springBoot jpa 多数据源的动态切换

    这周笨小葱一直在研究如何使用springBoot的多数据源配置。

    看了3天的网上的博客，发现大多数都是多数据源的配置，并没有很详细的关于使用springBoot的多数据源动态切换的配置。前者整体配置过程是在springBoot的原有的jpa实体管理工厂（entityManagerFactory）的基础上（这里，entityManagerFactory会绑定一个数据源，而transactionManager只需将entityManagerFactory注入就可以绑定数据源了）再次创建一个实体类管理工厂，然后绑定另外一个数据源，但是各自entityManagerFactory都需要绑定各自的repository。这种配置适合一个用户操作不同的数据库。而如果要不同的用户操作不同的数据源，同时对应同一个repository。那么就不能够实现啦。所以需要实现数据源的动态切换。

    这里第一种配置，笨小葱就不详解了，网上有很多资料。

    详细说一下，关于springBoot jpa的多数据源动态切换。

   

      这里我们配置2个数据源，通过动态数据源来切换，对应一个entityManagerFactory，一个repository。主要功能是不同的用户操作不同的数据库，但是他们的数据库结构是一样的，所调用的controller方法也是一样的。

     实现原理：

      1、扩展Spring的AbstractRoutingDataSource抽象类（该类充当了DataSource的路由中介, 能有在运行时, 根据某种key值来动态切换到真正的DataSource上。）

    从AbstractRoutingDataSource的源码中：

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean

 

    我们可以看到，它继承了AbstractDataSource，而AbstractDataSource不就是javax.sql.DataSource的子类，So我们可以分析下它的getConnection方法：

public Connection getConnection() throws SQLException {      return determineTargetDataSource().getConnection();  }     public Connection getConnection(String username, String password) throws SQLException {       return determineTargetDataSource().getConnection(username, password);  }

 

    获取连接的方法中，重点是determineTargetDataSource()方法，看源码：

/**      * Retrieve the current target DataSource. Determines the      * {@link #determineCurrentLookupKey() current lookup key}, performs      * a lookup in the {@link #setTargetDataSources targetDataSources} map,      * falls back to the specified      * {@link #setDefaultTargetDataSource default target DataSource} if necessary.      * @see #determineCurrentLookupKey()      */      protected DataSource determineTargetDataSource() {          Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");          Object lookupKey = determineCurrentLookupKey();          DataSource dataSource = this.resolvedDataSources.get(lookupKey);          if (dataSource == null && (this.lenientFallback || lookupKey == null)) {              dataSource = this.resolvedDefaultDataSource;          }          if (dataSource == null) {              throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");          }          return dataSource;      }

 

    上面这段源码的重点在于determineCurrentLookupKey()方法，这是AbstractRoutingDataSource类中的一个抽象方法，而它的返回值是你所要用的数据源dataSource的key值，有了这个key值，resolvedDataSource（这是个map,由配置文件中设置好后存入的）就从中取出对应的DataSource，如果找不到，就用配置默认的数据源。

    看完源码，应该有点启发了吧，没错！你要扩展AbstractRoutingDataSource类，并重写其中的determineCurrentLookupKey()方法，来实现数据源的切换：

package com.datasource.test.util.database; import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource; /** * 获取数据源（依赖于spring） * @author linhy */public class DynamicDataSource extends AbstractRoutingDataSource{    @Override    protected Object determineCurrentLookupKey() {        return DataSourceHolder.getDataSource();    }}

 

    DataSourceHolder这个类则是我们自己封装的对数据源进行操作的类：

package com.datasource.test.util.database; /** * 数据源操作 * @author linhy */public class DataSourceHolder {    //线程本地环境    private static final ThreadLocal<String> dataSources = new ThreadLocal<String>();    //设置数据源    public static void setDataSource(String customerType) {        dataSources.set(customerType);    }    //获取数据源    public static String getDataSource() {        return (String) dataSources.get();    }    //清除数据源    public static void clearDataSource() {        dataSources.remove();    } }

创建完这2个类之后，只需要在调用controller的方法之前调用对应的数据源就可以了。调用数据源即：

DataSourceHolder.setDataSource (xxxx);

这样在执行controller方法之前就完成了当前线程（http请求）的数据源切换。

这个方法也是参考的网上的。但是如何将其整合入springBoot中，还需要自己调试一下。笨小葱花了2天时间，终于配置调试好了。下面配上springBoot的各个文件。

