当业务的访问量（数据库的查询）非常大时，为了降低数据库的压力，希望有多个数据库进行负载均衡，避免所有的查询都集中在一台数据库，造成数据库压力过大。mysql支持一主多从，即在写库的数据库发生变动时，会同步到所有从库，只是同步过程中，会有一定的延迟（除非业务中出现，立即写立即读，否则稍微的延迟是可以接收的）。
当数据库有主从之分了，那应用代码也应该读写分离了。那代码执行时，该如何决定选择哪个数据库呢。
方案一：
就像配置多个数据源那样（见博文spring boot学习6之mybatis+PageHelper分页插件+jta多数据源事务整合），将dao都分别放到不通的包下，指明哪个包下dao接口或配置文件走哪个数据库，service层程序员决定走主库还是从库。
缺点：相同的dao接口和配置文件要复制多份到不同包路径下，不易维护和扩展。
方案二：
使用AbstractRoutingDataSource+aop+annotation在dao层决定数据源。
缺点：不支持事务。因为事务在service层开启时，就必须拿到数据源了。
方案三：
使用AbstractRoutingDataSource+aop+annotation在service层决定数据源，可以支持事务.
缺点：类内部方法通过this.xx()方式相互调用时，aop不会进行拦截，需进行特殊处理。
方案二和方案三的区别就是数据源的决定是方案dao还是service，所以本博文例子代码会都含有。
项目结构
pom.xml
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
</parent>
<dependencies>
<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>1.3.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.29</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
</dependency>
<!-- 分页插件 -->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper</artifactId>
<version>4.1.6</version>
</dependency>
</dependencies>本例子的数据库，都是在本地的mysql中建立3个库，test,test_01,test_02，例子是为了测试代码的读写分离，而是mysqld
application.yml
logging:
config: classpath:logback.xml
path: d:/logs
server:
port: 80
session-timeout: 60
mybatis:
mapperLocations: classpath:/com/fei/springboot/dao/*.xml
typeAliasesPackage: com.fei.springboot.dao
mapperScanPackage: com.fei.springboot.dao
configLocation: classpath:/mybatis-config.xml
mysql:
datasource:
readSize: 2 #读库个数
type: com.alibaba.druid.pool.DruidDataSource
mapperLocations: classpath:/com/fei/springboot/dao/*.xml
configLocation: classpath:/mybatis-config.xml
write:
url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf-8
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
minIdle: 5
maxActive: 100
initialSize: 10
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxPoolPreparedStatementPerConnectionSize: 50
removeAbandoned: true
filters: stat
read01:
url: jdbc:mysql://127.0.0.1:3306/test_01?useUnicode=true&characterEncoding=utf-8
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
minIdle: 5
maxActive: 100
initialSize: 10
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxPoolPreparedStatementPerConnectionSize: 50
removeAbandoned: true
filters: stat
read02:
url: jdbc:mysql://127.0.0.1:3306/test_02?useUnicode=true&characterEncoding=utf-8
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
minIdle: 5
maxActive: 100
initialSize: 10
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxPoolPreparedStatementPerConnectionSize: 50
removeAbandoned: true
filters: stat
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<!-- 使全局的映射器启用或禁用缓存。 -->
<setting name="cacheEnabled" value="true" />
<!-- 全局启用或禁用延迟加载。当禁用时，所有关联对象都会即时加载。 -->
<setting name="lazyLoadingEnabled" value="true" />
<!-- 当启用时，有延迟加载属性的对象在被调用时将会完全加载任意属性。否则，每种属性将会按需要加载。 -->
<setting name="aggressiveLazyLoading" value="true"/>
<!-- 是否允许单条sql 返回多个数据集 (取决于驱动的兼容性) default:true -->
<setting name="multipleResultSetsEnabled" value="true" />
<!-- 是否可以使用列的别名 (取决于驱动的兼容性) default:true -->
<setting name="useColumnLabel" value="true" />
<!-- 允许JDBC 生成主键。需要驱动器支持。如果设为了true，这个设置将强制使用被生成的主键，有一些驱动器不兼容不过仍然可以执行。 default:false -->
<setting name="useGeneratedKeys" value="false" />
<!-- 指定 MyBatis 如何自动映射 数据基表的列 NONE：不隐射 PARTIAL:部分 FULL:全部 -->
<setting name="autoMappingBehavior" value="PARTIAL" />
<!-- 这是默认的执行类型 （SIMPLE: 简单； REUSE: 执行器可能重复使用prepared statements语句；BATCH: 执行器可以重复执行语句和批量更新） -->
<setting name="defaultExecutorType" value="SIMPLE" />
<setting name="defaultStatementTimeout" value="25" />
<setting name="defaultFetchSize" value="100" />
<setting name="safeRowBoundsEnabled" value="false" />
<!-- 使用驼峰命名法转换字段。 -->
<setting name="mapUnderscoreToCamelCase" value="true" />
<!-- 设置本地缓存范围 session:就会有数据的共享 statement:语句范围 (这样就不会有数据的共享 ) defalut:session -->
<setting name="localCacheScope" value="SESSION" />
<!-- 默认为OTHER,为了解决oracle插入null报错的问题要设置为NULL -->
<setting name="jdbcTypeForNull" value="NULL" />
<setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString" />
</settings>
</configuration>
读取配置多个数据源
DataSourceConfiguration.java
