修改Request 中的数据

拦截器修改参数

@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object handler) throws Exception {
//在这里request中获取参数并修改。
return true;
}

@Override
public void postHandle(HttpServletRequest request,
HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {

}

@Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex)
throws Exception {

}

于是我看了

HttpServletRequestWrapper

源码，在

Filter

中测试了，发现可以成功修改传递过来的参数

public class HTMLFilter implements Filter {

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

FilteredRequest requestWrapper = new FilteredRequest((HttpServletRequest) request);
requestWrapper.getParameter("paramName");
chain.doFilter(new FilteredRequest(request), response);
}

static class FilteredRequest extends HttpServletRequestWrapper {

public FilteredRequest(ServletRequest request) {
super((HttpServletRequest) request);
}

public String getParameter(String paramName) {
String value = super.getParameter(paramName);
return value + "modify";
}

}

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

public void init(FilterConfig paramFilterConfig) throws ServletException {
// TODO Auto-generated method stub

}

}

测试结果如下图

接下来我们分析下代码

request.getParameter("paramName")

package javax.servlet

ServletRequest

ServletRequest

public abstract String getParameter(String paramString);

package javax.servlet;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.Map;

public abstract interface ServletRequest
{
public abstract Object getAttribute(String paramString);

public abstract Enumeration<String> getAttributeNames();

public abstract String getCharacterEncoding();

public abstract void setCharacterEncoding(String paramString)  throws UnsupportedEncodingException;

public abstract int getContentLength();

public abstract String getContentType();

public abstract ServletInputStream getInputStream()   throws IOException;

public abstract String getParameter(String paramString);

public abstract Enumeration<String> getParameterNames();

public abstract String[] getParameterValues(String paramString);

public abstract Map<String, String[]> getParameterMap();

public abstract String getProtocol();

public abstract String getScheme();

public abstract String getServerName();

public abstract int getServerPort();

public abstract BufferedReader getReader()   throws IOException;

public abstract String getRemoteAddr();

public abstract String getRemoteHost();

public abstract void setAttribute(String paramString, Object paramObject);

public abstract void removeAttribute(String paramString);

public abstract Locale getLocale();

public abstract Enumeration<Locale> getLocales();

public abstract boolean isSecure();

public abstract RequestDispatcher getRequestDispatcher(String paramString);

/**
* @deprecated
*/
public abstract String getRealPath(String paramString);

public abstract int getRemotePort();

public abstract String getLocalName();

public abstract String getLocalAddr();

public abstract int getLocalPort();

public abstract ServletContext getServletContext();

public abstract AsyncContext startAsync()  throws IllegalStateException;

public abstract AsyncContext startAsync(ServletRequest paramServletRequest, ServletResponse paramServletResponse)   throws IllegalStateException;

public abstract boolean isAsyncStarted();

public abstract boolean isAsyncSupported();

public abstract AsyncContext getAsyncContext();

public abstract DispatcherType getDispatcherType();
}

public String getParameter(String paramName) {
String value = super.getParameter(paramName);
return value + "modify";
}

super.getParameter

ServletRequestWrapper

public String getParameter(String name)
{
return request.getParameter(name);
}

public class ServletRequestWrapper  implements ServletRequest

ServletRequest

Controller

request.getParameter("paramName")

ServletRequest

HttpServletRequestWrapper

public class HttpServletRequestWrapper   extends ServletRequestWrapper   implements HttpServletRequest
{
public HttpServletRequestWrapper(HttpServletRequest request)
{
super(request);
}

private HttpServletRequest _getHttpServletRequest() {
return (HttpServletRequest)super.getRequest();
}

public String getAuthType()
{
return _getHttpServletRequest().getAuthType();
}

public Cookie[] getCookies()
{
return _getHttpServletRequest().getCookies();
}

public long getDateHeader(String name)
{
return _getHttpServletRequest().getDateHeader(name);
}

public String getHeader(String name)
{
return _getHttpServletRequest().getHeader(name);
}

public Enumeration<String> getHeaders(String name)
{
return _getHttpServletRequest().getHeaders(name);
}

public Enumeration<String> getHeaderNames()
{
return _getHttpServletRequest().getHeaderNames();
}

public int getIntHeader(String name)
{
return _getHttpServletRequest().getIntHeader(name);
}

public String getMethod()
{
return _getHttpServletRequest().getMethod();
}

public String getPathInfo()
{
return _getHttpServletRequest().getPathInfo();
}

public String getPathTranslated()
{
return _getHttpServletRequest().getPathTranslated();
}

public String getContextPath()
{
return _getHttpServletRequest().getContextPath();
}

public String getQueryString()
{
return _getHttpServletRequest().getQueryString();
}

public String getRemoteUser()
{
return _getHttpServletRequest().getRemoteUser();
}

public boolean isUserInRole(String role)
{
return _getHttpServletRequest().isUserInRole(role);
}

public Principal getUserPrincipal()
{
return _getHttpServletRequest().getUserPrincipal();
}

public String getRequestedSessionId()
{
return _getHttpServletRequest().getRequestedSessionId();
}

public String getRequestURI()
{
return _getHttpServletRequest().getRequestURI();
}

public StringBuffer getRequestURL()
{
return _getHttpServletRequest().getRequestURL();
}

public String getServletPath()
{
return _getHttpServletRequest().getServletPath();
}

public HttpSession getSession(boolean create)
{
return _getHttpServletRequest().getSession(create);
}

public HttpSession getSession()
{
return _getHttpServletRequest().getSession();
}

public boolean isRequestedSessionIdValid()
{
return _getHttpServletRequest().isRequestedSessionIdValid();
}

public boolean isRequestedSessionIdFromCookie()
{
return _getHttpServletRequest().isRequestedSessionIdFromCookie();
}

//省略底下的方法