Spring学习笔记（十三）JdbcTemplate工具类的使用

JdbcTemplate就是Spring框架给我们封装好的简单对数据库操作的工具类，返回Map数据，返回List_Map数据，返回一个值，返回一个对象，返回一个List<对象>，添加修改删除

源码获取github

1.介绍JdbcTemplate工具类

Spring是一个IoC和AOP的容器框架，并且它是一站式开源框架ORM是我们学过的MyBatis，JdbcTemplate就是Spring框架给我们封装好的简单对数据库操作的工具类，需要这个spring-jdbc.jar

2.sql文件

SET FOREIGN_KEY_CHECKS=0;

------

-- Table structure for oa_user

------

DROP TABLE IF EXISTS `oa_user`;
CREATE TABLE `oa_user` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(255) DEFAULT NULL,
  `sex` varchar(255) DEFAULT NULL,
  `money` decimal(7,2) DEFAULT NULL,
  `birthday` date DEFAULT NULL,
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB AUTO_INCREMENT=21 DEFAULT CHARSET=utf8mb4;

------

-- Records of oa_user

------

INSERT INTO `oa_user` VALUES ('1', '悟空', '男', '888.00', null);
INSERT INTO `oa_user` VALUES ('2', '八戒', '男', '999.00', null);
INSERT INTO `oa_user` VALUES ('3', '天蓬元帅', '女', '1000.00', null);
INSERT INTO `oa_user` VALUES ('4', '悟能', '男', '666.00', null);
INSERT INTO `oa_user` VALUES ('5', '法悟法', '女', '544.00', null);
INSERT INTO `oa_user` VALUES ('6', '悟', '女', '562.00', null);
INSERT INTO `oa_user` VALUES ('7', '悟', '女', '562.00', null);
INSERT INTO `oa_user` VALUES ('14', '嫦娥', '女', '1213.00', null);
INSERT INTO `oa_user` VALUES ('15', '月兔', '女', '2113.00', null);
INSERT INTO `oa_user` VALUES ('16', '和尚', '男', '455.00', '2018-08-05');
INSERT INTO `oa_user` VALUES ('18', '沙僧', '男', '455.00', '2018-08-05');
INSERT INTO `oa_user` VALUES ('19', '唐僧', '男', '220.00', '2018-08-09');
INSERT INTO `oa_user` VALUES ('20', '唐僧', '男', '220.00', '2018-08-09');

------

-- Table structure for skill

------

DROP TABLE IF EXISTS `skill`;
CREATE TABLE `skill` (
  `skill_id` int(11) NOT NULL AUTO_INCREMENT,
  `skill_name` varchar(255) DEFAULT NULL,
  `num` int(11) DEFAULT NULL,
  `fk_teacher_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`skill_id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4;

------

-- Records of skill

------

INSERT INTO `skill` VALUES ('2', 'JS', '75', null);
INSERT INTO `skill` VALUES ('7', 'CSS', '66', null);
INSERT INTO `skill` VALUES ('8', 'java', '66', null);
INSERT INTO `skill` VALUES ('9', 'vue', '56', '9999');

------

-- Table structure for sys_role

------

DROP TABLE IF EXISTS `sys_role`;
CREATE TABLE `sys_role` (
  `role_id` int(11) NOT NULL AUTO_INCREMENT,
  `role_name` varchar(32) DEFAULT NULL,
  `role_key` varchar(32) DEFAULT NULL,
  `status` int(1) DEFAULT '1' COMMENT '1可用 -1禁用',
  PRIMARY KEY (`role_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

------

-- Records of sys_role

------

INSERT INTO `sys_role` VALUES ('-100', '超级管理员', 'ADMIN', '1');

------

-- Table structure for sys_user

------

DROP TABLE IF EXISTS `sys_user`;
CREATE TABLE `sys_user` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT,
  `account` varchar(32) NOT NULL,
  `password` varchar(128) NOT NULL,
  `user_name` varchar(32) DEFAULT '',
  `status` int(1) NOT NULL DEFAULT '1' COMMENT '1可用 -1删除  2禁用',
  `login_time` datetime DEFAULT CURRENT_TIMESTAMP,
  `ip` varchar(128) DEFAULT NULL,
  `fk_role_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`user_id`),
  KEY `fk_role_id` (`fk_role_id`),
  CONSTRAINT `sys_user_ibfk_1` FOREIGN KEY (`fk_role_id`) REFERENCES `sys_role` (`role_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

------

-- Records of sys_user

------

INSERT INTO `sys_user` VALUES ('-999', 'super', 'super', '唐僧', '1', '2018-07-28 18:47:39', null, '-100');
INSERT INTO `sys_user` VALUES ('-888', 'admin', 'admin', '悟空', '1', '2018-07-03 18:48:21', null, '-100');

3.实例化该工具类

<bean class="org.springframework.jdbc.core.JdbcTemplate" >
    <property name="dataSource" 赋值/>
    ------
bean>

4.配置数据源

数据源就是连接数据，而以后工作当中我们推荐使用“连接池”，

什么是连接池？

我的理解为预先建立好一堆Connection，使用时候从池中获取，不适应不是销毁而是把连接再次放回到池中

连接池的工作原理？

Java代码如何实现–>Map/List 存Connection

开源的连接池有哪些？

C3p0、dbcp、德鲁伊druid(阿里巴巴的)

<bean id="druidDataSource" class="com.alibaba.druid.pool.DruidDataSource" destroy-method="close">
   <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
   <property name="url" value="jdbc:mysql://localhost:3306/cy42_mss"/>
   <property name="username" value="root"/>
   <property name="password" value="root"/>
bean>


