馬士兵Spring-聲明式事務管理-annotation
阿新 • • 發佈:2017-05-23
con his pri 默認值 bsp nco cti generated span 1.事務加在DAO層還是service層?
service中可能多涉及多種DAO的操作,比如存了一個User之後,需要保存一條日誌信息;如果在DAO中分別設置事務的話,一個DAO下面方法拋出異常了,但是不會影響到另一個DAO下面的方法,這是兩個事務;因此事務要加在Service層;
2.需求:存一個user的同時,記錄一個日誌,說這個user被存了;
3.代碼實現:--這邊是spring管理hibernate下的transaction;
1)DAO實現:UserDAOImpl.java --保存User
package com.cy.dao.impl; import javax.annotation.Resource;View Codeimport org.hibernate.Session; import org.hibernate.SessionFactory; import org.springframework.stereotype.Component; import com.cy.dao.UserDAO; import com.cy.model.User; @Component public class UserDAOImpl implements UserDAO { @Resource private SessionFactory sessionFactory; //保存Userpublic void save(User user) { Session s = sessionFactory.getCurrentSession(); s.save(user); } }
2)DAO實現:LogDAOImpl.java --保存Log
package com.cy.dao.impl; import javax.annotation.Resource; import org.hibernate.Session; import org.hibernate.SessionFactory; importView Codeorg.springframework.stereotype.Component; import com.cy.dao.LogDAO; import com.cy.model.Log; @Component("logDAO") public class LogDAOImpl implements LogDAO { @Resource private SessionFactory sessionFactory; //保存日誌信息 public void save(Log log) { Session s = sessionFactory.getCurrentSession(); s.save(log); throw new RuntimeException("error!"); } }
3)User實體 和 Log實體:
User.java:
package com.cy.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; @Entity public class User { private int id; private String username; private String password; @Id @GeneratedValue public int getId() { return id; } public void setId(int 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; } }View Code
Log.java:
package com.cy.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; /** * * @author chengyu * 表名和我們的類名不一樣,[email protected](name="xxx"); */ @Entity @Table(name="t_log") public class Log { private int id; private String msg; @Id @GeneratedValue public int getId() { return id; } public void setId(int id) { this.id = id; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; } }View Code
4)UserService中保存User後,插入一條日誌記錄:
package com.cy.service; import javax.annotation.Resource; import org.springframework.stereotype.Component; import org.springframework.transaction.annotation.Transactional; import com.cy.dao.LogDAO; import com.cy.dao.UserDAO; import com.cy.model.Log; import com.cy.model.User; @Component("userService") public class UserService { @Resource private UserDAO userDAO; @Resource private LogDAO logDAO; public void init() { System.out.println("init"); } /** * 插入一個用戶的同時,記錄一條日誌 * @Transactional 默認情況:如果catch到任何的RuntimeException,自動回滾 */ @Transactional public void add(User user) { userDAO.save(user); Log log = new Log(); log.setMsg("a user saved!"); logDAO.save(log); } public UserDAO getUserDAO() { return userDAO; } public void setUserDAO( UserDAO userDAO) { this.userDAO = userDAO; } public void destroy() { System.out.println("destroy"); } }
5)beans.xml中的配置:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"> <context:annotation-config /> <context:component-scan base-package="com.cy"/> <!-- 如果下面使用到了占位符的方式,請在locations下面去找 --> <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <value>classpath:jdbc.properties</value> </property> </bean> <bean id="dataSource" destroy-method="close" class="org.apache.commons.dbcp.BasicDataSource"> <property name="driverClassName" value="${jdbc.driverClassName}"/> <property name="url" value="${jdbc.url}"/> <property name="username" value="${jdbc.username}"/> <property name="password" value="${jdbc.password}"/> </bean> <!-- 初始化SessionFactory annotatedClasses : 接收對那些類做了註解 --> <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="annotatedClasses"> <list> <value>com.cy.model.User</value> <value>com.cy.model.Log</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop> <prop key="hibernate.show_sql">true</prop> </props> </property> </bean> <bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> <tx:annotation-driven transaction-manager="txManager"/> </beans>
6)測試代碼:
package com.cy.service; import org.junit.Test; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.cy.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception { ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); UserService service = (UserService)ctx.getBean("userService"); System.out.println(service.getClass()); service.add(new User()); ctx.destroy(); } }View Code
測試結果:
因為在LogDAOImpl中插入日誌時,throw new RuntimeException("error!");
User和Log都插入失敗,User插入後回滾了;
4. @Transactional settings的配置:
事務的傳播特性:在當前的執行環境裏頭,到底有沒有事務,另外根據這個事務的配置情況執行到我這個當前方法的時候,當前這個方法怎麽樣來處理這個事務;1.propagation: transaction的產生過程;事務的傳播方式;
REQUIRED:@Transactional註解的默認值; 如果有就使用原來的,如果沒有就創建一個新的;@Transactional(propagation=Propagation.REQUIRED)
MANDATORY: 強制的,必須的;當前這個方法要執行,必須得有一個Transaction;如果沒有transaction會拋異常;
[email protected](propagation=Propagation.MANDATORY),那麽測試方法中調用此add方法之前,就必須得有一個transaction;
NESTED:在一個內嵌的transaction裏面執行;
原來有一個transaction了,相當於在這個裏面內嵌了一個transaction,不在原來的transaction裏面執行了,而是在內嵌的transaction裏面執行, 內部的transaction回滾的時候不會影響外面的
transaction;
NEVER: 我這個方法要執行,必須不能有事務;要是有事務,拋異常;
NOT_SUPPORTED: 這個方法要想執行必須不能有事務;要是有事務把這個事務掛起,執行完我這個方法,原來的事務再繼續;
REQUIRES_NEW:創建一新的transaction,如果當前有transaction,將此transaction掛起;
SUPPORTS: 支持當前的transaction,要是有我就有,要是沒有我也就沒有,就不在事務裏執行;
2.isolation: 隔離級別;
3.readOnly: 如果設置為true,在transaction裏面沒有update。insert、delete這方面操作;比如上面的例子,[email protected](readOnly=true)的話,就會報錯:
Caused by: java.sql.SQLException: Connection is read-only. Queries leading to data modification are not allowed;
如果確認沒有寫的操作,可以設置為true,這時候spring會使用只讀的Connection,readOnly的connection比讀寫的Connection執行效率要高;可以提高性能;
再者,如果這個方法裏面規定只能讀,那麽可以設置為true,防止別人進行更改操作;
4.timeout: 一個事務如果時間太長的話,就把它終止掉;
5.rollbackFor: 默認情況下,RuntimeException會導致回滾;HibernateException本身就是一種運行期異常;
可以在rollbackFor裏面寫清楚,什麽情況下會回滾,比如寫自己定義的MyException,如果拋出MyException,就會回滾;
6.noRollbackFor: 在某些異常下不會回滾,其他的會回滾;
required圖解:
在執行了method1,method1裏面調用了method2,如果說在method1裏面已經有transaction了,那麽method2裏面就不需要再創建新的transaction了;
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馬士兵Spring-聲明式事務管理-annotation