Spring Boot配置多數據源動態切換數據源

一、應用場景

我們再開發中經常遇到應用不同數據庫的數據，比如一部分需要使用Mysql下的數據庫，一部分需要使用Sql Server的數據庫，主從庫分離等等。這是需要我們配置多數據源來滿足開發需要。

二、多數據源

1、引入依賴

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>

	<dependency>
		<groupId>com.alibaba</groupId>
		<artifactId>fastjson</artifactId>
		<version>1.2.47</version>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>

        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>  
    </dependencies>

2、application.properties配置

server.port=8090

spring.datasource.db1.url=jdbc:mysql://127.0.0.1:3306/db1?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.db1.username=root
spring.datasource.db1.password=123456
spring.datasource.db1.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db1.max-idle=10
spring.datasource.db1.max-wait=10000
spring.datasource.db1.min-idle=5
spring.datasource.db1.initial-size=5

spring.datasource.db2.url=jdbc:mysql://127.0.0.1:3306/db2?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.db2.username=root
spring.datasource.db2.password=123456
spring.datasource.db2.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db2.max-idle=10
spring.datasource.db2.max-wait=10000
spring.datasource.db2.min-idle=5
spring.datasource.db2.initial-size=5
#mybatis
mybatis.mapper-locations=classpath*:mapper/*.xml
mybatis.type-aliases-package=com.springboot.mapper

3、創建model、mapper、service、controller相關包類

@RestController
@RequestMapping("article")
public class ArticleController {
	@Autowired
	private ArticleService articleService;
	
	@RequestMapping("arts")
	public List<Article> getArtList() {
		
		List<Article> arts =articleService.getArticleList();
		return arts;
	}
}

/**
 * @author: william
 * @Description: TODO
 * @date: 2018年5月26日 上午10:16:43
 * @version: v1.0.0
 */

@RestController
@RequestMapping("label")
public class LabelController {
	@Autowired
	private LabelService labelService;
	
	@RequestMapping("/{labid}")
	public Label getLabelByid(@PathVariable int labid) {
		return labelService.getLabelByid(labid);
	}
	
}

-----------service-------------------------

@Service
public class ArticleService {
	@Autowired
	private ArticleMapper articleMapper;
	
	@Datasource("db1")		//自定義註解，指明使用數據源
	public List<Article> getArticleList(){
		return articleMapper.getArticleList();
	}
	
}

@Service
public class LabelService {

	@Autowired
	private LabelMapper labelMapper;
	
	@Datasource("db2")
	public Label getLabelByid(int labid) {
		return labelMapper.getLabelByid(labid);
	}
	
}

model、mapper就省略了

4、關鍵點，下面是數據源配置

/**
 * @author: william
 * @Description: 多數據源初始化配置類
 * @date: 2018年5月26日 上午10:39:36
 * @version: v1.0.0
 */
@Configuration
public class DataSourceConfig {
    //數據源1
    @Bean(name = "db1")
  @ConfigurationProperties(prefix = "spring.datasource.db1") // application.properteis中對應屬性的前綴
    public DataSource db1() {
        return DataSourceBuilder.create().build();
    }

    //數據源2
    @Bean(name = "db2")
    @ConfigurationProperties(prefix = "spring.datasource.db2") 
    public DataSource db2() {
        return DataSourceBuilder.create().build();
    }

    /**
     * 利用AOP在不同數據源動態切換
     * @return
     */
    @Primary
    @Bean(name = "dynamicDataSource")
    public DataSource dynamicDataSource() {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        // 默認數據源
        dynamicDataSource.setDefaultTargetDataSource(db1());
        // 多數據源
        Map<Object, Object> dsMap = new HashMap();
        dsMap.put("db1", db1());
        dsMap.put("db2", db2());

        dynamicDataSource.setTargetDataSources(dsMap);
        return dynamicDataSource;
    }

    /**
     * 配置@Transactional註解事物
     * @return
     */
    @Bean
    public PlatformTransactionManager transactionManager() {
        return new DataSourceTransactionManager(dynamicDataSource());
    }
}

public class DataSourceContextHolder {
    
    public static final String DEFAULT_DS = "db1";

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    // 設置數據源名
    public static void setDB(String dbType) {
        System.out.println("===========使用"+dbType+"數據源");
        contextHolder.set(dbType);
    }

    // 獲取數據源
    public static String getDB() {
        return (contextHolder.get());
    }

    // 清除數據源
    public static void clearDB() {
        contextHolder.remove();
    }
}

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        System.out.println("數據源爲"+DataSourceContextHolder.getDB());
        return DataSourceContextHolder.getDB();
    }
}

@Aspect
@Component
public class DynamicDataSourceAspect {

	/**
	 * 通過AOP前置通知，利用註解切換數據源
	 * @param point
	 */
    @Before("@annotation(Datasource)")
    public void beforeSwitchDS(JoinPoint point){
        Class<?> className = point.getTarget().getClass();
        String methodName = point.getSignature().getName();
        //得到方法的參數
        Class[] argClass = ((MethodSignature)point.getSignature()).getParameterTypes();
        String dataSource = DataSourceContextHolder.DEFAULT_DS;
        try {
            // 反射得到方法對象
            Method method = className.getMethod(methodName, argClass);
            //判斷是否使用@Datasource註解
            if (method.isAnnotationPresent(Datasource.class)) {
            	Datasource annotation = method.getAnnotation(Datasource.class);
                //得到註解上數據源
                dataSource = annotation.value();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        //動態設置數據源
        DataSourceContextHolder.setDB(dataSource);
    }

    @After("@annotation(Datasource)")
    public void afterSwitchDS(JoinPoint point){
        DataSourceContextHolder.clearDB();
    }
}

/**
 * 自定義註解,

@Retention定義生命週期

@Target定義作用範圍，方法上

*/@Retention(RetentionPolicy.RUNTIME)@Target({ElementType.METHOD})public @interface Datasource { String value() default "db1";}

5、最好注意一點，禁用掉默認的單數據源

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class Application {
    public static void main(String[] args) {

        SpringApplication.run(Application.class,args);
    }
}

6、建立mysql數據庫