spring boot+mybatis 多数据源切换(实例讲解)

所属分类：软件编程 / java 阅读数： 26

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由于公司业务划分了多个数据库，开发一个项目会同事调用多个库，经过学习我们采用了注解+aop的方式实现的

1.首先定义一个注解类

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface TargetDataSource {
 String value();//此处接收的是数据源的名称
}

2.然后建一个配置类，这个在项目启动时会加载数据源，一开始采用了HikariCP，查资料说是最快性能最好的，然后又发现了阿里的druid，这个功能比较全面，而且性能也还可以，最主要他还有监控功能，具体实现看如下代码

package com.example.demo.datasource;
 
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import com.example.demo.datasource.DynamicDataSource;
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import lombok.extern.slf4j.Slf4j;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.transaction.PlatformTransactionManager;
import org.w3c.dom.NodeList;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
 
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.sql.DataSource;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.io.File;
import com.alibaba.druid.support.http.StatViewServlet;
/**
 * Author: wangchao
 * Version：
 * Date:  2017/9/11
 * Description:数据源配置
 * Modification History:
 * Date    Author    Version   Description
 * --------------------------------------------------------------
 * Why & What is modified:
 */
 
@Configuration
@EnableScheduling
public class DataSourceConfig {
 
 /*@Autowired
 private DBProperties properties;*/
 @Value("${datasource.filePath}")
 private String filePath;//数据源配置
 
 @Bean(name = "dataSource")
 public DataSource dataSource() {
  //按照目标数据源名称和目标数据源对象的映射存放在Map中
  Map<Object, Object> targetDataSources = new HashMap<>();
  //查找xml数据连接字符串
  targetDataSources=getdataMap(filePath);
  //动态获取DBProperties类申明的属性
  /*Field[] fields=properties.getClass().getDeclaredFields();
  for(int i=0;i<fields.length;i++)
  {
   targetDataSources.put(fields[i].getName(), getFieldValueByName(fields[i].getName(),properties));
  }*/
  //采用是想AbstractRoutingDataSource的对象包装多数据源
  DynamicDataSource dataSource = new DynamicDataSource();
  dataSource.setTargetDataSources(targetDataSources);
  //设置默认的数据源，当拿不到数据源时，使用此配置
  //dataSource.setDefaultTargetDataSource(properties.getUzaiTravel());
  return dataSource;
 }
 
 @Bean
 public PlatformTransactionManager txManager() {
  return new DataSourceTransactionManager(dataSource());
 }
 
 /**
 *获取数据源集合
 */
 
 private Map<Object, Object> getdataMap(String fiePath)
 {
 
  try {
   Map<Object, Object> targetDataSources = new HashMap<>();
   File xmlFile = new File(fiePath);
 
   DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
 
   DocumentBuilder builder = builderFactory.newDocumentBuilder();
 
   Document doc = builder.parse(xmlFile);
 
   doc.getDocumentElement().normalize();
 
   System.out.println("Root element: " + doc.getDocumentElement().getNodeName());
 
   NodeList nList = doc.getElementsByTagName("db");
   for(int i = 0 ; i<nList.getLength();i++) {
 
    Node node = nList.item(i);
    Element ele = (Element)node;
 
    /*HikariConfig config = new HikariConfig();
    config.setDriverClassName(ele.getElementsByTagName("driver-class").item(0).getTextContent());
    config.setJdbcUrl(ele.getElementsByTagName("jdbc-url").item(0).getTextContent());
    config.setUsername(ele.getElementsByTagName("username").item(0).getTextContent());
    config.setPassword(ele.getElementsByTagName("password").item(0).getTextContent());
    //config.addDataSourceProperty("password", ele.getElementsByTagName("password").item(0).getTextContent());
    HikariDataSource dataSource = new HikariDataSource(config);*/
 
 
    DruidDataSource dataSource = new DruidDataSource();
    dataSource.setDriverClassName(ele.getElementsByTagName("driver-class").item(0).getTextContent());
    dataSource.setUsername(ele.getElementsByTagName("username").item(0).getTextContent());
    dataSource.setPassword(ele.getElementsByTagName("password").item(0).getTextContent());
    dataSource.setUrl(ele.getElementsByTagName("jdbc-url").item(0).getTextContent());
    dataSource.setInitialSize(5);
    dataSource.setMinIdle(1);
    dataSource.setMaxActive(10);// 启用监控统计功能
    dataSource.setFilters("stat");//设置是否显示sql语句
    targetDataSources.put(ele.getElementsByTagName("databasename").item(0).getTextContent(), dataSource);
   }
   return targetDataSources;
  }
  catch (Exception ex)
  {
   return null;
  }
 
