Spring事务

2019-05-14 本文已影响0人 employeeeee

分布式项目总会面临分布式事务的问题。公司的项目中有多个子系统用户同步信息的问题。最近要研究解决一下出现分布式事务时候的解决办法。把学习的过程记录一下

Spring事务管理的特点

提供的统一的API接口支持不同的资源
提供声明式事务管理
方便与spring框架集成
多个资源的事务的管理同步

Spring抽象事务

PlatformTranscationManager
TranscationStatus
TranscationDefinition

Public interface TranscationDefinition(){
int getPropagation Behavior();
int getIsolationLevel();
String getName();
int getTimeOut();
boolean isReadOnly();
}

public interface TranscationStatus extends SavepointManager{
boolean isNewTransaction();
boolean hasSavepoint();
void setRollbackOnly();
boolean isRollbackOnly();
boolean isCompleted();
}

启用spring事务可以通过代码的方式也可以通过注解的方式，在自己的项目中我用注解的方式更多一些主要就是简单不需要写那么的代码而注解完成事务及回滚也是通过代理的方式来完成的。在本地的测试中使用springboot + h2数据库+jpa的方式这样会方便一点

jpa在自己写的实际项目中用的比较少但是确实是更方便了一点不需要再xml文件中进行对应只要在实体类中通过@Entity @column 这种方式来进行对应而且对于dao层 mybatis的dao层需要一个实现类

而在jpa中实现是通过 repository 从名字可以看出来仓库在其中会有很多增删改差的方法直接调用就可以不需要自己在实现类中写了

测试的代码参考了慕课网上大漠风老师课程中思路

service中的方法是使用了通过代码和通过注解两种方式

domain 类

package com.emp.transcationjap.domain;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

/**
 * Created with IntelliJ IDEA.
 * User: employeeeee
 * Date: 2019/5/13
 * Time: 16:15
 * Description: No Description
 */
@Entity(name = "customer")
public class Customer {
    @Id
    @GeneratedValue
    private Long id;

    @Column(name = "user_name", length = 6)
    private String username;

    private String password;

    private String role;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getRole() {
        return role;
    }

    public void setRole(String role) {
        this.role = role;
    }
}

dao层Repository

package com.emp.transcationjap.dao;

import com.emp.transcationjap.domain.Customer;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * Created with IntelliJ IDEA.
 * User: employeeeee
 * Date: 2019/5/13
 * Time: 16:17
 * Description: No Description
 */
public interface CustomerRepository extends JpaRepository<Customer,Long> {

}

两个service

package com.emp.transcationjap.service;

import com.emp.transcationjap.dao.CustomerRepository;
import com.emp.transcationjap.domain.Customer;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * User: employeeeee
 * Date: 2019/5/13
 * Time: 16:21
 * Description: No Description
 */
@Service
public class CustomerServiceTcInAnnotation {
    @Resource
    CustomerRepository customerRepository;

    @Transactional
    public Customer save(Customer customer) throws Exception{
       return customerRepository.save(customer);
    }

    public List<Customer> saveAll(List<Customer> customerList) throws Exception{
        return customerRepository.saveAll(customerList);
    }

}

package com.emp.transcationjap.service;

import com.emp.transcationjap.dao.CustomerRepository;
import com.emp.transcationjap.domain.Customer;
import org.springframework.stereotype.Service;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.support.DefaultTransactionDefinition;

import javax.annotation.Resource;

/**
 * Created with IntelliJ IDEA.
 * User: employeeeee
 * Date: 2019/5/13
 * Time: 16:21
 * Description: No Description
 */
@Service
public class CustomerServiceTcInCode {
    @Resource
    private CustomerRepository customerRepository;
    @Resource
    private PlatformTransactionManager  transactionManager;

    public Customer save(Customer customer) {
        DefaultTransactionDefinition def = new DefaultTransactionDefinition();
        //隔离机制 所有的操作都会进行排队 对性能的影响比较大
        def.setIsolationLevel(DefaultTransactionDefinition.ISOLATION_SERIALIZABLE);
        //传播机制
        def.setPropagationBehavior(DefaultTransactionDefinition.PROPAGATION_SUPPORTS);
        def.setTimeout(15);
        TransactionStatus status = transactionManager.getTransaction(def);
        try{
            customerRepository.save(customer);
            return customer;
        }catch (Exception e){
            transactionManager.rollback(status);
            throw e;
        }
    }
}

controller

package com.emp.transcationjap.web;

import com.emp.transcationjap.dao.CustomerRepository;
import com.emp.transcationjap.domain.Customer;
import com.emp.transcationjap.service.CustomerServiceTcInAnnotation;
import com.emp.transcationjap.service.CustomerServiceTcInCode;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;
import java.util.List;

/**
 * Created with IntelliJ IDEA.
 * User: employeeeee
 * Date: 2019/5/13
 * Time: 16:55
 * Description: No Description
 */
@RestController
@RequestMapping("/test")
public class CustomerController {
    @Resource
    private CustomerServiceTcInAnnotation customerServiceTcInAnnotation;

    @Resource
    private CustomerServiceTcInCode customerServiceTcInCode;

    @Resource
    private  CustomerRepository customerRepository;

    @RequestMapping("/code")
    public void saveInCode(Customer customer){
        customer.setId(1001L);
        customer.setUsername("zhou");
        customer.setPassword("123456");
        customer.setRole("user");
        customerServiceTcInCode.save(customer);
    }

    @RequestMapping("/anno")
    public void saveInAnno(Customer customer) throws Exception {
        customer.setId(1002L);
        customer.setUsername("KrisW");
        customer.setPassword("123456");
        customer.setRole("user");
        customerServiceTcInAnnotation.save(customer);
    }

    @RequestMapping("/saveAll")
    @Transactional
    public void saveAll() throws Exception {

        Customer customer1 = new Customer();
        customer1.setId(1003L);
        customer1.setUsername("kunkun");
        customer1.setPassword("123456");
        customer1.setRole("user");

        Customer customer2 = new Customer();
        customer2.setId(1004L);
        customer2.setUsername("liu");
        customer2.setPassword("123456");
        customer2.setRole("user");


        Customer customer3 = new Customer();
        customer3.setId(1005L);
        customer3.setUsername("KrisWuuuuu");
        customer3.setPassword("123456");
        customer3.setRole("user");

        customerServiceTcInCode.save(customer1);
        customerServiceTcInCode.save(customer2);
        customerServiceTcInCode.save(customer3);
    }

    @RequestMapping("/getAll")
    public List<Customer> getAll(){
        List<Customer> customerList = customerRepository.findAll();
        return customerList;
    }

}

然后就在web上进行测试就OK了
那么有了事务和没有事务的区别是什么呢
就是在saveAll的方法中
我让第三个用户的名字超出了 length为6的限制所以就会报错
然后查询出来的结果会是这样的

image.png

也就是说虽然项目报错了但是前两条数据还是已经加入到了数据库中这样显然不是我们想要的效果当我们加上事务时候
就会出现回滚也就是前两条数据就不会被添加到数据库中了