Springboot系列--简单的配置实现数据库读写分离

1 配置文件

#多数据源
datasource:
#从库数量
readSize: 2
# 使用druid数据源
type: com.alibaba.druid.pool.DruidDataSource
#主库
master:
url: jdbc:mysql://127.0.0.1:3306/master?useUnicode=true&characterEncoding=utf8
username: root
password: xxx
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 1
maxWait: 60000
minIdle: 1
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQueryTimeout: 900000
validationQuery: SELECT 1
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20
slave:
url: jdbc:mysql://127.0.0.1:3306/slave?useUnicode=true&characterEncoding=utf8
username: root
password: xxx
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 1
maxWait: 60000
minIdle: 1
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQueryTimeout: 900000
validationQuery: SELECT 1
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20

这里我只配置了一个主库和一个从库，你也可以配置多个从库，根据你自己项目需求来。

2 DataSourceConfig

@Configuration
public class DataSourceConfig {
@Value("${datasource.type}")
private Class<? extends DataSource> dataSourceType;

@Bean(name = "masterDataSource")
@ConfigurationProperties(prefix = "datasource.master")
public DataSource masterDataSource() {
return DataSourceBuilder.create().type(dataSourceType).build();
}

@Bean(name = "slaveDataSource")
@ConfigurationProperties(prefix = "datasource.slave")
public DataSource slaveDataSource() {
return DataSourceBuilder.create().type(dataSourceType).build();
}

//动态数据源
@Bean(name = "dynamicDataSource")
//解决互相依赖关系
@DependsOn({ "masterDataSource", "slaveDataSource"})
@Primary
public DataSource getDataSource() {
DynamicDataSource dataSource = new DynamicDataSource();
dataSource.setTargetDataSources(targetDataSources());
return dataSource;
}

private Map<Object, Object> targetDataSources() {
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(DataSourceType.MASTER.getType(), masterDataSource());
targetDataSources.put(DataSourceType.SLAVE.getType(), slaveDataSource());
return targetDataSources;
}
}

3 主从库枚举

public enum DataSourceType {
SLAVE("slave", "从库"),
MASTER("master", "主库");

private String type;
private String name;

DataSourceType(String type, String name) {
this.type = type;
this.name = name;
}

public String getType() {
return type;
}

public void setType(String type) {
this.type = type;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

4 通过继承AbstractRoutingDataSource实现其动态选择数据源

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

public class DynamicDataSource extends AbstractRoutingDataSource {

@Override
protected Object determineCurrentLookupKey() {
if (DynamicDataSourceHolder.getDataSouce() != null) {
return DynamicDataSourceHolder.getDataSouce();
}
return DataSourceType.MASTER.getType();
}
}

5 设置本地线程全局变量,保证线程安全

public class DynamicDataSourceHolder {

private static final ThreadLocal<String> holder = new ThreadLocal<>();

public static void putDataSource(DataSourceType dataSourceType) {
holder.set(dataSourceType.getType());
}

public static String getDataSouce() {
return holder.get();
}
}

6 自定义注解

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
@Inherited
public @interface DataSource {

/**
* 数据库路由
*/
DataSourceType value() default DataSourceType.MASTER;
}

7 AOP进行动态数据源操作

这个是核心，处理读写分离和自定义注解

ps:我写了两个类切面，DataSourcePartAspect 这个先执行，默认mapper有select，query的走从库 ;delete,update,insert走主库

DataSourceAspect后执行，也就是注解的优先级高于前面的默认的，保证注解优先。

@Aspect
@Component
@Order(-1)
@Slf4j
public class DataSourcePartAspect {
/**
* mapper 查询操作默认使用从库
*/
@Before("execution(* com..service..*.select*(..)) || execution(* com..service..*.get*(..))|| execution(* com..service..*.query*(..))")
public void setReadDataSourceType() {
DynamicDataSourceHolder.putDataSource(DataSourceType.SLAVE);
log.info("dataSource 切换到：{}",DataSourceType.SLAVE.getName());
}

/**
* mapper 修改删除操作默认使用主库库
*/
@Before("execution(* com..service..*.insert*(..)) || execution(* com..service..*.update*(..)) || execution(* com..service..*.delete*(..))")
public void setWriteDataSourceType() {
DynamicDataSourceHolder.putDataSource(DataSourceType.MASTER);
log.info("dataSource 切换到：{}",DataSourceType.MASTER.getName());
}

}

import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Aspect
@Component
@Order(0)
@Slf4j
public class DataSourceAspect{

/**
* 注解方式
* @param joinPoint
* @param dataSource
*/
@Before(value = "@annotation(dataSource)")
public void dataSourcePoint(JoinPoint joinPoint, DataSource dataSource) {
DynamicDataSourceHolder.putDataSource(dataSource.value());
}

}

@Component
public class TestService{

@Autowired
private SourceMapper sourceMapper;

@DataSource(DataSourceType.MASTER)
public String save() {
System.out.println(this.sourceMapper.deleteByPrimaryKey("1"));
return null;
}

//没有注解默认走主库
//@DataSource(DataSourceType.SLAVE)
public String query() {
System.out.println("查询结果：" + JSONObject.toJSONString(this.sourceMapper.selectByPrimaryKey("1")));
return null;
}
}