过滤器接口与实现字符编码过滤器实…

[1]过滤器的原理

 

[2]过滤链

[3]Filter接口

 

*public void init(FilterConfig filterConfig)throwsServletException//过滤器初始化方法，此方法在过滤器初始化时被调用

*public void doilter(ServletRequest request , ServletResponseresponse,FilterChain chain)throws IOException,ServletException//对请求进行过滤 处理

*public void destroy();//销毁方法，以便释放资源

[4]FilterConfig接口

 

*public Strng getFilterName();//用于获取过滤器的名字

*public ServletContext getServletContent();//获取Servlet上下文

*public String getInitParameter(String name);//获取过滤器的初始化参数值

*public Enumeration getInitParameterNames();//获取过滤器的所有初始化参数

[5]FilterChain接口

public void doFilter(ServletRequest request request,ServletResponse response)throws IOException , ServletException

[6]过滤器的配置

 

[html] viewplaincopyprint?

1.   
2.     <</SPAN>filter>  
3.           
4.         <</SPAN>filter-name>CharactorFilter</</SPAN>filter-name>  
5.           
6.         <</SPAN>filter-class>com.lyq.CharactorFilter</</SPAN>filter-class>  
7.           
8.         <</SPAN>init-param>  
9.               
10.             <</SPAN>param-name>encoding</</SPAN>param-name>  
11.               
12.             <</SPAN>param-value>UTF-8</</SPAN>param-value>  
13.         </</SPAN>init-param>  
14.     </</SPAN>filter>  
15.       
16.     <</SPAN>filter-mapping>  
17.           
18.         <</SPAN>filter-name>CharactorFilter</</SPAN>filter-name>  
19.           
20.         <</SPAN>url-pattern>/*</</SPAN>url-pattern>  
21.     </</SPAN>filter-mapping>  

                                        CharactorFilter                                com.lyq.CharactorFilter                                                                                encoding                                                UTF-8                                                                        CharactorFilter                                /*        

[7]实现字符乱码过滤器处理实例

JSP文件

[html] viewplaincopyprint?

1. <</SPAN>body>  
2.     <</SPAN>form action="AddServlet" method="post">  
3.     <</SPAN>table align="center" border="1" width="350">  
4.         <</SPAN>tr>  
5.             <</SPAN>td class="2" align="center" colspan="2">  
6.                 <</SPAN>h2>添加图书信息</</SPAN>h2>  
7.             </</SPAN>td>  
8.         </</SPAN>tr>  
9.         <</SPAN>tr>  
10.             <</SPAN>td align="right">图书编号：</</SPAN>td>  
11.             <</SPAN>td>  
12.                 <</SPAN>input type="text" name="id">  
13.             </</SPAN>td>  
14.         </</SPAN>tr>  
15.         <</SPAN>tr>  
16.             <</SPAN>td align="right">图书名称：</</SPAN>td>  
17.             <</SPAN>td>  
18.                 <</SPAN>input type="text" name="name">  
19.             </</SPAN>td>  
20.         </</SPAN>tr>  
21.         <</SPAN>tr>  
22.             <</SPAN>td align="right">作　　者：</</SPAN>td>  
23.             <</SPAN>td>  
24.                 <</SPAN>input type="text" name="author">  
25.             </</SPAN>td>  
26.         </</SPAN>tr>  
27.         <</SPAN>tr>  
28.             <</SPAN>td align="right">价　　格：</</SPAN>td>  
29.             <</SPAN>td>  
30.                 <</SPAN>input type="text" name="price">  
31.             </</SPAN>td>  
32.         </</SPAN>tr>  
33.         <</SPAN>tr>  
34.             <</SPAN>td class="2" align="center" colspan="2">  
35.                 <</SPAN>input type="submit" value="添　加">  
36.             </</SPAN>td>  
37.         </</SPAN>tr>  
38.     </</SPAN>table>  
39. </</SPAN>form>  
40.  </</SPAN>body>  

添加图书信息

图书编号：图书名称：作　　者：价　　格：

servlet文件

[html] viewplaincopyprint?

1. public void doPost(HttpServletRequest request, HttpServletResponse response)  
2.             throws ServletException, IOException {  
3.         request.setCharacterEncoding("utf-8");  
4.         response.setContentType("text/html;charset=utf-8");  
5.         //获取PrintWriter  
6.         PrintWriter out = response.getWriter();  
7.         //获取图书编号  
8.         String id = request.getParameter("id");  
9.         //获取图书名称  
10.         String name=request.getParameter("name");  
11.         //获取作者  
12.         String author =request.getParameter("author");  
13.         //获取价格  
14.         String price= request.getParameter("price");  
15.         //添加成功  
16.         out.print("<</SPAN>h2>图书信息添加成功</</SPAN>h2><</SPAN>hr>");  
17.         out.print("图书编号:"+id+"<</SPAN>br>");  
18.         out.print("图书名称:"+name+"<</SPAN>br>");  
19.         out.print(" 作者:"+author+"<</SPAN>br>");  
20.         out.print("体格:"+price+"<</SPAN>br>");  
21.         out.flush();//刷新流  
22.         out.close();//关闭流  
23.     }  

