过滤器

1. 过滤器基本概念:(3W1H: why, what, where，how)为什么需用到过滤器？项目开发中，经常会涉及到重复代码的实现！注册 ----> Servlet 【1. 设置编码】 ----> JSP修改 ----> Servlet 【1. 设置编码】 ---> JSP其他，如判断用户是否登陆，只有登陆才能有操作权限！

等的人心好烦

230人浏览 · 2017-12-03 14:54:15

等的人心好烦 · 2017-12-03 14:54:15 发布

1. 过滤器

基本概念:

(3W1H: why, what, where，how)

为什么需用到过滤器？

项目开发中，经常会涉及到重复代码的实现！

修改 ----> Servlet 【1. 设置编码】 ---> JSP

其他，

如判断用户是否登陆，只有登陆才能有操作权限！

涉及到重复判断：获取session，取出session数据，判断是否为空,为空说明没有登陆，不能操作；只有登陆后，才能操作！

如何解决：

1. 抽取重复代码，封装

2. 每个用到重复代码的地方，手动的调用！

过滤器，设计执行流程：

1. 用户访问服务器

2. 过滤器：对Servlet请求进行拦截

3. 先进入过滤器，过滤器处理

4. 过滤器处理完后，在放行，此时，请求到达Servlet/JSP

5. Servlet处理

6. Servlet处理完后，再回到过滤器, 最后在由tomcat服务器相应用户；

(过滤器就像回家的门！)

过滤器,HelloWorld案例

Javax.servlet.*;

|-- interface Filter 及过滤器

开发步骤：

1. 写一个普通java类，实现Filter接口

2. 配置过滤器

HelloFilter.java:

package cn.itcast.a_filter_hello;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/*
 * 过滤器,测试
 */
public class HelloFilter implements Filter{
	//创建实例
	public HelloFilter(){
		System.out.println("1.创建过滤器实例");
	}
	
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("2.执行过滤器初始化方法");
	}

	

	//过滤器业务处理方法,在请求到达servlet之前先进入此方法处理共用的业务逻辑操作
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("3.执行过滤器业务处理方法");
		//放行(去到Servlet)
		chain.doFilter(request,response);
		System.out.println("5.Servlet处理完成,又回到过滤器");
	}
	@Override
	public void destroy() {
		System.out.println("6.销毁过滤器实例");
		
	}
}

IndexServlet.java:

package cn.itcast.a_filter_hello;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class IndexServlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		System.out.println("4. 处理用户请求开始");
	}

}

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
  <!-- 过滤器配置 -->
  <filter>
  	<!-- 内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 过滤器类的全名 -->
    <filter-class>cn.itcast.a_filter_hello.HelloFilter</filter-class>
  </filter>
  <filter-mapping>
  	<!-- filter内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 拦截所有资源 -->
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <servlet>
    <servlet-name>IndexServlet</servlet-name>
    <servlet-class>cn.itcast.a_filter_hello.IndexServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>IndexServlet</servlet-name>
    <url-pattern>/index</url-pattern>
  </servlet-mapping>
</web-app>

配置多个过滤器:

HelloFilter2.java:

package cn.itcast.a_filter_hello;

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;

public class HelloFilter2 implements Filter{

	

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		System.out.println("第二个过滤器");
		//放行
		chain.doFilter(request, response);
		System.out.println("第二个过滤器执行结束");
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		// TODO Auto-generated method stub
		
	}
	@Override
	public void destroy() {
		// TODO Auto-generated method stub
		
	}
}

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:web="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" version="2.4">
  <!-- 过滤器配置 -->
  <filter>
  	<!-- 内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 过滤器类的全名 -->
    <filter-class>cn.itcast.a_filter_hello.HelloFilter</filter-class>
  </filter>
  <filter-mapping>
  	<!-- filter内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 拦截所有资源 -->
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <!-- 配置第二个过滤器 -->
  <filter>
  	<filter-name>hello_filter2</filter-name>
  	<filter-class>cn.itcast.a_filter_hello.HelloFilter2</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>hello_filter2</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <servlet>
    <servlet-name>IndexServlet</servlet-name>
    <servlet-class>cn.itcast.a_filter_hello.IndexServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>IndexServlet</servlet-name>
    <url-pattern>/index</url-pattern>
  </servlet-mapping>
</web-app>

