html:
<form action="/WEB24/EnCoding" method="get">
<input type="text" name="username">
<input type="submit" value="提交">
</form>
filter:
package web.filter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
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.HttpServletRequestWrapper;
public class EncodingFilter implements Filter{
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
//被增强的对象
final HttpServletRequest req = (HttpServletRequest) request;
HttpServletRequest newProxyInstance = (HttpServletRequest) Proxy.newProxyInstance(req.getClass().getClassLoader(),
req.getClass().getInterfaces(),
new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
String mothodName = method.getName();
if("getParameter".equals(mothodName)) {
String invoke = (String) method.invoke(req, args);
System.out.println("乱码"+invoke);
invoke = new String(invoke.getBytes("iso8859-1"),"UTF-8");
return invoke;
}
return method.invoke(req, args);
}
});
chain.doFilter(newProxyInstance, response);
}
@Override
public void destroy() {
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
}
servlet:
String parameter = request.getParameter("username");
System.out.println(parameter);
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write(parameter);
web.xml
<filter>
<filter-name>EncodingFilter</filter-name>
<filter-class>web.filter.EncodingFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>EncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>