SpringBoot多数据源改造(一)

今天做一个需求，业务项目需要访问另一个项目的数据库。

常用两种方案：

1、另一个项目提供一个RestFul API，供调用方通过feign或其它httpClient等方式来访问。

2、项目中通过配置多数据源访问另一个项目库，当然必须有访问权限。

经过对比分析，决定采用第二种方案，原因：一方面，有访问另一个数据源的权限。另一方面，减少一层中间API服务可用性的依赖。

于是开始动手：

第一步,增加新数据源的配置类

@Configuration
@MapperScan(basePackages = {"com.XXX.ecc.YYY.dao"}, sqlSessionTemplateRef  = "sqlSessionTemplate2")
public class DataSource2Config {

   /**
    * 创建datasource对象
    * @return
    */
   @Bean(name = "dataSource2")
   @ConfigurationProperties(prefix = "YYY.datasource.prefix")// prefix值必须是application.properteis中对应属性的前缀
   public DataSource dataSource2() {
      return DataSourceBuilder.create().build();
   }

   /**
    * 创建sql工程
    * @param dataSource
    * @return
    * @throws Exception
    */
   @Bean(name = "sqlSessionFactory2")
   public SqlSessionFactory sqlSessionFactory2(@Qualifier("dataSource2") DataSource dataSource) throws Exception {
      SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
      bean.setDataSource(dataSource);
      //对应mybatis.type-aliases-package配置
      bean.setTypeAliasesPackage("com.XXX.ecc.cloudbiz.domain");
      //对应mybatis.mapper-locations配置
      bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:YYY_sqlmap/**/*.xml"));
      //开启驼峰映射
      bean.getObject().getConfiguration().setMapUnderscoreToCamelCase(true);
      return bean.getObject();
   }

   /**
    * 配置事务管理
    * @param dataSource
    * @return
    */
   @Bean(name = "transactionManager2")
   public DataSourceTransactionManager transactionManager2(@Qualifier("dataSource2") DataSource dataSource) {
      return new DataSourceTransactionManager(dataSource);
   }

   /**
    * sqlSession模版，用于配置自动扫描pojo实体类
    * @param sqlSessionFactory
    * @return
    * @throws Exception
    */
   @Bean(name = "sqlSessionTemplate2")
   public SqlSessionTemplate sqlSessionTemplate2(@Qualifier("sqlSessionFactory2") SqlSessionFactory sqlSessionFactory) throws Exception {
      return new SqlSessionTemplate(sqlSessionFactory);
   }
}

第二步：
在resources下增加YYY_sqlmap文件夹，并且创建YYYMapper.xml,在@MapperScan(basePackages = {"com.XXX.ecc.YYY.dao"}指定的包下，创建YYYMapper.java文件。

第三步：改造原有数据源：增加MapperScan注解，增加事务配置及sessionFactory方法，并在事务、datasource、sessionfactory的方法加上@Primary注解，做为主数据源

@Configuration
@MapperScan(basePackages = {"com.XXX.ecc.zzz.dao"}, sqlSessionTemplateRef  = "sqlSessionTemplate")
public class DruidConfig {

    private Logger logger = LoggerFactory.getLogger(getClass());

    @Value("${spring.datasource.url}")
    private String dbUrl;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Value("${spring.datasource.driver-class-name}")
    private String driverClassName;

    @Value("${spring.datasource.initialSize}")
    private int initialSize;

    @Value("${spring.datasource.minIdle}")
    private int minIdle;

    @Value("${spring.datasource.maxActive}")
    private int maxActive;

    @Value("${spring.datasource.maxWait}")
    private int maxWait;

    @Value("${spring.datasource.timeBetweenEvictionRunsMillis}")
    private int timeBetweenEvictionRunsMillis;

    @Value("${spring.datasource.minEvictableIdleTimeMillis}")
    private int minEvictableIdleTimeMillis;

    @Value("${spring.datasource.validationQuery}")
    private String validationQuery;

    @Value("${spring.datasource.testWhileIdle}")
    private boolean testWhileIdle;

    @Value("${spring.datasource.testOnBorrow}")
    private boolean testOnBorrow;