首先:创建上面的2个类。

DynamicDataSource.java :

package cc.study.springboot.domain;import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;/** * Created by Administrator on 2015/11/25. */public class DynamicDataSource extends AbstractRoutingDataSource {    @Override    protected Object determineCurrentLookupKey() {        return DataSourceHolder.getDataSource();    }}

DataSourceHolder.java :

package cc.study.springboot.domain;/** * Created by Administrator on 2015/11/25. */public class DataSourceHolder {    //线程本地环境    private static final ThreadLocal<String> dataSources = new ThreadLocal<String>();    //设置数据源    public static void setDataSource(String customerType) {        dataSources.set(customerType);    }    //获取数据源    public static String getDataSource() {        return (String) dataSources.get();    }    //清除数据源   public static void clearDataSource() {        dataSources.remove();    }}

然后是多数据源与动态数据源的配置，以及entityManagerFactory和transactionManager的配置文件

application-data.xml:

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"       >    <bean id="ds1" name="ds1"          class="org.springframework.jdbc.datasource.DriverManagerDataSource" primary="true">  //这里多数据源,springBoot启动时需要指定一个默认的数据源，所以需要加primary="true",否则会出现数据源bean匹配失败错误        <property name="driverClassName" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/>        <property name="url" value="jdbc:sqlserver://127.0.0.1:1433;databaseName=xxx"/>        <property name="username" value="test"/>        <property name="password" value="xxx"/>    </bean>    <bean id="ds2" name="ds2"          class="org.springframework.jdbc.datasource.DriverManagerDataSource" >        <property name="driverClassName" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/>        <property name="url" value="jdbc:sqlserver://127.0.0.1:1433;databaseName=cc"/>        <property name="username" value="test"/>        <property name="password" value="xxx"/>    </bean>    <!--动态选择数据源-->    <bean id="dataSource" class="cc.study.springboot.domain.DynamicDataSource" >        <property name="targetDataSources">            <map key-type="java.lang.String">                <entry key="1" value-ref="ds1"/>                <entry key="2" value-ref="ds2"/>            </map>        </property>       <property name="defaultTargetDataSource" ref="ds1"/> //不可少    </bean>    <bean id="entityManagerFactory"          class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"          destroy-method="destroy" >        <property name="dataSource" ref="dataSource" />     //这里将动态数据源bean注入        <property name="jpaVendorAdapter">             <bean                    class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">                <property name="databasePlatform" value="org.hibernate.dialect.SQLServer2008Dialect"/>                <property name="showSql" value="true"/>            </bean>        </property>        <property name="packagesToScan" value="cc.study.springboot.domain"/>        <property name="jpaPropertyMap">            <map>                <entry key="javax.persistence.schema-generation.database.action" value="none"/>            </map>        </property>    </bean>    <bean id="transactionManager"          class="org.springframework.orm.jpa.JpaTransactionManager">        <property name="entityManagerFactory"                  ref="entityManagerFactory"/>    </bean>    <tx:annotation-driven transaction-manager="transactionManager"/></beans>

配置完成后，需要让springBoot在启动时候，创建application上下文对象的时候加载这个xml文档，创建数据源bean

package cc.study.springboot;import org.springframework.beans.factory.annotation.Autowire;import org.springframework.beans.factory.annotation.Configurable;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.EnableAutoConfiguration;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.ImportResource;/*@SpringBootApplication is a convenience annotation that adds all of the following:    @Configuration tags the class as a source of bean definitions for the application context.    @EnableAutoConfiguration. This annotation tells Spring Boot to “guess” how you will want to configure Spring,     based on the jar dependencies that you have added. Since spring-boot-starter-web added Tomcat and Spring MVC,     the auto-configuration will assume that you are developing a web application and setup Spring accordingly.     This flags the application as a web application and activates key behaviors such as setting up a DispatcherServlet.    @ComponentScan tells Spring to look for other components, configurations, and services in the the hello package, allowing it to find the HelloController.*/ </span><span style="white-space:pre">@Configuration@Configurable(autowire = Autowire.BY_NAME)    //定义bean的注入方式@EnableAutoConfiguration@ComponentScan@ImportResource("classpath:application-data.xml")class Application {    public static void main(String[] args) {        ApplicationContext ctx = SpringApplication.run(Application.class, args);           }}