package com.fei.springboot.config.dbconfig;
import javax.sql.DataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
/**
* 数据库源配置
* @author Jfei
*
*/
@Configuration
public class DataSourceConfiguration {
private static Logger log = LoggerFactory.getLogger(DataSourceConfiguration.class);
@Value("${mysql.datasource.type}")
private Class<? extends DataSource> dataSourceType;
/**
* 写库 数据源配置
* @return
*/
@Bean(name = "writeDataSource")
@Primary
@ConfigurationProperties(prefix = "mysql.datasource.write")
public DataSource writeDataSource() {
log.info("-------------------- writeDataSource init ---------------------");
return DataSourceBuilder.create().type(dataSourceType).build();
}
/**
* 有多少个从库就要配置多少个
* @return
*/
@Bean(name = "readDataSource01")
@ConfigurationProperties(prefix = "mysql.datasource.read01")
public DataSource readDataSourceOne() {
log.info("-------------------- read01 DataSourceOne init ---------------------");
return DataSourceBuilder.create().type(dataSourceType).build();
}
@Bean(name = "readDataSource02")
@ConfigurationProperties(prefix = "mysql.datasource.read02")
public DataSource readDataSourceTwo() {
log.info("-------------------- read02 DataSourceTwo init ---------------------");
return DataSourceBuilder.create().type(dataSourceType).build();
}
}
MybatisConfiguration.java
package com.fei.springboot.config.dbconfig;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicInteger;
import javax.sql.DataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.transaction.PlatformTransactionManager;
import com.fei.springboot.util.SpringContextUtil;
import com.github.pagehelper.PageHelper;
@Configuration
@AutoConfigureAfter(DataSourceConfiguration.class)
@MapperScan(basePackages="com.fei.springboot.dao")
public class MybatisConfiguration {
private static Logger log = LoggerFactory.getLogger(MybatisConfiguration.class);
@Value("${mysql.datasource.readSize}")
private String readDataSourceSize;
//XxxMapper.xml文件所在路径
@Value("${mysql.datasource.mapperLocations}")
private String mapperLocations;
// 加载全局的配置文件
@Value("${mysql.datasource.configLocation}")
private String configLocation;
@Autowired
@Qualifier("writeDataSource")
private DataSource writeDataSource;
@Autowired
@Qualifier("readDataSource01")
private DataSource readDataSource01;
@Autowired
@Qualifier("readDataSource02")
private DataSource readDataSource02;
@Bean(name="sqlSessionFactory")
public SqlSessionFactory sqlSessionFactorys() throws Exception {
log.info("-------------------- sqlSessionFactory init ---------------------");
try {
SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
// sessionFactoryBean.setDataSource(roundRobinDataSouce);
sessionFactoryBean.setDataSource(roundRobinDataSouceProxy());
// 读取配置
sessionFactoryBean.setTypeAliasesPackage("com.fei.springboot.domain");
//设置mapper.xml文件所在位置
Resource[] resources = new PathMatchingResourcePatternResolver().getResources(mapperLocations);
sessionFactoryBean.setMapperLocations(resources);
//设置mybatis-config.xml配置文件位置
sessionFactoryBean.setConfigLocation(new DefaultResourceLoader().getResource(configLocation));
//添加分页插件、打印sql插件
Interceptor[] plugins = new Interceptor[]{pageHelper(),new SqlPrintInterceptor()};
sessionFactoryBean.setPlugins(plugins);
return sessionFactoryBean.getObject();
} catch (IOException e) {
log.error("mybatis resolver mapper*xml is error",e);
return null;
} catch (Exception e) {
log.error("mybatis sqlSessionFactoryBean create error",e);
return null;
}
}
/**
* 分页插件
* @return
*/
@Bean
public PageHelper pageHelper() {
PageHelper pageHelper = new PageHelper();
Properties p = new Properties();
p.setProperty("offsetAsPageNum", "true");
p.setProperty("rowBoundsWithCount", "true");
p.setProperty("reasonable", "true");
p.setProperty("returnPageInfo", "check");
p.setProperty("params", "count=countSql");
pageHelper.setProperties(p);
return pageHelper;
}
/**
* 把所有数据库都放在路由中
* @return
*/
@Bean(name="roundRobinDataSouceProxy")
public AbstractRoutingDataSource roundRobinDataSouceProxy() {
Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
//把所有数据库都放在targetDataSources中,注意key值要和determineCurrentLookupKey()中代码写的一至，
