閒暇之餘，寫點最近的收穫，寫一點心得，便於以後參考方便，另外可以幫助有這樣需求的人少走彎路。

          整合多個數據源，很多部落格會提到springboot整合jdbcTemplete為例子，網上有很多，今天主要推薦的是整合 pagehelper + tk-mybatis 多資料來源問題。

              其實很簡單，我的整合思路分為以下幾個步驟。

              一、建立java配置類，這個配置類裡面主要內容有dataSource、sqlSessionFactory、transactionManager、sqlSessionTemplete、具體實現如下：

@Configuration
@MapperScan(/*basePackages = "com.batman.bysj.common.dao.mapper",*/
sqlSessionTemplateRef = "bysjSqlSessionTemplate", basePackageClasses = TestMapper.class)
@EnableConfigurationProperties(value = BysjDruidDBProperties.class)
public class BysjDruidDBAutoConfiguration {
private Logger logger 
 
= LoggerFactory.getLogger(BysjDruidDBAutoConfiguration.class);
private final BysjDruidDBProperties bysjDruidDBProperties;
@Autowired
public BysjDruidDBAutoConfiguration(BysjDruidDBProperties bysjDruidDBProperties) {
this.bysjDruidDBProperties = bysjDruidDBProperties;
    }
@Bean(name = "bysjDataSource"
 
)
@Primary  //在同樣的DataSource中，首先使用被標註的DataSource
public DataSource bysjDataSource() {
DruidDataSource datasource = new DruidDataSource();
datasource.setUrl(bysjDruidDBProperties.getUrl());
datasource.setUsername(bysjDruidDBProperties.getUsername());
datasource.setPassword(bysjDruidDBProperties.getPassword());
datasource.setDriverClassName(bysjDruidDBProperties.getDriverClassName());
//configuration
datasource.setInitialSize(bysjDruidDBProperties.getInitialSize());
datasource.setMinIdle(bysjDruidDBProperties.getMinIdle());
datasource.setMaxActive(bysjDruidDBProperties.getMaxActive());
datasource.setMaxWait(bysjDruidDBProperties.getMaxWait() == 0 ? bysjDruidDBProperties.getMaxWait() : 6000);
datasource.setTimeBetweenEvictionRunsMillis(bysjDruidDBProperties.getTimeBetweenEvictionRunsMillis());
datasource.setMinEvictableIdleTimeMillis(bysjDruidDBProperties.getMinEvictableIdleTimeMillis());
datasource.setValidationQuery(bysjDruidDBProperties.getValidationQuery());
datasource.setTestWhileIdle(bysjDruidDBProperties.isTestWhileIdle());
datasource.setTestOnBorrow(bysjDruidDBProperties.isTestOnBorrow());
datasource.setTestOnReturn(bysjDruidDBProperties.isTestOnReturn());
datasource.setPoolPreparedStatements(bysjDruidDBProperties.isPoolPreparedStatements());
datasource.setMaxPoolPreparedStatementPerConnectionSize(bysjDruidDBProperties.getMaxPoolPreparedStatementPerConnectionSize());
try {
datasource.setFilters(bysjDruidDBProperties.getFilters());
        } catch (SQLException e) {
logger.error("druid configuration initialization filter", e);
        }
datasource.setConnectionProperties(bysjDruidDBProperties.getConnectionProperties());
return datasource;
    }
@Bean(name = "bysjSqlSessionFactory")
@Primary
public SqlSessionFactory bysjSqlSessionFactory(@Qualifier("bysjDataSource") DataSource dataSource) throws Exception {
SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
bean.setDataSource(dataSource);
bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(
"classpath:mapper/bysj/*.xml"));
return bean.getObject();
    }
@Bean(name = "bysjTransactionManager")
@Primary
public DataSourceTransactionManager bysjTransactionManager(@Qualifier("bysjDataSource") DataSource dataSource) {
return new DataSourceTransactionManager(dataSource);
    }
@Bean(name = "bysjSqlSessionTemplate")
@Primary
public SqlSessionTemplate bysjSqlSessionTemplate(@Qualifier("bysjSqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
return new SqlSessionTemplate(sqlSessionFactory);
    }
}

          需要注意的是需要標記@Primary註解，spring需要知道當前主要載入哪一個，上面的註解有MapperScan指定mybatis掃描的mapper檔案位置以及所需要sqlSessionFactory的id，事務管理器可以配也可以不配(需要事務就配上)，sqlSessionTemplete也可配可不配(可以從sqlSessionFactory中獲取)。@EnableConfigurationProperties這樣就可以springboot啟動時自動掃描了，另外需要在spring.factories中配置，具體這點會在寫下部落格說明springboot中的自動配置是怎麼實現的。  

