Spring JDBCの例

JdbcTemplateクラスを使用したSpring JDBCフレームワークに関連する概念を理解するために、次のStudentテーブルですべてのCRUD操作を実装する簡単な例を作成しましょう。

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

先に進む前に、機能するEclipse IDEを用意し、次の手順を実行してSpringアプリケーションを作成します。

Steps	Description
1	Create a project with a name SpringExample and create a package com.finddevguides under the src folder in the created project.
2	Add required Spring libraries using Add External JARs option as explained in the Spring Hello World Example chapter.
3	Add Spring JDBC specific latest libraries* mysql-connector-java.jar, org.springframework.jdbc.jar and** org.springframework.transaction.jar *in the project. You can download required libraries if you do not have them already.
4	Create DAO interface StudentDAO and list down all the required methods. Though it is not required and you can directly write StudentJDBCTemplate class, but as a good practice, let’s do it.
5	Create other required Java classes Student, StudentMapper, StudentJDBCTemplate and MainApp under the com.finddevguides package.
6	Make sure you already created* Student *table in TEST database. Also make sure your MySQL server is working fine and you have read/write access on the database using the give username and password.
7	Create Beans configuration file Beans.xml under the* src* folder.
8	The final step is to create the content of all the Java files and Bean Configuration file and run the application as explained below.

以下は、データアクセスオブジェクトインターフェイスファイル StudentDAO.java の内容です-

package com.finddevguides;

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 table.
  */
   public void create(String name, Integer age);

  /* *
     * This is the method to be used to list down
 *a record from the Student table corresponding
     * to a passed student id.
   */
   public Student getStudent(Integer id);

  /* *
     * This is the method to be used to list down
 *all the records from the Student table.
  */
   public List<Student> listStudents();

  /* *
     * This is the method to be used to delete
 *a record from the Student table corresponding
     * to a passed student id.
   */
   public void delete(Integer id);

  /* *
     * This is the method to be used to update
 *a record into the Student table.
  */
   public void update(Integer id, Integer age);
}

以下は Student.java ファイルの内容です

package com.finddevguides;

public class Student {
   private Integer age;
   private String name;
   private Integer id;

   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;
   }
}

以下は StudentMapper.java ファイルの内容です

package com.finddevguides;

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

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;
   }
}

定義済みのDAOインターフェイスStudentDAOの実装クラスファイル StudentJDBCTemplate.java を次に示します。

package com.finddevguides;

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

public class StudentJDBCTemplate implements StudentDAO {
   private DataSource dataSource;
   private JdbcTemplate jdbcTemplateObject;

   public void setDataSource(DataSource dataSource) {
      this.dataSource = dataSource;
      this.jdbcTemplateObject = new JdbcTemplate(dataSource);
   }
   public void create(String name, Integer age) {
      String SQL = "insert into Student (name, age) values (?, ?)";
      jdbcTemplateObject.update( SQL, name, age);
      System.out.println("Created Record Name = " + name + " Age = " + age);
      return;
   }
   public Student getStudent(Integer id) {
      String SQL = "select *from Student where id = ?";
      Student student = jdbcTemplateObject.queryForObject(SQL,
         new Object[]{id}, new StudentMapper());

      return student;
   }
   public List<Student> listStudents() {
      String SQL = "select* from Student";
      List <Student> students = jdbcTemplateObject.query(SQL, new StudentMapper());
      return students;
   }
   public void delete(Integer id) {
      String SQL = "delete from Student where id = ?";
      jdbcTemplateObject.update(SQL, id);
      System.out.println("Deleted Record with ID = " + id );
      return;
   }
   public void update(Integer id, Integer age){
      String SQL = "update Student set age = ? where id = ?";
      jdbcTemplateObject.update(SQL, age, id);
      System.out.println("Updated Record with ID = " + id );
      return;
   }
}

以下は MainApp.java ファイルの内容です

package com.finddevguides;

import java.util.List;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.finddevguides.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);
      studentJDBCTemplate.create("Nuha", 2);
      studentJDBCTemplate.create("Ayan", 15);

      System.out.println("------Listing Multiple Records--------" );
      List<Student> students = studentJDBCTemplate.listStudents();

      for (Student record : students) {
         System.out.print("ID : " + record.getId() );
         System.out.print(", Name : " + record.getName() );
         System.out.println(", Age : " + record.getAge());
      }

      System.out.println("----Updating Record with ID = 2 -----" );
      studentJDBCTemplate.update(2, 20);

      System.out.println("----Listing Record with ID = 2 -----" );
      Student student = studentJDBCTemplate.getStudent(2);
      System.out.print("ID : " + student.getId() );
      System.out.print(", Name : " + student.getName() );
      System.out.println(", Age : " + student.getAge());
   }
}

以下は設定ファイル Beans.xml です

<?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>

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

</beans>

ソースおよびBean構成ファイルの作成が完了したら、アプリケーションを実行しましょう。すべてがあなたのアプリケーションでうまくいけば、それは次のメッセージを印刷します-

------Records Creation--------
Created Record Name = Zara Age = 11
Created Record Name = Nuha Age = 2
Created Record Name = Ayan Age = 15
------Listing Multiple Records--------
ID : 1, Name : Zara, Age : 11
ID : 2, Name : Nuha, Age : 2
ID : 3, Name : Ayan, Age : 15
----Updating Record with ID = 2 -----
Updated Record with ID = 2
----Listing Record with ID = 2 -----
ID : 2, Name : Nuha, Age : 20

この例では使用していない操作を自分で試して削除できますが、Spring JDBCフレームワークに基づいた1つの作業アプリケーションがあり、プロジェクト要件に基づいて高度な機能を追加することができます。 NamedParameterJdbcTemplate クラスと SimpleJdbcTemplate クラスを使用するデータベースにアクセスする他の方法があるため、これらのクラスの学習に興味がある場合は、Spring Frameworkのリファレンスマニュアルをご確認ください。

Spring-jdbc-example

Spring JDBCの例