package com.rlovep.filiter;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.DispatcherType;
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.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
/**
* 过滤器必须实现Filter接口
*
*/
/**
*
* @ClassName: HelloFiliter
* @Description: 监听器实现
* @author peace w_peace@163.com
* @date 18 Nov 2015 3:31:39 pm
*
*/
/*
* @WebFilter(urlPatterns="/*")
* urlPatterns="/*"过滤所有路径
* 参考servlet
* dispatcherTypes=DispatcherType.FORWARD触发过滤器的时机为转发。该值如果不写，时机为REQUEST
* initParams={@WebInitParam(name="encoding",value="utf-8"),
@WebInitParam(name="driver",value="msql"配置参数。
*/
@WebFilter(urlPatterns="/*",dispatcherTypes=DispatcherType.FORWARD,
initParams={@WebInitParam(name="encoding",value="utf-8"),
@WebInitParam(name="driver",value="msql")}
)
public class HelloFiliter implements Filter {
/**
* Default constructor.
*/
public HelloFiliter() {
System.out.println("filter构造");
}
public void init(FilterConfig fConfig) throws ServletException {
System.out.println("filter初始化");
//通过fConfig获得参数
FilterConfig filterConfig=fConfig;
String encoding=filterConfig.getInitParameter("encoding");
//或者通过迭代获得
Enumeration<String> names = filterConfig.getInitParameterNames();
while (names.hasMoreElements()) {
String string = (String) names.nextElement();
String value=filterConfig.getInitParameter(string);
System.out.println(string+"="+value);
}
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
System.out.println("对请求执行过滤");
// 放行 (去到service)
// 如果有下一个过滤器，进入下一个过滤器，否则就执行访问service
chain.doFilter(request, response);
System.out.println("对响应进行过滤");
}
public void destroy() {
System.out.println("filter消灭");
}
}