过滤器执行流程

OOAD 面向对象的分析与设计

使用RationRose 时序图

过滤器相关API

|-- interface Filter 过滤器核心接口

Void init(filterConfig); 初始化方法，在服务器启动时候执行

Void doFilter(request,response,filterChain); 过滤器拦截的业务处理方法

Voiddestroy(); 销毁过滤器实例时候调用

|-- interface FilterConfig 获取初始化参数信息

String	getInitParameter(java.lang.String name)
Enumeration	getInitParameterNames()

web.xml中配置:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <!-- 过滤器配置 -->
  <filter>
  	<!-- 配置初始化参数 -->
  	<init-param>
		<param-name>encoding</param-name>
		<param-value>UTF-8</param-value>
	</init-param>
	<init-param>
		<param-name>path</param-name>
		<param-value>c:/...</param-value>
	</init-param>
  	<!-- 内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 过滤器类的全名 -->
    <filter-class>cn.itcast.a_filter_hello.HelloFilter</filter-class>
  </filter>
  <filter-mapping>
  	<!-- filter内部名称 -->
    <filter-name>hello_filter</filter-name>
    <!-- 拦截所有资源 -->
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <!-- 配置第二个过滤器 -->
  <filter>
  	<filter-name>hello_filter2</filter-name>
  	<filter-class>cn.itcast.a_filter_hello.HelloFilter2</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>hello_filter2</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <servlet>
    <servlet-name>IndexServlet</servlet-name>
    <servlet-class>cn.itcast.a_filter_hello.IndexServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>IndexServlet</servlet-name>
    <url-pattern>/index</url-pattern>
  </servlet-mapping>
</web-app>

HelloFilter.java:

@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("2.执行过滤器初始化方法");
		
		//获取过滤器在web.xml中配置的初始化参数
		String encoding=filterConfig.getInitParameter("encoding");
		System.out.println(encoding);
		
		//获取过滤器在web.xml中配置的初始化参数的名称
		Enumeration<String> enums=filterConfig.getInitParameterNames();
		while(enums.hasMoreElements()){
			//获取所有参数的名称:encoding,path
			String name=enums.nextElement();
			//获取名称对应的值
			String value=filterConfig.getInitParameter(name);
			System.out.println(name+"\t"+value);
		}
	}

|-- interface FilterChain 过滤器链参数；一个个过滤器形成一个执行链；

voiddoFilter(ServletRequest request, ServletResponse response) ; 执行下一个过滤器或放行

对指定的请求拦截

/* 表示拦截所有的请求

<filter-mapping>

<filter-name>hello_filter2</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

默认拦截的类型：(直接访问或者重定向)

<dispatcher>REQUEST</dispatcher>

拦截转发：

<dispatcher>FORWARD</dispatcher>

拦截包含的页面(RequestDispatcher.include(/page.jsp); 对page.jsp也执行拦截)

<dispatcher>INCLUDE</dispatcher>

拦截声明式异常信息：

<dispatcher>ERROR</dispatcher>

web.xml:

<!-- 配置第二个过滤器 -->
  <!-- 演示:拦截指定的请求 -->
  <filter>
  	<filter-name>hello_filter2</filter-name>
  	<filter-class>cn.itcast.a_filter_hello.HelloFilter2</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>hello_filter2</filter-name>
  		<!-- 1. 拦截所有
		<url-pattern>/*</url-pattern>
		 -->
		 
		 <!-- 2. 拦截指定的jsp 
		 <url-pattern>/index.jsp</url-pattern>
		 <url-pattern>/list.jsp</url-pattern>
		 -->
		 <!-- 拦截所有的jsp
		 <url-pattern>*.jsp</url-pattern>
		  -->
		 <!-- 3. 根据servlet的内部名称拦截
		 <servlet-name>IndexServlet</servlet-name>
		 -->
		 <!-- 拦截指定的servlet 
		 <url-pattern>/index</url-pattern>
		 -->
		 <!-- 4. 指定拦截指定的类型 -->
		 <url-pattern>/*</url-pattern>
		 <!-- 拦截直接访问的请求或者重定向的资源 -->
		 <dispatcher>REQUEST</dispatcher>
		 <!--<dispatcher>FORWARD</dispatcher>--> 
	</filter-mapping>
  
