MyBatisPlus插件扩展_OptimisticLockerInterceptor乐观锁插件的使用

淩亂°似流年 2023-10-18 17:46 18阅读 0赞

## 场景 ##

项目搭建专栏：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/column/info/37194][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_column_info_37194]

### 简介 ###

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 = yourVersion+1 where version = yourVersion
 *  如果version不对，就更新失败

## 实现 ##

### 插件配置 ###

来到项目下的applicationContext.xml中配置sqlSessionFactoryBean的地方。

<bean id="sqlSessionFactoryBean" class="com.baomidou.mybatisplus.spring.MybatisSqlSessionFactoryBean">
      
      <property name="dataSource" ref="dataSource"></property>
      <property name="configLocation" value="classpath:mybatis-config.xml"></property>
      
      <property name="typeAliasesPackage" value="com.badao.beans"></property> 
      
      <property name="globalConfig" ref="globalConfiguration"></property> 
      
      <property name="plugins">
       <list>
        
        <bean class="com.baomidou.mybatisplus.plugins.PaginationInterceptor"></bean>
        
        <bean class="com.baomidou.mybatisplus.plugins.SqlExplainInterceptor">
         <property name="stopProceed" value="true" />
        </bean>
        
        <bean class="com.baomidou.mybatisplus.plugins.PerformanceInterceptor">
         
         
               
               <property name="format" value="true" />
        </bean>
        
        <bean class="com.baomidou.mybatisplus.plugins.OptimisticLockerInterceptor"></bean>
       </list>
      </property> 
     </bean>

### 添加Version ###

#### 1.实体类添加Version ####

@Version
    private Integer version;
    
    并生成set和get方法
    
    完整实体类
    
    package com.badao.beans;
    
    import java.io.Serializable;
    
    import com.baomidou.mybatisplus.activerecord.Model;
    import com.baomidou.mybatisplus.annotations.TableField;
    import com.baomidou.mybatisplus.annotations.TableId;
    import com.baomidou.mybatisplus.annotations.TableName;
    import com.baomidou.mybatisplus.annotations.Version;
    import com.baomidou.mybatisplus.enums.IdType;
    import com.mchange.util.FailSuppressedMessageLogger;
    
    @TableName(value="employee")
    public class Employee  extends Model<Model>{
     
     @TableId(value="id",type=IdType.AUTO)
     private Integer id;
     //@TableField(value="last_name")
     private String name;
     private String email;
     private Integer gender;
     private Integer age;
     @TableField(exist=false)
     private String remark;
     @Version
        private Integer version;
     public Integer getVersion() {
      return version;
     }
     public void setVersion(Integer version) {
      this.version = version;
     }
     public String getRemark() {
      return remark;
     }
     public void setRemark(String remark) {
      this.remark = remark;
     }
     public Integer getId() {
      return id;
     }
     public void setId(Integer id) {
      this.id = id;
     }
     public String getName() {
      return name;
     }
     public void setName(String name) {
      this.name = name;
     }
     public String getEmail() {
      return email;
     }
     public void setEmail(String email) {
      this.email = email;
     }
     public Integer getGender() {
      return gender;
     }
     public void setGender(Integer gender) {
      this.gender = gender;
     }
     public Integer getAge() {
      return age;
     }
     public void setAge(Integer age) {
      this.age = age;
     }
     
     /***
      * 必须指定当前实体类的主键属性
      */
     @Override
     protected Serializable pkVal() {
      // TODO Auto-generated method stub
      return id;
     }
     
    }

#### 2.数据库字段添加version ####

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

保存后给version赋值

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

#### 3.测试 ####

编写测试方法

/***
      *   乐观锁插件
      */
     @Test
     public void testOptimisticLockerInterceptor() {
      //更新操作
      Employee employee = new Employee();
      employee.setId(3);
      employee.setName("OptimisticLockerInterceptor");
      employee.setAge(23);
      employee.setVersion(1);
      employeeMapper.updateById(employee);
      
     }

一定要设置版本！！！ employee.setVersion(1);

运行结果

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

此时版本统一会成功更新。

更新成功后数据库的version字段会自动变成2。

假如此时另一个人也执行了更新操作，此时数据库的version会变成3。

然后自己再次进行更新时使用version为2去进行更新，结果：

![Image 1][]![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

更新了0条。

## 源码下载 ##

[https://download.csdn.net/download/badao\_liumang\_qizhi/11147706][https_download.csdn.net_download_badao_liumang_qizhi_11147706]

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_column_info_37194]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/column/info/37194
[Image 1]: 
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20190427213843681.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20190427213911205.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[https_download.csdn.net_download_badao_liumang_qizhi_11147706]: https://download.csdn.net/download/badao_liumang_qizhi/11147706