实现html标签转义功能

package cn.itcast.web.decorator;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;//对HttpServletRequest对象包装/装饰public class MyRequest extends HttpServletRequestWrapper{ 	//HttpServletRequestWrapper是适配器	//HttpServletRequestWrapper已经重写了request的所有方法，只不过是空方法，继承这个类既不用自己重写很多方法又能让自定义的类继承于request	private HttpServletRequest request;	public MyRequest(HttpServletRequest request) {		super(request);   //继承后必须的操作        可以不管		this.request = request;	}	//重写父类的方法	public String getParameter(String name) {//表单项的名字		String value = null;		//取得客户端的请求方式[GET/POST]		String method = request.getMethod();   //返回的必须是大写的		if("GET".equals(method)){   			try {				value = request.getParameter(name);//乱码				byte[] buf = value.getBytes("ISO8859-1");				value = new String(buf,"UTF-8");//正码			} catch (Exception e) {				e.printStackTrace();			}		}else if("POST".equals(method)){			try {				request.setCharacterEncoding("UTF-8");				value = request.getParameter(name);//正码			} catch (Exception e) {				e.printStackTrace();			}		}		value = filter(value);		return value;	}	//转义方法	public String filter(String message) {        if (message == null)            return (null);        char content[] = new char[message.length()];        message.getChars(0, message.length(), content, 0);        StringBuffer result = new StringBuffer(content.length + 50);        for (int i = 0; i < content.length; i++) {            switch (content[i]) {            case '<':                result.append("<");                break;            case '>':                result.append(">");                break;            case '&':                result.append("&");                break;            case '"':                result.append(""");                break;            default:                result.append(content[i]);            }        }        return (result.toString());    }}