项目中用到了MongoDB,准备用来存储业务数据,前提是要实现事务,保证数据一致性,MongoDB从4.0开始支持事务,提供了面向复制集的多文档事务特性。能满足在多个操作,文档,集合,数据库之间的事务性,事务的特性。多文档事务在4.0版本仅支持复制集,对分片集群的事务性支持计划在4.2版本中实现。由于我也算是一个java小白,没怎么弄清java事务机制,于是先建了个测试项目进行测试。在本例中可以看到多数据源下事务的使用,请重点关注后面记录的爬坑记。
代码已上传到github 传送门 https://github.com/devmuyuer/trans-demo
Mongo Transaction
项目介绍
springboot 2.1.3
MongoDB 4.0.3
本项目主要为了测试MongoDB事务,由于正式项目还用了其它数据源,所以加入了 Oracle, MySQL的事务,包括多数据源的配置和使用
使用说明
- 1.导入MongoDB的依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
- 2.配置MongoDB的连接
spring:
# mongodb 连接
data:
mongodb:
uri: mongodb://192.168.0.68:27017,192.168.0.69:27017,192.168.0.70:27017/glcloud?replicaSet=rs0
database: glcloud
- 3.编写entity类
当id设置为 ObjectId 类型和添加 @Id 注解时时,MongoDB数据库会自动生成主键,我们在保存对象时就不用设置id的值
MongoUnit
/**
* 用户
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
@Data
@Document(collection = "test_unit")
public class MongoUnit {
private static final long serialVersionUID = 1L;
/**
* Id
*/
@Id
private ObjectId id;
/**
* unitId
*/
private String unitId;
/**
* unitName
*/
private String unitName;
}
MongoUser
package com.example.demo.entity.mongo;
import lombok.Data;
import org.bson.types.ObjectId;
import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;
/**
* 用户
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
@Data
@Document(collection = "test_user")
public class MongoUser {
private static final long serialVersionUID = 1L;
/**
* Id
*/
@Id
private ObjectId id;
/**
* userId
*/
private String userId;
/**
* userName
*/
private String userName;
/**
* unitId 关联testUser
*/
private String unitId;
}
- 4.编写dao层的方法
只需继承MongoRepository即可。
package com.example.demo.repository.mongo;
import com.example.demo.entity.mongo.MongoUser;
import org.springframework.data.mongodb.repository.MongoRepository;
/**
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
public interface MongoUserRepository extends MongoRepository<MongoUser, String> {
}
package com.example.demo.repository.mongo;
import com.example.demo.entity.mongo.MongoUnit;
import org.springframework.data.mongodb.repository.MongoRepository;
/**
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
public interface MongoUnitRepository extends MongoRepository<MongoUnit, String> {
}
- 5.Service层
package com.example.demo.service.mongo.impl;
import com.example.demo.common.SystemException;
import com.example.demo.entity.mongo.MongoUser;
import com.example.demo.repository.mongo.MongoUserRepository;
import com.example.demo.service.mongo.MongoUserService;
import com.example.demo.common.R;
import com.example.demo.common.RUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
/**
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
@Service
@Slf4j
public class MongoUserServiceImpl implements MongoUserService {
@Autowired
MongoUserRepository mongoUserRepository;
/**
* 新增
* @param mongoUser
* @return
*/
@Override
public R save(MongoUser mongoUser) {
MongoUser mongoUserSave = mongoUserRepository.save(mongoUser);
log.info("用户信息保存:testUserSave = "+ mongoUserSave);
return RUtil.success("");
}
@Override
@Transactional(value = "MONGO_TRANSACTION_MANAGER", propagation = Propagation.REQUIRED)
public R bathSave(String unitId, Boolean rollBack) {
for (int i = 0; i <= 10; i++) {
//注释这段则可以正常添加数据,测试回滚则throw异常信息
if (unitId.equals("003") && rollBack) {
throw new SystemException("测试回滚故意抛出的异常");
}
MongoUser user = new MongoUser();
user.setUserId(unitId + "U0" + i);
user.setUserName("用户" + i);
user.setUnitId(unitId);
save(user);
}
return RUtil.success("");
}
}
package com.example.demo.service.mongo.impl;
import com.example.demo.enums.REnum;
import com.example.demo.common.SystemException;
import com.example.demo.entity.mongo.MongoUnit;
import com.example.demo.repository.mongo.MongoUnitRepository;
import com.example.demo.service.mongo.MongoUnitService;
import com.example.demo.service.mongo.MongoUserService;
import com.example.demo.common.R;
import com.example.demo.common.RUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
/**
* @author muyuer 182443947@qq.com
* @version 1.0
* @date 2019-02-25 09:10
*/
@Service
@Slf4j
public class MongoUnitServiceImpl implements MongoUnitService {
@Autowired
MongoUnitRepository mongoUnitRepository;
