Note 32 Using static resources and handling Chinese garbled characters in SpringMVC

First, the use of static resources

There is the following code snippet in WebConfig.java

 

1 @Override // 配置静态资源处理
2     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
3         // TODO Auto-generated method stub
4         configurer.enable();
5     }

 

At this point, a default Handler will be registered: DefaultServletHttpRequestHandler, this Handler is also used to process static files, and it will try to map /*. When the DispatcherServelt is mapped /( / and /* is different), and no suitable Handler is found to process the request, it will be handed over DefaultServletHttpRequestHandler to be processed. Note: The static resources here are placed in the web root directory, not under WEB-INF. 
　　Maybe the description here is a bit difficult to understand (I think so too), so just give an example, for example: there is a picture in the webroot directory: 1.png we know that the files in the web root directory (webroot) in the Servelt specification can be accessed directly , but because the DispatcherServletconfigured mapping path is: / , it intercepts almost all requests, resulting in 1.png inaccessibility, then registering one DefaultServletHttpRequestHandlercan solve this problem. In fact, it can be understood as a DispatcherServletbroken Servletfeature (the files in the root directory can be accessed directly), DefaultServletHttpRequestHandlerwhich helps to return this feature.

Q:　 What is the difference between /and /*　? 
Answer:  /All urls except jsp will be intercepted, and all urls /* will be intercepted, including jsp. For example: there is a test.jsp under the webroot, when DispatcherServlet configuring the mapping / , the browser enters: http://localhost:8083/test.jsp  This jsp can be accessed directly and does not go through DispatcherServlet , and when DispatcherServlet configuring the mapping /* , this The request will be DispatcherServlet blocked.

Use JSTL tags:

<%@ taglib uri="http://www.springframework.org/tags" prefix="s"%>

<img src="<s:url value="/resources/profile/images/profile_img.png" />" > Use the images in the corresponding directory, and use other static resources similarly.

 

2. Dealing with Chinese garbled characters - the solution for garbled characters after the form submission controller obtains Chinese parameters

Note: jsp page encoding is set to UTF-8

1. The form submission method must be post, and the spring coding filter under the get method has no effect

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<form action="${ctx}/user/addUser" name="userForm" method="post">    

2. Modify web.xml and add an encoding filter as follows (note that the value of the forceEncoding parameter needs to be set to true) web.xml is in the WEB-INF directory

<filter>
        <filter-name>characterEncodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
        <init-param>
            <param-name>forceEncoding</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>characterEncodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
      </filter-mapping>