Spring教程36篇：Spring 编程式事务管理

Spring 编程式事务管理

编程式事务管理方法允许你在对你的源代码编程的帮助下管理事务。这给了你极大地灵活性，但是它很难维护。

在我们开始之前，至少要有两个数据库表，在事务的帮助下我们可以执行多种 CRUD 操作。以 Student 表为例，用下述 DDL 可以在 MySQL TEST 数据库中创建该表：

  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，用来存储基于年份的学生的标记。这里 SID 是 Student 表的外键。

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

让我们直接使用 PlatformTransactionManager 来实现编程式方法从而实现事务。要开始一个新事务，你需要有一个带有适当的 transaction 属性的 TransactionDefinition 的实例。这个例子中，我们使用默认的 transaction 属性简单的创建了 DefaultTransactionDefinition 的一个实例。

当 TransactionDefinition 创建后，你可以通过调用 getTransaction() 方法来开始你的事务，该方法会返回 TransactionStatus 的一个实例。 TransactionStatus 对象帮助追踪当前的事务状态，并且最终，如果一切运行顺利，你可以使用 PlatformTransactionManager 的 commit() 方法来提交这个事务，否则的话，你可以使用 rollback() 方法来回滚整个操作。

现在让我们编写我们的 Spring JDBC 应用程序，它能够在 Student 和 Mark 表中实现简单的操作。让我们适当的使用 Eclipse IDE，并按照如下所示的步骤来创建一个 Spring 应用程序：

下面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();
    }

下面是 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 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;
    import org.springframework.transaction.PlatformTransactionManager;
    import org.springframework.transaction.TransactionDefinition;
    import org.springframework.transaction.TransactionStatus;
    import org.springframework.transaction.support.DefaultTransactionDefinition;
    public class StudentJDBCTemplate implements StudentDAO {
       private DataSource dataSource;
       private JdbcTemplate jdbcTemplateObject;
       private PlatformTransactionManager transactionManager;
       public void setDataSource(DataSource dataSource) {
          this.dataSource = dataSource;
          this.jdbcTemplateObject = new JdbcTemplate(dataSource);
       }
       public void setTransactionManager(
          PlatformTransactionManager transactionManager) {
          this.transactionManager = transactionManager;
       }
       public void create(String name, Integer age, Integer marks, Integer year){
          TransactionDefinition def = new DefaultTransactionDefinition();
          TransactionStatus status = transactionManager.getTransaction(def);
          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);
             transactionManager.commit(status);
          } catch (DataAccessException e) {
             System.out.println("Error in creating record, rolling back");
             transactionManager.rollback(status);
             throw e;
          }
          return;
       }
       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;
       }
    }

现在让我们改变主应用程序文件 MainApp.java，如下所示：

  package com.tutorialspoint;
    import java.util.List;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import com.tutorialspoint.StudentJDBCTemplate;
    public class MainApp {
       public static void main(String[] args) {
          ApplicationContext context = 
                 new ClassPathXmlApplicationContext("Beans.xml");
          StudentJDBCTemplate studentJDBCTemplate = 
          (StudentJDBCTemplate)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());
          }
       }
    }

下面是配置文件 Beans.xml 的内容：

  <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-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="password"/>
       </bean>

       <!-- 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" />
          <property name="transactionManager"  ref="transactionManager" />    
       </bean>

    </beans>

当你完成了创建源和 bean 配置文件后，让我们运行应用程序。如果你的应用程序运行顺利的话，那么将会输出如下所示的消息：

  ------Records creation--------

  Created Name = Zara, Age = 11

  Created Name = Nuha, Age = 20
    Created Name = Ayan, Age = 25
    ------Listing all the records--------
    ID : 1, Name : Zara, Marks : 99, Year : 2010, Age : 11
    ID : 2, Name : Nuha, Marks : 97, Year : 2010, Age : 20
    ID : 3, Name : Ayan, Marks : 100, Year : 2011, Age : 25

作者：陈

来源：https://www.w3cschool.cn/wkspring/urw31mme.html