eclipse创建一个简单的MyBatis项目

1.创建一个web应用程序

输入项目名称

2.在lib文件夹中添加jar包

 

链接：https://pan.baidu.com/s/1AjhcveNCVokizsrrF_-YLA
提取码：gza8

3.在src文件夹中创建com.demo.po，com.demo.mapper，com.demo.dao三个包，并创建MyBatis框架配置文件mybatis-config.xml文件，在mapper目录下创建数据实体映射文件CommodityStorageMapper.xml，在po目录下创建名为CommodityStorage的实体类。如下图所示：

 4.在MySQL中创建数据库my_db

create database if not exists my_db character set utf8 collate utf8_general_ci;
use my_db;

drop table if exists commodity_storage;
create table commodity_storage(
commodity_id varchar(45) primary key,
commodity_name varchar(45) not null,
enter_date date not null,
commodity_amount int(10) UNSIGNED not null,
commodity_supplier varchar(45) not null
)ENGINE=innoDB default charset=utf8;

insert into commodity_storage values
('C001','帽子','2020-03-08',150,'新丰慧'),
('C002','运动裤','2020-05-06',230,'新丰慧'),
('C003','衬衣','2020-07-20',80,'天利'),
('C004','口罩','2020-03-08',1500,'万源'),
('C005','遮阳镜','2020-05-06',68,'利风'),
('C006','运动鞋','2020-03-08',800,'利风'),
('C007','风衣','2020-03-08',460,'天利'),
('C008','救生圈','2020-05-06',180,'奥体'),
('C009','玩具','2020-03-08',390,'奥体');

5.mybatis-config.xml配置文件的编写

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
   <!-- 默认使用的环境 ID（比如：default="development"）
    也就是说我们可以配置多套<environment>环境-->
    <environments default="my_dev">
<!--
   每个 environment 元素定义的环境 ID
   -->
        <environment id="my_dev">
        <!--
            transactionManager 事务管理器
            type的值有JDBC和MANAGED
                JDBC – 这个配置直接使用了 JDBC 的提交和回滚设施，它依赖从数据源获得的连接来管理事务作用域。
        -->
            <transactionManager type="JDBC"/>
            <!--
              dataSourcedataSource 数据源 dbcp c3p0 druid
              type="[UNPOOLED|POOLED|JNDI]"
              POOLED意思有连接池的连接
              UNPOOLED意思没有连接池的连接
              -->
            <dataSource type="POOLED">
<!--                JDBC 驱动-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
<!--                url数据库的 JDBC URL地址。-->
                <property name="url" value="jdbc:mysql://localhost:3306/my_db"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>

<!--            defaultTransactionIsolationLevel – 默认的连接事务隔离级别。&ndash;&gt;-->
<!--            <property name="defaultTransactionIsolationLevel" value=""/>-->

<!--            defaultNetworkTimeout – 等待数据库操作完成的默认网络超时时间（单位：毫秒）&ndash;&gt;-->
<!--            <property name="efaultNetworkTimeout" value=""/>-->

            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!-- 使用相对于类路径的资源引用 -->
<mapper resource="com/demo/mapper/CommodityStorageMapper.xml"/>
        <!-- 使用完全限定资源定位符（URL）
        不推荐使用
        <mapper url="E:\JetBrains\mybatis学习\Mybatis-study\Mybatis-03\src\main\java\asia\xiaojiang\mybatis03\dao\UserMapper.xml"/>
        -->

        <!-- 使用映射器接口实现类的完全限定类名
         使用注意点：
            接口和其配置文件必须同名， 必须在同一个包下
         -->
        <!--  <mapper class="asia.xiaojiang.mybatis03.dao.UserMapper"/>-->
        <!-- 将包内的映射器接口实现全部注册为映射器
        使用包扫描注意点：
            接口和其配置文件必须同名， 必须在同一个包下
        -->
<!--        <package name="asia.xiaojiang.mybatis03.dao"/>-->
    </mappers>
</configuration>