@Autowired
MongoUserService mongoUserService;
/**
* 新增
*
* @param unit
* @return
*/
@Override
public R save(MongoUnit unit) {
MongoUnit mongoUnitSave = mongoUnitRepository.save(unit);
log.info("单位信息保存:testUnitSave = " + mongoUnitSave);
return RUtil.success("");
}
@Override
@Transactional(value = "MONGO_TRANSACTION_MANAGER")
public R bathSave(Boolean rollBack) {
try {
for (int i = 0; i < 4; i++) {
MongoUnit unit = new MongoUnit();
unit.setUnitId("00" + i);
unit.setUnitName("单位" + i);
mongoUserService.bathSave(unit.getUnitId(),rollBack);
save(unit);
}
return RUtil.success("");
} catch (SystemException e) {
log.error("保存数据失败:msg: {}", e.getMessage());
throw new SystemException(REnum.ERROR.getCode(), "保存数据失败 Error:" + e.getMessage());
}
}
}
- 6.Controller
package com.example.demo.controller;
import com.example.demo.enums.DbTypeEnum;
import com.example.demo.service.mongo.MongoUserService;
import com.example.demo.common.R;
import com.example.demo.service.primary.PrimaryUserService;
import com.example.demo.service.slave.SlaveUserService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
/**
* @author muyuer 182443947@qq.com
* @date 2019-02-25 10:59
*/
@RestController
@Slf4j
@RequestMapping(path="test/user")
public class TestUserController {
@Autowired
MongoUserService mongoUserService;
@Autowired
PrimaryUserService primaryUserService;
@Autowired
SlaveUserService slaveUserService;
/**
* 新增
* @param dbType
* @param unitId
* @param rollBack
* @return
*/
@PostMapping("/bathSave/{dbType}/{unitId}/{rollBack}")
public R bathSave(@PathVariable DbTypeEnum dbType, @PathVariable String unitId, @PathVariable Boolean rollBack){
switch (dbType) {
case MONGO:
return mongoUserService.bathSave(unitId, rollBack);
case PRIMARY:
return primaryUserService.bathSave(unitId, rollBack);
default:
return slaveUserService.bathSave(unitId, rollBack);
}
}
}
package com.example.demo.controller;
import com.example.demo.enums.DbTypeEnum;
import com.example.demo.service.mongo.MongoUnitService;
import com.example.demo.common.R;
import com.example.demo.service.primary.PrimaryUnitService;
import com.example.demo.service.slave.SlaveUnitService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
/**
* @author muyuer 182443947@qq.com
* @date 2019-02-25 10:59
*/
@RestController
@Slf4j
@RequestMapping(path="test/unit")
public class TestUnitController {
@Autowired
MongoUnitService mongoUnitService;
@Autowired
PrimaryUnitService primaryUnitService;
@Autowired
SlaveUnitService slaveUnitService;
/**
* 新增
* @param dbType 数据库
* @param rollBack 是否回滚
* @return
*/
@PostMapping("/bathSave/{dbType}/{rollBack}")
public R bathSave(@PathVariable DbTypeEnum dbType, @PathVariable Boolean rollBack) {
switch (dbType) {
case MONGO:
return mongoUnitService.bathSave(rollBack);
case PRIMARY:
return primaryUnitService.bathSave(rollBack);
default:
return slaveUnitService.bathSave(rollBack);
}
}
}
测试
PostMan post 地址
MONGO库 不回滚 http://localhost:8077/test/unit/bathSave/MONGO/0
MONGO库 回滚 http://localhost:8077/test/unit/bathSave/MONGO/1
Oracle库 不回滚 http://localhost:8077/test/unit/bathSave/PRIMARY/0
Oracle库 回滚 http://localhost:8077/test/unit/bathSave/PRIMARY/1
MySQL库 不回滚 http://localhost:8077/test/unit/bathSave/SLAVE/0
MySQL库 回滚 http://localhost:8077/test/unit/bathSave/SLAVE/1
在实际应用中爬过的坑
1.MongoDB的版本必须是4.0
2.MongoDB事务功能必须是在多副本集的情况下才能使用,否则报错"Sessions are not supported by the MongoDB cluster to which this client is connected",4.2版本会支持分片事务。
3.事务控制只能用在已存在的集合中,也就是集合需要手工添加不会由jpa创建会报错"Cannot create namespace glcloud.test_user in multi-document transaction."
4.多数据源时需要指定事务 @Transactional(value = "transactionManager") 如果只有1个数据源不需要指定value
5.事务注解到类上时,该类的所有 public 方法将都具有该类型的事务属性,但一般都是注解到方法上便于实现更精确的事务控制
6.事务传递性,事务子方法上不必添加事务注解,如果子方法也提供api调用可用注解propagation = Propagation.REQUIRED也就是继承调用它的事务,如果没有事务则新起一个事务
7.启动类上的@EnableTransactionManagement注解,并不是像网上所说必需添加的注解,因为spring boot 默认开始了这个注解的。
-
8.有人说:注解必须是@Transactional(rollbackFor = { Exception.class }) 测试并不需要rollbackFor = { Exception.class },因为本例中自定义异常类继承自RuntimeException spring boot事物默认在遇到RuntimeException不论rollbackFor的异常是啥,都会进行事务的回滚,加上rollbackFor=Exception.class,可以让事物在遇到非运行时异常时也回滚
具体rollbackFor用法可参考: