装饰者模式

/**
 *装饰者模式：
 *	a.装饰者类和被装饰者类必须实现同一个接口或继承同一个类
 *	b.在装饰者类中,必须要有被装饰者的引用
 *	c.在装饰者类中对需要增强的方法,进行增强
 *	d.在装饰者类中对不需要增强的方法,调用原来的业务逻辑
 *HttpServletRequestWrapper：
 *	提供HttpServletRequest接口的实现,Servlet开发人员只要继承子类接口就可以了.
 *
 */

import java.io.IOException;
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 {
			HttpServletRequest req = (HttpServletRequest) request;
			String method = req.getMethod();
			if("get".equalsIgnoreCase(method)){
				MyRequest myRequest = new MyRequest(req);
				//放行
				chain.doFilter(myRequest, response);
			}else if("post".equalsIgnoreCase(method)){
				req.setCharacterEncoding("utf-8");
				//放行
				chain.doFilter(req, response);
			}else{
				//放行
				chain.doFilter(request, response);
			}
	}

	@Override
	public void destroy() {

	}

}

import java.io.UnsupportedEncodingException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class MyRequest extends HttpServletRequestWrapper{

	public MyRequest(HttpServletRequest request) {
		super(request);
	}
	
	@Override
	public String getParameter(String name) {
		//获取乱码的内容
		String value = super.getParameter(name);
		try {
			return new String(value.getBytes("iso-8859-1"),"utf-8");
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return super.getParameter(name);
	}
	
}