6.关系数据实体类文件CommodityStorage.java

CommodityStorage.java

package com.demo.po;
import java.util.Date;
public class CommodityStorage {
    private String commodityId;
    private String commodityName;
    private Date enterDate;    
    private Integer commodityAmount;    
    private String commoditySupplier;
    public String getCommodityId() {
        return commodityId;
    }
    public void setCommodityId(String commodityId) {
        this.commodityId = commodityId;
    }
    public String getCommodityName() {
        return commodityName;
    }
    public void setCommodityName(String commodityName) {
        this.commodityName = commodityName;
    }
    public Date getEnterDate() {
        return enterDate;
    }
    public void setEnterDate(Date enterDate) {
        this.enterDate = enterDate;
    }
    public Integer getCommodityAmount() {
        return commodityAmount;
    }
    public void setCommodityAmount(Integer commodityAmount) {
        this.commodityAmount = commodityAmount;
    }
    public String getCommoditySupplier() {
        return commoditySupplier;
    }
    public void setCommoditySupplier(String commoditySupplier) {
        this.commoditySupplier = commoditySupplier;
    }    
}

7.关系数据实体映射文件CommodityStorageMapper.xml

CommodityStorageMapper.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.demo.po.CommodityStorage">
    <!-- 插入商品库存信息 -->
    <insert id="insertCommodity" parameterType="com.demo.po.CommodityStorage">
       insert into commodity_storage values(#{commodityId},#{commodityName},#{enterDate},
       #{commodityAmount},#{commoditySupplier})
    </insert>
    
     <!-- 更新商品库存操作 -->
    <update id="updateCommodity" parameterType="com.demo.po.CommodityStorage">
       update commodity_storage set commodity_amount=#{commodityAmount} where commodity_supplier=#{commoditySupplier}
    </update>
    
      <!-- 删除商品库存操作 -->
    <delete id="deleteCommodity" parameterType="String">
       delete from commodity_storage where commodity_name=#{commodityName}
    </delete>
    
       <!-- 检索单条商品库存操作 -->
    <select id="findCommodityById" parameterType="String" resultType="com.demo.po.CommodityStorage">
       select commodity_id as commodityId, commodity_name as commodityName 
       enter_date as enterDate,commodity_amount as commodityAmount, 
       commodity_supplier as commoditySupplier from commodity_storage where commodity_id=#{commodityId}
    </select>
    
     <!-- 检索多条商品库存操作 -->
    <select id="findCommodityByAmount" parameterType="Integer" resultType="com.demo.po.CommodityStorage">
       select commodity_id as commodityId, commodity_name as commodityName 
       enter_date as enterDate,commodity_amount as commodityAmount, 
       commodity_supplier as commoditySupplier from commodity_storage where commodity_amount &lt;#{commodityAmount}
    </select>
    
    
</mapper>

8.dao层负责实现Java应用程序到关系数据表的持久化操作，在com.demo.dao包下添加MyDemoDAO文件

MyDemoDAO.java

package com.demo.dao;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.Date;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import com.demo.po.CommodityStorage;
import com.sun.xml.internal.bind.v2.schemagen.xmlschema.List;

public class MyDemoDAO {

    private SqlSession sqlSession;
    
    public MyDemoDAO()
    {
        //sqlsession实例初始化
        try {
            InputStream ips = Resources.getResourceAsStream("mybatis-config.xml");
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(ips);
            sqlSession = sessionFactory.openSession();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    //插入商品库存
    public void insertCustomer(CommodityStorage cs)
    {
        //第一个参数为映射文件CommodityStorageMapper.xml中的namespace加上<insert>节点的id
        //第二个参数为语句中的pojo实例
        int rows= sqlSession.insert("com.demo.po.CommodityStorage.insertCommodity",cs);
        if(rows>0)
        {
            System.out.println("数据插入成功！");
        }else {
            System.out.println("数据插入失败！");
        }
        sqlSession.commit();
        sqlSession.close();    
    }
    
