponse.SC\_BAD\_REQUEST, msg);  
\}  
\}

protected void doPost(HttpServletRequest req, HttpServletResponse resp)  
throws ServletException, IOException \{

String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_post_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }

protected void doDelete(HttpServletRequest req,  
HttpServletResponse resp)  
throws ServletException, IOException \{

String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_delete_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }

仔细阅读可以看出来，如果我们在HttpServlet的实现类中使用super.doGet()等这样类似的方法，就会出现405。这在源码中也有一定体现，即“http.method\_delete\_not\_supported”  
在HttpServlet基本遵循模板方法模式，所有非重写HTTP方法返回此HTTP 405错误“不支持方法”。当你重写这样的方法，你应该不调用super方法，因为否则你将仍然得到HTTP 405错误。

解决办法  
**在我们正常实现的时候，[不可以调用super.xxx][super.xxx]()方法，而是重新去实现这些方法，就ok了。**

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NoaVhpblhpbl9IYXJib3Vy_size_16_color_FFFFFF_t_70]: /images/20211109/1783755b3da34f5482b306e4f762251e.png
[super.xxx]: http://xn--super-ni1hm4c38ubm9ey04b.xxx