使用JdbcTemplate和Druid技术简化持久层的编写

目录

1.依赖导入

2.编写数据库连接信息 jdbc.properties

3.编写xml配置文件

4.基于jdbcTemplate的CRUD使用

5.基于jdbcTemplate的持久层编写示例

1.依赖导入

<dependencies>

      <!-- 数据库驱动和连接池-->
      <dependency>
          <groupId>mysql</groupId>
          <artifactId>mysql-connector-java</artifactId>
          <version>8.0.25</version>
      </dependency>

      <dependency>
          <groupId>com.alibaba</groupId>
          <artifactId>druid</artifactId>
          <version>1.2.8</version>
      </dependency>

      <!-- spring-jdbc -->
      <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-jdbc</artifactId>
          <version>6.0.6</version>
      </dependency>

</dependencies> 

2.编写数据库连接信息 jdbc.properties

atguigu.url=jdbc:mysql://localhost:3306/数据库名
atguigu.driver=com.mysql.cj.jdbc.Driver
atguigu.username=root（自己的账号）
atguigu.password=root（自己的密码）

3.编写xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 
       http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">


    <!-- 导入外部属性文件 -->
    <context:property-placeholder location="classpath:jdbc.properties" />

    <!-- 配置数据源 -->
    <bean id="druidDataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="${atguigu.url}"/>
        <property name="driverClassName" value="${atguigu.driver}"/>
        <property name="username" value="${atguigu.username}"/>
        <property name="password" value="${atguigu.password}"/>
    </bean>

    <!-- 配置 JdbcTemplate -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <!-- 装配数据源 -->
        <property name="dataSource" ref="druidDataSource"/>
    </bean>
    
</beans>

4.基于jdbcTemplate的CRUD使用

public class JdbcTemplateTest {


    /**
     * 使用jdbcTemplate进行DML动作
     */
    @Test
    public void testDML(){

        ApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("spring-ioc.xml");

        JdbcTemplate jdbcTemplate = applicationContext.getBean(JdbcTemplate.class);

        //TODO 执行插入一条学员数据
        String sql = "insert into students (id,name,gender,age,class) values (?,?,?,?,?);";
    /*
        参数1: sql语句
        参数2: 可变参数,占位符的值
     */
        int rows = jdbcTemplate.update(sql, 9,"十一", "男", 18, "二年三班");

        System.out.println("rows = " + rows);

    }


    /**
     * 查询单条实体对象
     *   public class Student {
     *     private Integer id;
     *     private String name;
     *     private String gender;
     *     private Integer age;
     *     private String classes;
     */
    @Test
    public void testDQLForPojo(){

        String sql = "select id , name , age , gender , class as classes from students where id = ? ;";

        ApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("spring-ioc.xml");

        JdbcTemplate jdbcTemplate = applicationContext.getBean(JdbcTemplate.class);

        //根据id查询
        Student student = jdbcTemplate.queryForObject(sql,  (rs, rowNum) -> {
            //自己处理结果映射
            Student stu = new Student();
            stu.setId(rs.getInt("id"));
            stu.setName(rs.getString("name"));
            stu.setAge(rs.getInt("age"));
            stu.setGender(rs.getString("gender"));
            stu.setClasses(rs.getString("classes"));
            return stu;
        }, 2);

        System.out.println("student = " + student);
    }



    /**
     * 查询实体类集合
     */
    @Test
    public void testDQLForListPojo(){

        String sql = "select id , name , age , gender , class as classes from students  ;";

        ApplicationContext applicationContext =
                new ClassPathXmlApplicationContext("spring-ioc.xml");

        JdbcTemplate jdbcTemplate = applicationContext.getBean(JdbcTemplate.class);
    /*
        query可以返回集合!
        BeanPropertyRowMapper就是封装好RowMapper的实现,要求属性名和列名相同即可
     */
        List<Student> studentList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class));

        System.out.println("studentList = " + studentList);
    }

}

5.基于jdbcTemplate的持久层编写示例

//接口
public interface StudentDao {

    /**
     * 查询全部学生数据
     * @return
     */
    List<Student> queryAll();
}

//实现类
public class StudentDaoImpl implements StudentDao {

    private JdbcTemplate jdbcTemplate;

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    /**
     * 查询全部学生数据
     * @return
     */
    @Override
    public List<Student> queryAll() {

        String sql = "select id , name , age , gender , class as classes from students ;";

        /*
          query可以返回集合!
          BeanPropertyRowMapper就是封装好RowMapper的实现,要求属性名和列名相同即可
         */
        List<Student> studentList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class));

        return studentList;
   }
}