一、引言
本文次要介绍一种优雅、平安、易用，反对事务管理的Spring Boot整合多数据源的形式，本文中不针对多数据源是什么、为什么用、什么时候用做介绍，小伙伴可依据本身状况酌情驳回
舒适提醒：
基于以下常识有肯定利用与实际后，能更好地了解本篇文章
- Lambda、ThreadLocal、栈、队列、自定义注解
- IoC、AOP、Druid、Maven、Spring Boot
因为本文次要解说代码的具体实现，代码与正文较多，若感到浏览体验不佳，可配合开源代码，应用代码编辑器进行浏览
多数据源Gitee地址
对应我的项目模块为hei-dynamic-datasource
二、大抵思路
- 通过配置类与yml配置文件先拆卸好默认数据源与多数据源
- 再通过自定义注解与AOP，找到指标类或办法，并指定其应用的数据源Key值
- 最初通过继承AbstractRoutingDataSource类，返回经AOP解决后的数据源Key值，从第一步拆卸好的数据源中找到对应配置并利用
三、测试用例
在类或办法上加上@DataSource("value")就能够指定不同数据源
@Service// 办法上的注解比类上注解优先级更高@DataSource("slave2")public class DynamicDataSourceTestService { @Autowired private SysUserDao sysUserDao; @Transactional public void updateUser(Long id){ SysUserEntity user = new SysUserEntity(); user.setUserId(id); user.setMobile("13500000002"); sysUserDao.updateById(user); } @Transactional @DataSource("slave1") public void updateUserBySlave1(Long id){ SysUserEntity user = new SysUserEntity(); user.setUserId(id); user.setMobile("13500000001"); sysUserDao.updateById(user); } @DataSource("slave2") @Transactional public void updateUserBySlave2(Long id){ SysUserEntity user = new SysUserEntity(); user.setUserId(id); user.setMobile("13500000003"); sysUserDao.updateById(user); // 测试事务 int i = 1/0; }}@RunWith(SpringRunner.class)@SpringBootTestpublic class DynamicDataSourceTest { @Autowired private DynamicDataSourceTestService dynamicDataSourceTestService; @Test public void test(){ Long id = 1L; dynamicDataSourceTestService.updateUser(id); dynamicDataSourceTestService.updateUserBySlave1(id); dynamicDataSourceTestService.updateUserBySlave2(id); }}四、我的项目构造
五、代码示例及解析
5.1、maven相干依赖
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId></dependency>5.2、yml配置
dynamic: datasource: slave1: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/hei?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai username: root password: 123456 slave2: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/hei?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai username: root password: 1234565.3、自定义注解(DataSource)
// 定义作用范畴为（办法、接口、类、枚举、注解）@Target({ElementType.METHOD, ElementType.TYPE})// 保障运行时能被JVM或应用反射的代码应用@Retention(RetentionPolicy.RUNTIME)// 生成Javadoc时让应用了@DataSource这个注解的中央输入@DataSource这个注解或不同内容@Documented// 类继承中让子类继承父类@DataSource注解@Inheritedpublic @interface DataSource { // @DataSource注解里传的参，这里次要传配置文件中不同数据源的标识，如@DataSource("slave1") String value() default "";}5.4、切面类(DataSourceAspect)
// 申明、定义切面类@Aspect@Component/** * 让该bean的执行程序优先级最高，并不能管制加载入IoC的程序 * 如果一个办法被多个 @Around 加强，那就能够应用该注解指定程序 */@Order(Ordered.HIGHEST_PRECEDENCE)public class DataSourceAspect { protected Logger logger = LoggerFactory.getLogger(getClass()); // 指明告诉在应用@DataSource注解标注下才触发 @Pointcut("@annotation(io.renren.commons.dynamic.datasource.annotation.DataSource) " + "|| @within(io.renren.commons.dynamic.datasource.annotation.DataSource)") public void dataSourcePointCut() { } // 对告诉办法的具体实现并采纳盘绕告诉设定办法与切面的执行程序，即在办法执行前和后触发 @Around("dataSourcePointCut()") /** * ProceedingJoinPoint继承了JoinPoint，相较于JoinPoint裸露了proceed办法，该类仅配合实现around告诉 * JoinPoint类，用来获取代理类和被代理类的信息 * 调用proceed办法，示意继续执行指标办法（即加了@DataSource注解的办法） */ public Object around(ProceedingJoinPoint point) throws Throwable { // 通过反射取得被代理类（指标对象） Class targetClass = point.getTarget().getClass(); System.out.println("targetClass:" + targetClass); /** * 取得被代理类（指标对象）的办法签名 * signature加签是一种简略、 低成本、保障数据安全的形式 */ MethodSignature signature = (MethodSignature) point.getSignature(); /** * 取得被代理类（指标对象）的办法 * 这里取得办法也能够通过反射和getTarget()，但步骤更多更简单 */ Method method = signature.getMethod(); System.out.println("method:" + method); // 取得被代理类（指标对象）的注解对象 DataSource targetDataSource = (DataSource) targetClass.getAnnotation(DataSource.class); System.out.println("targetDataSource:" + targetDataSource); // 取得被代理类（指标对象）的办法的注解对象 DataSource methodDataSource = method.getAnnotation(DataSource.class); System.out.println("methodDataSource:" + methodDataSource); // 判断被代理类（指标对象）的注解对象或者被代理类（指标对象）的办法的注解对象不为空 if (targetDataSource != null || methodDataSource != null) { String value; // 优先用被代理类（指标对象）的办法的注解对象的值进行后续赋值 if (methodDataSource != null) { value = methodDataSource.value(); } else { value = targetDataSource.value(); } /** * DynamicContextHolder是本人实现的栈数据结构 * 将注解对象的值入栈 */ DynamicContextHolder.push(value); logger.debug("set datasource is {}", value); } try { // 继续执行被代理类（指标对象）的办法 return point.proceed(); } finally { // 清空栈中数据 DynamicContextHolder.poll(); logger.debug("clean datasource"); } }}5.5、多数据源上下文操作反对类(DynamicContextHolder)
