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使用JdbcTemplate和Druid技術簡化持久層的編寫

作者:W-琑 更新時間: 2024-03-07 編程語言

目錄

1.依賴導入

2.編寫數據庫連接信息 jdbc.properties

3.編寫xml配置文件

4.基于jdbcTemplate的CRUD使用

5.基于jdbcTemplate的持久層編寫示例


1.依賴導入

<dependencies>

      <!-- 數據庫驅動和連接池-->
      <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.編寫數據庫連接信息 jdbc.properties

atguigu.url=jdbc:mysql://localhost:3306/數據庫名
atguigu.driver=com.mysql.cj.jdbc.Driver
atguigu.username=root(自己的賬號)
atguigu.password=root(自己的密碼)

3.編寫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">


    <!-- 導入外部屬性文件 -->
    <context:property-placeholder location="classpath:jdbc.properties" />

    <!-- 配置數據源 -->
    <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">
        <!-- 裝配數據源 -->
        <property name="dataSource" ref="druidDataSource"/>
    </bean>
    
</beans>

4.基于jdbcTemplate的CRUD使用

public class JdbcTemplateTest {


    /**
     * 使用jdbcTemplate進行DML動作
     */
    @Test
    public void testDML(){

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

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

        //TODO 執行插入一條學員數據
        String sql = "insert into students (id,name,gender,age,class) values (?,?,?,?,?);";
    /*
        參數1: sql語句
        參數2: 可變參數,占位符的值
     */
        int rows = jdbcTemplate.update(sql, 9,"十一", "男", 18, "二年三班");

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

    }


    /**
     * 查詢單條實體對象
     *   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);

        //根據id查詢
        Student student = jdbcTemplate.queryForObject(sql,  (rs, rowNum) -> {
            //自己處理結果映射
            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);
    }



    /**
     * 查詢實體類集合
     */
    @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就是封裝好RowMapper的實現,要求屬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的持久層編寫示例

//接口
public interface StudentDao {

    /**
     * 查詢全部學生數據
     * @return
     */
    List<Student> queryAll();
}

//實現類
public class StudentDaoImpl implements StudentDao {

    private JdbcTemplate jdbcTemplate;

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

    /**
     * 查詢全部學生數據
     * @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就是封裝好RowMapper的實現,要求屬性名和列名相同即可
         */
        List<Student> studentList = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Student.class));

        return studentList;
   }
}

原文鏈接:https://blog.csdn.net/weixin_69134926/article/details/136075177

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