过滤器拦截路径配置
1.具体资源路径：/index.jsp 只有访问index.jsp资源时，过滤器才会被执行
2.拦截目录：/user/* 访问/user下的所有资源时，过滤器都会被执行
3.后缀名拦截：*.jsp 访问所有jsp资源时，过滤器都会被执行
4.拦截所有资源：/* 访问所有资源时，过滤器都会被执行
package com.example.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
/*
过滤器快速入门程序
*/
//@WebFilter("/index.jsp")// 1.具体资源路径：/index.jsp 只有访问index.jsp资源时，过滤器才会被执行
//@WebFilter("/user/findAllServlet")// 2.拦截目录：/user/* 访问/user下的所有资源时，过滤器都会被执行
@WebFilter("*.jsp")// 3.后缀名拦截：*.jsp 访问所有jsp资源时，过滤器都会被执行
//@WebFilter("/*")// 4.访问所有资源之前,都会执行该过滤器
public class FilterDemo4 implements Filter {
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
System.out.println("filterDemo4...");
//放行
chain.doFilter(req, resp);
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void destroy() {
}
}
过滤器拦截方式配置
拦截方式配置：资源被访问的方式
注解配置：
设置dispatcherTypes属性
1.REQUEST：默认值，浏览器直接请求资源
2.FORWARD：转发访问资源
3.INCLUDE：包含访问资源
4.ERROR：错误跳转资源
5.ASYNC：异步访问资源
package com.example.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
// 浏览器直接请求index.jsp资源时，该过滤器会被执行
//@WebFilter(value = "/index.jsp",dispatcherTypes = DispatcherType.REQUEST)
// 只有转发访问index.jsp时，该过滤器才会被执行
//@WebFilter(value = "/index.jsp",dispatcherTypes = DispatcherType.FORWARD)
//浏览器直接请求index.jsp或者转发访问index.jsp。该过滤器才会被执行
@WebFilter(value = "/index.jsp",dispatcherTypes = {DispatcherType.FORWARD,DispatcherType.REQUEST})
public class FilterDemo5 implements Filter {
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
System.out.println("filterDemo5...");
//放行
chain.doFilter(req, resp);
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void destroy() {
}
}
servlet：
package com.example.servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet(name = "updateServlet", value = "/user/updateServlet")
public class ServletDemo2 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("updateServlet...");
//转发
request.getRequestDispatcher("/index.jsp").forward(request, response);
}
}
web.xml配置
设置<dispatcher></dispatcher>标签即可
<dispatcher>REQUEST</dispatcher>
过滤器链（配置多个过滤器）
执行顺序：如果有两个过滤器：过滤器1 和过滤器2
1.过滤器1
2.过滤器2
3.资源执行
4.过滤器2
5.过滤器1
package com.example.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter("/*")
public class FilterDemo6 implements Filter {
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
System.out.println("filterDemo6执行了...");
//放行
chain.doFilter(req, resp);
System.out.println("FilterDemo6回来了...");
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void destroy() {
}
}
package com.example.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter("/*")
public class FilterDemo7 implements Filter {
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
System.out.println("filterDemo7执行了...");
//放行
chain.doFilter(req, resp);
System.out.println("FilterDemo7回来了...");
}
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void destroy() {
}
}
过滤器先后顺序问题：
1.注解配置：按照类名的字符串比较规则，值小的先执行
如：AFilter 和 BFilter AFliter就先执行了（按类名大小来执行顺序的）
2.web.xml配置：<filter-mapping>谁定义在上边，谁先执行
<filter>
<filter-name>filedemo1</filter-name>
<filter-class>com.tomcat1.web.filter.FilterDemo7</filter-class>
</filter>
<filter-mapping>
<filter-name>filedemo1</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
<filter-name>filedemo2</filter-name>
<filter-class>com.tomcat1.web.filter.FilterDemo6</filter-class>
</filter>
<filter-mapping>
<filter-name>filedemo2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
标签：void,配置,jsp,过滤器,import,拦截,servlet,public From： https://www.cnblogs.com/qihaokuan/p/17072799.html