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本篇实际上和mybatisext项目并没有太大关系了，但在实际项目中脱离不开多个数据源，尤其是主从分离，同样网上一些资料大同小异而且大部分并不能真正解决问题，所以单独提出来说一下

假设我们就是要解决一个主从分离，数据源定义在了application.properties中如下：

datasources.master.driverClassName=com.mysql.cj.jdbc.Driverdatasources.master.url=xxxdatasources.master.username=xxxdatasources.master.password=xxxdatasources.master.type=com.alibaba.druid.pool.DruidDataSourcedatasources.master.filters=statdatasources.master.maxActive= 20datasources.master.initialSize= 1datasources.master.maxWait= 60000datasources.master.minIdle =1datasources.master.timeBetweenEvictionRunsMillis= 60000datasources.master.minEvictableIdleTimeMillis=300000datasources.master.validationQuery= select 'x'datasources.master.testWhileIdle= truedatasources.master.testOnBorrow=falsedatasources.master.testOnReturn= falsedatasources.master.poolPreparedStatements=truedatasources.master.maxOpenPreparedStatements= 20datasources.slave.driverClassName=com.mysql.cj.jdbc.Driverdatasources.slave.url=xxxdatasources.slave.username=xxxdatasources.slave.password=xxxdatasources.slave.type=com.alibaba.druid.pool.DruidDataSourcedatasources.slave.filters=statdatasources.slave.maxActive= 20datasources.slave.initialSize= 1datasources.slave.maxWait= 60000datasources.slave.minIdle =1datasources.slave.timeBetweenEvictionRunsMillis= 60000datasources.slave.minEvictableIdleTimeMillis=300000datasources.slave.validationQuery= select 'x'datasources.slave.testWhileIdle= truedatasources.slave.testOnBorrow=falsedatasources.slave.testOnReturn= falsedatasources.slave.poolPreparedStatements=truedatasources.slave.maxOpenPreparedStatements= 20

定义一个枚举类，针对这两个数据源

public enum DataSourceType {    Master,    Slave,}

动态数据源定义，保证线程安全引用了ThreadLocal类记录当前使用的数据源

public class DynamicDataSource extends AbstractRoutingDataSource {    private static final ThreadLocal
   
     contextHolder = new ThreadLocal<>();    public static void setDataSourceType(DataSourceType dataSourceType){        contextHolder.set(dataSourceType);    }    public static DataSourceType getDataSourceType() {        return contextHolder.get();    }    public static void clear(){        contextHolder.remove();    }    @Override    protected Object determineCurrentLookupKey(){        return DynamicDataSource.getDataSourceType();    }}
   

然后进行mybatis配置的注入

@Configuration@MapperScan({"cw.frame.mybatisext.test.mapper"})public class MyBatisConfig {    @Autowired    private Environment environment;    @Autowired    private MySqlInterceptor mySqlInterceptor;    @Bean    public MySqlInterceptor mySqlInterceptor(){        return new MySqlInterceptor();    }    @Bean    public DataSource masterDataSource() throws Exception{        return DruidDataSourceFactory.createDataSource(this.getDataSourceProperty("datasources.master."));    }    @Bean    public DataSource slaveDataSource() throws Exception{        return DruidDataSourceFactory.createDataSource(this.getDataSourceProperty("datasources.slave."));    }    /**     * @Primary 该注解表示在同一个接口有多个实现类可以注入的时候，默认选择哪一个，而不是让@autowire注解报错     * @Qualifier 根据名称进行注入，通常是在具有相同的多个类型的实例的一个注入（例如有多个DataSource类型的实例）     * @DependsOn 解决循环依赖问题，在系统自动创建datasource前创建指定数据源     * @param masterDataSource     * @param slaveDataSource     * @return     */    @Bean    @Primary    @DependsOn({ "masterDataSource", "slaveDataSource"})    public DynamicDataSource dataSource(@Qualifier("masterDataSource") DataSource masterDataSource, @Qualifier("slaveDataSource") DataSource slaveDataSource){        Map
   
