要了解有关Spring JDBC框架与JdbcTemplate类的概念，让我们写这将实现所有在下面Student表的CRUD操作的简单例子。
CREATE TABLE Student( ID INT NOT NULL AUTO_INCREMENT, NAME VARCHAR(20) NOT NULL, AGE INT NOT NULL, PRIMARY KEY (ID) );
在开始之前，让我们使用Eclipse IDE，并按照下面的步骤来创建一个Spring应用程序：
| 步骤 | 描述 |
|---|---|
| 1 | Create a project with a name SpringExample and create a package com.yiibai 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 andMainApp under the com.yiibai 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. |
以下是数据访问对象接口文件StudentDAO.java的内容：
package com.yiibai; 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); }
以下是Student.java文件的内容：
package com.yiibai; 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.yiibai; 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; } }
下面是实现类文件StudentJDBCTemplate.java 定义DAO接口StudentDAO：
package com.yiibai; 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.yiibai; import java.util.List; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yiibai.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()); } }
以下是配置文件beans.xml文件：
<?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.yiibai.StudentJDBCTemplate"> <property name="dataSource" ref="dataSource" /> </bean> </beans>
创建源代码和bean配置文件完成后，让我们运行应用程序。如果一切顺利，这将打印以下信息：
------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
你可以尝试删除操作，我在例子中没有使用过，但现在你有一个工作的应用程序基于Spring的JDBC框架，它可以扩展到根据项目要求增加复杂的功能。还有其他的方法来访问，将使用针对NamedParameterJdbcTemplate和SimpleJdbcTemplate类的数据库，所以如果你有兴趣学习这些课程，请参考Spring框架手册。
