最近做项目，发现要修改request的参数内容。因为想要在request的paramMap里面默认注入,modifier和modifierName,这些内容。但是这个Map是不能修改的。所以采用了如下办法：下面的办法网上也有的这里只做备份。
1. 创建request转换器
package com.tmall.lafite.web.base; import java.util.Enumeration;
import java.util.Map;
import java.util.Vector; import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper; class ParameterRequestWrapper extends HttpServletRequestWrapper { private Map<String, String[]> params; public ParameterRequestWrapper(HttpServletRequest request,
Map<String, String[]> newParams) {
super(request); this.params = newParams; // RequestDispatcher.forward parameter
renewParameterMap(request);
} @Override
public String getParameter(String name) {
String result = ""; Object v = params.get(name);
if (v == null) {
result = null;
} else if (v instanceof String[]) {
String[] strArr = (String[]) v;
if (strArr.length > 0) {
result = strArr[0];
} else {
result = null;
}
} else if (v instanceof String) {
result = (String) v;
} else {
result = v.toString();
} return result;
} @Override
public Map<String, String[]> getParameterMap() {
return params;
} @Override
public Enumeration<String> getParameterNames() {
return new Vector<String>(params.keySet()).elements();
} @Override
public String[] getParameterValues(String name) {
String[] result = null; Object v = params.get(name);
if (v == null) {
result = null;
} else if (v instanceof String[]) {
result = (String[]) v;
} else if (v instanceof String) {
result = new String[] { (String) v };
} else {
result = new String[] { v.toString() };
} return result;
} private void renewParameterMap(HttpServletRequest req) { String queryString = req.getQueryString(); if (queryString != null && queryString.trim().length() > 0) {
String[] params = queryString.split("&"); for (int i = 0; i < params.length; i++) {
int splitIndex = params[i].indexOf("=");
if (splitIndex == -1) {
continue;
} String key = params[i].substring(0, splitIndex); if (!this.params.containsKey(key)) {
if (splitIndex < params[i].length()) {
String value = params[i].substring(splitIndex + 1);
this.params.put(key, new String[] { value });
}
}
}
}
} }
2. 转换filter
package com.tmall.lafite.web.base; import java.io.IOException;
import java.util.HashMap;
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; public class ParamFilter implements Filter { @Override
public void init(FilterConfig filterConfig) throws ServletException {
// TODO Auto-generated method stub } @Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
Map<String, String[]> m = new HashMap<String, String[]>(
request.getParameterMap());
request = new ParameterRequestWrapper((HttpServletRequest) request, m); chain.doFilter(request, response);
} @Override
public void destroy() {
// TODO Auto-generated method stub } }
3. web.xml
<!-- request参数转化器 -->
<filter>
<filter-name>ParameterFilter</filter-name>
<filter-class>com.tmall.lafite.web.base.ParamFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>ParameterFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</filter-mapping>
本文转自：http://blog.csdn.net/a9529lty/article/details/25478989