jdbcTemplate基础

Employee.java:

package com.atguigu.bean;

import lombok.Data;
import lombok.ToString;

/**
 * @Title: Employee
 * @Description:
 * @Author:
 * @Version: 1.0
 * @create 2020/6/9 9:16
 */
@Data
@ToString
public class Employee {

    private Integer empId;
    private String empName;
    private double salary;
}

EmployeeDao.java:

package com.atguigu.dao;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import com.atguigu.bean.Employee;

@Repository
public class EmployeeDao {
    
    @Autowired
    JdbcTemplate jdbcTemplate;
    
    public void saveEmployee(Employee employee){
        String sql = "INSERT INTO employee(emp_name,salary) VALUES(?,?)";
        jdbcTemplate.update(sql, employee.getEmpName(),employee.getSalary());
    }

}

ApplicationContext.xml:

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <beans xmlns="http://www.springframework.org/schema/beans"
 3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4        xmlns:context="http://www.springframework.org/schema/context"
 5        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">
 6 
 7     <!--配置包扫描-->
 8     <context:component-scanbase-package="com.atguigu"></context:component-scan>
 9 
10     <!--引入外部配置文件-->
11     <context:property-placeholder location="classpath:db.properties"/>
12 
13     <!--实验1：测试数据源
14 ${}取出配置文件中的值
15 #{}Spring的表达式语言
16     -->
17     <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
18         <property name="user" value="${jdbc.username}"/>
19         <property name="password" value="${jdbc.password}"/>
20         <property name="jdbcUrl" value="${jdbc.jdbcUrl}"/>
21         <property name="driverClass" value="${jdbc.dirverClass}"/>
22     </bean>
23 
24     <!-- Spring提供了一个类JdbcTemplate，我们用它操作数据库；
25         导入Spring的数据库模块
26             spring-jdbc-4.0.0.RELEASE.jar
27             spring-orm-4.0.0.RELEASE.jar
28             spring-tx-4.0.0.RELEASE.jar
29          -->
30     <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
31         <constructor-arg name="dataSource" ref="dataSource"></constructor-arg>
32     </bean>
33 
34     <!-- 配置一个具有  具名参数  功能的JdbcTemplate；NamedParameterJdbcTemplate -->
35     <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
36         <!-- 使用构造器方式注入一个数据源 -->
37         <constructor-arg name="dataSource" ref="dataSource"></constructor-arg>
38     </bean>
39 </beans>

db.properties:

jdbc.username=root
jdbc.password=root
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/jdbc_template?serverTimezone=GMT%2B8
jdbc.dirverClass=com.mysql.cj.jdbc.Driver

TxTest.java:

package com.atguigu.test;

import com.atguigu.bean.Employee;

import com.atguigu.dao.EmployeeDao;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.namedparam.BeanPropertySqlParameterSource;
import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @Title: TxTest
 * @Description:
 * @Author:
 * @Version: 1.0
 * @create 2020/6/8 23:50
 */
public class TxTest {

    ApplicationContext ioc = new ClassPathXmlApplicationContext("ApplicationContext.xml");
    JdbcTemplate jdbcTemplate = ioc.getBean(JdbcTemplate.class);
    NamedParameterJdbcTemplate namedJdbcTemplate = ioc.getBean(NamedParameterJdbcTemplate.class);
    @Test
    public void test() throws SQLException {
        DataSource bean = ioc.getBean(DataSource.class);
        Connection connection = bean.getConnection();
        System.out.println(connection);
        connection.close();
    }

    /**
     * 实验2：将emp_id=5的记录的salary字段更新为1300.00
     */
    @Test
    public void test02(){
        String sql = "UPDATE employee SET salary=? WHERE emp_id=?";
        int update = jdbcTemplate.update(sql, 1300.00,5);
        System.out.println("更新员工："+update);
    }

    /**
     * 实验3：批量插入；
     */
    @Test
    public void test03(){
        String  sql ="INSERT INTO employee(emp_name,salary) VALUES(?,?)";
        //List<Object[]>
        //List的长度就是sql语句要执行的次数
        //Object[]：每次执行要用的参数
        List<Object[]> batchArgs = new ArrayList<Object[]>();
        batchArgs.add(new Object[]{"张三",1998.98});
        batchArgs.add(new Object[]{"李四",2998.98});
        batchArgs.add(new Object[]{"王五",3998.98});
        batchArgs.add(new Object[]{"赵六",4998.98});

        int[] is = jdbcTemplate.batchUpdate(sql, batchArgs);
        for (int i : is) {
            System.out.println(i);
        }
    }

    /**
     * 实验5：查询salary>4000的数据库记录，封装为List集合返回
     */
    @Test
    public void test05(){
        String sql = "SELECT emp_id empId,emp_name empName,salary FROM employee WHERE salary>?";
        //封装List；集合里面元素的类型
        List<Employee> list = jdbcTemplate.query(sql, new BeanPropertyRowMapper<>(Employee.class), 4000);

        for (Employee employee : list) {
            System.out.println(employee);
        }
    }

    /**
     * 实验6：查询最大salary
     */
    @Test
    public void test06(){
        String sql = "select max(salary) from employee";
        //无论是返回单个数据还是单个对象，都是调用queryForObject
        Double object = jdbcTemplate.queryForObject(sql, Double.class);
        System.out.println(object);
    }

    /**
     * 实验7：使用带有具名参数的SQL语句插入一条员工记录，并以Map形式传入参数值
     *
     * 具名参数：（具有名字的参数，参数不是占位符了，而是一个变量名）
     *         语法格式：   :参数名
     * Spring有一个支持具名参数功能的JdbcTemplate
     *
     * 占位符参数：?的顺序千万不能乱。传参的时候一定注意；
     */
    @Test
    public void test07(){
        String sql = "INSERT INTO employee(emp_name,salary) VALUES(:empName,:salary)";

        //Map
        Map<String, Object> paramMap = new HashMap<>();
        //将所有具名参数的值都放在map中；
        paramMap.put("empName", "田七");
        paramMap.put("salary", 9887.98);
        int update = namedJdbcTemplate.update(sql, paramMap);
        System.out.println(update);
    }

    /**
     * 实验8：重复实验7，以SqlParameterSource形式传入参数值
     */
    @Test
    public void test08(){
        String sql = "INSERT INTO employee(emp_name,salary) VALUES(:empName,:salary)";
        Employee employee = new Employee();
        employee.setEmpName("哈哈");
        employee.setSalary(998.98);

        //
        int i = namedJdbcTemplate.update(sql, new BeanPropertySqlParameterSource(employee));
        System.out.println(i);

    }

    /**
     * 实验9：创建BookDao，自动装配JdbcTemplate对象
     */
    @Test
    public void test09(){
        EmployeeDao bean = ioc.getBean(EmployeeDao.class);
        Employee employee = new Employee();
        employee.setEmpName("哈哈2");
        employee.setSalary(998.98);
        bean.saveEmployee(employee);
    }
}