     dataSourceMap = new HashMap<>();        dataSourceMap.put(DataSourceType.Master, masterDataSource);        dataSourceMap.put(DataSourceType.Slave, slaveDataSource);        DynamicDataSource dynamicDataSource = new DynamicDataSource();        dynamicDataSource.setTargetDataSources(dataSourceMap);        dynamicDataSource.setDefaultTargetDataSource(masterDataSource);        return dynamicDataSource;    }    /**     * 根据数据源创建SqlSessionFactory     * mybatis拦截器需要手动设置一下 fb.setPlugins(new Interceptor[]{mySqlInterceptor});     * @param dynamicDataSource     * @return     * @throws Exception     */    @Bean    public SqlSessionFactory sqlSessionFactory(DynamicDataSource dynamicDataSource) throws Exception{        SqlSessionFactoryBean fb = new SqlSessionFactoryBean();        // 因为手动创建了SqlSessionFactory，所以需要手动设置拦截器        fb.setPlugins(new Interceptor[]{mySqlInterceptor});        fb.setDataSource(dynamicDataSource);        return fb.getObject();    }    /**     * 配置事务管理器     * @param dataSource     * @return     * @throws Exception     */    @Bean    public DataSourceTransactionManager transactionManager(DynamicDataSource dataSource) throws Exception{        return new DataSourceTransactionManager(dataSource);    }    private Properties getDataSourceProperty(String prefixKey){        String[] keys = {                "driverClassName", "url", "username", "password", "type", "filters", "maxActive", "initialSize",                "maxWait", "minIdle", "timeBetweenEvictionRunsMillis", "minEvictableIdleTimeMillis",                "validationQuery", "testWhileIdle", "testOnBorrow", "testOnReturn",                "poolPreparedStatements", "maxOpenPreparedStatements"        };        Properties properties = new Properties();        for (String key : keys){            properties.put(key, environment.getProperty(prefixKey + key));        }        return properties;    }}
   

这里特别说明一下：

最后在做一个切片定义

@Aspect@Componentpublic class DynamicDataSourceAspect {    @Before("@annotation(DataSource)")    public void beforeExecute(JoinPoint point){    }    @Around("@annotation(DataSource)")    public Object aroundExecute(ProceedingJoinPoint proceedingJoinPoint) throws Throwable{        Class
    classType = proceedingJoinPoint.getTarget().getClass();        String methodName = proceedingJoinPoint.getSignature().getName();        Class[] argClass = ((MethodSignature)proceedingJoinPoint.getSignature()).getParameterTypes();        DataSourceType lastDataSourceType = null;        boolean resetDataSourceType = false;        Method method = classType.getMethod(methodName, argClass);        if (method.isAnnotationPresent(DataSource.class)){            DataSourceType dataSourceType = method.getAnnotation(DataSource.class).value();            lastDataSourceType = DynamicDataSource.getDataSourceType();            if (lastDataSourceType == null){                DynamicDataSource.setDataSourceType(dataSourceType);                resetDataSourceType = true;            } else {                switch (lastDataSourceType){                    case Master:                        break;                    case Slave:                        if (dataSourceType == DataSourceType.Master){                            DynamicDataSource.setDataSourceType(dataSourceType);                            resetDataSourceType = true;                        }                        break;                }            }        }        Object result = proceedingJoinPoint.proceed();        if (resetDataSourceType){            if (lastDataSourceType == null){                DynamicDataSource.clear();            } else {                DynamicDataSource.setDataSourceType(lastDataSourceType);            }        }        return result;    }    @After("@annotation(DataSource)")    public void afterExecute(JoinPoint point){    }}

所有带@DataSource注解的都会进入切片，动态设置数据源

到此为止，介绍完了关于mybatis的拦截器全ORM实现的方案和mybatisext的项目，源代码

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