Spring Boot 快速入门之持久篇（三）

一、前言

上一篇文章介绍了 Spring Boot 的一些 web 相关的内容，咱们接下这边文章就来讲一下开发离不开的数据。本篇以 MySql+MyBatis 为主。

二、整合 mysql 和 mybatis

2.1 配置 mysql 和 mybatis 版本

<properties>
	<java.version>1.8</java.version>
	<mysql.version>5.1.44</mysql.version>
	<mybatis.version>3.4.5</mybatis.version>
	<mybatis.springboot.version>1.3.1</mybatis.springboot.version>
</properties>

2.2 添加依赖

<dependencies>
	<!-- mybatis -->
	<dependency>
		<groupId>org.mybatis</groupId>
		<artifactId>mybatis</artifactId>
		<version>${mybatis.version}</version>
	</dependency>
	<dependency>
		<groupId>org.mybatis.spring.boot</groupId>
		<artifactId>mybatis-spring-boot-starter</artifactId>
		<version>${mybatis.springboot.version}</version>
	</dependency>
	<!-- mysql -->
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>${mysql.version}</version>
	</dependency>
</dependencies>

2.3 配置数据连接

在 application-dev.properties 中添加以下配置，可以在不同配置文件配置对应的数据源，需要时切换 application.properties 中的 spring.profiles.active=dev 即可。

#JDBC
spring.datasource.driverClassName = com.mysql.jdbc.Driver
spring.datasource.url = jdbc:mysql://127.0.0.1:3306/springboot?allowMultiQueries=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
spring.datasource.username = root
spring.datasource.password = Admin12345*

三、配置 Generator

3.1 添加 Generator 插件依赖

在 pom.xml 中添加以下配置：

<plugin>
	<groupId>org.mybatis.generator</groupId>
	<artifactId>mybatis-generator-maven-plugin</artifactId>
	<version>1.3.3</version>
	<configuration>
		<verbose>true</verbose>
		<overwrite>true</overwrite>
	</configuration>
	<dependencies>
		<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java
    	配置这个依赖主要是为了等下在配置MG的时候可以不用配置classPathEntry这样的一个属性，避免
   		代码的耦合度太高 -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.38</version>
		</dependency>
	</dependencies>
</plugin>

3.2 新增 generator 配置文件

在 resource 文件夹下创建 generatorConfig.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>

    <context id="ssm" targetRuntime="MyBatis3">
        <plugin type="org.mybatis.generator.plugins.EqualsHashCodePlugin" />
        <plugin type="org.mybatis.generator.plugins.SerializablePlugin" />
        <plugin type="org.mybatis.generator.plugins.CaseInsensitiveLikePlugin" />
        <!-- <plugin type="org.mybatis.generator.plugins.ToStringPlugin"></plugin> -->
        <commentGenerator>
            <property name="suppressDate" value="true" />
            <property name="suppressAllComments" value="true" />
        </commentGenerator>

        <!-- 数据库连接 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://127.0.0.1:3306/springboot" userId="root" password="Admin12345*">
        </jdbcConnection>

        <javaTypeResolver>
            <property name="forceBigDecimals" value="false" />
        </javaTypeResolver>

        <!-- entity -->
        <javaModelGenerator targetPackage="com.y.springboot.model" targetProject="src/main/java">
            <property name="constructorBased" value="true" />
            <property name="enableSubPackages" value="true" />
            <property name="trimStrings" value="true" />
        </javaModelGenerator>

        <!--xml-->
        <sqlMapGenerator targetPackage="mybatis" targetProject="src/main/resources">
            <property name="enableSubPackages" value="true" />
        </sqlMapGenerator>

        <!--mapper.java-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.y.springboot.mapper" targetProject="src/main/java">
            <property name="enableSubPackages" value="true" />
        </javaClientGenerator>

        <!-- 需要生成的表  tableName(表名) domainObjectName(生成的java类名称)-->
        <table schema="mybatis" tableName="user" domainObjectName="User">
            <property name="constructorBased" value="true" />
            <property name="useActualColumnNames" value="false" />
            <property name="ignoreQualifiersAtRuntime" value="true" />
        </table>
    </context>
</generatorConfiguration>

四、测试

4.1 创建数据库表 user

CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(255) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

4.2 生成 entity、mapper 和 xml

选择 IDEA 右侧 Maven--> Plugins --> mybatis-generator -->mybatis-generator:generator
会将数据库表按照 generatorConfig 配置的路径名称生成对应的 java 实体类和 xml 方法

4.3 配置 spring 自动扫描和自动注入

在 application.properties 中添加：

#实体映射路径
#路径填写generatorConfig.xml中配置的路径
mybatis.mapper-locations = classpath:mybatis/*.xml 
mybatis.type-aliases-package = com.tes.sys.com.healthsafe.model

修改 SpringbootApplication

package com.y.springboot.springboot;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication(scanBasePackages = "com.y.springboot")
@MapperScan("com.y.springboot.mapper")
public class SpringbootApplication  {


    public static void main(String[] args) {
        SpringApplication.run(SpringbootApplication.class, args);
    }

}

4.4 测试类

TestService.java

package com.y.springboot.service;

import com.y.springboot.model.User;

public interface TestService {
    int addUser(User user);
}

TestServiceImpl.java

package com.y.springboot.service;

import com.y.springboot.mapper.UserMapper;
import com.y.springboot.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class TestServiceImpl implements TestService {
    @Autowired
    private UserMapper userMapper;
    @Override
    public int addUser(User user) {
        return userMapper.insertSelective(user);
    }
}

TestController.java

package com.y.springboot.springboot.controller;

import com.y.springboot.model.User;
import com.y.springboot.service.TestServiceImpl;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("test")
public class TestController {
    @Autowired
    private TestServiceImpl testService;

    @ApiOperation(value = "新增用户",notes = "新增用户测试")
    @RequestMapping(value = "add",method = RequestMethod.POST)
    @ResponseBody
    public String add(){
        User user = new User();
        user.setUserName("测试");
        user.setAge(20);
        int row = testService.addUser(user);
        if(row>0){
            return "新增成功";
        }else{
            return "新增失败";
        }
    }
}

测试效果图：

4.5 拓展 Example 的用法

本次使用 generator 生成的 java 实体会伴随一个对应的 Example 文件，可以用作去重/排序/分页/条件查询等操作

    public void exampleTest(){
        UserExample userExample = new UserExample();
        //userName等于‘测试’且年龄等于20
        userExample.createCriteria().andUserNameEqualTo("测试").andAgeEqualTo(20);
        //按照年龄降序排序
        userExample.setOrderByClause("age desc");
        List<User> userList = userMapper.selectByExample(userExample);
    }

更多详细 Example 操作请自行 baidu~