servlet利用拦截器改写request和response

这些天在对一个项目进行二次开发，要对输入和输出的数据做一些修改，但是上一个开发人员没有进行良好的封装，所有数据直接从request.getParameter()，获取，然后response.getWrite()直接进行输出操作,如果我要一个一个程序去修改的话，应用程序上40多个servlet都得改程序，第一工作量比较大，第二自己看着恶心，以后出了问题BOSS还得找我，所以干脆想了个办法，利用拦截器继承改写request和response，这样所有进入应用程序的数据都在我的掌控下了。具体实现见如下代码！

1.web.xml的拦截器配置

<filter>  <filter-name>changeResponseFilter</filter-name>  <filter-class>*.filter.ChangeResponseFilter</filter-class>  </filter>  <filter-mapping>  <filter-name>changeResponseFilter</filter-name>  <url-pattern>*</url-pattern>  </filter-mapping>

2.拦截器实现

package com.bjfulei.robo.machine.filter;import java.io.IOException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;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.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.bjfulei.robo.machine.util.ThreeDES;import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;import BO.inter.param.InGeneralParam;import BO.systools.ListMgr;import net.sf.json.JSONObject;/**** Title:ChangeResponseFilter.java* Description: * Company: www.bjfulei.com.cn* author： mingliang* mail: [e-mail]* date: 2016年8月23日 下午6:54:58 */public class ChangeResponseFilter implements Filter {public void destroy() {}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {MyResponseWrapper responseWrapper = new MyResponseWrapper((HttpServletResponse) response);MyRequestWrapper requestWrapper = new MyRequestWrapper((HttpServletRequest) request);chain.doFilter(requestWrapper, responseWrapper);MyWriter writer = responseWrapper.getMyWriter();if (writer != null) {String content = writer.getContent();response.getWriter().write(ListMgr.string2Unicode2(<span style="font-family: Arial, Helvetica, sans-serif;">content</span>));response.getWriter().flush();response.getWriter().close();}}public void init(FilterConfig arg0) throws ServletException {}}

3.request改写类

package com.bjfulei.robo.machine.filter;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;public class MyRequestWrapper extends HttpServletRequestWrapper {private Map<String,String> paramMap;public MyRequestWrapper(HttpServletRequest request) {super(request);paramMap =getParameterMap(request);}/** * FIXME 修改后的获取参数方法 * @param name * @return */public String getParameter(String name){return paramMap.get(name);}/** * FIXME 修改参数值的方法 * @param name * @return */public String updateParameter(String name,String value){return paramMap.put(name,value);}public Map<String,String> getParameterMap(){return paramMap;}@SuppressWarnings("rawtypes")public static Map<String,String> getParameterMap(HttpServletRequest request) {    // 参数Map    Map properties = request.getParameterMap();    // 返回值Map    Map<String,String> returnMap = new HashMap<String,String>();    Iterator entries = properties.entrySet().iterator();    Map.Entry entry;    String name = "";    String value = "";    while (entries.hasNext()) {        entry = (Map.Entry) entries.next();        name = (String) entry.getKey();        Object valueObj = entry.getValue();        if(null == valueObj){            value = "";        }else if(valueObj instanceof String[]){            String[] values = (String[])valueObj;            for(int i=0;i<values.length;i++){                value = values[i] + ",";            }            value = value.substring(0, value.length()-1);        }else{            value = valueObj.toString();        }        returnMap.put(name, value);    }    return returnMap;}}

4.response改写类

package com.bjfulei.robo.machine.filter;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpServletResponseWrapper;public class MyResponseWrapper extends HttpServletResponseWrapper {private MyWriter myWriter;public MyResponseWrapper(HttpServletResponse response) {super(response);try {myWriter = new MyWriter(response.getWriter());} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}@Overridepublic PrintWriter getWriter() throws IOException {return myWriter;}public MyWriter getMyWriter() {return myWriter;}}

package com.bjfulei.robo.machine.filter;import java.io.PrintWriter;public class MyWriter extends PrintWriter{private StringBuilder buffer;public MyWriter(PrintWriter out) {super(out);buffer = new StringBuilder();}@Overridepublic void write(char[] buf, int off, int len) {// super.write(buf, off, len);char[] dest = new char[len];System.arraycopy(buf, off, dest, 0, len);buffer.append(dest);}@Overridepublic void write(char[] buf) {super.write(buf);}@Overridepublic void write(int c) {super.write(c);}@Overridepublic void write(String s, int off, int len) {super.write(s, off, len);}@Overridepublic void write(String s) {//super.write(s);buffer.append(s);}public String getContent(){return buffer.toString();}public void flush(){    }public void close(){    }}

利用拦截器实现了所有输入输出数据流的自定义，分享到博客来，希望对新手有所帮助！