  <servlet>
    <servlet-name>IndexServlet</servlet-name>
    <servlet-class>cn.itcast.a_filter_hello.IndexServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>IndexServlet</servlet-name>
    <url-pattern>/index</url-pattern>
  </servlet-mapping>

ServletTest.java:

package cn.itcast.a_filter_hello;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletTest extends HttpServlet{
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
	}
}

IndexServlet.java:

package cn.itcast.a_filter_hello;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class IndexServlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		//response.sendRedirect(request.getContextPath()+"/servletTest");
		request.getRequestDispatcher("/servletTest").forward(request, response);
	}

}

共性问题：

1.      过滤器：方法参数没有自动命名，说明没有关联源码

--à 关联tomcat或servlet源代码

         2.连接池：多刷新几次，报错！

                   -à 连接没关

                            QueryRunnerqr = new QueryRunner();

                            qr.update(con,sql);

                            // 这里con一定要关闭

             -à注意：dataSource确定一个项目创建一次

                            QueryRunner qr =new QueryRunner(dataSource);

                   à 修改连接池参数配置

         3. 编码

                   //设置POST提交的请求的编码

                   request.setCharacterEncoding("UTF-8");

                   //设置相应体的编码

                   response.setCharacterEncoding("UTF-8");

                   //设置页面打开时候时候的编码格式、设置相应体的编码

                   response.setContentType("text/html;charset=UTF-8");

                   开发中：

                            工作区间编码、项目编码、request/response、数据库编码一致！

2.案例

过滤器-编码统一处理

几乎每一个Servlet都要涉及编码处理：处理请求数据中文问题！

【GET/POST】

每个servlet都要做这些操作，把公用的代码抽取-过滤器实现！

代码实现思路:

1. Login.jsp 登陆，输入“中文”

2. LoginServlet.java 直接处理登陆请求

3. EncodingFilter.java 过滤器处理请求数据编码：GET/POST

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
  </head>
  
  <body>
  	<form name="frmLogin" action="${pageContext.request.contextPath }/login" method="post">
  	   用户名: <input type="text" name="userName"><br/>
  	  <input type="submit" value="POST提交" >
  	</form>
  	<hr/>
  	<form name="frmLogin" action="${pageContext.request.contextPath }/login" method="get">
  	   用户名: <input type="text" name="userName"><br/>
  	  <input type="submit" value="GET提交" >
  	</form>
  </body>
</html>

LoginServlet.java:

package cn.itcast.a_loginFilter;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		// 获取请求数据 
		String name = request.getParameter("userName");
		System.out.println("用户：" + name);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doGet(request, response);
	}

}

EncodingFilter.java:

package cn.itcast.a_loginFilter;

import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

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.HttpServletResponse;

/**
 * 编码处理统一写到这里(servlet中不需要再处理编码)
 */
public class EncodingFilter implements Filter {

	// 过滤器业务处理方法：处理的公用的业务逻辑操作
	@Override
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		
		// 转型
		final HttpServletRequest request = (HttpServletRequest) req;    
		HttpServletResponse response = (HttpServletResponse) res;
		
		// 一、处理公用业务
		request.setCharacterEncoding("UTF-8");					// POST提交有效
		response.setContentType("text/html;charset=UTF-8");
		
		/*
		 * 出现GET中文乱码，是因为在request.getParameter方法内部没有进行提交方式判断并处理。
		 * String name = request.getParameter("userName");
		 * 
		 * 解决：对指定接口的某一个方法进行功能扩展，可以使用代理!
		 *      对request对象(目标对象)，创建代理对象！
		 */
		HttpServletRequest proxy =  (HttpServletRequest) Proxy.newProxyInstance(
				request.getClass().getClassLoader(), 		// 指定当前使用的累加载器
				new Class[]{HttpServletRequest.class}, 		// 对目标对象实现的接口类型
				new InvocationHandler() {					// 事件处理器
					@Override
					public Object invoke(Object proxy, Method method, Object[] args)
							throws Throwable {
						// 定义方法返回值
						Object returnValue = null;
						// 获取方法名
						String methodName = method.getName();
						// 判断：对getParameter方法进行GET提交中文处理
						if ("getParameter".equals(methodName)) {
							
