手摸手，一起來學習SpringBoot 2（一）準備工作之回顧XML方式配置Spring

前言

相信在平常的項目中，大家對SpringBoot已經用的滾瓜爛熟了，現在準備寫一系列文章來記錄、重溫下知識體系，以查缺補漏。文筆有限，多多包涵！

進入SpringBoot之前，先來回顧下用XML的方式配置Spring。

一、項目搭建

1. 創建maven項目xmlssm，不需要選模版
   
   

2. 在pom.xml中加入<packaging>war</packaging>聲明打成war包

3. 右擊項目選擇open module setting，然後在Module下點擊+號選擇Web，設置如下：
   
   

二、項目配置

1. 在pom中加入SpringMVC依賴

   <?xml version="1.0" encoding="UTF-8"?>
   <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/xsd/maven-4.0.0.xsd">
       <modelVersion>4.0.0</modelVersion>
   
       <groupId>com.junya</groupId>
       <artifactId>xmlssm</artifactId>
       <version>1.0-SNAPSHOT</version>
       <packaging>war</packaging>
   
       <dependencies>
           <dependency>
               <groupId>org.springframework</groupId>
               <artifactId>spring-webmvc</artifactId>
               <version>5.1.10.RELEASE</version>
           </dependency>
       </dependencies>
   
   </project>
   

2. 右鍵resources目錄，New -> XML Configuration File -> Spring Config，創建Spring的配置文件applicationContext.xml和SpringMVC的配置文件spring-servlet.xml。

   注：Spring容器是SpringMVC容器的父容器，子容器可以訪問父容器，而父容器訪問不到子容器的東西，一般Spring父容器用來掃描除controller之外的東西。

3. 新建controller和service包，在applicationContext.xml中配置如下：

   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
          xmlns:context="http://www.springframework.org/schema/context"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
   
       <context:component-scan base-package="com.junya" use-default-filters="true">
           <!-- 排除掉controller -->
           <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
       </context:component-scan>
   </beans>
   

   Spring-servlet.xml中配置如下：

   <?xml version="1.0" encoding="UTF-8"?>
   <beans xmlns="http://www.springframework.org/schema/beans"
          xmlns:context="http://www.springframework.org/schema/context"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns:mvc="http://www.springframework.org/schema/mvc"
          xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">
   
       <context:component-scan base-package="com.junya" use-default-filters="false">
           <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
       </context:component-scan>
       <mvc:annotation-driven/>
   </beans>
   

4. 在web.xml中加載兩個配置

   <?xml version="1.0" encoding="UTF-8"?>
   <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
            version="4.0">
   
       <context-param>
           <param-name>contextConfigLocation</param-name>
           <param-value>classpath:applicationContext.xml</param-value>
       </context-param>
       <listener>
           <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
       </listener>
       
       <servlet>
           <servlet-name>springmvc</servlet-name>
           <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
           <init-param>
               <param-name>contextConfigLocation</param-name>
               <param-value>classpath:spring-servlet.xml</param-value>
           </init-param>
       </servlet>
       <servlet-mapping>
           <servlet-name>springmvc</servlet-name>
           <url-pattern>/</url-pattern>
       </servlet-mapping>
   </web-app>
   

三、寫restful接口測試

1. 新建HelloService和HelloController類

   package com.junya.service;
   
   import org.springframework.stereotype.Service;
   
   /**
    * @program com.junya
    * @description:
    * @author: zhangchao
    * @date: 2020/05/12 23:19
    * @since: 1.0.0
    */
   @Service
   public class HelloService {
   
       public String sayHello() {
           return "你好啊！！";
       }
       
   }
   

   package com.junya.controller;
   
   import com.junya.service.HelloService;
   import org.springframework.beans.factory.annotation.Autowired;
   import org.springframework.web.bind.annotation.GetMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   /**
    * @program com.junya
    * @description: 測試
    * @author: zhangchao
    * @date: 2020/05/12 23:14
    * @since: 1.0.0
    */
   @RestController
   public class HelloController {
       @Autowired
       private HelloService helloService;
   
       @GetMapping("/hello")
       public String hello() {
           return helloService.sayHello();
       }
   
   }
   

2. 啓動Tomcat，訪問http://localhost:8080/hello

   有亂碼？只需在@GetMapping裏改下請求的編碼：

   @GetMapping(value = "/hello",produces = "text/html;charset=utf-8")
   

   重啓Tomcat：

   一切正常！