Spring 声明式事务管理

声明式事务管理方法允许您借助配置而不是源代码中的硬编码来管理事务。 这意味着您可以将事务管理与业务代码分开。 您只使用注解或基于 XML 的配置来管理事务。 bean 配置将指定要事务的方法。 以下是与声明性事务相关的步骤 −

• 我们使用 <tx:advice /> 标签，它创建了一个事务处理建议，同时我们定义了一个切入点，该切入点匹配我们希望进行事务的所有方法并引用事务建议。

• 如果方法名称已包含在事务配置中，则创建的建议将在调用该方法之前开始事务。

• 目标方法将在 try / catch 块中执行。

• 如果该方法正常完成，AOP 建议将成功提交事务，否则将执行回滚。

让我们看看上述步骤是如何工作的，但在开始之前，重要的是至少有两个数据库表，我们可以在事务的帮助下在其上执行各种 CRUD 操作。 让我们以一个 Student 表为例，该表可以在 MySQL TEST 数据库中创建，其 DDL 如下： −

CREATE TABLE Student(
   ID   INT NOT NULL AUTO_INCREMENT,
   NAME VARCHAR(20) NOT NULL,
   AGE  INT NOT NULL,
   PRIMARY KEY (ID)
);

第二个表是Marks，我们将根据年限为学生维护分数。 这里 SID 是 Student 表的外键。

CREATE TABLE Marks(
   SID INT NOT NULL,
   MARKS  INT NOT NULL,
   YEAR   INT NOT NULL
);

现在，让我们编写 Spring JDBC 应用程序，它将在 Student 和 Marks 表上实现简单的操作。让我们有一个可以工作的 Eclipse IDE，并按照以下步骤创建一个 Spring 应用程序 −

以下是数据访问对象接口文件StudentDAO.java的内容

package com.tutorialspoint;

import java.util.List;
import javax.sql.DataSource;

public interface StudentDAO {
   /** 
      * This is the method to be used to initialize
      * database resources ie. connection.
   */
   public void setDataSource(DataSource ds);
   
   /** 
      * This is the method to be used to create
      * a record in the Student and Marks tables.
   */
   public void create(String name, Integer age, Integer marks, Integer year);
   
   /** 
      * This is the method to be used to list down
      * all the records from the Student and Marks tables.
   */
   public List<StudentMarks> listStudents();
}

以下是 StudentMarks.java 文件的内容

package com.tutorialspoint;

public class StudentMarks {
   private Integer age;
   private String name;
   private Integer id;
   private Integer marks;
   private Integer year;
   private Integer sid;

   public void setAge(Integer age) {
      this.age = age;
   }
   public Integer getAge() {
      return age;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getName() {
      return name;
   }
   public void setId(Integer id) {
      this.id = id;
   }
   public Integer getId() {
      return id;
   }
   public void setMarks(Integer marks) {
      this.marks = marks;
   }
   public Integer getMarks() {
      return marks;
   }
   public void setYear(Integer year) {
      this.year = year;
   }
   public Integer getYear() {
      return year;
   }
   public void setSid(Integer sid) {
      this.sid = sid;
   }
   public Integer getSid() {
      return sid;
   }
}

以下是 StudentMarksMapper.java 文件的内容

package com.tutorialspoint;

import java.sql.ResultSet;
import java.sql.SQLException;
import org.springframework.jdbc.core.RowMapper;

public class StudentMarksMapper implements RowMapper<StudentMarks> {
   public StudentMarks mapRow(ResultSet rs, int rowNum) throws SQLException {
      StudentMarks studentMarks = new StudentMarks();
      studentMarks.setId(rs.getInt("id"));
      studentMarks.setName(rs.getString("name"));
      studentMarks.setAge(rs.getInt("age"));
      studentMarks.setSid(rs.getInt("sid"));
      studentMarks.setMarks(rs.getInt("marks"));
      studentMarks.setYear(rs.getInt("year"));

      return studentMarks;
   }
}

下面是定义的 DAO 接口 StudentDAO 的实现类文件 StudentJDBCTemplate.java

package com.tutorialspoint;

import java.util.List;
import javax.sql.DataSource;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;

public class StudentJDBCTemplate implements StudentDAO {
   private JdbcTemplate jdbcTemplateObject;

   public void setDataSource(DataSource dataSource) {
      this.jdbcTemplateObject = new JdbcTemplate(dataSource);
   }
   public void create(String name, Integer age, Integer marks, Integer year){
      try {
         String SQL1 = "insert into Student (name, age) values (?, ?)";
         jdbcTemplateObject.update( SQL1, name, age);

