Springboot動態切換數據源的具體實現與原理分析

// 切換sqlserver數據源:
DataSourceContextHolder.setDataBaseType(DataSourceEnum.SQLSERVER_DATASOURCE);
......
// 切換mysql數據源    
DataSourceContextHolder.setDataBaseType(DataSourceEnum.MYSQL_DATASOURCE);

# sqlserver數據源1:前綴為:spring.datasource.sqlserver
spring.datasource.sqlserver.driver-class-name=com.microsoft.sqlserver.jdbc.SQLServerDriver
spring.datasource.sqlserver.jdbc-url=jdbc:sqlserver://localhost:1433;DatabaseName=test
spring.datasource.sqlserver.username=sa
spring.datasource.sqlserver.password=sa
# mysql數據源1:前綴為:spring.datasource.mysql
spring.datasource.mysql.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.mysql.jdbc-url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false&allowMultiQueries=true
spring.datasource.mysql.username=root
spring.datasource.mysql.password=root
# sqlLite數據源1:前綴為:spring.datasource.sqlite
spring.datasource.sqlite.driver-class-name=org.sqlite.JDBC
spring.datasource.sqlite.jdbc-url=jdbc:sqlite:D://sqllite//test.db
spring.datasource.sqlite.username=
spring.datasource.sqlite.password=
# sqlserver數據源2:前綴為:spring.datasource.sqlserver2
spring.datasource.sqlserver2.driver-class-name=com.microsoft.sqlserver.jdbc.SQLServerDriver
spring.datasource.sqlserver2.jdbc-url=jdbc:sqlserver://localhost;DatabaseName=test1
spring.datasource.sqlserver2.username=sa
spring.datasource.sqlserver2.password=sa
# 配置數據庫連接池信息
spring.datasource.hikari.maximum-pool-size=32
spring.datasource.hikari.minimum-idle=16

public enum DataSourceEnum {
    MYSQL_DATASOURCE,
    SQLSERVER_DATASOURCE,
    SQLSERVER2_DATASOURCE,
    SQLLITE_DATASOURCE
}

public class DataSourceContextHolder {

    /**
     * 通過ThreadLocal保證線程安全
     */
    private static final ThreadLocal<DataSourceEnum> contextHolder = new ThreadLocal<>();

    /**
     * 設置數據源變量
     * @param dataSourceEnum 數據源變量
     */
    public static void setDataBaseType(DataSourceEnum dataSourceEnum) {
        System.out.println("修改數據源為：" + dataSourceEnum);
        contextHolder.set(dataSourceEnum);
    }

    /**
     * 獲取數據源變量
     * @return 數據源變量
     */
    public static DataSourceEnum getDataBaseType() {
        DataSourceEnum dataSourceEnum = contextHolder.get() == null ? DataSourceEnum.MYSQL_DATASOURCE : contextHolder.get();
        System.out.println("當前數據源的類型為：" + dataSourceEnum);
        return dataSourceEnum;
    }

    /**
     * 清空數據類型
     */
    public static void clearDataBaseType() {
        contextHolder.remove();
    }

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataBaseType();
    }
}

@Configuration
public class DataSourceConfig {
    @Bean(name = "sqlserverDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.sqlserver")
    public DataSource getDateSource1() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "sqlserver2DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.sqlserver2")
    public DataSource getDateSource11() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "mysqlDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.mysql")
    public DataSource getDateSource2() {
        return DataSourceBuilder.create().build();
    }


    @Bean(name = "sqlLiteDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.sqlite")
    public DataSource getDateSource3() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "dynamicDataSource")
    public DynamicDataSource DataSource(@Qualifier("sqlserverDataSource") DataSource sqlserverDataSource,
                                        @Qualifier("sqlserver2DataSource") DataSource sqlserver2DataSource,
                                        @Qualifier("mysqlDataSource") DataSource mysqlDataSource,
                                        @Qualifier("sqlLiteDataSource") DataSource sqlLiteDataSource) {
        //配置多數據源
        Map<Object, Object> targetDataSource = new HashMap<>();
        targetDataSource.put(DataSourceEnum.SQLSERVER_DATASOURCE, sqlserverDataSource);
        targetDataSource.put(DataSourceEnum.MYSQL_DATASOURCE, mysqlDataSource);
        targetDataSource.put(DataSourceEnum.SQLLITE_DATASOURCE, sqlLiteDataSource);
        targetDataSource.put(DataSourceEnum.SQLSERVER2_DATASOURCE, sqlserver2DataSource);
        DynamicDataSource dataSource = new DynamicDataSource();
        //多數據源
        dataSource.setTargetDataSources(targetDataSource);
        //默認數據源
        dataSource.setDefaultTargetDataSource(sqlserverDataSource);
        return dataSource;
    }
    @Bean(name = "SqlSessionFactory")
    public SqlSessionFactory test1SqlSessionFactory(@Qualifier("dynamicDataSource") DataSource dynamicDataSource)
            throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dynamicDataSource);
        return bean.getObject();
    }

    @Bean(name = "JdbcTemplate")
    public JdbcTemplate test1JdbcTemplate(@Qualifier("dynamicDataSource") DataSource dynamicDataSource) {
        return new JdbcTemplate(dynamicDataSource);
    }
}

@Nullable
private Map<Object, Object> targetDataSources; 

@Nullable
private Object defaultTargetDataSource;

private boolean lenientFallback = true;

private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();

@Nullable
private Map<Object, DataSource> resolvedDataSources;

@Nullable
private DataSource resolvedDefaultDataSource;