 }
 //访问的ip
 @Value("${druid.IP}")
 private String IP;
 //登录名
 @Value("${druid.druidLgoinName}")
 private String druidLgoinName;
 //密码
 @Value("${druid.druidLgoinPassword}")
 private String druidLgoinPassword;
 
 @Bean
 public ServletRegistrationBean DruidStatViewServle() {
  //org.springframework.boot.context.embedded.ServletRegistrationBean提供类的进行注册.
  ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
  //添加初始化参数：initParams
 
  //白名单：
  servletRegistrationBean.addInitParameter("allow",IP);
  //IP黑名单 (存在共同时，deny优先于allow) : 如果满足deny的话提示:Sorry, you are not permitted to view this page.
  // servletRegistrationBean.addInitParameter("deny", "192.168.1.73");
  //登录查看信息的账号密码.
  servletRegistrationBean.addInitParameter("loginUsername",druidLgoinName);
  servletRegistrationBean.addInitParameter("loginPassword",druidLgoinPassword);
  //是否能够重置数据.
  servletRegistrationBean.addInitParameter("resetEnable","false");
  return servletRegistrationBean;
 }
 
 /**
 
  * 注册一个：filterRegistrationBean
 
  * @return
 
 */
 @Bean
 public FilterRegistrationBean druidStatFilter2(){
  FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new WebStatFilter());
  //添加过滤规则.
  filterRegistrationBean.addUrlPatterns("/*");
  //添加不需要忽略的格式信息.
  filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
  return filterRegistrationBean;
 }
 
}

3.动态数据源，从之前已加载的数据源中选取，DynamicDataSource和DynamicDataSourceHolder配合使用

public class DynamicDataSource extends AbstractRoutingDataSource{
 //数据源路由，此方用于产生要选取的数据源逻辑名称
 @Override
 protected Object determineCurrentLookupKey() {
  //从共享线程中获取数据源名称
  return DynamicDataSourceHolder.getDataSource();
 }
}

public class DynamicDataSourceHolder {
 /**
  * 本地线程共享对象
  */
 private static final ThreadLocal<String> THREAD_LOCAL = new ThreadLocal<>();
 
 public static void putDataSource(String name) {
  THREAD_LOCAL.set(name);
 }
 
 public static String getDataSource() {
  return THREAD_LOCAL.get();
 }
 
 public static void removeDataSource() {
  THREAD_LOCAL.remove();
 }
}

4.就是使用aop，在dao层切换数据源

@Component
@Aspect
public class DataSourceAspect {
 //切换放在mapper接口的方法上，所以这里要配置AOP切面的切入点
 @Pointcut("execution( * com.example.demo.dao.*.*(..))")
 public void dataSourcePointCut() {
 }
 
 @Before("dataSourcePointCut()")
 public void before(JoinPoint joinPoint) {
  Object target = joinPoint.getTarget();
  String method = joinPoint.getSignature().getName();
  Class<?>[] clazz = target.getClass().getInterfaces();
  Class<?>[] parameterTypes = ((MethodSignature) joinPoint.getSignature()).getMethod().getParameterTypes();
  try {
   Method m = clazz[0].getMethod(method, parameterTypes);
   //如果方法上存在切换数据源的注解，则根据注解内容进行数据源切换
   if (m != null && m.isAnnotationPresent(TargetDataSource.class)) {
    TargetDataSource data = m.getAnnotation(TargetDataSource.class);
    String dataSourceName = data.value();
    DynamicDataSourceHolder.putDataSource(dataSourceName);
 
   } else {
 
   }
  } catch (Exception e) {
 
  }
 }
 
 //执行完切面后，将线程共享中的数据源名称清空
 @After("dataSourcePointCut()")
 public void after(JoinPoint joinPoint){
  DynamicDataSourceHolder.removeDataSource();
 }
}

数据连接都配置在xml里面