mybatis-plus+springboot实现读写分离
mybatis-plus是mybatis的增强版，他相较于原始的mybatis少许多配置，而且使用也足够简单，由于最近写的一篇文章是关于mysql主从配置的，所以把代码层面的编写也加上来。mybatis-plus的官方地址,mybatis-plus是兼容mybatis的，所以不需要过多担心迁移后出现问题，相反还可以提高开发速度
接下来我们开始配置
首先引入依赖:
com.baomidou
mybatis-plus-boot-starter
3.1.1
mysql
mysql-connector-java
然后对配置数据源
spring:
datasource:
hikari:
master:
driverClassName: com.mysql.cj.jdbc.Driver
jdbc-url: jdbc:mysql://localhost:3306/mptest?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
username: root
password: 123456
slave:
driverClassName: com.mysql.cj.jdbc.Driver
jdbc-url: jdbc:mysql://localhost:3307/mptest?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
username: root
password: 123456这里要注意是jdbc-url，而且链接还要加上时区，不然会报奇奇怪怪的错误，当时就是被这个小问题卡了挺久
网上很多都是基于aop在service层上实现分离，这里因为我以前在慕课网的翔仔老师（我最喜欢的讲师，讲课很亲切很清晰）实战课上学过ssm的基于拦截器的配置，如今把这个技术对接上springboot、mybatis-plus做一个回顾。
基本的思路就是当实现一个mybatis的拦截器，对增删改查操作进行拦截，再根据语句类型分配给不同的数据源
然后看一下实现方式
package com.gdut.imis.esclientdemo.dyna;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.lang.Nullable;
/**
* @author lulu
* @Date 2019/6/8 12:13
*/
public class DynamicDataSource extends AbstractRoutingDataSource {
@Nullable
@Override
protected Object determineCurrentLookupKey() {
return DynamicDataSourceHolder.getDbType();
}
}
这个类用来决定使用哪个数据源，我们新建一个holder来存放相应的datasource
package com.gdut.imis.esclientdemo.dyna;
import lombok.extern.slf4j.Slf4j;
/**
* @author lulu
* @Date 2019/6/8 12:14
*/
@Slf4j
public class DynamicDataSourceHolder {
private static ThreadLocal contextHolder = new ThreadLocal<>();
public static final String DB_MASTER = "master";
public static final String DB_SLAVE = "slave";
public static String getDbType() {
String db = contextHolder.get();
if (db == null) {
db = DB_MASTER;
}
return db;
}
public static void setDBType(String str) {
log.info("数据源为" + str);
contextHolder.set(str);
}
public static void clearDbType() {
contextHolder.remove();
}
}
如果有多个从数据库，可以用一个枚举或者集合封装把从数据库信息添加进去
拦截器实现：
package com.gdut.imis.esclientdemo.dyna;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import java.util.Locale;
import java.util.Properties;
/**
* @author lulu
* @Date 2019/6/8 12:18
*/
@Slf4j
//指定拦截哪些方法,update包括增删改
@Intercepts({ @Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class }),
@Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class,
RowBounds.class, ResultHandler.class }) })
public class DynamicDataSourceInterceptor implements Interceptor{
private static final String REGEX=".*insert\\u0020.*|.*delete\\u0020.*|.*update\\u0020.*";
@Override
public Object intercept(Invocation invocation) throws Throwable {
boolean synchronizationActive= TransactionSynchronizationManager.isActualTransactionActive();
String lookupKey=DynamicDataSourceHolder.DB_MASTER;
if(!synchronizationActive){
Object[] objects=invocation.getArgs();
MappedStatement ms=(MappedStatement)objects[0];
if(ms.getSqlCommandType().equals(SqlCommandType.SELECT)){
//如果selectKey为自增id查询主键,使用主库
if(ms.getId().contains(SelectKeyGenerator.SELECT_KEY_SUFFIX)){
lookupKey=DynamicDataSourceHolder.DB_MASTER;
}else{
BoundSql boundSql=ms.getSqlSource().getBoundSql(objects[1]);
String sql=boundSql.getSql().toLowerCase(Locale.CHINA).replaceAll("[\\t\\n\\r]"," ");
if(sql.matches(REGEX)){
lookupKey=DynamicDataSourceHolder.DB_MASTER;
}else{
//这里如果有多个从数据库，则添加挑选过程
lookupKey=DynamicDataSourceHolder.DB_SLAVE;
}
}
}
}else{
lookupKey=DynamicDataSourceHolder.DB_MASTER;
}
DynamicDataSourceHolder.setDBType(lookupKey);
return invocation.proceed();
