Spring - Spring集成web环境 -基本三层架构搭建案例

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文章目录

Spring集成web环境-基本三层架构搭建

新建项目（案例）

new project-maven-骨架-选择setting.xml路径

编写一些类和接口

导入需要依赖

   <dependencies>
     <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>5.1.32</version>
     </dependency>

     <dependency>
       <groupId>c3p0</groupId>
       <artifactId>c3p0</artifactId>
       <version>0.9.1.2</version>
     </dependency>

     <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>druid</artifactId>
       <version>1.1.10</version>
     </dependency>

     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
       <version>4.12</version>
       <scope>test</scope>
     </dependency>

     <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-context</artifactId>
       <version>5.0.5.RELEASE</version>
     </dependency>

     <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-test</artifactId>
       <version>5.0.5.RELEASE</version>
     </dependency>
         </dependencies>

spring.xml和properties文件

<?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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

<!--    加载外部的properties文件-->
    <context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder>
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/mybatis"></property>
        <property name="user" value="root"></property>
        <property name="password" value="$12345"></property>

    </bean>

<!--    配置Dao-->
    <bean id="userDao" class="com.taotao.dao.impl.UserDaoImpl"></bean>

<!--    配置service-->
    <bean id="userService" class="com.taotao.service.impl.UserServiceImpl">
        <property name="userDao" ref="userDao"/>
    </bean>
</beans>

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=12345

添加servlet、jsp、tomcat依赖

    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>3.0.1</version>
      <scope>provided</scope>
    </dependency>

    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.2.1</version>
      <scope>provided</scope>
    </dependency>


  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.tomcat.maven</groupId>
        <artifactId>tomcat7-maven-plugin</artifactId>
        <version>2.2</version>
      </plugin>
    </plugins>

  </build>

模拟web层

编写servlet

webServlet = userServlet

package com.taotao.web;

import com.taotao.service.UserService;
import com.taotao.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

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;

/**
 * create by 刘鸿涛
 * 2022/4/14 20:25
 */
@SuppressWarnings("all")
@WebServlet("/userServlet")
public class UserServlet extends HttpServlet 
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        UserServiceImpl userServiceImpl = app.getBean(UserServiceImpl.class);
        userServiceImpl.save();
    

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
        this.doGet(req, resp);

成功测试运行

Spring集成web环境-ContextLoderListener监听器的分析

监听器演示

编写类实现监听器

package com.taotao.listener;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * create by 刘鸿涛
 * 2022/4/14 20:55
 */
@SuppressWarnings("all")
public class ContextLoaderListener implements ServletContextListener 

    public void contextInitialized(ServletContextEvent servletContextEvent) 
        //初始化Spring容器
        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        //将Spring的应用上下文对象存储到ServletContest域中
        ServletContext servletContext = servletContextEvent.getServletContext();
        servletContext.setAttribute("app",app);
    

    public void contextDestroyed(ServletContextEvent servletContextEvent)

在web.xml配置监听器

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Archetype Created Web Application</display-name>
  
<!--  配置监听器-->
  <listener>
    <listener-class>com.taotao.listener.ContextLoaderListener</listener-class>
  </listener>
</web-app>

重新编写servlet

package com.taotao.web;

import com.taotao.service.UserService;
import com.taotao.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
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;

/**
 * create by 刘鸿涛
 * 2022/4/14 20:25
 */
@SuppressWarnings("all")
@WebServlet("/userServlet")
public class UserServlet extends HttpServlet 
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
//        ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext.xml");
        ServletContext servletContext = this.getServletContext();
        //向上转型
        ApplicationContext app = (ApplicationContext) servletContext.getAttribute("app");
        UserServiceImpl userServiceImpl = app.getBean(UserServiceImpl.class);
        userServiceImpl.save();
    

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
        this.doGet(req, resp);

成功测试运行

解耦spring.xml

撤除加载容器

package com.taotao.listener;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * create by 刘鸿涛
 * 2022/4/14 20:55
 */
@SuppressWarnings("all")
public class ContextLoaderListener implements ServletContextListener 

    public void contextInitialized(ServletContextEvent servletContextEvent) 
        //初始化Spring容器
        ApplicationContext app = new ClassPathXmlApplicationContext("");
        //将Spring的应用上下文对象存储到ServletContest域中
        ServletContext servletContext = servletContextEvent.getServletContext();
        servletContext.setAttribute("app",app);
    

    public void contextDestroyed(ServletContextEvent servletContextEvent)

编写web.xml

<!--  全局初始化参数-->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>applicationContext.xml</param-value>
  </context-param>

读取web.xml中全局参数

重新编写ContextLoaderListener.java

package com.taotao.listener;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * create by 刘鸿涛
 * 2022/4/14 20:55
 */
@SuppressWarnings("all")
public class ContextLoaderListener implements ServletContextListener 

    public void contextInitialized(ServletContextEvent servletContextEvent) 

        ServletContext servletContext = servletContextEvent.getServletContext();

        //读取web.xml中的全局参数
        String contextConfigLocation = servletContext.getInitParameter("contextConfigLocation");
        //初始化Spring容器
        ApplicationContext app = new ClassPathXmlApplicationContext(contextConfigLocation);
        //将Spring的应用上下文对象存储到ServletContest域中

        servletContext.setAttribute("app",app);
    

    public void contextDestroyed(ServletContextEvent servletContextEvent)

成功测试运行

解耦app对象1

创建编写类

 package com.taotao.listener;

import org.springframework.context.ApplicationContext;

import javax.servlet.ServletContext;

/**
 * create by 刘鸿涛
 * 2022/4/14 21:21
 */
@SuppressWarnings("all")
public class WebApplicationContextUtils 
    public static ApplicationContext getWebApplicationContext(ServletContext servletContext)
        return (ApplicationContext) servletContext.getAttribute("app");

编写Servlet

package com.taotao.web;

import com.taotao.listener.WebApplicationContextUtils;
import com.taotao.service.UserService;
import com.taotao.service.impl.UserServiceImpl;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax

Spring集成web环境


ApplicationContext应用上下文获取方式

应用上下文对象是通过new ClasspathXmlApplicationContext(spring配置文件) 方式获取的，但是每次从容器中获得Bean时都要编写new ClasspathXmlApplicationContext(spring配置文件)，这样的弊端是配置文件加载多次，应用上下文对象创建多次。

在Web项目中，可以使用ServletContextListener监听Web应用的启动，我们可以在Web应用启动时，就加载Spring的配置文件，创建应用上下文对象ApplicationContext，在将其存储到最大的域servletContext域中，这样就可以在任意位置从域中获得应用上下文ApplicationContext对象了。


Spring提供获取应用上下文的工具


Spring提供了一个监听器ContextLoaderListener就是对上述功能的封装，该监听器内部加载Spring配置文件，创建应用上下文对象，并存储到ServletContext域中，提供了一个客户端工具WebApplicationContextUtils供使用者获得应用上下文对象。

所以我们需要做的只有两件事：

1在web.xml中配置ContextLoaderListener监听器（导入spring-web坐标）

2使用WebApplicationContextUtils获得应用上下文对象ApplicationContext


导入Spring集成web的坐标


<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>5.0.5.RELEASE</version>
</dependency>



配置ContextLoaderListener监听器


<!--全局参数-->
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</context-param>
<!--Spring的监听器-->
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>



通过工具获得应用上下文对象


//在servlet 中
ServletContext servletContext = this.getServletContext();
ApplicationContext applicationContext =WebApplicationContextUtils.getWebApplicationContext(servletContext);
Object obj = applicationContext.getBean("id");//根据模块

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