02-使用动态代理解决全局乱码问题

package www.test.web.filter;

import java.io.IOException;
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;

public class EncodingFilter implements Filter{

@Override
public void init(FilterConfig filterConfig) throws ServletException {
}

@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
final HttpServletRequest req = (HttpServletRequest) request;
//使用动态代码解决全局乱码问题
HttpServletRequest enhanceRequset = (HttpServletRequest) Proxy.newProxyInstance(
//loader ,和目标类相同的类加载器
request.getClass().getClassLoader(),
// interfaces  :代表与目标对象实现的所有接口字节码对象数组
request.getClass().getInterfaces(),

// h : 具体的操作，InvocationHandler接口
new InvocationHandler() {

@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
//对 getParameter 方法进行增强
String name = method.getName();//获得目标对象的方法名称
if("getParameter".equals(name)){
String invoke = (String) method.invoke(req, args);//乱码
//转码
invoke = new String(invoke.getBytes("iso8859-1"),"UTF-8");
return invoke;
}
return method.invoke(req, args);
}
});
chain.doFilter(enhanceRequset, response);
}

@Override
public void destroy() {
}

}

动态代理：实际开发中一般用于拦截。判断不同的角色，决定是否可以调用这个方法。