							// 获取请求数据值【 <input type="text" name="userName">】
							String value = request.getParameter(args[0].toString());	// 调用目标对象的方法
							
							// 获取提交方式
							String methodSubmit = request.getMethod(); // 直接调用目标对象的方法
							
							// 判断如果是GET提交，需要对数据进行处理  (POST提交已经处理过了)
							if ("GET".equals(methodSubmit)) {
								if (value != null && !"".equals(value.trim())){
									// 处理GET中文
									value = new String(value.getBytes("ISO8859-1"),"UTF-8");
								}
							} 
							return value;
						}
						else {
							// 执行request对象的其他方法
							returnValue = method.invoke(request, args);
						}
						
						return returnValue;
					}
				});
		
		// 二、放行 (执行下一个过滤器或者servlet)
		chain.doFilter(proxy, response);		// 传入代理对象
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		
	}

	@Override
	public void destroy() {
		
	}
}

web.xml:

<!--1.  编码处理过滤器配置-->
	<filter>
		<filter-name>encoding</filter-name>
		<filter-class>cn.itcast.a_loginFilter.EncodingFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>encoding</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
<servlet>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>cn.itcast.a_loginFilter.LoginServlet</servlet-class>
	</servlet>
<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>

过滤器-无效数据过滤

模拟：论坛过滤敏感词汇！

实现思路：

1. Dis.jsp 讨论区页面

2. DisServlet.java 处理提交

---》获取请求参数

---》保存到request域

-----》跳转dis.jsp 【从request取数据显示(处理后)】

3. DataFilter.java 过滤器

----》编码

---》无效数据处理

即：在上一个案例基础上，再添加无效数据过滤的相关代码!

JSP引入ckeditor组件：客户端组件，便于用户输入内容！

dis.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">   
	<!-- 引入ckeditor组件(给用户输入提供方便) --> 
	<script src="${pageContext.request.contextPath }/ckeditor/ckeditor.js"></script>
	<link rel="stylesheet" href="${pageContext.request.contextPath }/ckeditor/samples/sample.css">
  </head>
</html>

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
	
	<!--1.  编码处理过滤器配置-->
	<filter>
		<filter-name>encoding</filter-name>
		<filter-class>cn.itcast.a_loginFilter.EncodingFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>encoding</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	 
	 
	 <!-- 2. 无效数据过滤器配置 -->
	 <filter>
	 	<filter-name>dataFilter</filter-name>
	 	<filter-class>cn.itcast.b_filter_data.DateFilter</filter-class>
	 </filter>
	 <filter-mapping>
	 	<filter-name>dataFilter</filter-name>
	 	<url-pattern>/*</url-pattern>
	 </filter-mapping>
	
	<servlet>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>cn.itcast.a_loginFilter.LoginServlet</servlet-class>
	</servlet>
  <servlet>
    <servlet-name>DisServlet</servlet-name>
    <servlet-class>cn.itcast.b_filter_data.DisServlet</servlet-class>
  </servlet>



	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
  <servlet-mapping>
    <servlet-name>DisServlet</servlet-name>
    <url-pattern>/dis</url-pattern>
  </servlet-mapping>
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

DisServlet.java

package cn.itcast.b_filter_data;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DisServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		// 获取请求数据 
		String content = request.getParameter("content");
		// 保存到request
		request.setAttribute("content", "Content：" + content);
		// 转发
		request.getRequestDispatcher("/dis.jsp").forward(request, response);
		
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doGet(request, response);
	}

}

DateFilter.java

package cn.itcast.b_filter_data;

import java.io.IOException;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.List;

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.HttpServletResponse;

/**
 * 无效数据过滤
 */
public class DateFilter implements Filter {
	
	// 初始化无效数据
	private List<String> dirtyData;
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		// 模拟几个数据
		dirtyData = new ArrayList<String>();
		dirtyData.add("NND");
		dirtyData.add("炸使馆");
	}

	@Override
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		
		// 转型
		final HttpServletRequest request = (HttpServletRequest) req;    
		HttpServletResponse response = (HttpServletResponse) res;
		
		// 一、处理公用业务
		request.setCharacterEncoding("UTF-8");					// POST提交有效
		response.setContentType("text/html;charset=UTF-8");
		