下面需要在调用controller中的方法之前，添加一个aop切面。用于根据需求修改数据源。

package cc.study.springboot.service;import cc.study.springboot.domain.DataSourceHolder;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;import org.aspectj.lang.annotation.Pointcut;import org.springframework.context.annotation.Configuration;/** * Created by Administrator on 2015/12/16. */@Aspect     //注解的方式配置aop@Configurationpublic class dataSourceAspect {    @Pointcut("execution(* cc.study.springboot.controller..*.*(..))")    private void anyMethod(){}//定义一个切入点    @Before("anyMethod()")    public void dataSourceChange()    {        System.out.print("更改数据源为cc");        DataSourceHolder.setDataSource("2");        /*这里根据用户的类型来更改对应的数据源*/    }}

下面附上controller，domain和repository的代码

UserInfoController.java:

package cc.study.springboot.controller;import cc.study.springboot.domain.DataSourceHolder;import cc.study.springboot.domain.User;import cc.study.springboot.repository.UserRepository;import org.springframework.beans.factory.annotation.Value;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RestController;import javax.inject.Inject;import javax.servlet.http.HttpServletRequest;@RestControllerpublic class UserInfoController {    @Inject    private UserRepository repo;    @Value("${datasource.secondary.url}")    private String url;    @RequestMapping(value = "/userInfo/{id}", method = RequestMethod.GET)    public ResponseEntity<?> getUser(@PathVariable("id") String id,HttpServletRequest request) {    /*  WebApplicationContext wct= WebApplicationContextUtils.getWebApplicationContext(request.getSession().getServletContext());        ComboPooledDataSource ds= (ComboPooledDataSource) wct.getBean("dataSource");        ds.setJdbcUrl(url);*/        User u = repo.findByUsername(id);        return new ResponseEntity<Object>(u, HttpStatus.OK);    }    @RequestMapping(value = "/user", method = RequestMethod.GET)    public ResponseEntity<?> userLogin() {        DataSourceHolder.setDataSource("2");        User u = repo.findByUsername("80045");        return new ResponseEntity<Object>(u, HttpStatus.OK);       /* try {            if("0".equals(loginPost("http://192.168.0.69/SITApps/SITPortal/PortalPage/VerificationUser.aspx", "username=" + username + "&password=" + password)))            {                return new ResponseEntity<>( HttpStatus.OK);            }        } catch (Exception e) {            e.printStackTrace();        }        return new ResponseEntity<Object>(HttpStatus.BAD_REQUEST);*/    }}

User.java:

package cc.study.springboot.domain;import com.fasterxml.jackson.annotation.JsonIgnore;import javax.persistence.*;@Entity@Table(name = "t_mobile_person")public class User {    private String username;    private String password;    private String factoryCode;    private String departmentCode;    private String permissionSys;    private String permissionMonitor;    private String realname;    @Id    @Column(name = "person_id")    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    @Column(name = "password")    @JsonIgnore    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    @Column(name = "factory_code")    public String getFactoryCode() {        return factoryCode;    }    public void setFactoryCode(String factoryCode) {        this.factoryCode = factoryCode;    }    @Column(name = "department_code")    public String getDepartmentCode() {        return departmentCode;    }    public void setDepartmentCode(String departmentCode) {        this.departmentCode = departmentCode;    }    @Column(name = "permission_sys")    @JsonIgnore    public String getPermissionSys() {        return permissionSys;    }    public void setPermissionSys(String permissionSys) {        this.permissionSys = permissionSys;    }    @Column(name = "permission_monitor")    @JsonIgnore    public String getPermissionMonitor() {        return permissionMonitor;    }    public void setPermissionMonitor(String permissionMonitor) {        this.permissionMonitor = permissionMonitor;    }    @Column(name = "REALNAME")    public String getRealname() {        return realname;    }    public void setRealname(String realname) {        this.realname = realname;    }}

UserRepository.java:

package cc.study.springboot.repository;import cc.study.springboot.domain.User;import org.springframework.data.repository.CrudRepository;import org.springframework.stereotype.Repository;import org.springframework.transaction.annotation.Transactional;@Repository@Transactionalpublic interface UserRepository extends CrudRepository<User, String> {    User findByUsername(String id);}

ok,搞定了。后面我会传上项目源码。项目源码：http://download.csdn.net/detail/sunshine920103/9379127