SpringBoot整合MybatisPlus3.X之乐观锁(十三)

主要适用场景

意图：

当要更新一条记录的时候，希望这条记录没有被别人更新

乐观锁实现方式：

取出记录时，获取当前version
更新时，带上这个version
执行更新时， set version = newVersion where version = oldVersion
如果version不对，就更新失败

乐观锁配置需要2步记得两步

1.插件配置

spring xml:

<bean class="com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor"/>

spring boot:

@Bean

public OptimisticLockerInterceptor optimisticLockerInterceptor() {

    return new OptimisticLockerInterceptor();

}

2.注解实体字段 `@Version` 必须要!

@Version
private Integer version;

特别说明:

支持的数据类型只有:int,Integer,long,Long,Date,Timestamp,LocalDateTime
整数类型下 newVersion = oldVersion + 1
newVersion 会回写到 entity 中
仅支持 updateById(id) 与 update(entity, wrapper) 方法
在 update(entity, wrapper) 方法下, wrapper 不能复用!!!

示例

示例Java代码（参考代码）

int id = 100;

int version = 2;



User u = new User();

u.setId(id);

u.setVersion(version);

u.setXXX(xxx);



if(userService.updateById(u)){

    System.out.println("Update successfully");

}else{

    System.out.println("Update failed due to modified by others");

}

示例SQL原理

update tbl_user set name = 'update',version = 3 where id = 100 and version = 2

pom.xml

<dependencies>

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter</artifactId>

        </dependency>

        <dependency>

            <groupId>com.baomidou</groupId>

            <artifactId>mybatis-plus-boot-starter</artifactId>

            <version>3.2.0</version>

        </dependency>

        <dependency>

            <groupId>org.projectlombok</groupId>

            <artifactId>lombok</artifactId>

        </dependency>

        <!-- https://mvnrepository.com/artifact/p6spy/p6spy -->

        <dependency>

            <groupId>p6spy</groupId>

            <artifactId>p6spy</artifactId>

            <version>3.8.0</version>

        </dependency>

        <dependency>

            <groupId>com.h2database</groupId>

            <artifactId>h2</artifactId>

            <scope>runtime</scope>

        </dependency>



        <dependency>

            <groupId>com.alibaba</groupId>

            <artifactId>fastjson</artifactId>

            <version>1.2.49</version>

            <scope>test</scope>

        </dependency>

        <!-- for testing -->

        <dependency>

            <groupId>org.springframework.boot</groupId>

            <artifactId>spring-boot-starter-test</artifactId>

            <scope>test</scope>

        </dependency>

    </dependencies>

配置类

@Configuration

public class MybatisPlusOptLockerConfig {



    @Bean

    public OptimisticLockerInterceptor optimisticLockerInterceptor() {

        return new OptimisticLockerInterceptor();

    }

}

实体类

@Data

public class User {



    @TableId(value = "id", type = IdType.AUTO)

    private Long id;

    private String name;

    private Integer age;

    private String email;

    @Version

    private Integer version;

}

Mapper

public interface UserMapper extends BaseMapper<User> {



}

启动类

@SpringBootApplication

@MapperScan("com.mp.locker.mapper")  //不加在容器里面获取不了

public class LockerApplication {



    public static void main(String[] args) {

        SpringApplication.run(LockerApplication.class, args);

    }



}

application.yml

spring:

  datasource:

    driver-class-name: com.p6spy.engine.spy.P6SpyDriver

    url: jdbc:p6spy:h2:tcp://192.168.180.115:19200/~/mem/test

    username: root

    password: test

测试类

@SpringBootTest

class LockerApplicationTests {



    @Autowired(required = false)

    UserMapper userMapper;



    @Test

    public void testUpdateByIdSucc() {

        User user = new User();

        user.setAge(18);

        user.setEmail("test@baomidou.com");

        user.setName("optlocker");

        user.setVersion(1);

        userMapper.insert(user);

        Long id = user.getId();

        //INSERT INTO user ( name, version, email, age ) VALUES ( 'optlocker', 1, 'test@baomidou.com', 18 )

        User userUpdate = new User();

        userUpdate.setId(id);

        userUpdate.setAge(19);

        userUpdate.setVersion(1);

        //UPDATE user SET version=2, age=19 WHERE id=6 AND version=1

        Assert.assertEquals("Should update success", 1, userMapper.updateById(userUpdate));

        //6 optlocker   19  test@baomidou.com   2  值变成2

        Assert.assertEquals("Should version = version+1", 2, userUpdate.getVersion().intValue());

    }



    @Test

    public void testUpdateByIdFail() {

        User user = new User();

        user.setAge(18);

        user.setEmail("test@baomidou.com");

        user.setName("optlocker");

        user.setVersion(1);

        //INSERT INTO user ( name, version, email, age ) VALUES ( 'optlocker', 1, 'test@baomidou.com', 18 )

        userMapper.insert(user);

        Long id = user.getId();



        User userUpdate = new User();

        userUpdate.setId(id);

        userUpdate.setAge(19);

        userUpdate.setVersion(0);

        //UPDATE user SET version=1, age=19 WHERE id=7 AND version=0

        userMapper.updateById(userUpdate);

    }



    @Test

    public void testUpdateByIdSuccWithNoVersion() {

        User user = new User();

        user.setAge(18);

        user.setEmail("test@baomidou.com");

        user.setName("optlocker");

        user.setVersion(1);

        userMapper.insert(user);

        Long id = user.getId();



        User userUpdate = new User();

        userUpdate.setId(id);

        userUpdate.setAge(19);

        userUpdate.setVersion(null);

        Assert.assertEquals("Should update success as no version passed in", 1, userMapper.updateById(userUpdate));

        User updated = userMapper.selectById(id);

        Assert.assertEquals("Version not changed", 1, updated.getVersion().intValue());

        Assert.assertEquals("Age updated", 19, updated.getAge().intValue());

    }



    /**

     * 批量更新带乐观锁

     * <p>

     * update(et,ew) et:必须带上version的值才会触发乐观锁

     */

    @Test

    public void testUpdateByEntitySucc() {

        QueryWrapper<User> ew = new QueryWrapper<>();

        ew.eq("version", 1);

        int count = userMapper.selectCount(ew);



        User entity = new User();

        entity.setAge(28);

        entity.setVersion(1);



        Assert.assertEquals("updated records should be same", count, userMapper.update(entity, null));

        ew = new QueryWrapper<>();

        ew.eq("version", 1);

        Assert.assertEquals("No records found with version=1", 0, userMapper.selectCount(ew).intValue());

        ew = new QueryWrapper<>();

        ew.eq("version", 2);

        Assert.assertEquals("All records with version=1 should be updated to version=2", count, userMapper.selectCount(ew).intValue());

    }



}

巴特西

SpringBoot整合MybatisPlus3.X之乐观锁(十三)

主要适用场景

1.插件配置

2.注解实体字段 `@Version` 必须要!

示例

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巴特西

SpringBoot整合MybatisPlus3.X之乐观锁(十三)

主要适用场景

1.插件配置

2.注解实体字段 @Version 必须要!

示例

最新文章

热门文章

2.注解实体字段 `@Version` 必须要!