		HttpServletRequest proxy =  (HttpServletRequest) Proxy.newProxyInstance(
				request.getClass().getClassLoader(), 		// 指定当前使用的累加载器
				new Class[]{HttpServletRequest.class}, 		// 对目标对象实现的接口类型
				new InvocationHandler() {					// 事件处理器
					@Override
					public Object invoke(Object proxy, Method method, Object[] args)
							throws Throwable {
						// 定义方法返回值
						Object returnValue = null;
						// 获取方法名
						String methodName = method.getName();
						// 判断：对getParameter方法进行GET提交中文处理
						if ("getParameter".equals(methodName)) {
							
							// 获取请求数据值【 <input type="text" name="userName">】
							String value = request.getParameter(args[0].toString());	// 调用目标对象的方法
							
							// 获取提交方式
							String methodSubmit = request.getMethod(); // 直接调用目标对象的方法
							
							// 判断如果是GET提交，需要对数据进行处理  (POST提交已经处理过了)
							if ("GET".equals(methodSubmit)) {
								if (value != null && !"".equals(value.trim())){
									// 处理GET中文
									value = new String(value.getBytes("ISO8859-1"),"UTF-8");
								}
							} 
							
							// 中文数据已经处理完： 下面进行无效数据过滤   
							//【如何value中出现dirtyData中数据，用****替换】  
							for (String data : dirtyData) {
								// 判断当前输入数据(value), 是否包含无效数据
								if (value.contains(data)){
									value = value.replace(data, "*****");
								}
							}
							// 处理完编码、无效数据后的正确数据
							return value;
						}
						else {
							// 执行request对象的其他方法
							returnValue = method.invoke(request, args);
						}
						
						return returnValue;
					}
				});
		
		// 二、放行 (执行下一个过滤器或者servlet)
		chain.doFilter(proxy, response);		// 传入代理对象
	}



	@Override
	public void destroy() {
		
	}
}

登陆权限判断

登陆，提交到登陆Servlet处理其业务！

-à登陆成功, 跳转到首页，显示欢迎信息+ 列表信息

-à登陆失败，跳转到登陆！

要求：

只有登陆后，才可以访问首页,显示列表

如果没有登陆，直接访问首页列表，要跳转到登陆!

实现思路：

1. Login.jsp 登陆页面

2. List.jsp 列表显示

3. LoginServlet.java 登陆处理servlet

4. IndexServlet.java 首页列表查询Servlet

5. LoginFilter.java 登陆验证过滤器

(用之前的表：

admin存储登陆用户, 登陆用

employee 存储员工信息，列表显示用！

)

实现步骤：

1. 建库、建表、建项目、引入jar文件

2. entity

a) Admin.java

b) Employee.java

3. Dao

a) AdminDao

b) EmployeeDao

4. Servcie

5. Servlet

6. Jsp

http://localhost:8080/emp_sys/login.jsp 可以直接访问

http://localhost:8080/emp_sys/login 可以直接访问

http://localhost:8080/emp_sys/index 不能直接访问

http://localhost:8080/emp_sys/list.jsp 不能直接访问

Admin.java:

package cn.itcast.entity;

/**
 * 1. 管理员实体类开发
 */
public class Admin {

	private int id; 
	private String userName;
	private String pwd;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPwd() {
		return pwd;
	}
	public void setPwd(String pwd) {
		this.pwd = pwd;
	}
	
	
}

Employee.java

package cn.itcast.entity;

/**
 * 1. 员工
 */
public class Employee {

	private int empId;
	private String empName;
	private int dept_id;
	
	public int getEmpId() {
		return empId;
	}
	public void setEmpId(int empId) {
		this.empId = empId;
	}
	public String getEmpName() {
		return empName;
	}
	public void setEmpName(String empName) {
		this.empName = empName;
	}
	public int getDept_id() {
		return dept_id;
	}
	public void setDept_id(int deptId) {
		dept_id = deptId;
	}
}

IAdminDao.java

package cn.itcast.dao;

import cn.itcast.entity.Admin;

/**
 * 2. 管理员数据访问层接口设计
 */
public interface IAdminDao {

	/**
	 * 根据用户名密码查询
	 * @param admin
	 * @return
	 */
	Admin findByNameAndPwd(Admin admin);
}

