Spring连接数据库程序实现（JDBC）

Spring中的JDBC连接与直接使用JDBC连接是有区别的，spring对连接做了很大封装，消除冗余代码。

1.创建数据库表结构：

CREATE TABLE `user` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `age` int DEFAULT NULL,
  `sex` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

2.创建对应的数据库表的pojo

public class User {
    private int id;
    private String name;
    private int age;
    private String sex;


    public User() {
    }

    public User(int id, String name, int age, String sex) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    //慈此处省略 get/set方法
}

3. 创建表与实体间的映射

public class UserRowMapper implements RowMapper {

    public Object mapRow(ResultSet resultSet, int i) throws SQLException {
        User user = new User(resultSet.getInt("id"), resultSet.getString("name"),
                resultSet.getInt("age"), resultSet.getString("sex"));
        return user;
    }
}

4. 创建数据操作接口

public interface UserService {

    public void save(User user);

    public List<User> getUsers();
}

5.创建数据操作接口实现类

public class UserServiceImpl implements UserService {

    private JdbcTemplate jdbcTemplate;

    //设置数据源
    public void setDataSource(DataSource dateSource) {
        this.jdbcTemplate = new JdbcTemplate(dateSource);
    }

    public void save(User user) {
        jdbcTemplate.update("insert into user(name, age, sex) values(?, ?, ?)",
                new Object[]{user.getName(), user.getAge(), user.getSex()},
                new int[]{Types.VARCHAR, Types.INTEGER, Types.VARCHAR});

    }

    @SuppressWarnings("unchecked")
    public List<User> getUsers() {
        List list = jdbcTemplate.query("select * from user", new UserRowMapper());
        return list;
    }
}

6. 创建spring配置文件

<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-2.5.xsd ">


        <!--配置数据源-->
        <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">
                <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/spring-DB"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
        </bean>

        <!--配置业务bean-->
        <bean id="userService" class="com.demo.cn.spring.jdbc.UserServiceImpl">
                <!--向属性dataSource注入数据源-->
                <property name="dataSource" ref="dataSource"/>
        </bean>

</beans>

7.测试

public class SpringJDBCTest {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean.xml");
        UserService userService = (UserService) context.getBean("userService");
        User user = new User();
        user.setName("张三");
        user.setAge(18);
        user.setSex("男");
        //保存一条记录
        userService.save(user);

        List<User> person = userService.getUsers();
        System.out.println("获取所有的user");
        for (User user1 : person) {
            System.out.println(user1.getId() + " " + user1.getName() + " " + user1.getAge() + " " + user1.getSex() );

        }

    }
}

运用结果为：

编写以上示例需要导入jdbc相关jar包或者maven依赖：

以maven依赖为例：

 <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.47</version>
    </dependency>

      <!-- https://mvnrepository.com/artifact/org.apache.commons/commons-dbcp2 -->
      <dependency>
          <groupId>org.apache.commons</groupId>
          <artifactId>commons-dbcp2</artifactId>
          <version>2.1.1</version>
      </dependency>