    //更新商品库存
    
    public void updateCustomer(CommodityStorage cs)
    {
        //第一个参数为映射文件CommodityStorageMapper.xml中的namespace加上<update>节点的id
        //第二个参数为语句中的pojo实例
        int rows= sqlSession.update("com.demo.po.CommodityStorage.updateCommodity",cs);
        if(rows>0)
        {
            System.out.println("数据更新成功！");
        }else {
            System.out.println("数据更新失败！");
        }
        sqlSession.commit();
        sqlSession.close();    
    }
    //删除商品库存
    public void deleteCustomer(String name)
    {
        //第一个参数为映射文件CommodityStorageMapper.xml中的namespace加上<delete>节点的id
        //第二个参数为语句中的pojo实例
        int rows= sqlSession.delete("com.demo.po.CommodityStorage.deleteCommodity",name);
        if(rows>0)
        {
            System.out.println("数据删除成功！");
        }else {
            System.out.println("数据删除失败！");
        }
        sqlSession.commit();
        sqlSession.close();    
    }
    
    //检索单条商品库存
    public void findCommodityById(String Commodityid)
    {
        //第一个参数为映射文件CommodityStorageMapper.xml中的namespace加上<select>节点的id
        //第二个参数为语句中的pojo实例
        CommodityStorage cs1= sqlSession.selectOne("com.demo.po.CommodityStorage.findCommodityById",Commodityid);
        System.out.println(cs1.getCommodityId()+"\t"+cs1.getCommodityName()+"\t"+cs1.getCommodityAmount()
        +"\t"+cs1.getCommoditySupplier()+"\t"+cs1.getEnterDate());
        
        sqlSession.close();    
    }
    
    //检索多条商品库存
    
    public void findCommodityByAmount(Integer amount)
    {
        //第一个参数为映射文件CommodityStorageMapper.xml中的namespace加上<select>节点的id
        //第二个参数为语句中的pojo实例
        List<CommodityStorage> list= sqlSession.selectList("com.demo.po.CommodityStorage.findCommodityByAmount",amount);
        for(int i=0;i<list.size();i++)
        {
            CommodityStorage cs1=list.get(i);
            System.out.println(cs1.getCommodityId()+"\t"+cs1.getCommodityName()+"\t"+cs1.getCommodityAmount()
            +"\t"+cs1.getCommoditySupplier()+"\t"+cs1.getEnterDate());
        }
        
        
        sqlSession.close();    
    }
    
    
    
    
    
    
    public static void main(String[] args) {
        MyDemoDAO dao=null;
        CommodityStorage cs=null;

        //插入商品库存数据
        /*
        dao=new MyDemoDAO();
        cs=new CommodityStorage();
        cs.setCommodityId("C010");
        cs.setCommodityName("乒乓球");
        cs.setCommoditySupplier("天利");
        cs.setCommodityAmount(34);
        Date now=new Date();
        cs.setEnterDate(now);
        dao.insertCustomer(cs);
        */
        
        //修改商品库存数据
        dao=new MyDemoDAO();
        cs=new CommodityStorage();
        cs.setCommoditySupplier("新丰慧");
        cs.setCommodityAmount(180);
        dao.updateCustomer(cs);
        
        //删除商品库存数据
        dao=new MyDemoDAO();
        dao.deleteCustomer("口罩");
        
        
        
    }

}

9.调试报错

解决办法是mybatis包和MySQL的包版本不兼容导致，将mysql-connector-java-5.0.8-bin.jar更换为mysql-connector-java-5.1.34-bin.jar，运行成功

检查数据库中文乱码

 解决办法是修改mybatis-config.xml文件中的数据库连接url如下：

<property name="url" value="jdbc:mysql://localhost:3306/my_db?useUnicode=true&amp;characterEncoding=UTF-8"/>