}
@Override
public Object plugin(Object target) {
//增删改查的拦截，然后交由intercept处理
if(target instanceof Executor){
return Plugin.wrap(target,this);
}else{
return target;
}
}
@Override
public void setProperties(Properties properties) {
}
}
config配置
package com.gdut.imis.esclientdemo.config;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.gdut.imis.esclientdemo.dyna.DynamicDataSource;
import com.gdut.imis.esclientdemo.dyna.DynamicDataSourceHolder;
import com.gdut.imis.esclientdemo.dyna.DynamicDataSourceInterceptor;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.JdbcType;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
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;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy;
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;
/**
* @author lulu
* @Date 2019/6/8 16:12
*/
@Configuration // 该注解类似于spring配置文件
@MapperScan(basePackages = "com.gdut.imis.esclientdemo.dao*")
public class MyBatisPlusConfig {
/**
* 配置数据源
* @return
*/
@Bean(name = "master")
@ConfigurationProperties(prefix = "spring.datasource.hikari.master")
public DataSource master() {
return DataSourceBuilder.create().build();
}
@Bean(name = "slave")
@ConfigurationProperties(prefix = "spring.datasource.hikari.slave")
public DataSource slave() {
return DataSourceBuilder.create().build();
}
@Primary
@Bean(name = "dynamicDataSource")
public DynamicDataSource dataSource(@Qualifier("master") DataSource master,
@Qualifier("slave") DataSource slave) {
Map targetDataSource = new HashMap<>();
targetDataSource.put(DynamicDataSourceHolder.DB_MASTER, master);
targetDataSource.put(DynamicDataSourceHolder.DB_SLAVE, slave);
DynamicDataSource dataSource = new DynamicDataSource();
dataSource.setTargetDataSources(targetDataSource);
return dataSource;
}
@Bean
public PaginationInterceptor paginationInterceptor() {
return new PaginationInterceptor();
}
@Bean
public DynamicDataSourceInterceptor dynamicDataSourceInterceptor(){
return new DynamicDataSourceInterceptor();
}
/**
* 根据数据源创建SqlSessionFactory
*/
@Bean(name = "SqlSessionFactory")
public SqlSessionFactory test1SqlSessionFactory()
throws Exception {
//配置mybatis,对应mybatis-config.xml
MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
//懒加载
LazyConnectionDataSourceProxy p=new LazyConnectionDataSourceProxy();
p.setTargetDataSource(dataSource(master(),slave()));
sqlSessionFactory.setDataSource(p);
//需要mapper文件时加入扫描，sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/mapper/*/*Mapper.xml"));
MybatisConfiguration configuration = new MybatisConfiguration();
configuration.setJdbcTypeForNull(JdbcType.NULL);
configuration.setMapUnderscoreToCamelCase(true);
configuration.setUseGeneratedKeys(true);
configuration.setCacheEnabled(false);
sqlSessionFactory.setConfiguration(configuration);
//加入上面的两个拦截器
Interceptor interceptor[]={paginationInterceptor(),dynamicDataSourceInterceptor()};
sqlSessionFactory.setPlugins(interceptor);
return sqlSessionFactory.getObject();
}
/**
* 配置事务管理器
*/
@Bean
public DataSourceTransactionManager transactionManager(DynamicDataSource dataSource) throws Exception {
return new DataSourceTransactionManager(dataSource);
}
}
然后mybatis-plus基础使用非常简单，基本方法只要继承baseMapper就可以了
编写一个小例子
@Test
public void insert(){
User u=new User();
u.setAge(21);
u.setEmail("[email protected]");
u.setId(3L);
u.setName("tjl");
userMapper.insert(u);
userMapper.selectList(null).forEach(System.out::println);
}结果
此致，整合完毕，github地址（由于本人较懒，没有新建另一个项目可能有点奇怪），官方文档也有更简便的搭建方法