java - SpringMvc Post表单数据的一个问题

Question

spring-mvc 前端post表单数据到后台，后台没有接收到，并且用HttpServletRequest获取参数列表为空，下面为代码：

web.xml:

<servlet>
        <servlet-name>embers</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:conf/embers-mvc.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
        <async-supported>true</async-supported>
    </servlet>

    <servlet-mapping>
        <servlet-name>embers</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

mvc配置文件：

<context:component-scan base-package="embers.blog.controller" />

controller：

@Controller
public class BugTestController {
    
    
    @RequestMapping(value="/demo",method=RequestMethod.POST)
    public String demo(HttpServletRequest request,HttpServletResponse response) throws IOException{
        System.out.println(request.getParameterMap());
        System.out.println(request.getParameter("username"));
        System.out.println(request.getParameter("password"));
        System.out.println(request.getContentType());
        System.out.println("//");
        response.setContentType("text/html");
        response.getWriter().println("keke");
        response.getWriter().flush();
        response.getWriter().close();
        return null;
    }
}

我已经调试过无数次了，如果设定为GET方法，然后把参数放在URL上是完全没有问题的，用json提交，配置json转换也是没有问题的，就是默认的POST表单数据有问题，下面是调试工具生成的表单完整报文：

POST /BugTest/rest/demo HTTP/1.1
Host: 127.0.0.1:8080
Content-Type: application/x-www-form-urlencoded
Cache-Control: no-cache

username=111wqfewrf&password=321&=

一直都是好好的，这么简单的demo，现在突然不行了，好久没写springmvc了，我漏了什么吗？

Answer 1

By the way, even if you use springmvc’s annotation: RequestParam, you can’t get it, and the entire form data is empty

I used a tool to write the message character by character. I also tried it with jsp and got the same 400

<form action="${pageContext.request.contextPath }/demo.ember" method="post">
        <input type="text" name="username"/>
        <input type="text" name="password"/>
        <input type="submit" value="提交"/>
</form>

Error return:

HTTP Status 400 - Required String parameter 'username' is not present

Browser debugging, message sent:

Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding:gzip, deflate
Accept-Language:en-US,en;q=0.8
Cache-Control:max-age=0
Connection:keep-alive
Content-Length:26
Content-Type:application/x-www-form-urlencoded
Cookie:JSESSIONID=7872810B7BE203B784A906C3D49418D1
Host:localhost:8080
Origin:http://localhost:8080
Referer:http://localhost:8080/BugTest/demo.jsp
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.97 Safari/537.36

username=wsa&password=esdx

In the background, use HttpServelet to get the ContentType, which is indeed application/x-www-form-urlencoded, but when you get the entire ParameterMap or a single Parameter, it is empty. When you get the body, it is also empty, but change it to GET and put the parameters in the url. No problem at all

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I arrived at the company today and typed the code again. The company can get the exact same code, and all the tests are passable. I don’t know why I can’t get it at home. Let’s analyze the reason:
Initially estimated to be the tomcat version. The bug caused by the tomcat version used in the company is 8.0.29. I don’t know about it at home. I will go back tonight to check the tomcat version and check the bug list of this version

Continuous updates. . .

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It’s fixed. It’s a bug in tomcat8.0.29. Please pay attention when using form data. Of course, don’t worry about writing rest

Answer 2

What about the form? Are you sure those fields are written in the form?