//否则切换数据源时找不到正确的数据源
targetDataSources.put(DataSourceType.write.getType(), writeDataSource);
targetDataSources.put(DataSourceType.read.getType()+"1", readDataSource01);
targetDataSources.put(DataSourceType.read.getType()+"2", readDataSource02);
final int readSize = Integer.parseInt(readDataSourceSize);
// MyAbstractRoutingDataSource proxy = new MyAbstractRoutingDataSource(readSize);
//路由类，寻找对应的数据源
AbstractRoutingDataSource proxy = new AbstractRoutingDataSource(){
private AtomicInteger count = new AtomicInteger(0);
/**
* 这是AbstractRoutingDataSource类中的一个抽象方法，
* 而它的返回值是你所要用的数据源dataSource的key值，有了这个key值，
* targetDataSources就从中取出对应的DataSource，如果找不到，就用配置默认的数据源。
*/
@Override
protected Object determineCurrentLookupKey() {
String typeKey = DataSourceContextHolder.getReadOrWrite();
if(typeKey == null){
// System.err.println("使用数据库write.............");
// return DataSourceType.write.getType();
throw new NullPointerException("数据库路由时，决定使用哪个数据库源类型不能为空...");
}
if (typeKey.equals(DataSourceType.write.getType())){
System.err.println("使用数据库write.............");
return DataSourceType.write.getType();
}
//读库， 简单负载均衡
int number = count.getAndAdd(1);
int lookupKey = number % readSize;
System.err.println("使用数据库read-"+(lookupKey+1));
return DataSourceType.read.getType()+(lookupKey+1);
}
};
proxy.setDefaultTargetDataSource(writeDataSource);//默认库
proxy.setTargetDataSources(targetDataSources);
return proxy;
}
@Bean
public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
//事务管理
@Bean
public PlatformTransactionManager annotationDrivenTransactionManager() {
return new DataSourceTransactionManager((DataSource)SpringContextUtil.getBean("roundRobinDataSouceProxy"));
}
}
重点是roundRobinDataSouceProxy()方法，它把所有的数据库源交给AbstractRoutingDataSource类，并由它的determineCurrentLookupKey()进行决定数据源的选择，其中读库进行了简单的负载均衡（轮询）。
DataSourceType.java
package com.fei.springboot.config.dbconfig;
public enum DataSourceType {
read("read", "从库"),
write("write", "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;
}
}
package com.fei.springboot.config.dbconfig;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* 本地线程，数据源上下文
* @author Jfei
*
*/
public class DataSourceContextHolder {
private static Logger log = LoggerFactory.getLogger(DataSourceContextHolder.class);
//线程本地环境
private static final ThreadLocal<String> local = new ThreadLocal<String>();
public static ThreadLocal<String> getLocal() {
return local;
}
/**
* 读库
*/
public static void setRead() {
local.set(DataSourceType.read.getType());
log.info("数据库切换到读库...");
}
/**
* 写库
*/
public static void setWrite() {
local.set(DataSourceType.write.getType());
log.info("数据库切换到写库...");
}
public static String getReadOrWrite() {
return local.get();
}
public static void clear(){
local.remove();
}
}
写库、读库的注解
package com.fei.springboot.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface ReadDataSource {
}
package com.fei.springboot.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface WriteDataSource {
}
UserMapper.java
package com.fei.springboot.dao;
import java.util.List;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import com.fei.springboot.domain.User;
@Mapper
public interface UserMapper {
@Insert("insert sys_user(id,user_name) values(#{id},#{userName})")
void insert(User u);
@Select("select id,user_name from sys_user where id=#{id} ")
User findById(@Param("id")String id);
//注：方法名和要UserMapper.xml中的id一致
List<User> query(@Param("userName")String userName);
}
如果想在dao进行数据源的决定，在aop的拦截路径写明是dao
DataSourceAopInDao.java
package com.fei.springboot.aop;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import com.fei.springboot.config.dbconfig.DataSourceContextHolder;
import com.fei.springboot.config.dbconfig.DataSourceType;
/**
* 在dao层决定数据源(注：如果用这方式，service层不能使用事务，否则出问题，因为打开事务打开时，就会觉得数据库源了）
* @author Jfei
*
*/
//@Aspect
//@Component
public class DataSourceAopInDao {
private static Logger log = LoggerFactory.getLogger(DataSourceAopInDao.class);
@Before("execution(* com.fei.springboot.dao..*.find*(..)) "
+ " or execution(* com.fei.springboot.dao..*.get*(..)) "
+ " or execution(* com.fei.springboot.dao..*.query*(..))")
