使用过滤器为每个页面加一个公用的尾部

本文介绍了一种通过Servlet过滤器实现所有页面底部统一添加自定义Footer的方法。具体包括两个核心类：FootFilter用于实现过滤逻辑，FooltResponseWrapper用于包装HttpServletResponse对象以拦截输出。此外还展示了在web.xml中的配置方式。

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1，

package com.syyz.emp.filter;

import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

public class FootFilter implements Filter{

private String footer = null;

public void init(FilterConfig config) throws ServletException {
// TODO Auto-generated method stub
footer = config.getInitParameter("footer");
}

public void destroy() {
// TODO Auto-generated method stub

}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stubr
//响应对象进行封装
FooltResponseWrapper wrapper = new FooltResponseWrapper((HttpServletResponse)response);
//调用链中下一下对象
chain.doFilter(request, response);
//响应数据修改处理
CharArrayWriter outbuffer = new CharArrayWriter();
String outstring = wrapper.toString();
//取得</doby>标记的位置，准备插入foot
int position = outstring.indexOf("<body>")-1;
outbuffer.write("<hr/>"+footer+"<hr/><body><html>");
response.setContentType("gbk");
PrintWriter out = response.getWriter();
out.write(outbuffer.toString());
out.flush();
out.close();
}

}

2，

package com.syyz.emp.filter;

import java.io.CharArrayWriter;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

//想所有的页面输出尾部
public class FooltResponseWrapper extends HttpServletResponseWrapper{

private CharArrayWriter buffer = null;

public FooltResponseWrapper(HttpServletResponse response) {
super(response);
buffer = new CharArrayWriter();
// TODO Auto-generated constructor stub
}

//取得字符数组输出流的字符输出流
public PrintWriter getWriter(){
return new PrintWriter(buffer);

}

public String toString(){
return buffer.toString();
}

}

3配置：

<filter>
<filter-name>FootFilter</filter-name>
<filter-class>com.syyz.emp.filter.FootFilter</filter-class>
<init-param>
<param-name>footer</param-name>
<param-value>@syyz POWERED BY SYYZ --zjs</param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>FootFilter</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>