IEmployeeDao.java

package cn.itcast.dao;

import java.util.List;

import cn.itcast.entity.Employee;

/**
 * 2. 员工数据访问层接口设计
 */
public interface IEmployeeDao {

	/**
	 * 查询所有的员工
	 * @return
	 */
	List<Employee> getAll();
}

AdminDao.java

package cn.itcast.dao.impl;

import java.sql.SQLException;

import org.apache.commons.dbutils.handlers.BeanHandler;

import cn.itcast.dao.IAdminDao;
import cn.itcast.entity.Admin;
import cn.itcast.utils.JdbcUtils;

public class AdminDao implements IAdminDao {

	@Override
	public Admin findByNameAndPwd(Admin admin) {
		try {
			String sql = "select * from admin where userName=? and pwd=?";
			return JdbcUtils.getQueryRuner()//
					.query(sql, 
							new BeanHandler<Admin>(Admin.class),
							admin.getUserName(),
							admin.getPwd());
		} catch (SQLException e) {
			throw new RuntimeException(e);
		}
	}

}

EmployeeDao.java

package cn.itcast.dao.impl;

import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.handlers.BeanListHandler;

import cn.itcast.dao.IEmployeeDao;
import cn.itcast.entity.Employee;
import cn.itcast.utils.JdbcUtils;

public class EmployeeDao implements IEmployeeDao {

	@Override
	public List<Employee> getAll() {
		String sql = "select * from employee";
		try {
			return JdbcUtils.getQueryRuner()//
				.query(sql, new BeanListHandler<Employee>(Employee.class));
		} catch (SQLException e) {
			throw new RuntimeException(e);
		}
	}

}

IAdminService.java

package cn.itcast.service;

import cn.itcast.entity.Admin;

/**
 * 3. 管理员业务逻辑层
 */
public interface IAdminService {

	/**
	 * 根据用户名密码查询
	 * @param admin
	 * @return
	 */
	Admin findByNameAndPwd(Admin admin);
}

IEmployeeService.java

package cn.itcast.service;

import java.util.List;

import cn.itcast.entity.Employee;

/**
 * 2. 员工业务逻辑层
 * @author Jie.Yuan
 *
 */
public interface IEmployeeService {

	/**
	 * 查询所有的员工
	 * @return
	 */
	List<Employee> getAll();
}

AdminService.java

package cn.itcast.service.impl;

import cn.itcast.dao.IAdminDao;
import cn.itcast.dao.impl.AdminDao;
import cn.itcast.entity.Admin;
import cn.itcast.service.IAdminService;

public class AdminService implements IAdminService{
	
	// 创建dao对象
	private IAdminDao adminDao = new AdminDao();

	@Override
	public Admin findByNameAndPwd(Admin admin) {
		try {
			return adminDao.findByNameAndPwd(admin);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

}

EmployeeService.java

package cn.itcast.service.impl;

import java.util.List;

import cn.itcast.dao.IEmployeeDao;
import cn.itcast.dao.impl.EmployeeDao;
import cn.itcast.entity.Employee;
import cn.itcast.service.IEmployeeService;

public class EmployeeService implements IEmployeeService {

	private IEmployeeDao employeeDao = new EmployeeDao();
	
	@Override
	public List<Employee> getAll() {
		try {
			return employeeDao.getAll();
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

}

IndexServlet.java

package cn.itcast.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.entity.Admin;
import cn.itcast.entity.Employee;
import cn.itcast.service.IAdminService;
import cn.itcast.service.IEmployeeService;
import cn.itcast.service.impl.AdminService;
import cn.itcast.service.impl.EmployeeService;

public class IndexServlet extends HttpServlet {

	// Service实例
	private IEmployeeService employeeService = new EmployeeService();
	// 跳转资源
	private String uri;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		try {
			// 调用service查询所有
			List<Employee> list = employeeService.getAll();
			request.setAttribute("listEmp", list);
			// 进入首页jsp
			uri = "/list.jsp";
		} catch (Exception e) {
			e.printStackTrace();
			uri = "/error/error.jsp";
		}
		// 转发
		request.getRequestDispatcher(uri).forward(request, response);

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doGet(request, response);
	}

}

LoginServlet.java

package cn.itcast.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.itcast.entity.Admin;
import cn.itcast.service.IAdminService;
import cn.itcast.service.impl.AdminService;

