白话Spring（中级篇）---拦截器（上）

[一知半解，就是给自己挖坑]

本文我们来演示SpringMVC中使用的拦截器的配置与使用方法，作为中级篇的内容，我们将不会设计源码解读。有兴趣的读者请参考官方文档及源码进行学习。

准备工作：

a.操作系统：win7 x64

b.开发工具：eclipse mars j2ee版本，maven3.3.2，Spring 4
-----------------------------------------------------------------------------------------------------------------------------------------------------------
1.使用maven创建web-app工程interceptor工程，工程具体结构如下：



2.配置pom文件，具体内容如下：【注：此pom文件直接从别的工程复制而来，可能引入了多余的包】

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion>
<groupId>com.java.maven</groupId>
<artifactId>interceptor</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>interceptor Maven Webapp</name>
<url>http://maven.apache.org</url>
<properties>
<build.file.encoding>UTF-8</build.file.encoding>
<cpu.version>1.0-SNAPSHOT</cpu.version>
<cpu.common.version>1.0.0-SNAPSHOT</cpu.common.version>
<jsp.version>2.0</jsp.version>
<servlet-api.version>6.1.5</servlet-api.version>
<spring.version>4.0.5.RELEASE</spring.version>
<mybatis.version>3.3.0</mybatis.version>
<junit.version>4.5</junit.version>
<dubbo.version>2.8.4.RELEASE</dubbo.version>
<zkclient.version>0.1</zkclient.version>
<zookeeper.version>3.4.6</zookeeper.version>
<tomcat-jdbc.version>7.0.53</tomcat-jdbc.version>
<aspectj.version>1.6.11</aspectj.version>
<jdbc.driver.groupId>org.postgresql</jdbc.driver.groupId>
<jdbc.driver.artifactId>postgresql</jdbc.driver.artifactId>
<jdbc.driver.version>9.4-1205-jdbc4</jdbc.driver.version>
<uap.version>0.9-SNAPSHOT</uap.version>
<mybatis-spring.version>1.2.3</mybatis-spring.version>
<shiro.version>1.2.4</shiro.version>
<commons-codec.version>1.9</commons-codec.version>
<esapi.version>2.1.0</esapi.version>
<oauth2.version>1.0.0</oauth2.version>
<springside.version>4.3.0-RELEASE</springside.version>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>

<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>

<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.4</version>
</dependency>
<!-- spring -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!--spring end -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>${aspectj.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.13</version>
</dependency>
</dependencies>
<build>
<finalName>interceptor</finalName>
</build>
</project>

3.配置web.xml文件，具体内容如下：

<?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/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>Shiro11</display-name>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<filter>
<filter-name>encoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encoding</filter-name>
<url-pattern>*</url-pattern>
</filter-mapping>
<servlet>
<servlet-name>springMvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-mvc.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>springMvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>

4.配置spring-mvc.xml文件，具体内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc"
xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
<context:component-scan base-package="interceptor" />
<!-- 视图处理 -->
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"></property>
<property name="suffix" value=".jsp"></property>
</bean>
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/helloworld"/>
<bean class="interceptor.HelloWorldInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
</beans>

5.创建HelloWorldController.java文件，具体内容如下：

package interceptor;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

/**
*@author 作者 E-mail：ingo
*@version 创建时间：2016年3月29日下午19:03:31
*类说明
*/
@Controller
@RequestMapping(value="helloworld")
public class HelloWorldController {
@RequestMapping(method=RequestMethod.POST)
public ModelAndView sayHello(String fname,String lname){
System.out.println("hello");
ModelAndView mv = new ModelAndView();
System.out.println("fname:"+fname);
System.out.println("lname:"+lname);
mv.setViewName("/hello");
return mv;
}
}

6.创建index.jsp，hello.jsp，具体内容如下：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>login</title>
</head>
<body>
<form action="helloworld" method="post">
<p>First name: <input type="text" name="fname" /></p>
<p>Last name: <input type="text" name="lname" /></p>
<input type="submit" value="Submit" />
</form>
</body>
</html>

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
helloworld
</body>
</html>

--------------------------------------------------------------------------------------------------------------------------------------------------------

准备工作完了，重头戏来了，各位看官请睁大眼睛！！！

--------------------------------------------------------------------------------------------------------------------------------------------------------

7.创建HelloWorldInterceptor.java文件，具体内容如下：

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

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class  HelloWorldInterceptor implements HandlerInterceptor {

/**
* preHandle方法是进行处理器拦截用的，顾名思义，该方法将在Controller处理之前进行调用，SpringMVC中的Interceptor拦截器是链式的，可以同时存在
* 多个Interceptor，然后SpringMVC会根据声明的前后顺序一个接一个的执行，而且所有的Interceptor中的preHandle方法都会在
* Controller方法调用之前调用。SpringMVC的这种Interceptor链式结构也是可以进行中断的，这种中断方式是令preHandle的返
* 回值为false，当preHandle的返回值为false的时候整个请求就结束了。
*/
@Override
public boolean preHandle(HttpServletRequest request,
HttpServletResponse response, Object handler) throws Exception {
System.out.println("preHandle");
return true;
}

/**
* 这个方法只会在当前这个Interceptor的preHandle方法返回值为true的时候才会执行。postHandle是进行处理器拦截用的，它的执行时间是在处理器进行处理之
* 后，也就是在Controller的方法调用之后执行，但是它会在DispatcherServlet进行视图的渲染之前执行，也就是说在这个方法中你可以对ModelAndView进行操
* 作。这个方法的链式结构跟正常访问的方向是相反的，也就是说先声明的Interceptor拦截器该方法反而会后调用，这跟Struts2里面的拦截器的执行过程有点像，
* 只是Struts2里面的intercept方法中要手动的调用ActionInvocation的invoke方法，Struts2中调用ActionInvocation的invoke方法就是调用下一个Interceptor
* 或者是调用action，然后要在Interceptor之前调用的内容都写在调用invoke之前，要在Interceptor之后调用的内容都写在调用invoke方法之后。
*/
@Override
public void postHandle(HttpServletRequest request,
HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
// TODO Auto-generated method stub
System.out.println("postHandle");
}

/**
* 该方法也是需要当前对应的Interceptor的preHandle方法的返回值为true时才会执行。该方法将在整个请求完成之后，也就是DispatcherServlet渲染了视图执行，
* 这个方法的主要作用是用于清理资源的，当然这个方法也只能在当前这个Interceptor的preHandle方法的返回值为true时才会执行。
*/
@Override
public void afterCompletion(HttpServletRequest request,
HttpServletResponse response, Object handler, Exception ex)
throws Exception {
// TODO Auto-generated method stub
System.out.println("afterCompletion");
}

}

8.测试方法：部署项目到tomcat，在浏览器中输入localhost/interceptor/helloworld观察控制台，浏览器界面变化。

--------------------------------------------------------------------------------------------------------------------------------------------------------

至此，白话Spring（中级篇）---拦截器（上）结束

参考资料：

spring官方文档

其他博文：http://haohaoxuexi.iteye.com/blog/1750680