        二、接下來給出properties檔案。

@ConfigurationProperties(prefix = "spring.datasource")
public class BysjDruidDBProperties {
private String url;
private String username;
private String password;
private String driverClassName;
private int initialSize;
private int minIdle;
private int maxActive;
private long maxWait;
private long timeBetweenEvictionRunsMillis;
private long minEvictableIdleTimeMillis;
private String validationQuery;
private boolean testWhileIdle;
private boolean testOnBorrow;
private boolean testOnReturn;
private boolean poolPreparedStatements;
private int maxPoolPreparedStatementPerConnectionSize;
private String filters;
private String connectionProperties;
public String getUrl() {
return url;
    }
public void setUrl(String url) {
this.url = url;
    }
public String getUsername() {
return username;
    }
public void setUsername(String username) {
this.username = username;
    }
public String getPassword() {
return password;
    }
public void setPassword(String password) {
this.password = password;
    }
public String getDriverClassName() {
return driverClassName;
    }
public void setDriverClassName(String driverClassName) {
this.driverClassName = driverClassName;
    }
public int getInitialSize() {
return initialSize;
    }
public void setInitialSize(int initialSize) {
this.initialSize = initialSize;
    }
public int getMinIdle() {
return minIdle;
    }
public void setMinIdle(int minIdle) {
this.minIdle = minIdle;
    }
public int getMaxActive() {
return maxActive;
    }
public void setMaxActive(int maxActive) {
this.maxActive = maxActive;
    }
public long getMaxWait() {
return maxWait;
    }
public void setMaxWait(long maxWait) {
this.maxWait = maxWait;
    }
public long getTimeBetweenEvictionRunsMillis() {
return timeBetweenEvictionRunsMillis;
    }
public void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) {
this.timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
    }
public long getMinEvictableIdleTimeMillis() {
return minEvictableIdleTimeMillis;
    }
public void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
this.minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
    }
public String getValidationQuery() {
return validationQuery;
    }
public void setValidationQuery(String validationQuery) {
this.validationQuery = validationQuery;
    }
public boolean isTestWhileIdle() {
return testWhileIdle;
    }
public void setTestWhileIdle(boolean testWhileIdle) {
this.testWhileIdle = testWhileIdle;
    }
public boolean isTestOnBorrow() {
return testOnBorrow;
    }
public void setTestOnBorrow(boolean testOnBorrow) {
this.testOnBorrow = testOnBorrow;
    }
public boolean isTestOnReturn() {
return testOnReturn;
    }
public void setTestOnReturn(boolean testOnReturn) {
this.testOnReturn = testOnReturn;
    }
public boolean isPoolPreparedStatements() {
return poolPreparedStatements;
    }
public void setPoolPreparedStatements(boolean poolPreparedStatements) {
this.poolPreparedStatements = poolPreparedStatements;
    }
public int getMaxPoolPreparedStatementPerConnectionSize() {
return maxPoolPreparedStatementPerConnectionSize;
    }
public void setMaxPoolPreparedStatementPerConnectionSize(int maxPoolPreparedStatementPerConnectionSize) {
this.maxPoolPreparedStatementPerConnectionSize = maxPoolPreparedStatementPerConnectionSize;
    }
public String getFilters() {
return filters;
    }
public void setFilters(String filters) {
this.filters = filters;
    }
public String getConnectionProperties() {
return connectionProperties;
    }
public void setConnectionProperties(String connectionProperties) {
this.connectionProperties = connectionProperties;
    }
}

            三、接下來就是配置application.yml檔案了，和平常配置資料庫一樣按照提示即可，網上可以搜到很多。

            四、要配置另一個數據源就在走一遍一、二、三，不過要注意，給的bean的名稱不能重複，你懂得。

            五、多謝讀者能看到最後，最大的坑就在於通用mapper，當我們所有的資料來源都配置好了之後，當我們呼叫通用的時候會出現sqlSessionFactory只會是primary的那個，另一個不起作用，這是因為MapperAutoConfiguration中只配置了一個sqlSesisonFactory，這樣就會出現自動切換資料來源，需要新增一個List<SqlSessionFactory>這樣就可以動態配置了。實現如下：

@Configuration
@ConditionalOnBean(SqlSessionFactory.class)
@EnableConfigurationProperties(MapperProperties.class)
@AutoConfigureAfter(MybatisAutoConfiguration.class)
public class CustomizedMapperAutoConfiguration {
private final List<SqlSessionFactory> sqlSessionFactoryList;
@Autowired
private       MapperProperties  properties;
public CustomizedMapperAutoConfiguration(List<SqlSessionFactory> sqlSessionFactoryList) {
this.sqlSessionFactoryList = sqlSessionFactoryList;
    }
@PostConstruct
public void addPageInterceptor() {
MapperHelper mapperHelper = new MapperHelper();
mapperHelper.setConfig(properties);
if (properties.getMappers().size() > 0) {
for (Class mapper : properties.getMappers()) {
mapperHelper.registerMapper(mapper);
            }
        } else {
mapperHelper.registerMapper(Mapper.class);
        }
for (SqlSessionFactory sqlSessionFactory : sqlSessionFactoryList) {
mapperHelper.processConfiguration(sqlSessionFactory.getConfiguration());
        }
    }
}

                   心得有二，第一看懂原始碼很重要，第二和同事聊聊可能會有心得思路，到了最後一步真不知道怎麼弄了，問了下同事，豁然開朗，還是年輕、年輕.......