基于注解的形式在Spring中实现对多数据源配置和使用

     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);
		}
	}

}


    5、在Spring的配置文件中增加数据源配置以及AOP拦截规则:


		
		
		
		
	
	
	
		
		
		
		
	
	
	
	
		  
               
             	  
                
               
		
		
		
	

	
		
		
	
	
	
		
	

	
        
        	
	        
            
        
    
    
    


    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;
	}
}

 



 
   
  

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