Java Filter¹ýÂËÆ÷ʹÓÃ

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 1¡¢½¨Á¢Ò»¸öServlet²¢ÇÒʵÏÖFilter½Ó¿Ú
¸ÃÀàÐèҪʵÏÖFilter½Ó¿ÚÖеÄinit()   doFilter()    destory()·½·¨
ÆäÖÐinit()·½·¨×Ô¶¯ÔÚÏîÄ¿Æô¶¯µÄʱºò¼ÓÔØ£¬doFilter()ÔÚµ÷ÓÃxmlÅäÖõÄ·¾¶ÊǼÓÔØ£¬destory()·½·¨ÔÚÍ˳öÏîÄ¿µÄʱºò½øÐС£
public class TestFilter implements Filter{
public void init(FilterConfig filterConfig) throws ServletException{
System.out.println("³õʼ»¯Filter");
}
public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) throws Exception{
System.out.println("½øÐÐdoFilter");
chain(request,response);     //ʹÓÃÕâÒ»¾ä¼ÌÐøServletÇëÇó
}
public void destory(){
System.out.println("¹ýÂËÆ÷Ïú»Ù");
}
}
2¡¢ÔÚxmlÖÐÅäÖÃFilter
<filter>
<filter-name></filter-name>
<filter-class></filter-class>
</filter>
<filter-mapping>
<filter-name></filter-name>
<url-pattern>/*</url-pattern> //ÕâÀïÏë¶ÔÄĸö·¾¶½øÐйýÂ˾ÍÌîдÄĸö
</filter-mapping>
Ó¦Óãº
±àÂë¹ýÂË
public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) throws Exception{
System.out.println("½øÐÐdoFilter"±àÂë¹ýÂË);
try
  {
   request.setCharacterEncoding("GB2312") ;
  }
  catch (Exception e)
  {
   e.printStackTrace();
  }
 
  chain.doFilter(request,response) ;
}
xmlÖеÄÅäÖãº
<url-pattern>/*</url-pattern>  ¶ÔËùÓÐÇëÇ󶼹ýÂË
Ãô¸Ð´Ê»ã¹ýÂË
public void doFilter(ServletRequest request,
                     ServletResponse response,
                     FilterChain chain)
              throws IOExce