java修改请求参数的值
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网上查了一些资料,解决方案是使用Wrapper,重写HttpServletRequestWrapper,如下:
package com.gdcn.bpaf.security.yale;
import java.util.Enumeration;
import java.util.Map;
import java.util.Vector;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
@SuppressWarnings("unchecked")
public class ParameterRequestWrapper extends HttpServletRequestWrapper {
private Map params;
public ParameterRequestWrapper(HttpServletRequest request, Map newParams) {
super(request);
this.params = newParams;
}
public Map getParameterMap() {
return params;
}
public Enumeration getParameterNames() {
Vector l = new Vector(params.keySet());
return l.elements();
}
public String[] getParameterValues(String name) {
Object v = params.get(name);
if (v == null) {
return null;
} else if (v instanceof String[]) {
return (String[]) v;
} else if (v instanceof String) {
return new String[] { (String) v };
} else {
return new String[] { v.toString() };
}
}
public String getParameter(String name) {
Object v = params.get(name);
if (v == null) {
return null;
} else if (v instanceof String[]) {
String[] strArr = (String[]) v;
if (strArr.length > 0) {
return strArr[0];
} else {
return null;
}
} else if (v instanceof String) {
return (String) v;
} else {
return v.toString();
}
}
}
�0�22.使用
//然后在另一个地方使用时,按下面这样用,假如我要修改username的值
HashMap m=new HashMap(request.getParameterMap());
/*
关键部分,如果不转换成String数组,如果在下面这样是有时:
eg:
HttpSession session = request.getSession();
Map map = request.getParameterMap();
Set keySet = map.keySet();
for (Iterator iterator = keySet.iterator(); iterator.hasNext();)
{
String key = (String)iterator.next();
String values[] = (String[])map.get(key); //这个地方就会报错,因为username一个String不能转换成String数组
if (values.length == 1)
session.setAttribute(key, values[0]);
else
session.setAttribute(key, values);
}
异常
就会出现java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.String;
package com.gdcn.bpaf.security.yale;
import java.util.Enumeration;
import java.util.Map;
import java.util.Vector;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
@SuppressWarnings("unchecked")
public class ParameterRequestWrapper extends HttpServletRequestWrapper {
private Map params;
public ParameterRequestWrapper(HttpServletRequest request, Map newParams) {
super(request);
this.params = newParams;
}
public Map getParameterMap() {
return params;
}
public Enumeration getParameterNames() {
Vector l = new Vector(params.keySet());
return l.elements();
}
public String[] getParameterValues(String name) {
Object v = params.get(name);
if (v == null) {
return null;
} else if (v instanceof String[]) {
return (String[]) v;
} else if (v instanceof String) {
return new String[] { (String) v };
} else {
return new String[] { v.toString() };
}
}
public String getParameter(String name) {
Object v = params.get(name);
if (v == null) {
return null;
} else if (v instanceof String[]) {
String[] strArr = (String[]) v;
if (strArr.length > 0) {
return strArr[0];
} else {
return null;
}
} else if (v instanceof String) {
return (String) v;
} else {
return v.toString();
}
}
}
�0�22.使用
//然后在另一个地方使用时,按下面这样用,假如我要修改username的值
HashMap m=new HashMap(request.getParameterMap());
/*
关键部分,如果不转换成String数组,如果在下面这样是有时:
eg:
HttpSession session = request.getSession();
Map map = request.getParameterMap();
Set keySet = map.keySet();
for (Iterator iterator = keySet.iterator(); iterator.hasNext();)
{
String key = (String)iterator.next();
String values[] = (String[])map.get(key); //这个地方就会报错,因为username一个String不能转换成String数组
if (values.length == 1)
session.setAttribute(key, values[0]);
else
session.setAttribute(key, values);
}
异常
就会出现java.lang.ClassCastException: java.lang.String cannot be cast to [Ljava.lang.String;
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