public void doPost(HttpServletRequest request, HttpServletResponse response)                        throws ServletException, IOException {        request.setCharacterEncoding("utf-8");                response.setContentType("text/html;charset=utf-8");                //获取PrintWriter                PrintWriter out = response.getWriter();                //获取图书编号                String id = request.getParameter("id");                //获取图书名称                String name=request.getParameter("name");                //获取作者                String author =request.getParameter("author");                //获取价格                String price= request.getParameter("price");                //添加成功                out.print("

图书信息添加成功

---

");                out.print("图书编号:"+id+"
");                out.print("图书名称:"+name+"
");                out.print(" 作者:"+author+"
");                out.print("体格:"+price+"
");                out.flush();//刷新流                out.close();//关闭流        }

过滤器文件

[html] viewplaincopyprint?

1. package com.lyq;  
2. import java.io.IOException;  
3.   
4. import javax.servlet.Filter;  
5. import javax.servlet.FilterChain;  
6. import javax.servlet.FilterConfig;  
7. import javax.servlet.ServletException;  
8. import javax.servlet.ServletRequest;  
9. import javax.servlet.ServletResponse;  
10.   
11. public class CharactorFilter implements Filter {  
12.     // 字符编码  
13.     String encoding = null;  
14.     public void destroy() {  
15.         encoding = null;  
16.     }  
17.     public void doFilter(ServletRequest request, ServletResponse response,  
18.             FilterChain chain) throws IOException, ServletException {  
19.         // 判断字符编码是否为空  
20.         if(encoding != null){  
21.             // 设置request的编码格式  
22.             request.setCharacterEncoding(encoding);  
23.             // 设置response字符编码  
24.             response.setContentType("text/html; charset="+encoding);  
25.         }  
26.         // 传递给下一过滤器  
27.         chain.doFilter(request, response);  
28.     }  
29.     public void init(FilterConfig filterConfig) throws ServletException {  
30.         // 获取初始化参数  
31.         encoding = filterConfig.getInitParameter("encoding");  
32.     }  
33. }  

package com.lyq;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;public class CharactorFilter implements Filter {        // 字符编码        String encoding = null;        public void destroy() {                encoding = null;        }        public void doFilter(ServletRequest request, ServletResponse response,                        FilterChain chain) throws IOException, ServletException {                // 判断字符编码是否为空                if(encoding != null){                        // 设置request的编码格式                        request.setCharacterEncoding(encoding);                        // 设置response字符编码                response.setContentType("text/html; charset="+encoding);                }                // 传递给下一过滤器                chain.doFilter(request, response);        }        public void init(FilterConfig filterConfig) throws ServletException {                // 获取初始化参数                encoding = filterConfig.getInitParameter("encoding");        }}

web配置文件

[html] viewplaincopyprint?

1.   
2.     <</SPAN>filter>  
3.           
4.         <</SPAN>filter-name>CharactorFilter</</SPAN>filter-name>  
5.           
6.         <</SPAN>filter-class>com.lyq.CharactorFilter</</SPAN>filter-class>  
7.           
8.         <</SPAN>init-param>  
9.               
10.             <</SPAN>param-name>encoding</</SPAN>param-name>  
11.               
12.             <</SPAN>param-value>UTF-8</</SPAN>param-value>  
13.         </</SPAN>init-param>  
14.     </</SPAN>filter>  
15.       
16.     <</SPAN>filter-mapping>  
17.           
18.         <</SPAN>filter-name>CharactorFilter</</SPAN>filter-name>  
19.           
20.         <</SPAN>url-pattern>/*</</SPAN>url-pattern>  
21.     </</SPAN>filter-mapping>  
22.   <</SPAN>servlet>  
23.     <</SPAN>description>This is the description of my J2EE component</</SPAN>description>  
24.     <</SPAN>display-name>This is the display name of my J2EE component</</SPAN>display-name>  
25.     <</SPAN>servlet-name>AddServlet</</SPAN>servlet-name>  
26.     <</SPAN>servlet-class>com.lyq.AddServlet</</SPAN>servlet-class>  
27.   </</SPAN>servlet>  
28.      
29.   <</SPAN>servlet-mapping>  
30.     <</SPAN>servlet-name>AddServlet</</SPAN>servlet-name>  
31.     <</SPAN>url-pattern>/AddServlet</</SPAN>url-pattern>  
32.   </</SPAN>servlet-mapping>  
33.   <</SPAN>welcome-file-list>  
34.     <</SPAN>welcome-file>index.jsp</</SPAN>welcome-file>  
35.   </</SPAN>welcome-file-list>