零基礎嘗試mybatis-plus讀寫分離

在知乎看到一個這樣的問題：“為什麼別選電腦專業？” 來源：https://www.zhihu.com/question/465369002/answer/2213759239 這個話題有756人關註，以及1,721,580人次瀏覽。以下是一位匿名用戶的高贊回答，內容可能比較主觀化，僅代表作者個人觀 ...

看了好幾篇博友寫的文章，關於spring-boot整合mybatis-plus實現讀寫分離，不過都是缺這少那的，跑不起來，所以自己實操了一次，做個記錄

實現方式為使用Aop切麵

1、增加資料庫枚舉類

/**
 * 資料庫類型
 */
public enum DBTypeEnum {
    /**
     * 主節點
     */
    MASTER,
    /**
     * 從
     */
    SLAVE
}

2、配置數據源

/**
 * 多數據源配置
 */
@AutoConfigureBefore(DruidDataSourceAutoConfigure.class)
@Configuration
@ConfigurationProperties(prefix = "spring.datasource.druid")
@Data
public class DataSourceConfig {

    private int initialSize;
    private int maxActive;
    private int minIdle;
    private long maxWait;
    private long minEvictableIdleTimeMillis;
    private long timeBetweenEvictionRunsMillis;
    private boolean testWhileIdle;

    /**
     * 配置主數據源
     *
     * @return 數據源
     */
    @Bean(name = "masterDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.druid.master" )
    public DataSource masterDataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        parseDruidConfig(druidDataSource);
        return druidDataSource;
    }

    /**
     * 配置從數據源
     *
     * @return 數據源
     */
    @Bean(name = "slaveDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.druid.slave")
    public DataSource slaveDataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        parseDruidConfig(druidDataSource);
        return druidDataSource;
    }

    private void parseDruidConfig(DruidDataSource dataSource) {
        dataSource.setInitialSize(initialSize);
        dataSource.setMaxActive(maxActive);
        dataSource.setMinIdle(minIdle);
        dataSource.setMaxWait(maxWait);
        dataSource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        dataSource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        dataSource.setTestWhileIdle(testWhileIdle);
    }

    /**
     * 配置路由數據源
     *
     * @param masterDataSource 主節點
     * @param slaveDataSource 從節點
     * @return 數據源
     */
    @Bean(name = "myRoutingDataSource")
    @DependsOn({"masterDataSource", "slaveDataSource"})
    @Primary
    public DataSource myRoutingDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,
                                          @Qualifier("slaveDataSource") DataSource slaveDataSource) {
        Map<Object, Object> targetDataSources = new HashMap<>(3);
        targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);
        targetDataSources.put(DBTypeEnum.SLAVE, slaveDataSource);
        MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource();
        //設置預設數據源
        myRoutingDataSource.setDefaultTargetDataSource(masterDataSource);
        myRoutingDataSource.setTargetDataSources(targetDataSources);
        return myRoutingDataSource;
    }
}

3、線程輪循切換主從資料庫(多主多從的情況下適用)

/**
 * 通過ThreadLocal將數據源設置到每個線程上下文中
 */
public class DataSourceContextHolder {
    private static final ThreadLocal<DBTypeEnum> CONTEXT_HOLDER = new ThreadLocal<>();

    private static final AtomicInteger COUNTER = new AtomicInteger(-1);

    public static void set(DBTypeEnum dbType) {
        CONTEXT_HOLDER.set(dbType);
    }

    public static DBTypeEnum get() {
        return CONTEXT_HOLDER.get();
    }

    public static void clear(){
        CONTEXT_HOLDER.remove();
    }

    public static void master() {
        set(DBTypeEnum.MASTER);
        System.out.println("切換到master");
    }

    public static void slave() {
        //  輪詢
        int index = COUNTER.getAndIncrement() % 2;
        if (COUNTER.get() > 9999) {
            COUNTER.set(-1);
        }
//        if (index == 0) {
//            set(DBTypeEnum.SLAVE1);
//            System.out.println("切換到slave1");
//        } else {
//            set(DBTypeEnum.SLAVE2);
//            System.out.println("切換到slave2");
//        }
        set(DBTypeEnum.SLAVE);
        System.out.println("切換到slave2");
    }
}

4、聲明路由數據源key(多主多從的情況下適用)

/**
 * 聲明路由數據源key
 */
public class MyRoutingDataSource extends AbstractRoutingDataSource {
    @Nullable
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.get();
    }
}

5、強制使用主/從資料庫註解

/**
 * 強制使用主資料庫註解
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface DataSourceMaster {
}

/**
 * 強制使用從資料庫註解
 */
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface DataSourceSlave {
}

6、切麵類(從庫註解會報錯，不知道什麼原因)

/**
 * 使用aop實現數據源切換
 */
@Aspect
@Component
public class DataSourceAop {

//    /**
//     * 需要讀的方法,切麵
//     */
//    @Pointcut("!@annotation(com.readWriteSeparation.annotation.DataSourceSlave)" +
//            "|| execution(* com.readWriteSeparation.service..*.select*(..)) " +
//            "|| execution(* com.readWriteSeparation.service..*.get*(..))" +
//            "|| execution(* com.readWriteSeparation.service..*.query*(..))" +
//            "|| execution(* com.readWriteSeparation.service..*.find*(..)))")
//    public void readPointcut() { }

    /**
     * 需要讀的方法,切麵
     */
    @Pointcut("execution(* com.readWriteSeparation.service..*.select*(..)) " +
            "|| execution(* com.readWriteSeparation.service..*.get*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.query*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.find*(..)))")
    public void readPointcut() { }

    /**
     * 寫切麵
     */
    @Pointcut("@annotation(com.readWriteSeparation.annotation.DataSourceMaster) " +
            "|| execution(* com.readWriteSeparation.service..*.insert*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.save*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.add*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.update*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.edit*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.delete*(..))" +
            "|| execution(* com.readWriteSeparation.service..*.remove*(..))")
    public void writePointcut() { }

    @Before("readPointcut()")
    public void read() {
        DataSourceContextHolder.slave();
    }

    @Before("writePointcut()")
    public void write() {
        DataSourceContextHolder.master();
    }

    @After("readPointcut()")
    public void readAfter() {
        DataSourceContextHolder.clear();
    }

    @After("writePointcut()")
    public void writeAfter() {
        DataSourceContextHolder.clear();
    }
}

7、.yml文件配置

spring:
  datasource:
    druid:
      master:
        username: root
        password: 12345678
        url: jdbc:mysql://192.168.10.15/zeroStart?characterEncoding=UTF-8&useSSL=true&requireSSL=false&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai&allowMultiQueries=true
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.zaxxer.hikari.HikariDataSource
      slave:
        username: root
        password: 12345678
        url: jdbc:mysql://localhost:3306/zeroStart?characterEncoding=UTF-8&useSSL=true&requireSSL=false&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=Asia/Shanghai&allowMultiQueries=true
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.zaxxer.hikari.HikariDataSource

8、引入的依賴

<!--主從配置依賴-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>2.4.2</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-extension</artifactId>
            <version>${mybatis-plus.version}</version>
        </dependency>
        <!--主從end-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.7</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.2.16</version>
        </dependency>

配置到這就好了，業務代碼就不展示了