Spring JDBC - 多批次操作

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概述

以下示例将演示如何使用 Spring JDBC 在单个调用中执行多个批处理更新。我们将更新 Student 表中可用的记录，进行多批次操作，其中批次大小为 1。

语法

String SQL = "update Student set age = ? where id = ?";
int[][] updateCounts = jdbcTemplateObject.batchUpdate(SQL,students,1,
   new ParameterizedPreparedStatementSetter<Student>() {
   
   public void setValues(PreparedStatement ps, Student student)
      throws SQLException {
      ps.setInt(1, student.getAge());						
      ps.setInt(2, student.getId());	
   }
}); 

其中，

• SQL − 更新学生年龄的更新查询。

• jdbcTemplateObject − StudentJDBCTemplate 对象，用于更新数据库中的学生对象。

• ParameterizedPreparedStatementSetter − 批处理执行器，根据学生对象列表中识别的每个项目在 PerparedStatement 中设置值。

• updateCounts − 包含每个批次中每个更新查询的更新行数的 Int[][] 数组。

示例

为了理解上面提到的与 Spring JDBC 相关的概念，让我们编写一个示例，该示例将执行多批次操作。为了编写我们的示例，让我们准备好一个可用的 Eclipse IDE，并使用以下步骤创建 Spring 应用程序。

StudentDAO.java

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 list down
    * all the records from the Student table.
   */
   public List<Student> listStudents();  
   public void batchUpdate(final List<Student> students);
}

Student.java

以下是 Student.java 文件的内容。

package com.tutorialspoint;

// Student POJO for Student Table
public class Student {
   private Integer age;
   private String name;
   private Integer id;

   // setter/getter methods
   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;
   }
}

StudentMapper.java

以下是 StudentMapper.java 文件的内容。

package com.tutorialspoint;

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

// Row Mapper Object to map Student table entry with Student Object
public class StudentMapper implements RowMapper<Student> {
   public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
      Student student = new Student();
      student.setId(rs.getInt("id"));
      student.setName(rs.getString("name"));
      student.setAge(rs.getInt("age"));
      return student;
   }
}

StudentJDBCTemplate.java

以下是为已定义的 DAO 接口 StudentDAO 编写的实现类文件 StudentJDBCTemplate.java。

package com.tutorialspoint;

import java.sql.PreparedStatement;
import java.util.List;
import javax.sql.DataSource;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.ParameterizedPreparedStatementSetter;
import java.sql.SQLException;

// DAO instance to persist Student values
public class StudentJDBCTemplate implements StudentDAO {
   private DataSource dataSource;
   private JdbcTemplate jdbcTemplateObject;
   
   // set the datasource and jdbctemplate
   public void setDataSource(DataSource dataSource) {
      this.dataSource = dataSource;
      this.jdbcTemplateObject = new JdbcTemplate(dataSource);
   }
   
   // get all the students from the database
   public List<Student> listStudents() {
      String SQL = "select * from Student";
      List <Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());
      return students;
   }
   
   // update a batch of multiple students
   public void batchUpdate(final List<Student> students){
      String SQL = "update Student set age = ? where id = ?";
      int[][] updateCounts = jdbcTemplateObject.batchUpdate(
         SQL,students,1,new ParameterizedPreparedStatementSetter<Student>() {
            public void setValues(PreparedStatement ps, Student student)
               throws SQLException {
               ps.setInt(1, student.getAge());						
               ps.setInt(2, student.getId());	
            }
         }
      );
      System.out.println("Records updated!");
   }
}

MainApp.java

以下是 MainApp.java 文件的内容。

package com.tutorialspoint;

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

public class MainApp {
   public static void main(String[] args) {
      // Create the application context by reading Beans.xml
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
	  
      // Create the JDBCTemplate instance from spring context
      StudentJDBCTemplate studentJDBCTemplate = (StudentJDBCTemplate)context.getBean("studentJDBCTemplate");

      // get all the students
      List<Student> initialStudents = studentJDBCTemplate.listStudents();
      System.out.println("Initial Students");

      // print all the students
      for(Student student2: initialStudents){
         System.out.print("ID : " + student2.getId() );
         System.out.println(", Age : " + student2.getAge()); 
      }
      
      // create a new student to persist
      Student student = new Student();
      student.setId(1);
      student.setAge(17);

      // create another student to persist
      Student student1 = new Student();
      student1.setId(3);
      student1.setAge(18);

      // create a list of students to persist
      List<Student> students = new ArrayList<Student>();
      students.add(student);
      students.add(student1);
	  
      // persist list of students
      studentJDBCTemplate.batchUpdate(students);

      // get updated list of students      
      List<Student> updatedStudents = studentJDBCTemplate.listStudents();
      System.out.println("Updated Students");

      // print all the students including new students
      for(Student student3: updatedStudents){
         System.out.print("ID : " + student3.getId() );
         System.out.println(", Age : " + student3.getAge()); 
      }
   }
}

Beans.xml

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" 
   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.cj.jdbc.Driver"/>
      <property name = "url" value = "jdbc:mysql://:3306/TEST"/>
      <property name = "username" value = "root"/>
      <property name = "password" value = "admin"/>
   </bean>

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

输出

创建源文件和 bean 配置文件后，让我们运行应用程序。如果应用程序一切正常，它将打印以下消息。

Initial Students
ID : 1, Age : 15
ID : 3, Age : 16
records updated!
Updated Students
ID : 1, Age : 17
ID : 3, Age : 18