Application encoding filter of JSP Filter

A filter is a Web service component that adds functions to the request and Response Processing of a Web application.
Stages of the filter lifecycle:
Instantiate-> initialize ---> filter ---> destroy
• The Filter must implement the javax. servlet. Filter interface, which contains
-Init (...)
• Parameter type: FilterConfig (initialization parameter object)
-DoFilter (...)
• There are three types of parameters: ServletRequest, ServletResponse, and FilterChain.
-Destroy ()
Create a filter package under SRC and create a filterEncoding class to inherit the filter Interface
 
[Html] package filter;
 
Import java. io. IOException;
 
Import javax. servlet. Filter;
Import javax. servlet. FilterChain;
Import javax. servlet. FilterConfig;
Import javax. servlet. ServletException;
Import javax. servlet. ServletRequest;
Import javax. servlet. ServletResponse;
 
/**
* @ Author Administrator
* Character encoding filter
*/
Public class filterEncoding implements Filter {
Private String requestEncoding = "";
Private String responseEncoding = "";

Public void destroy (){
// TODO Auto-generated method stub
System. out. println ("the character encoding filter is destroyed! ");
}
 
Public void doFilter (ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// System. out. println ("encoding filter running... ");
// Obtain the filter chain
Request. setCharacterEncoding (requestEncoding );
Response. setContentType (responseEncoding );
// Execute the filter chain
Chain. doFilter (request, response );
 
}
 
Public void init (FilterConfig conif) throws ServletException {
// TODO Auto-generated method stub
System. out. println ("character encoding filter initialization! ");
// Obtain data in web. xml during initialization
RequestEncoding = conif. getInitParameter ("requestEncoding ");
ResponseEncoding = conif. getInitParameter ("responseEncoding ");

}
 
}

Package filter;

Import java. io. IOException;

Import javax. servlet. Filter;
Import javax. servlet. FilterChain;
Import javax. servlet. FilterConfig;
Import javax. servlet. ServletException;
Import javax. servlet. ServletRequest;
Import javax. servlet. ServletResponse;

/**
* @ Author Administrator
* Character encoding filter
*/
Public class filterEncoding implements Filter {
Private String requestEncoding = "";
Private String responseEncoding = "";
 
Public void destroy (){
// TODO Auto-generated method stub
System. out. println ("the character encoding filter is destroyed! ");
}

Public void doFilter (ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// System. out. println ("encoding filter running... ");
// Obtain the filter chain
Request. setCharacterEncoding (requestEncoding );
Response. setContentType (responseEncoding );
// Execute the filter chain
Chain. doFilter (request, response );

}

Public void init (FilterConfig conif) throws ServletException {
// TODO Auto-generated method stub
System. out. println ("character encoding filter initialization! ");
// Obtain data in web. xml during initialization
RequestEncoding = conif. getInitParameter ("requestEncoding ");
ResponseEncoding = conif. getInitParameter ("responseEncoding ");

}

}
Configure in web. xml
[Plain] <! -- Encoding filter start -->
<Filter>
<Filter-name> filterEncoding </filter-name>
<Filter-class> filter. filterEncoding </filter-class>
<Init-param>
<Param-name> requestEncoding </param-name>
<Param-value> UTF-8 </param-value>
</Init-param>
<Init-param>
<Param-name> responseEncoding </param-name>
<Param-value> text/html; charset = UTF-8 </param-value>
</Init-param>
</Filter>

<Filter-mapping>
<Filter-name> filterEncoding </filter-name>
<Url-pattern>/* </url-pattern>
</Filter-mapping>
<! -- Encoding filter end --