主要参考:基于注解的Spring多数据源配置和使用,在此感谢。。。
如下结合配置做简要说明:
1、定义一个用来指定数据源的注解,如下:
package com.ryan.core.datasource;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DataSource {
String value();
}
2、定义一个数据库切换工具类:
package com.ryan.core.datasource;
public class DataSourceContextHolder {
/**
* 注意:数据源标识保存在线程变量中,避免多线程操作数据源时互相干扰
*/
private static final ThreadLocal contextHolder = new ThreadLocal();
public static void setDbType(String dbType){
contextHolder.set(dbType);
}
public static String getDbType(){
return contextHolder.get();
}
public static void clearDbType(){
contextHolder.remove();
}
}
3、实现AbstractRoutingDataSource抽象类中的determineCurrentLookupKey方法,用于切换到指定的数据源:
package com.ryan.core.datasource;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicDataSource extends AbstractRoutingDataSource {
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContextHolder.getDbType();
}
}
4、定义AOP,增加切面拦截:
package com.ryan.core.datasource.aspect;
import java.lang.reflect.Method;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.ryan.core.datasource.DataSource;
import com.ryan.core.datasource.DataSourceContextHolder;
public class DataSourceAspect {
private static final Logger logger = LoggerFactory.getLogger(DataSourceAspect.class);
/**
* 拦截目标方法,获取由@DataSource指定的数据源标识,设置到线程存储中以便切换数据源
* @param point
* @throws Exception
*/
public void intercept(JoinPoint point) throws Exception
{
Class target = point.getTarget().getClass();
MethodSignature signature = (MethodSignature) point.getSignature();
// 默认使用目标类型的注解,如果没有则使用其实现接口的注解
for (Class clazz : target.getInterfaces()) {
resolveDataSource(clazz, signature.getMethod());
}
resolveDataSource(target, signature.getMethod());
}
/**
* 提取目标对象方法注解和类型注解中的数据源标识
* @param clazz
* @param method
*/
private void resolveDataSource(Class clazz, Method method)
{
try {
Class[] types = method.getParameterTypes();
// 默认使用类型注解
if (clazz.isAnnotationPresent(DataSource.class)) {
DataSource source = clazz.getAnnotation(DataSource.class);
DataSourceContextHolder.setDbType(source.value());
}
// 方法注解可以覆盖类型注解
Method m = clazz.getMethod(method.getName(), types);
if (m != null && m.isAnnotationPresent(DataSource.class)) {
DataSource source = m.getAnnotation(DataSource.class);
DataSourceContextHolder.setDbType(source.value());
}
} catch (Exception e) {
logger.error("数据源切换出现异常", e);
}
}
}
6、在Controller类或方法中增加@DataSource,示例中配置的Controller级别上,如下:
package com.ryan.controller;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
import com.ryan.core.datasource.DataSource;
import com.ryan.mapper.UserHolder;
import com.ryan.service.UserService;
@Controller
@RequestMapping(value="/cms/user")
@DataSource("cmsDataSource")
public class UserController {
@Autowired
private UserService userService;
@RequestMapping(value="/index")
public ModelAndView index(HttpServletRequest req, HttpServletResponse resp){
return new ModelAndView("/user/index");
}
@RequestMapping(value="/list", method={RequestMethod.POST}, produces="application/json;charset=UTF-8")
@ResponseBody
public List getList(@RequestBody UserHolder holder, HttpServletRequest req, HttpServletResponse resp){
List userList = this.userService.getList(holder);
return userList;
}
}