public void setReadDataSourceType() {
DataSourceContextHolder.setRead();
}
@Before("execution(* com.fei.springboot.dao..*.insert*(..)) "
+ " or execution(* com.fei.springboot.dao..*.update*(..))"
+ " or execution(* com.fei.springboot.dao..*.add*(..))")
public void setWriteDataSourceType() {
DataSourceContextHolder.setWrite();
}
/* @Before("execution(* com.fei.springboot.dao..*.*(..)) "
+ " and @annotation(com.fei.springboot.annotation.ReadDataSource) ")
public void setReadDataSourceType() {
//如果已经开启写事务了，那之后的所有读都从写库读
if(!DataSourceType.write.getType().equals(DataSourceContextHolder.getReadOrWrite())){
DataSourceContextHolder.setRead();
}
}
@Before("execution(* com.fei.springboot.dao..*.*(..)) "
+ " and @annotation(com.fei.springboot.annotation.WriteDataSource) ")
public void setWriteDataSourceType() {
DataSourceContextHolder.setWrite();
}*/
}
DataSourceAopInService.java
package com.fei.springboot.aop;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.PriorityOrdered;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import com.fei.springboot.config.dbconfig.DataSourceContextHolder;
import com.fei.springboot.config.dbconfig.DataSourceType;
/**
* 在service层觉得数据源
*
* 必须在事务AOP之前执行，所以实现Ordered,order的值越小，越先执行
* 如果一旦开始切换到写库，则之后的读都会走写库
*
* @author Jfei
*
*/
@Aspect
@EnableAspectJAutoProxy(exposeProxy=true,proxyTargetClass=true)
@Component
public class DataSourceAopInService implements PriorityOrdered{
private static Logger log = LoggerFactory.getLogger(DataSourceAopInService.class);
/* @Before("execution(* com.fei.springboot.service..*.find*(..)) "
+ " or execution(* com.fei.springboot.service..*.get*(..)) "
+ " or execution(* com.fei.springboot.service..*.query*(..))")
public void setReadDataSourceType() {
//如果已经开启写事务了，那之后的所有读都从写库读
if(!DataSourceType.write.getType().equals(DataSourceContextHolder.getReadOrWrite())){
DataSourceContextHolder.setRead();
}
}
@Before("execution(* com.fei.springboot.service..*.insert*(..)) "
+ " or execution(* com.fei.springboot.service..*.update*(..))"
+ " or execution(* com.fei.springboot.service..*.add*(..))")
public void setWriteDataSourceType() {
DataSourceContextHolder.setWrite();
}*/
@Before("execution(* com.fei.springboot.service..*.*(..)) "
+ " and @annotation(com.fei.springboot.annotation.ReadDataSource) ")
public void setReadDataSourceType() {
//如果已经开启写事务了，那之后的所有读都从写库读
if(!DataSourceType.write.getType().equals(DataSourceContextHolder.getReadOrWrite())){
DataSourceContextHolder.setRead();
}
}
@Before("execution(* com.fei.springboot.service..*.*(..)) "
+ " and @annotation(com.fei.springboot.annotation.WriteDataSource) ")
public void setWriteDataSourceType() {
DataSourceContextHolder.setWrite();
}
@Override
public int getOrder() {
/**
* 值越小，越优先执行
* 要优于事务的执行
* 在启动类中加上了@EnableTransactionManagement(order = 10)
*/
return 1;
}
}
UserService.java
package com.fei.springboot.service;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
import com.fei.springboot.annotation.ReadDataSource;
import com.fei.springboot.annotation.WriteDataSource;
import com.fei.springboot.dao.UserMapper;
import com.fei.springboot.domain.User;
import com.fei.springboot.util.SpringContextUtil;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
/**
* 如果需要事务，自行在方法上添加@Transactional
* 如果方法有内部有数据库操作，则必须指定@WriteDataSource还是@ReadDataSource
*
* 注：AOP ，内部方法之间互相调用时，如果是this.xxx()这形式，不会触发AOP拦截，可能会
* 导致无法决定数据库是走写库还是读库
* 方法：
* 为了触发AOP的拦截，调用内部方法时，需要特殊处理下，看方法getService()
*
* @author Jfei
*
*/
@Service
public class UserService {
@Autowired
private UserMapper userMapper;
@WriteDataSource
