demo: springboot+mybatis

谁借莪１个温暖的怀抱￠ 2021-10-13 00:25 306阅读 0赞

# 前言 #

最近因工作原因，需要研究下spring的事务部分和mybatis的多数据源的源码实现，这样才能更容易的在代码层面通过扩展/重写等方式去定制自己的实现。

以前虽然用过几次mybatis，但是却一直没抽出时间认真翻看下源码，趁这次机会，花点时间研究下，顺便做个笔记。

关于看源码，我向来是觉得只有一步步去debug整个流程，查看每一步的数据流向和数据状态，才会有个更清晰的深知。如果只是看的话，有些源码中各种继承、适配、代理、装饰等，会分不清当前使用的到底是哪个类。

于是乎，所谓工欲善其事，必先利其器。先搭建个极简单的mybatis的工程环境，用来调试源码。

这个工程用了spring boot+mybatis。mybatis采用java config的形式（是真心不喜欢xml配置，所以源码研究上也会避开xml的加载）

后面博文关于分析描述就会针对这个工程的配置来说了。

另外，代码中关于spring事务的注解先注释了。

说了这么多，是希望缓解自己又写了篇这么没技术含量的博客的尴尬，哎，最近这段时间写的博客确实有些凑数了。

# 工程代码 #

数据库脚本：

CREATE DATABASE `testdb` /*!40100 DEFAULT CHARACTER SET utf8 */
    
    -- ----------------------------
    -- Table structure for user
    -- ----------------------------
    DROP TABLE IF EXISTS `user`;
    CREATE TABLE `user` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `age` int(11) NOT NULL,
      `username` varchar(255) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8;

工程结构

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3g3NjM3OTUxNTE_size_16_color_FFFFFF_t_70][]

按工程结构，列一下文件代码：

User.java

public class User {
        int id;
        int age;
        String username;
    
        public User() {
        }
    
        public User(int id, int age, String username) {
            this.id = id;
            this.age = age;
            this.username = username;
        }
    
        public int getId() {
            return id;
        }
    
        public void setId(int id) {
            this.id = id;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", age=" + age +
                    ", username='" + username + '\'' +
                    '}';
        }
    }

MybatisConfig.java

@Configuration
    @MapperScan(basePackageClasses = {UserDao.class})
    //@EnableTransactionManagement //启用spring事务
    public class MybatisConfig {
    
        @Autowired
        private Environment environment;
    
        // 数据源配置
        @Bean
        public DataSource dataSource() {
            // mybatis自带的一个简易数据库连接池，只是为了debug代码，这个就不关心了
            PooledDataSource pooledDataSource = new PooledDataSource();
            pooledDataSource.setDriver(environment.getProperty("mysql.driver"));
            pooledDataSource.setUsername(environment.getProperty("mysql.username"));
            pooledDataSource.setPassword(environment.getProperty("mysql.passwd"));
            pooledDataSource.setUrl(environment.getProperty("mysql.url"));
            return pooledDataSource;
        }
    
        // spring事务管理的基础bean,事务部分会用到
        @Bean
        public PlatformTransactionManager transactionManager(DataSource dataSource) {
            DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
            transactionManager.setDataSource(dataSource);
            return transactionManager;
        }
    
        @Bean
        public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource) throws IOException {
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(dataSource);
            ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
            sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:/mapper/*.xml"));
            return sqlSessionFactoryBean;
        }
    }

UserController.java

@RestController
    @RequestMapping("/user")
    public class UserController {
    
        @Autowired
        IUserService userService;
    
        @GetMapping("/save")
        public String saveUser() {
            User user = new User(10, 100, "test user");
            try {
                return userService.saveUser(user) ? "save success" : "save fail";
            } catch (Exception ignore) {
                ignore.printStackTrace();// 不打印日志了，堆栈信息直接打到控制台看
                return "save error: " + ignore.getMessage();
            }
    
        }
    
        @GetMapping("/list")
        public String getUsers() throws Exception {
            return userService.getUsers().toString();
        }
    
        @GetMapping("/delete")
        public String deleteUser() throws Exception {
            return userService.deleteUser() ? "delete success" : "delete fail";
        }
    }

UserDao.java

@Repository
    public interface UserDao {
    
        boolean saveUser(User user);
    
        List<User> getUsers();
    
        boolean deleteUser();
    
    }

UserServiceImpl.java

@Service
    public class UserServiceImpl implements IUserService {
    
        @Autowired
        UserDao userDao;
    
        //@Transactional //指定这个方法的事务属性
        @Override
        public boolean saveUser(User user) throws Exception {
            boolean success = userDao.saveUser(user);
            // spring事务能力测试的时候，使用下面这段代码
            /*if (true) {
                throw new RuntimeException();
            }*/
            return success;
        }
    
        @Override
        public List<User> getUsers() throws Exception {
            return userDao.getUsers();
        }
    
        @Override
        public boolean deleteUser() throws Exception {
            return userDao.deleteUser();
        }
    }

IUserService.java

public interface IUserService {
    
        boolean saveUser(User user) throws Exception;
    
        List<User> getUsers() throws Exception;
    
        boolean deleteUser() throws Exception;
    
    }

WebApplication.java

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

UserMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org/DTD Mapper 3.0" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.xuxd.demo.dao.UserDao">
    
        <sql id="user_column">
            id,age,username
        </sql>
    
        <select id="getUsers" resultType="com.xuxd.demo.beans.User">
            select * from user
        </select>
    
        
        <insert id="saveUser" parameterType="com.xuxd.demo.beans.User">
            insert into user
            (<include refid="user_column"/>)
            values
            (#{id},#{age},#{username})
        </insert>
    
        <delete id="deleteUser">
            DELETE from USER where id = 10
        </delete>
    
    </mapper>

application.properties

#data source config
    mysql.driver=com.mysql.jdbc.Driver
    mysql.username=root
    mysql.passwd=123456
    mysql.url=jdbc:mysql://localhost:3306/testdb?useSSL=false

pom.xml

<?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.xuxd</groupId>
        <artifactId>spring-mybatis.demo</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <parent>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-parent</artifactId>
            <version>1.5.6.RELEASE</version>
        </parent>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-jdbc</artifactId>
                <version>4.3.1.RELEASE</version>
            </dependency>
    
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.3.1</version>
            </dependency>
    
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis-spring</artifactId>
                <version>1.2.5</version>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.43</version>
            </dependency>
        </dependencies>
    </project>

后续就用这个工程debug源码了。

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