<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
   
   <property name="dataSource" ref="druidDataSource"/>
   
   
bean>

5.User.java

package com.hs.model;

import java.math.BigDecimal;
import java.util.Date;

public class User {

   private Integer user_id;
   private String user_name;
   private String sex;
   //钱用BigDecimal
   private BigDecimal money;
   private Date birthday;

   public BigDecimal getMoney() {
      return money;
   }

   public void setMoney(BigDecimal money) {
      this.money = money;
   }

   public Date getBirthday() {
      return birthday;
   }

   public void setBirthday(Date birthday) {
      this.birthday = birthday;
   }

   public Integer getUser_id() {
      return user_id;
   }

   public void setUser_id(Integer user_id) {
      this.user_id = user_id;
   }

   public String getUser_name() {
      return user_name;
   }

   public void setUser_name(String user_name) {
      this.user_name = user_name;
   }

   public String getSex() {
      return sex;
   }

   public void setSex(String sex) {
      this.sex = sex;
   }

   @Override
   public String toString() {
      return "User{" +
            "user_id=" + user_id +
            ", user_name='" + user_name + '\'' +
            ", sex='" + sex + '\'' +
            ", money=" + money +
            ", birthday=" + birthday +
            '}';
   }
}

6.查询操作(预处理)

1.返回Map数据

package com.hs.test;

import com.hs.model.User;
import org.junit.Before;
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.RowMapper;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Date;
import java.util.List;
import java.util.Map;

public class JdbcTemplateTest {

   private ApplicationContext ac;
   private JdbcTemplate jdbcTemplate;

   @Before
   public void init() {
      ac = new ClassPathXmlApplicationContext("beans.xml");
      jdbcTemplate = ac.getBean("jdbcTemplate", JdbcTemplate.class);
   }

   /**
    * 返回Map数据
    */
   @Test
   public void test01() {
      /*String sql = "select * from oa_user where user_id = 3";
      Map map = this.jdbcTemplate.queryForMap(sql);*/
      String sql = "select * from oa_user where user_id = ?";
      Map map = jdbcTemplate.queryForMap(sql, 2);
      System.out.println(map);
   }
}

2.返回List_Map数据

/**
 * 返回List_Map数据
 */
@Test
public void test02() {
   String sql = "select * from oa_user";
   System.out.println(jdbcTemplate.queryForList(sql));
}

3.返回一个值

/**
 * 返回一个值
 */
@Test
public void test03() {
   String sql = "select count(*) from oa_user";
   System.out.println(jdbcTemplate.queryForObject(sql, Integer.class));

}

4.返回一个对象

/**
 * 返回一个对象
 */
@Test
public void test04() {
   String sql = "select * from oa_user where user_id = ?";
   User user = jdbcTemplate.queryForObject(sql, /*匿名内部类*/new RowMapper() {

      @Override
      public User mapRow(ResultSet rs, int rowNum) throws SQLException {

         User user = new User();
         user.setUser_id(rs.getInt("user_id"));
         user.setUser_name(rs.getString("User_name"));
         user.setSex(rs.getString("sex"));
         user.setMoney(rs.getBigDecimal("money"));
         user.setBirthday((Date) rs.getObject("birthday"));
         return user;
      }
   }, 2);
   System.out.println(user);

}

5.返回一个List<对象>

/**
 * 返回一个List<对象>
 */
@Test
public void test05() {
   String sql = "select * from oa_user where user_name like concat('%',?,'%')";
   List userList = jdbcTemplate.query(sql,/*处理一条一条的数据*/new UserRowMapper(), "沙僧");
   System.out.println(userList);
}

把匿名内部类提出来

/**
 * 对于外面那个类来说，这是一个内部类，外面那个类对于这个类来说，是外部类
 * 百度什么是内部类和特种？
 * private使这个类只能被这个类使用
 */
private class UserRowMapper implements RowMapper<User> {

   @Override
   public User mapRow(ResultSet rs, int rowNum) throws SQLException {
      System.out.println("---------");
      User user = new User();
      user.setUser_id(rs.getInt("user_id"));
      user.setUser_name(rs.getString("User_name"));
      user.setSex(rs.getString("sex"));
      user.setMoney(rs.getBigDecimal("money"));
      user.setBirthday((Date) rs.getObject("birthday"));
      return user;
   }
}

6.返回一个List<对象>——自动映射，类属性和查询的字段名字一样

/**
 * 返回一个List<对象>——自动映射，类属性和查询的字段名字一样
 */
@Test
public void test06() {
   String sql = "select * from oa_user where user_name like concat('%',?,'%')";
   List userList = jdbcTemplate.query(sql,/*处理一条一条的数据，，，可以不用写*/new BeanPropertyRowMapper(User.class), "沙僧");
   System.out.println(userList);
}

7.添加修改删除

/**
 * 添加修改删除
 */
@Test
public void test07() {
   String sql1 = "insert into oa_user(user_name,sex,money,birthday) values(?,?,?,?)";
   String sql2 = "update oa_user set user_name=?,sex=? where user_id = ?";
   String sql3 = "delete from oa_user where user_id = ?";
   int num1 = jdbcTemplate.update(sql1, "唐僧", "男", 220.00, "2018-8-9");
   int num2 = jdbcTemplate.update(sql2, "和尚", "男", 16);
   int num3 = jdbcTemplate.update(sql3, 17);
   System.out.println(num1+"--"+num2+"---"+num3);

}