@Transactional(propagation=Propagation.REQUIRED,isolation=Isolation.DEFAULT,readOnly=false)
public void insertUser(User u){
this.userMapper.insert(u);
//如果类上面没有@Transactional,方法上也没有，哪怕throw new RuntimeException,数据库也会成功插入数据
// throw new RuntimeException("测试插入事务");
}
/**
* 写事务里面调用读
* @param u
*/
public void wirteAndRead(User u){
getService().insertUser(u);//这里走写库，那后面的读也都要走写库
//这是刚刚插入的
User uu = getService().findById(u.getId());
System.out.println("==读写混合测试中的读(刚刚插入的)====id="+u.getId()+", user_name=" + uu.getUserName());
//为了测试,3个库中id=1的user_name是不一样的
User uuu = getService().findById("1");
System.out.println("==读写混合测试中的读====id=1, user_name=" + uuu.getUserName());
}
public void readAndWirte(User u){
//为了测试,3个库中id=1的user_name是不一样的
User uu = getService(). findById("1");
System.out.println("==读写混合测试中的读====id=1,user_name=" + uu.getUserName());
getService().insertUser(u);
}
@ReadDataSource
public User findById(String id){
User u = this.userMapper.findById(id);
return u;
}
@ReadDataSource
public PageInfo<User> queryPage(String userName,int pageNum,int pageSize){
Page<User> page = PageHelper.startPage(pageNum, pageSize);
//PageHelper会自动拦截到下面这查询sql
this.userMapper.query(userName);
return page.toPageInfo();
}
private UserService getService(){
// 采取这种方式的话，
//@EnableAspectJAutoProxy(exposeProxy=true,proxyTargetClass=true)
//必须设置为true
/* if(AopContext.currentProxy() != null){
return (UserService)AopContext.currentProxy();
}else{
return this;
}
*/
return SpringContextUtil.getBean(this.getClass());
}
}
所以UserService中增加了getService()方法进行处理。
写个controller进行简单测试
UserController.java
package com.fei.springboot.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import com.fei.springboot.domain.User;
import com.fei.springboot.service.UserService;
import com.github.pagehelper.PageInfo;
@Controller
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@RequestMapping("/hello")
@ResponseBody
public String hello(){
return "hello";
}
/**
* 测试插入
* @return
*/
@RequestMapping("/add")
@ResponseBody
public String add(String id,String userName){
User u = new User();
u.setId(id);
u.setUserName(userName);
this.userService.insertUser(u);
return u.getId()+" " + u.getUserName();
}
/**
* 测试读
* @param id
* @return
*/
@RequestMapping("/get/{id}")
@ResponseBody
public String findById(@PathVariable("id") String id){
User u = this.userService.findById(id);
return u.getId()+" " + u.getUserName();
}
/**
* 测试写然后读
* @param id
* @param userName
* @return
*/
@RequestMapping("/addAndRead")
@ResponseBody
public String addAndRead(String id,String userName){
User u = new User();
u.setId(id);
u.setUserName(userName);
this.userService.wirteAndRead(u);
return u.getId()+" " + u.getUserName();
}
/**
* 测试读然后写
* @param id
* @param userName
* @return
*/
@RequestMapping("/readAndAdd")
@ResponseBody
public String readAndWrite(String id,String userName){
User u = new User();
u.setId(id);
u.setUserName(userName);
this.userService.readAndWirte(u);
return u.getId()+" " + u.getUserName();
}
/**
* 测试分页插件
* @return
*/
@RequestMapping("/queryPage")
@ResponseBody
public String queryPage(){
PageInfo<User> page = this.userService.queryPage("tes", 1, 2);
StringBuilder sb = new StringBuilder();
sb.append("<br/>总页数=" + page.getPages());
sb.append("<br/>总记录数=" + page.getTotal()) ;
for(User u : page.getList()){
sb.append("<br/>" + u.getId() + " " + u.getUserName());
}
System.out.println("分页查询....\n" + sb.toString());
return sb.toString();
}
}
http://127.0.0.1/user/get/1 时，获取到的结果要么是库test_01要么是test_02中来的，其他方法也可以测试均符合预期结果。这里就不一一贴结果了。其他的类源码也不一一贴出来了。想看的可以到github上看或下载。
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