搭建SSM项目
提示
SpringBoot框架相较于Spring的优点:
- 快速创建项目
- 简化配置
- 简化代码
- 内嵌Servlet容器
- 容易部署
- 微服务
- ...
相较于SpringBoot的优点,传统SSM开发,项目创建复杂,需要进行大量配置,项目维护难度大。
SSM项目搭建流程:
- 建项目
- 引依赖
- 写配置
- 写代码
大体上就是这四步,下面开始搭建。
创建项目
打开Intellij IDEA,创建Maven项目。
GroupId: net.pjsk
ArtifactId: ssm
Version: 1.0-SNAPSHOT
引入依赖
项目创建好后引入需要的Maven依赖。
<?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>net.pjsk</groupId>
<artifactId>ssm</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!--springmvc-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.3.4</version>
</dependency>
<!-- Mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.5</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.5</version>
</dependency>
<!-- MySql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.21</version>
</dependency>
<!-- JDBC -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.3.4</version>
</dependency>
<!-- 数据库连接池 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.23</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<!-- 代码生成 -->
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.4.0</version>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.21</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
写配置
用到的依赖主要有Spring、SpringMVC、Mybatis、数据库连接、驱动相关的依赖。
依赖引进来之后开始进行基础的配置,配置好之后这些框架才能被使用,才能进行项目的开发。
在
resources
目录下新建datasource.properties
文件,用于保存数据库连接的信息。jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm_base
jdbc.username=root
jdbc.password=123456在
resources
目录下新建application.xml
文件,该文件是spring容器的配置文件。Spring的核心思想之一是IoC控制反转,它的实现方式是依赖注入,我们将用的到的依赖通通注册到容器中由Spring容器管理,并实现依赖注入。
<?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:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- springmvc -->
<mvc:annotation-driven/>
<mvc:default-servlet-handler/>
<!-- 组件扫描:会扫描Spring注解,被注解的Bean将会注册到Spring容器中 -->
<context:component-scan base-package="net.pjsk.*"/>
<!-- Mybatis -->
<!-- 引入数据库properties -->
<context:property-placeholder location="classpath:datasource.properties"/>
<!-- 数据库连接池 -->
<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
<property name="driverClassName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>
<!-- Mybatis核心对象 -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- mapper XML目录 -->
<property name="mapperLocations" value="classpath:mapper/*.xml"/>
<!-- 实体类别名 -->
<property name="typeAliasesPackage" value="net.pjsk.entity"/>
</bean>
<!-- Mapper扫描配置 -->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
<!-- mapper接口目录 -->
<property name="basePackage" value="net.pjsk.mapper"/>
</bean>
</beans>工程名右键,点击“添加框架支持”。
添加Web框架支持,项目会自动创建web目录。
|-web
|-WEB-INF
|-web.xml编辑web.xml。
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="https://jakarta.ee/xml/ns/jakartaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
version="5.0">
<servlet>
<servlet-name>springmvc</servlet-name>
<!-- 前置调度器:SpringMVC核心 -->
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<!-- 初始化参数 -->
<init-param>
<!-- 获取SpringMVC配置 (参数名不能写错)-->
<param-name>contextConfigLocation</param-name>
<!-- SpringMVC配置文件 -->
<param-value>classpath:application.xml</param-value>
</init-param>
<!-- 启动级别,随服务器一起启动 -->
<load-on-startup>1</load-on-startup>
</servlet>
<!-- servlet 映射 -->
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>将依赖添加到WEB-INF下的lib目录中,项目通过Tomcat启动后,会到该目录下读取所需依赖。如果没有添加,在运行时可能会报NoSuchXXX的错误。
写代码
配置写好后,就可以写代码了。
写Mapper
package net.pjsk.mapper;
import net.pjsk.entity.User;
import org.apache.ibatis.annotations.Param;
/**
* @author liyan
* @date 2021.2.27
*/
public interface UserMapper {
/**
* 通过id查询
*
* @param id
* @return
*/
User selectById(@Param("id") Long id);
}<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="net.pjsk.mapper.UserMapper">
<select id="selectById" resultType="user">
select *
from t_user u
where u.id = #{id}
</select>
</mapper>
写Service
package net.pjsk.service;
import net.pjsk.entity.User;
import org.springframework.stereotype.Service;
/**
* @author liyan
* @date 2021.2.27
*/
@Service
public interface IUserService {
/**
* 通过id查询
*
* @param id
* @return
*/
User getById(Long id);
}package net.pjsk.service.impl;
import net.pjsk.entity.User;
import net.pjsk.mapper.UserMapper;
import net.pjsk.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Optional;
/**
* @author liyan
* @date 2021.2.27
*/
@Service
public class UserServiceImpl implements IUserService {
@Autowired
private UserMapper userMapper;
@Override
public User getById(Long id) {
User user = this.userMapper.selectById(id);
return Optional.ofNullable(user).orElse(null);
}
}
写Controller
package net.pjsk.controller;
import net.pjsk.entity.User;
import net.pjsk.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import java.util.Optional;
/**
* @author liyan
* @date 2021.2.27
*/
@Controller
@RequestMapping(value = "user", produces = "application/json; charset=utf-8")
public class UserController {
@Autowired
private IUserService userService;
@ResponseBody
@GetMapping("/get/{id}")
public String getById(@PathVariable("id") Long id) {
User user = this.userService.getById(id);
return Optional.ofNullable(user).map(User::toString).orElse("null");
}
}
测试
启动Tomcat测试。