/**
 * 处理登陆请求
 * @author Jie.Yuan
 *
 */
public class LoginServlet extends HttpServlet {
	// Service实例
	private IAdminService adminService = new AdminService();
	// 跳转资源
	private String uri;

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		request.setCharacterEncoding("UTF-8");
		
		//1. 获取参数
		String userName = request.getParameter("userName");
		String pwd = request.getParameter("pwd");
		// 封装
		Admin admin = new Admin();
		admin.setUserName(userName);
		admin.setPwd(pwd);
		
		try {
			//2. 调用service处理业务
			Admin loginInfo = adminService.findByNameAndPwd(admin);
			// 判断:
			if (loginInfo == null){
				// 登陆失败
				uri = "/login.jsp";
			} else {
				// 登陆成功
				// 先，保存数据到session
				request.getSession().setAttribute("loginInfo", loginInfo);
				// 再，跳转到首页显示servlet(/index)
				uri = "/index";
			}
		} catch (Exception e) {
			// 测试
			e.printStackTrace();
			// 错误
			uri = "/error/error.jsp";
		}
		
		//3. 跳转
		request.getRequestDispatcher(uri).forward(request, response);
		
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		this.doGet(request, response);
	}

}

JdbcUtils.java

package cn.itcast.utils;

import javax.sql.DataSource;

import org.apache.commons.dbutils.QueryRunner;

import com.mchange.v2.c3p0.ComboPooledDataSource;

/**
 * 工具类
 * 1. 初始化C3P0连接池
 * 2. 创建DbUtils核心工具类对象
 */
public class JdbcUtils {

	/**
	 *  1. 初始化C3P0连接池
	 */
	private static  DataSource dataSource;
	static {
		dataSource = new ComboPooledDataSource();
	}
	
	/**
	 * 2. 创建DbUtils核心工具类对象
	 */
	public static QueryRunner getQueryRuner(){
		// 创建QueryRunner对象，传入连接池对象
		// 在创建QueryRunner对象的时候，如果传入了数据源对象；
		// 那么在使用QueryRunner对象方法的时候，就不需要传入连接对象；
		// 会自动从数据源中获取连接(不用关闭连接)
		return new QueryRunner(dataSource);
	}
}

c3p0-config.xml

<c3p0-config>
  <default-config>
     <property name="driverClass">com.mysql.jdbc.Driver</property> 
     <property name="jdbcUrl">jdbc:mysql:///jdbc_demo</property> 
     <property name="user">root</property> 
     <property name="password">root</property> 
     <property name="initialPoolSize">5</property> 
     <property name="maxPoolSize">10</property> 

  </default-config>

<!--  
  <named-config name="oracleConfig">
    <property name="driverClass">com.mysql.jdbc.Driver</property> 
     <property name="jdbcUrl">jdbc:mysql:///day17</property> 
     <property name="user">root</property> 
     <property name="password">root</property> 
     <property name="initialPoolSize">5</property> 
     <property name="maxPoolSize">10</property> 
   </named-config>-->

</c3p0-config>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

	<!-- 登陆验证过滤器 -->
	<filter>
		<filter-name>loginFilter</filter-name>
		<filter-class>cn.itcast.filter.LoginFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>loginFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	
	<servlet>
		<servlet-name>LoginServlet</servlet-name>
		<servlet-class>cn.itcast.servlet.LoginServlet</servlet-class>
	</servlet>
	<servlet>
		<servlet-name>IndexServlet</servlet-name>
		<servlet-class>cn.itcast.servlet.IndexServlet</servlet-class>
	</servlet>


	<servlet-mapping>
		<servlet-name>LoginServlet</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>IndexServlet</servlet-name>
		<url-pattern>/index</url-pattern>
	</servlet-mapping>
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
</web-app>

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
  </head>
  
  <body>
    This is my JSP page. <br>
  </body>
</html>

list.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!-- 引入jstl核心标签库 -->
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
  </head>
  
