package com.yyb.filter;import java.io.IOException;
import javax.servlet.*;/*** Created by Administrator on 2017/7/28.*/
public class FilterDemo implements Filter {@Override//Filter创建的时候执行init方法public void init(FilterConfig filterConfig) throws ServletException {//1、获得web.xml中filter 的名称<filter-name>FilterDemo</filter-name>
        System.out.println(filterConfig.getFilterName());//2、获得当前filter的初始化参数System.out.println(filterConfig.getInitParameter("aaa"));//3、获得servletContext
        filterConfig.getServletContext();System.out.println("init ....");}@Override//doFilter是Filter的核心过滤的方法/** request: 内部封装是客户端http请求的内容* response: 代表是响应* FilterChain: 过滤器链对象*/public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {System.out.println("quick1 running....");//放行请求
        chain.doFilter(request, response);}@Override//Filter对象销毁的时候执行destory方法public void destroy() {System.out.println("destroy...");}
}

<filter><filter-name>FilterDemo</filter-name><filter-class>com.yyb.filter.FilterDemo</filter-class></filter><filter-mapping><filter-name>FilterDemo</filter-name><url-pattern>/*</url-pattern></filter-mapping>

<filter><filter-name>FilterDemo</filter-name><filter-class>com.yyb.filter.FilterDemo</filter-class></filter><filter-mapping><filter-name>FilterDemo</filter-name><url-pattern>/*</url-pattern></filter-mapping>

 <filter-mapping><filter-name>FilterDemo</filter-name><!--<url-pattern>/*</url-pattern>--><servlet-name>FilterTest</servlet-name><servlet-name>FilterTest1</servlet-name></filter-mapping>

  <filter><filter-name>FilterDemo</filter-name><filter-class>com.yyb.filter.FilterDemo</filter-class></filter><filter-mapping><filter-name>FilterDemo</filter-name><url-pattern>/*</url-pattern><dispatcher>REQUEST</dispatcher></filter-mapping>

package com.ithiema.web.filter;import java.io.IOException;
import java.io.UnsupportedEncodingException;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{@Overridepublic void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)throws IOException, ServletException {//request.setCharacterEncoding("UTF-8");//在传递request之前对request的getParameter方法进行增强/** 装饰者模式(包装)* * 1、增强类与被增强的类要实现统一接口* 2、在增强类中传入被增强的类* 3、需要增强的方法重写 不需要增强的方法调用被增强对象的* *///被增强的对象HttpServletRequest req = (HttpServletRequest) request;//增强对象EnhanceRequest enhanceRequest = new EnhanceRequest(req);chain.doFilter(enhanceRequest, response);}@Overridepublic void destroy() {}@Overridepublic void init(FilterConfig filterConfig) throws ServletException {}}class EnhanceRequest extends HttpServletRequestWrapper{private HttpServletRequest request;public EnhanceRequest(HttpServletRequest request) {super(request);this.request = request;}//对getParaameter增强
    @Overridepublic String getParameter(String name) {String parameter = request.getParameter(name);//乱码try {parameter = new String(parameter.getBytes("iso8859-1"),"UTF-8");} catch (UnsupportedEncodingException e) {e.printStackTrace();}return parameter;}
}

public @interface MyAnno {//注解的属性
    String name();int age() default 28;
}

 @MyAnno(name="",age=20)public  void  show(){}@MyAnno(name="")public  void  show1(){}

public @interface MyAnno2 {//String value();　　   String[]value();
}

    //@MyAnno2("aa")//public  void  show2(){//}@MyAnno3({"name","age"})public  void  show3(){}

import java.lang.reflect.Method;/*** Created by Administrator on 2017/7/28.*/
public class MyAnnoParse {public static void main(String[]args) throws NoSuchMethodException {//解析show方法上面的@MyAnno//直接的目的是 获得show方法上的@MyAnno中的参数//获得show方法的字节码对象Class clazz = MyAnnoTest.class;Method method = clazz.getMethod("show", String.class);//获得show方法上的@MyAnnoMyAnno annotation = method.getAnnotation(MyAnno.class);//获得@MyAnno上的属性值System.out.println(annotation.name());//zhangsanSystem.out.println(annotation.age());//28//根据业务需求写逻辑代码
    }
}

isAnnotationPresent(Class<? extends Annotation> annotationClass) ： 判断该字节码对象身上是否使用该注解了
getAnnotation(Class<A> annotationClass) ：获得该字节码对象身上的注解对象