Spring JDBC 示例

Spring JDBC 示例

想要理解带有 jdbc 模板类的 Spring JDBC 框架的相关概念，让我们编写一个简单的示例，来实现下述 Student 表的所有 CRUD 操作。

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

在继续之前，让我们适当地使用 Eclipse IDE 并按照如下所示的步骤创建一个 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 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);
    }

下面是 Student.java 文件的内容：

    package com.tutorialspoint;
    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;
    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;
       }
    }

下面是为定义的 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.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;
       }
    }

以下是 MainApp.java 文件的内容：

    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);
          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());      
       }
    }

下述是配置文件 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>

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

    </beans>

当你完成创建源和 bean 配置文件后，运行应用程序。如果你的应用程序一切运行顺利的话，将会输出如下所示的消息：

    ------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

你可以尝试自己删除在我的例子中我没有用到的操作，但是现在你有一个基于 Spring JDBC 框架的工作应用程序，你可以根据你的项目需求来扩展这个框架，添加复杂的功能。还有其他方法来访问你使用 NamedParameterJdbcTemplate 和 SimpleJdbcTemplate 类的数据库，所以如果你有兴趣学习这些类的话，那么你可以查看 Spring 框架的参考手册。

作者：w3cschool | 来源：https://www.w3cschool.cn