AbstractRoutingDataSource實現讀寫分離

上一節說到mycat實現DB讀寫分離

這節說代碼如何和mycat實現讀寫分離

1、pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.mayikt</groupId>
	<artifactId>springboot-mybatis-02</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.4.RELEASE</version>
		<relativePath /> <!-- lookup parent from repository -->
	</parent>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-aop</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>1.3.2</version>
		</dependency>

		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.0.23</version>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<artifactId>maven-resources-plugin</artifactId>
				<version>3.1.0</version>
				<configuration>
					<encoding>UTF-8</encoding>
				</configuration>
			</plugin>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

2、application.yml配置兩個數據源，一讀一寫

spring:
  datasource:
    ###可讀數據源
    select:
      jdbc-url: jdbc:mysql://你的IP:8066/my_db1
      driver-class-name: com.mysql.jdbc.Driver
      username: user
      password: user
    ####可寫數據源  
    update:
      jdbc-url: jdbc:mysql://你的IP:8066/my_db1
      driver-class-name: com.mysql.jdbc.Driver
      username: root
      password: 123456
    type: com.alibaba.druid.pool.DruidDataSource

3、AppMybatis.java

package com.mayikt;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan(basePackages = "com.mayikt.mapper")
public class AppMybatis {

	public static void main(String[] args) {
		SpringApplication.run(AppMybatis.class, args);
	}

}

4、用註釋 bean的方法，配置兩個數據源 DataSourceConfig.java

package com.mayikt.config;

import javax.sql.DataSource;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class DataSourceConfig {

	// 創建可讀數據源
	@Bean(name = "selectDataSource")
	@ConfigurationProperties(prefix = "spring.datasource.select") // application.properteis中對應屬性的前綴
	public DataSource dataSource1() {
		return DataSourceBuilder.create().build();
	}

	// 創建可寫數據源
	@Bean(name = "updateDataSource")
	@ConfigurationProperties(prefix = "spring.datasource.update") // application.properteis中對應屬性的前綴
	public DataSource dataSource2() {
		return DataSourceBuilder.create().build();
	}

}

5、DataSourceContextHolder

.java

package com.mayikt.config;

import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;

@Component
@Lazy(false)
public class DataSourceContextHolder {
	// 採用ThreadLocal 保存本地多數據源
	private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

	// 設置數據源類型
	public static void setDbType(String dbType) {
		contextHolder.set(dbType);
	}

	public static String getDbType() {
		return contextHolder.get();
	}

	public static void clearDbType() {
		contextHolder.remove();
	}

}

6、DynamicDataSource.java

package com.mayikt.config;
//在Spring 2.0.1中引入了AbstractRoutingDataSource, 該類充當了DataSource的路由中介, 能有在運行時, 根據某種key值來動態切換到真正的DataSource上。

import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.stereotype.Component;

@Component
@Primary
public class DynamicDataSource extends AbstractRoutingDataSource {
	@Autowired
	@Qualifier("selectDataSource")
	private DataSource selectDataSource;

	@Autowired
	@Qualifier("updateDataSource")
	private DataSource updateDataSource;

	/**
	 * 這個是主要的方法，返回的是生效的數據源名稱
	 */
	@Override
	protected Object determineCurrentLookupKey() {
		System.out.println("DataSourceContextHolder：：：" + DataSourceContextHolder.getDbType());
		return DataSourceContextHolder.getDbType();
	}

	/**
	 * 配置數據源信息
	 */
	@Override
	public void afterPropertiesSet() {
		Map<Object, Object> map = new HashMap<>();
		map.put("selectDataSource", selectDataSource);
		map.put("updateDataSource", updateDataSource);
		setTargetDataSources(map);
		setDefaultTargetDataSource(updateDataSource);
		super.afterPropertiesSet();
	}
}

7、SwitchDataSourceAOP 這個主要做AOP攔截數據語句，判斷是DML還是查詢，走相應的數據源，實現讀寫分離

package com.mayikt.aop;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.context.annotation.Lazy;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import com.mayikt.config.DataSourceContextHolder;

@Aspect
@Component
@Lazy(false)
@Order(0) // Order設定AOP執行順序 使之在數據庫事務上先執行
public class SwitchDataSourceAOP {
	// 這裏切到你的方法目錄
	@Before("execution(* com.mayikt.service.*.*(..))")
	public void process(JoinPoint joinPoint) {
		String methodName = joinPoint.getSignature().getName();
		if (methodName.startsWith("get") || methodName.startsWith("count") || methodName.startsWith("find")
				|| methodName.startsWith("list") || methodName.startsWith("select") || methodName.startsWith("check")) {
			// 讀
			DataSourceContextHolder.setDbType("selectDataSource");
		} else {
			// 切換dataSource
			DataSourceContextHolder.setDbType("updateDataSource");
		}
	}
}

8、UserMapper.java做數據庫操作

package com.mayikt.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import com.mayikt.entity.UserEntity;

public interface UserMapper {
	@Select("SELECT user_name as userName FROM  user ")
	public List<UserEntity> findUser();

	@Select("insert into user(user_name) values (#{userName}); ")
	public List<UserEntity> insertUser(@Param("userName") String userName);
}

9、其它的server/controller自己實現。累了