后端工程创建过程（SSM框架搭建即项目初始化）

该后端工程的创建、开发过程均使用Intellij IDEA进行

1. 打开Intellij IDEA创建新的project，使用Spring Initializr创建springboot框架项目，步骤如下；

   
   创建springboot项目

填写Group和Artifact，其他默认 选择Web-Spring Web和SQL-Mybatis Framework、MySQL Driver 填写项目名称和项目存储路径，之后项目创建成功

注：必须开启maven的自动导入，即pom文件自动导入依赖库（在项目创建成功之后会在IDE右下方弹出提醒开启）

2. 完成mybatis相关的配置；

   
   创建mybatis-config.xml配置mybatis相关属性，代码如下：

// mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<!-- 配置文件的根元素 -->
<configuration>
    <!--配置全局属性-->
    <settings>
        <!--使用jdbc的getGeneratedKeys获取数据库自增主键值-->
        <setting name="useGeneratedKeys" value="true"/>
        <!--使用列标签替换列别名 默认未true-->
        <setting name="useColumnLabel" value="true" />
        <!--开启驼峰式命名转换：Table{create_time} -> Entity{createTime}-->
        <setting name="mapUnderscoreToCamelCase" value="true" />
    </settings>
</configuration>

完成spring配置（数据库、端口、配置文件路径等）代码如下：

// application.properties

#1.项目启动的端口
server.port=8080

#2.数据库连接参数
#2.1jdbc驱动，示数据库厂商决定，这是mysql的驱动
jdbc.driver=com.mysql.cj.jdbc.Driver
#2.2数据库连接url，包括ip(127.0.0.1)、端口(3306)、数据库名(testdb)
jdbc.url=jdbc:mysql://127.0.0.1:3306/ssm?useUnicode=true&characterEncoding=utf-8&useSSL=false
#2.3数据库账号名
jdbc.username=root
#2.4数据库密码
jdbc.password=511359588

#3.Mybatis配置
#3.1 mybatis配置文件所在路径
mybatis_config_file=mybatis-config.xml
#3.2 mapper文件所在路径，这样写可匹配mapper目录下的所有mapper，包括其子目录下的
mapper_path=/mapper/**/**.xml
#3.3 entity所在包
entity_package=com.evenzhu.ssm.entity

完成src路径下文件夹和class文件的创建，涉及代码如下：

// DataSourceConfiguration

package com.evenzhu.ssm.config.dao;


import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.beans.PropertyVetoException;

/**
 * 数据库配置类
 */
@Configuration
public class DataSourceConfiguration {

    @Value("${jdbc.driver}")
    private String jdbcDriver;
    @Value("${jdbc.url}")
    private String jdbcUrl;
    @Value("${jdbc.username}")
    private String jdbcUsername;
    @Value("${jdbc.password}")
    private String jdbcPassword;

    @Bean(name = "dataSouce")
    public ComboPooledDataSource createDataSouce() throws PropertyVetoException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass(jdbcDriver);
        dataSource.setJdbcUrl(jdbcUrl);
        dataSource.setUser(jdbcUsername);
        dataSource.setPassword(jdbcPassword);
        //关闭连接后不自动commit
        dataSource.setAutoCommitOnClose(false);
        return dataSource;
    }
}

// SessionFactoryConfiguration

package com.evenzhu.ssm.config.dao;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;
import java.io.IOException;

/**
 * 数据库sqlSession配置类
 */

@Configuration
public class SessionFactoryConfiguration {

    @Value("${mapper_path}")
    private String mapperPath;

    @Value("${mybatis_config_file}")
    private String mybatisConfigFilePath;

    @Autowired
    private DataSource dataSouce;
    @Value("${entity_package}")
    private String entityPackage;

    @Bean(name="sqlSessionFactory")
    public SqlSessionFactoryBean createSqlSessionFactoryBean() throws IOException {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setConfigLocation(new ClassPathResource(mybatisConfigFilePath));
        PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        String packageSearchPath = PathMatchingResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX+mapperPath;
        sqlSessionFactoryBean.setMapperLocations(resolver.getResources(packageSearchPath));
        sqlSessionFactoryBean.setDataSource(dataSouce);
        sqlSessionFactoryBean.setTypeAliasesPackage(entityPackage);
        return sqlSessionFactoryBean;
    }
}

// TransactionManagementConfiguration

package com.evenzhu.ssm.config.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.transaction.annotation.TransactionManagementConfigurer;

import javax.sql.DataSource;

/**
 * 事务配置类，不可缺少，尚未知具体作用
 */
@Configuration
@EnableTransactionManagement
public class TransactionManagementConfiguration implements TransactionManagementConfigurer{

    @Autowired
    private DataSource dataSource;

    @Override
    public PlatformTransactionManager annotationDrivenTransactionManager() {
        return new DataSourceTransactionManager(dataSource);
    }
}

// TestController

package com.evenzhu.ssm.controller;

import com.evenzhu.ssm.entity.TestEntity;
import com.evenzhu.ssm.service.TestService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/demoproject/test")
public class TestController {

    @Autowired
    private TestService testService ;

    @RequestMapping(value = "/get/{id}",method = RequestMethod.GET)
    public TestEntity test(@PathVariable Integer id){
        System.out.println("id:" + id);
        return testService.getById(id);
    }
}

3.运行项目会报错，那是因为项目缺少一些依赖，需要在pom中添加依赖；

在pom文件中添加第三方库的依赖，代码如下：

    <dependencies>
        ...
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
        </dependency>


        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

4.截止到目前已经完成了ssm项目的初步配置，接下来需要完成数据库操作相关的配置和代码；

创建以上文件夹和文件，涉及代码如下：

// TestDao.class

package com.evenzhu.ssm.dao;


import com.evenzhu.ssm.entity.TestEntity;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface TestDao {

    TestEntity getById(Integer id);

}

// TestEntity.class

package com.evenzhu.ssm.entity;

public class TestEntity {

    protected Integer id ;

    protected String magicId ;

    protected String firstName ;

    protected String lastName ;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getMagicId() {
        return magicId;
    }

    public void setMagicId(String magicId) {
        this.magicId = magicId;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

// TestService.class

package com.evenzhu.ssm.service;

import com.evenzhu.ssm.dao.TestDao;
import com.evenzhu.ssm.entity.TestEntity;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestService {

    @Autowired
    private TestDao testDao ;

    public TestEntity getById(Integer id){
        return testDao.getById(id);
    }
}

// TestDaoMapper.xml
 
<?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="com.evenzhu.ssm.dao.TestDao">
    <!-- 根据主键查询-->
    <select id="getById" resultType="com.evenzhu.ssm.entity.TestEntity" parameterType="java.lang.Integer" >
        select  *
        from test
        where id = #{id}
    </select>
</mapper>

数据库及表的创建

注：数据库配置在application.properties中，表名及SQL配置在
src/main/resources/mapper/**.xml中，配置信息一定要与数据库实际配置保持一致

浏览器测试请求成功，完成

注：篇中涉及的包名com.evenzhu.ssm必须改为读者自己项目的包名

全篇完，如有问题请评论私聊，我会及时回复并更新文章；