public class DynamicContextHolder { /** * Lambda结构 本地线程变量 * 用于防止屡次创立数据库连贯或者多线程应用同一个数据库连贯 * 缩小数据库连贯创立敞开对程序执行效率的影响与服务器压力 * * 这里应用数组队列实现栈数据结构，实现函数部分状态所需的后进先出"LIFO"环境 */ private static final ThreadLocal<Deque<String>> CONTEXT_HOLDER = ThreadLocal.withInitial(ArrayDeque::new); /** * 取得以后线程数据源 * * @return 数据源名称 */ public static String peek() { return CONTEXT_HOLDER.get().peek(); } /** * 设置以后线程数据源 * * @param dataSource 数据源名称 */ public static void push(String dataSource) { CONTEXT_HOLDER.get().push(dataSource); } /** * 清空以后线程数据源 */ public static void poll() { Deque<String> deque = CONTEXT_HOLDER.get(); deque.poll(); if (deque.isEmpty()) { CONTEXT_HOLDER.remove(); } }}5.6、多数据源类(DynamicDataSource)
public class DynamicDataSource extends AbstractRoutingDataSource { /** * 返回以后上下文环境的数据源key * 后续会依据这个key去找到对应的数据源属性 */ @Override protected Object determineCurrentLookupKey() { return DynamicContextHolder.peek(); }}5.7、多数据源配置类(DynamicDataSourceConfig)
/** * 通过@EnableConfigurationProperties(DynamicDataSourceProperties.class) * 将DynamicDataSourceProperties.class注入到Spring容器中 */@Configuration@EnableConfigurationProperties(DynamicDataSourceProperties.class)public class DynamicDataSourceConfig { // 这里properties曾经蕴含了yml配置中所对应的多数据源的属性了 @Autowired private DynamicDataSourceProperties properties; /** * 通过@ConfigurationProperties与@Bean，将yml配置文件对于druid中的属性配置，转化成bean，并将bean注入到容器中 * 这里作用是通过autowire作为参数利用到上面的dynamicDataSource()办法中 */ @Bean @ConfigurationProperties(prefix = "spring.datasource.druid") public DataSourceProperties dataSourceProperties() { return new DataSourceProperties(); } /** * 通过@Bean告知Spring容器，该办法会返回DynamicDataSource对象 * 通过dynamicDataSource()配置多数据源抉择逻辑，次要配置指标数据源和默认数据源 */ @Bean public DynamicDataSource dynamicDataSource(DataSourceProperties dataSourceProperties) { // 实例化本人实现的多数据源，其中实现了获取以后线程数据源名称的办法 DynamicDataSource dynamicDataSource = new DynamicDataSource(); // 设置多数据源属性 dynamicDataSource.setTargetDataSources(getDynamicDataSource()); // 工厂办法创立Druid数据源 DruidDataSource defaultDataSource = DynamicDataSourceFactory.buildDruidDataSource(dataSourceProperties); // 设置默认数据源属性 dynamicDataSource.setDefaultTargetDataSource(defaultDataSource); return dynamicDataSource; } private Map<Object, Object> getDynamicDataSource(){ Map<String, DataSourceProperties> dataSourcePropertiesMap = properties.getDatasource(); Map<Object, Object> targetDataSources = new HashMap<>(dataSourcePropertiesMap.size()); dataSourcePropertiesMap.forEach((k, v) -> { DruidDataSource druidDataSource = DynamicDataSourceFactory.buildDruidDataSource(v); targetDataSources.put(k, druidDataSource); }); return targetDataSources; }}5.8、多数据源工厂类(DynamicDataSourceFactory)
// 这里拜访权限是包公有class DynamicDataSourceFactory { static DruidDataSource buildDruidDataSource(DataSourceProperties properties) { DruidDataSource druidDataSource = new DruidDataSource(); druidDataSource.setDriverClassName(properties.getDriverClassName()); druidDataSource.setUrl(properties.getUrl()); druidDataSource.setUsername(properties.getUsername()); druidDataSource.setPassword(properties.getPassword()); druidDataSource.setInitialSize(properties.getInitialSize()); druidDataSource.setMaxActive(properties.getMaxActive()); druidDataSource.setMinIdle(properties.getMinIdle()); druidDataSource.setMaxWait(properties.getMaxWait()); druidDataSource.setTimeBetweenEvictionRunsMillis(properties.getTimeBetweenEvictionRunsMillis()); druidDataSource.setMinEvictableIdleTimeMillis(properties.getMinEvictableIdleTimeMillis()); druidDataSource.setMaxEvictableIdleTimeMillis(properties.getMaxEvictableIdleTimeMillis()); druidDataSource.setValidationQuery(properties.getValidationQuery()); druidDataSource.setValidationQueryTimeout(properties.getValidationQueryTimeout()); druidDataSource.setTestOnBorrow(properties.isTestOnBorrow()); druidDataSource.setTestOnReturn(properties.isTestOnReturn()); druidDataSource.setPoolPreparedStatements(properties.isPoolPreparedStatements()); druidDataSource.setMaxOpenPreparedStatements(properties.getMaxOpenPreparedStatements()); druidDataSource.setSharePreparedStatements(properties.isSharePreparedStatements()); try { druidDataSource.setFilters(properties.getFilters()); druidDataSource.init(); } catch (SQLException e) { e.printStackTrace(); } return druidDataSource; }}5.9、数据源属性类(DataSourceProperties)