         // Get the latest student id to be used in Marks table
         String SQL2 = "select max(id) from Student";
         int sid = jdbcTemplateObject.queryForInt( SQL2 );

         String SQL3 = "insert into Marks(sid, marks, year) " + "values (?, ?, ?)";
         jdbcTemplateObject.update( SQL3, sid, marks, year);
         System.out.println("Created Name = " + name + ", Age = " + age);
         
         // to simulate the exception.
         throw new RuntimeException("simulate Error condition") ;
      } 
      catch (DataAccessException e) {
         System.out.println("Error in creating record, rolling back");
         throw e;
      }
   }
   public List<StudentMarks> listStudents() {
      String SQL = "select * from Student, Marks where Student.id = Marks.sid";
      List <StudentMarks> studentMarks = jdbcTemplateObject.query(SQL, 
         new StudentMarksMapper());
      
      return studentMarks;
   }
}

现在让我们移动主应用程序文件MainApp.java，如下所示

package com.tutorialspoint;

import java.util.List;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");

      StudentDAO studentJDBCTemplate = 
         (StudentDAO)context.getBean("studentJDBCTemplate");
      
      System.out.println("------Records creation--------" );
      studentJDBCTemplate.create("Zara", 11, 99, 2010);
      studentJDBCTemplate.create("Nuha", 20, 97, 2010);
      studentJDBCTemplate.create("Ayan", 25, 100, 2011);

      System.out.println("------Listing all the records--------" );
      List<StudentMarks> studentMarks = studentJDBCTemplate.listStudents();
      
      for (StudentMarks record : studentMarks) {
         System.out.print("ID : " + record.getId() );
         System.out.print(", Name : " + record.getName() );
         System.out.print(", Marks : " + record.getMarks());
         System.out.print(", Year : " + record.getYear());
         System.out.println(", Age : " + record.getAge());
      }
   }
}

以下是配置文件Beans.xml

<?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:tx = "http://www.springframework.org/schema/tx"
   xmlns:aop = "http://www.springframework.org/schema/aop"
   xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd 
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

   <!-- Initialization for data source -->
   <bean id="dataSource" 
      class = "org.springframework.jdbc.datasource.DriverManagerDataSource">
      <property name = "driverClassName" value = "com.mysql.jdbc.Driver"/>
      <property name = "url" value = "jdbc:mysql://localhost:3306/TEST"/>
      <property name = "username" value = "root"/>
      <property name = "password" value = "cohondob"/>
   </bean>
  
   <tx:advice id = "txAdvice" transaction-manager = "transactionManager">
      <tx:attributes>
      <tx:method name = "create"/>
      </tx:attributes>
   </tx:advice>
	
   <aop:config>
      <aop:pointcut id = "createOperation" 
         expression = "execution(* com.tutorialspoint.StudentJDBCTemplate.create(..))"/>
      
      <aop:advisor advice-ref = "txAdvice" pointcut-ref = "createOperation"/>
   </aop:config>
	
   <!-- Initialization for TransactionManager -->
   <bean id = "transactionManager"
      class = "org.springframework.jdbc.datasource.DataSourceTransactionManager">
      
      <property name = "dataSource" ref = "dataSource" />    
   </bean>

   <!-- Definition for studentJDBCTemplate bean -->
   <bean id = "studentJDBCTemplate"  
      class = "com.tutorialspoint.StudentJDBCTemplate">
      <property name = "dataSource" ref = "dataSource"/>  
   </bean>

</beans>

创建完源和 bean 配置文件后，让我们运行应用程序。 如果您的应用程序一切正常，它将打印以下异常。 在这种情况下，事务将被回滚，并且不会在数据库表中创建记录。

------Records creation--------
Created Name = Zara, Age = 11
Exception in thread "main" java.lang.RuntimeException: simulate Error condition

您可以在删除异常后尝试上面的示例，在这种情况下，它应该提交事务并且您应该在数据库中看到一条记录。

❮ Spring 事务管理