  <body>
  	<h1>欢迎你，${sessionScope.loginInfo.userName }</h1>
  	<!-- 列表展示数据 -->
  	<table align="center" border="1" width="80%" cellpadding="3" cellspacing="0">
  		<tr>
  			<td>序号</td>
  			<td>编号</td>
  			<td>员工名称</td>
  		</tr>
  		<c:if test="${not empty requestScope.listEmp}">
	  		<c:forEach var="emp" items="${requestScope.listEmp}" varStatus="vs">
		  		<tr>
		  			<td>${vs.count }</td>
		  			<td>${emp.empId }</td>
		  			<td>${emp.empName }</td>
		  		</tr>
	  		</c:forEach>
  		</c:if>
  	</table>
  </body>
</html>

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
  </head>
  
  <body>
  <form name="frmLogin" action="${pageContext.request.contextPath }/login" method="post">
  	<table align="center" border="1">
  		<tr>
  			<td>用户名</td>
  			<td>
  				<input type="text" name="userName">
  			</td>
  		</tr>
  		<tr>
  			<td>密码</td>
  			<td>
  				<input type="password" name="pwd">
  			</td>
  		</tr>
  		<tr>
  			<td>
  				<input type="submit" value="亲，点我登陆！">
  			</td>
  		</tr>
  	</table>
  </form>
  </body>
</html>

LoginFilter.java

package cn.itcast.filter;

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;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * 登陆验证过滤器
 * 
 *  http://localhost:8080/emp_sys/login.jsp   可以直接访问
	http://localhost:8080/emp_sys/login      可以直接访问
	http://localhost:8080/emp_sys/index   不能直接访问
	http://localhost:8080/emp_sys/list.jsp   不能直接访问

 * @author Jie.Yuan
 *
 */
public class LoginFilter implements Filter {
	
	private String uri;

	/**
	 * 分析：
	 * 
		1. 先指定放行的资源，哪些资源不需要拦截：
		      login.jsp   +    /login  (request对象可以获取)
		2. 获取session，从session中获取登陆用户
		3. 判断是否为空：
		      为空， 说明没有登陆， 跳转到登陆
		       不为空， 已经登陆，放行！
	 */
	@Override
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		
		//0. 转换
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) res;
		
		//1. 获取请求资源，截取  
		String uri = request.getRequestURI();   // /emp_sys/login.jsp
		// 截取 【login.jsp或login】
		String requestPath = uri.substring(uri.lastIndexOf("/") + 1, uri.length());  
		
		//2. 判断： 先放行一些资源：/login.jsp、/login
		if ("login".equals(requestPath) || "login.jsp".equals(requestPath)) {
			// 放行
			chain.doFilter(request, response);
		}
		else {
			//3. 对其他资源进行拦截
			//3.1 先获取Session、获取session中的登陆用户(loginInfo)
			HttpSession session = request.getSession(false);
			// 判断
			if (session != null) {
				
				Object obj = session.getAttribute("loginInfo");
				
				//3.2如果获取的内容不为空，说明已经登陆，放行
				if (obj != null) {
					// 放行
					chain.doFilter(request, response);
				} else {
					//3.3如果获取的内容为空，说明没有登陆； 跳转到登陆
					uri = "/login.jsp";
				}
				
			} else {
				// 肯定没有登陆
				uri = "/login.jsp";
			}
			request.getRequestDispatcher(uri).forward(request, response);
		}
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
	}

	@Override
	public void destroy() {
	}

}

admin.sql

/*
SQLyog 企业版 - MySQL GUI v8.14 
MySQL - 5.5.40 
*********************************************************************
*/
/*!40101 SET NAMES utf8 */;

create table `admin` (
	`id` double ,
	`userName` varchar (90),
	`pwd` varchar (60)
); 
insert into `admin` (`id`, `userName`, `pwd`) values('1','123','123');

employee.sql

/*
SQLyog 企业版 - MySQL GUI v8.14 
MySQL - 5.5.40 
*********************************************************************
*/
/*!40101 SET NAMES utf8 */;

create table `employee` (
	`empId` double ,
	`empName` varchar (90),
	`dept_id` double 
); 
insert into `employee` (`empId`, `empName`, `dept_id`) values('1','李俊杰','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('2','何小青','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('3','Rose1','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('4','Rose2','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('5','Rose3','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('6','Rose4','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('7','Rose5','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('8','Rose6','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('9','Rose7','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('10','Rose8','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('11','Rose9','1');
insert into `employee` (`empId`, `empName`, `dept_id`) values('12','Rose10','1');

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