public class DataSourceProperties { /** * 可动静配置的数据库连贯属性 */ private String driverClassName; private String url; private String username; private String password; /** * Druid默认参数 */ private int initialSize = 2; private int maxActive = 10; private int minIdle = -1; private long maxWait = 60 * 1000L; private long timeBetweenEvictionRunsMillis = 60 * 1000L; private long minEvictableIdleTimeMillis = 1000L * 60L * 30L; private long maxEvictableIdleTimeMillis = 1000L * 60L * 60L * 7; private String validationQuery = "select 1"; private int validationQueryTimeout = -1; private boolean testOnBorrow = false; private boolean testOnReturn = false; private boolean testWhileIdle = true; private boolean poolPreparedStatements = false; private int maxOpenPreparedStatements = -1; private boolean sharePreparedStatements = false; private String filters = "stat,wall"; public String getDriverClassName() { return driverClassName; } public void setDriverClassName(String driverClassName) { this.driverClassName = driverClassName; } 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 int getInitialSize() { return initialSize; } public void setInitialSize(int initialSize) { this.initialSize = initialSize; } public int getMaxActive() { return maxActive; } public void setMaxActive(int maxActive) { this.maxActive = maxActive; } public int getMinIdle() { return minIdle; } public void setMinIdle(int minIdle) { this.minIdle = minIdle; } 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 long getMaxEvictableIdleTimeMillis() { return maxEvictableIdleTimeMillis; } public void setMaxEvictableIdleTimeMillis(long maxEvictableIdleTimeMillis) { this.maxEvictableIdleTimeMillis = maxEvictableIdleTimeMillis; } public String getValidationQuery() { return validationQuery; } public void setValidationQuery(String validationQuery) { this.validationQuery = validationQuery; } public int getValidationQueryTimeout() { return validationQueryTimeout; } public void setValidationQueryTimeout(int validationQueryTimeout) { this.validationQueryTimeout = validationQueryTimeout; } 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 isTestWhileIdle() { return testWhileIdle; } public void setTestWhileIdle(boolean testWhileIdle) { this.testWhileIdle = testWhileIdle; } public boolean isPoolPreparedStatements() { return poolPreparedStatements; } public void setPoolPreparedStatements(boolean poolPreparedStatements) { this.poolPreparedStatements = poolPreparedStatements; } public int getMaxOpenPreparedStatements() { return maxOpenPreparedStatements; } public void setMaxOpenPreparedStatements(int maxOpenPreparedStatements) { this.maxOpenPreparedStatements = maxOpenPreparedStatements; } public boolean isSharePreparedStatements() { return sharePreparedStatements; } public void setSharePreparedStatements(boolean sharePreparedStatements) { this.sharePreparedStatements = sharePreparedStatements; } public String getFilters() { return filters; } public void setFilters(String filters) { this.filters = filters; }}5.10、多数据源属性类(DynamicDataSourceProperties)
/** * 通过@ConfigurationProperties指定读取yml的前缀关键字 * 配合setDatasource()，即读取dynamic.datasource下的配置，将配置属性转化成bean * 容器执行程序是，在bean被实例化后，会调用后置解决，递归的查找属性，通过反射注入值 * * 因为该类只在DynamicDataSourceConfig类中应用，没有其它中央用到，所以没有应用@Component * 而是在DynamicDataSourceConfig类中用@EnableConfigurationProperties定义为bean */@ConfigurationProperties(prefix = "dynamic")public class DynamicDataSourceProperties { private Map<String, DataSourceProperties> datasource = new LinkedHashMap<>(); public Map<String, DataSourceProperties> getDatasource() { return datasource; } public void setDatasource(Map<String, DataSourceProperties> datasource) { this.datasource = datasource; }}六、最初
以上代码均已提交到开源我的项目中，对应我的项目模块为hei-dynamic-datasource
有须要的小伙伴可点击下方链接，clone代码到本地
多数据源Gitee地址