spring-jdbc

Spring框架对jdbc经行封装，使用jdbcTemplate 对数据库实现增删改查

1.搭建子模块：sprig-jdbc

2.导入依赖

<dependencies>
    <!--spring jdbc  Spring 持久化层支持jar包-->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>6.0.2</version>
    </dependency>
    <!-- MySQL驱动 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.30</version>
    </dependency>
    <!-- 数据源 -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.2.15</version>
    </dependency>
</dependencies>

3.创建jdbc配置文件文件jdbc.properties

jdbc.user=root
jdbc.password=root
jdbc.url=jdbc:mysql://localhost:3306/spring?characterEncoding=utf8&useSSL=false
jdbc.driver=com.mysql.cj.jdbc.Driver

4.配置spring的配置文件bean.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd">
    <!-- 引用外部配置文件-->
    <context:property-placeholder location="jdbc.properties"></context:property-placeholder>
    <!--配置数据源-->
    <bean id="druidDataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="driverClassName" value="${jdbc.driver}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.user}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
    <!--配置jdbcTemplate-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <!-- 装配数据源-->
        <property name="dataSource" ref="druidDataSource"></property>
    </bean>
</beans>

5.准备数据库与测试表

CREATE DATABASE `spring`;

use `spring`;

CREATE TABLE `t_emp` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) DEFAULT NULL COMMENT '姓名',
  `age` int(11) DEFAULT NULL COMMENT '年龄',
  `sex` varchar(2) DEFAULT NULL COMMENT '性别',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

6.实现CRUD

• (1)、创建测试类、整合Junit，注入jdbcTemplate

  
  @SpringJUnitConfig(locations = "classpath:bean.xml")
  @Component
  public class JDBCTemplateTest {
  @Autowired
  private JdbcTemplate jdbcTemplate;

}

- (2)、测试增删改功能
增删改都是调用jdbcTemplate的update()方法实现
```java
@Test
public void testAdd(){
String sql = "insert into t_emp values(null,?,?,?);";
int update = jdbcTemplate.update(sql, "lwj", 22, "男");
System.out.println(update);
}
@Test
public void testModify(){
String sql = "update t_emp set age=? where id=?";
int update = jdbcTemplate.update(sql, 18, 1);
System.out.println(update);
}
@Test
public void testDelete(){
String sql = "delete from t_emp where id=?";
int update = jdbcTemplate.update(sql, 2);
System.out.println(update);
}

• (3).测试查询数据返回对象
• 1、声明对象

  
  package com.lwj.spring6.jdbc;

public class Emp {
Integer id;
String name;
String age;
String sex;
//get set 方法
@Override
public String toString() {
return “Emp{” +
“id=” + id +
“, name='” + name + ”’ +
“, age='” + age + ”’ +
“, sex='” + sex + ”’ +
‘}’;
}
}

- 2.查询返回对象

    查询单个对象使用queryForObject方法
```java
@Test
    public void testQueryObject(){
        String sql = "select * from t_emp where id=?";
        Emp emp = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<>(Emp.class), 1);
        System.out.println(emp);
    }

• (4).测试查询方法放回List数组
• 查询list数组使用query方法

  @Test
  public void testQueryForList(){
      String sql = "select * from t_emp";
      List<Emp> emps = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Emp.class));
      System.out.println(emps);
  }

  (5).测试查询方法返回单个值

  @Test
  public void testQuerySingle(){
      String sql = "select count(id) from t_emp";
      Integer i = jdbcTemplate.queryForObject(sql, Integer.class);
      System.out.println(i);
  }