    @Value("${spring.datasource.testOnReturn}")
    private boolean testOnReturn;

    @Value("${spring.datasource.poolPreparedStatements}")
    private boolean poolPreparedStatements;

    @Value("${spring.datasource.filters}")
    private String filters;

    @Value("${spring.datasource.loginUserName}")
    private String loginUserName;

    @Value("${spring.datasource.loginUserPassword}")
    private String loginUserPassword;

    @Value("${spring.datasource.pwdDecrypt:config.decrypt=true}")
    private Properties pwdDecryptProperties;
    @Value("${spring.datasource.publicKey:''}")
    private String publicKey;

    @Value("${spring.datasource.allow}")
    private String allowIp;
    @Value("${spring.datasource.deny}")
    private String denyIp;
    @Bean
    public ServletRegistrationBean druidServlet() {
        ServletRegistrationBean reg = new ServletRegistrationBean();
        reg.setServlet(new StatViewServlet());
        reg.addUrlMappings("/druid/*");
        //IP白名单
        reg.addInitParameter("allow",allowIp);
        //IP黑名单
        reg.addInitParameter("deny",denyIp);
        //控制台管理用户
        reg.addInitParameter("loginUsername", loginUserName);
        reg.addInitParameter("loginPassword", loginUserPassword);
        return reg;
    }

    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new WebStatFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        filterRegistrationBean.addInitParameter("profileEnable", "true");
        filterRegistrationBean.addInitParameter("principalCookieName", "USER_COOKIE");
        filterRegistrationBean.addInitParameter("principalSessionName", "USER_SESSION");
        return filterRegistrationBean;
    }

    @Bean(name = "dataSource")
    @Primary
    public DataSource druidDataSource(){
        DruidDataSource datasource = new DruidDataSource();

        datasource.setUrl(this.dbUrl);
        datasource.setUsername(username);
        datasource.setPassword(password);
        datasource.setDriverClassName(driverClassName);
        datasource.setInitialSize(initialSize);
        datasource.setMinIdle(minIdle);
        datasource.setMaxActive(maxActive);
        datasource.setMaxWait(maxWait);
        datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
        datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
        datasource.setValidationQuery(validationQuery);
        datasource.setTestWhileIdle(testWhileIdle);
        datasource.setTestOnBorrow(testOnBorrow);
        datasource.setTestOnReturn(testOnReturn);
        datasource.setPoolPreparedStatements(poolPreparedStatements);
        try {
            datasource.setFilters(filters);
            pwdDecryptProperties.setProperty("config.decrypt.key",publicKey);
            datasource.setConnectProperties(pwdDecryptProperties);
        } catch (SQLException e) {
            logger.error("druid configuration initialization filter", e);
        }
        return datasource;
    }

    /**
     * 创建sql工程
     * @param dataSource
     * @return
     * @throws Exception
     */
    @Bean(name = "sqlSessionFactory")
    @Primary
    public SqlSessionFactory sqlSessionFactory2(@Qualifier("dataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        //对应mybatis.type-aliases-package配置
        bean.setTypeAliasesPackage("com.XXX.ecc.zzz.domain");
        //对应mybatis.mapper-locations配置
      bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:sqlmap/**/*.xml"));
        //开启驼峰映射
        bean.getObject().getConfiguration().setMapUnderscoreToCamelCase(true);
        return bean.getObject();
    }

    /**
     * 配置事务管理
     * @param dataSource
     * @return
     */
    @Bean(name = "transactionManager")
    @Primary
    public DataSourceTransactionManager transactionManager2(@Qualifier("dataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    /**
     * sqlSession模版，用于配置自动扫描pojo实体类
     * @param sqlSessionFactory
     * @return
     * @throws Exception
     */
    @Bean(name = "sqlSessionTemplate")
    @Primary
    public SqlSessionTemplate sqlSessionTemplate2(@Qualifier("sqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

第四步：在项目启动类上去掉@MapperScan注解

至此，配置完成，编译启动测试即可。

注意事项：
   1、@Primary在主数据源要配置上，否则在@Autowired时会出错或注入非期待的数据源
    2、@Qualifier：当一个接口有多个实现类的时候使用，通过指定名称的注入，