如何使用mybatis对mysql数据库进行操作，batis的增删改查

Posted 2020-08-27 笨蛋敏

1.先下载Mybatis和mysql connecrt的jar包

下载地址：

链接: https://pan.baidu.com/s/1kVFfF8N 密码: ypkb

导入jar包，maven的话可以直接配置pom

2.建立目录

如图所示

1.configuration.xml

在根目录里面创建这个mybatis配置文件

代码为：

<?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>  
     <typeAliases>  
    <!-- 设置typeAlias是为了在AppMapper.xml中不用每次写全App类的路径，而是用App代替 -->
         <typeAlias type="domain.App" alias="App" />
    </typeAliases> 
    <environments default="development">  
        <environment id="development">  
            <transactionManager type="JDBC" />  
            <dataSource type="POOLED">  
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://222.201.145.215/nziotdb"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>  
        </environment>  
    </environments>   
    <mappers>  
        <!-- 配置AppMapper.xml的路径 -->
        <mapper resource="mapperXml/AppMapper.xml" />
    </mappers>  
</configuration>  

其中里面配置了数据库服务器的地址，账号和密码，并且设置了映射文件mapperxml的路径

2.在domain下面建立实体类

package domain;

import java.io.Serializable;

public class App implements Serializable{
      
    /** 
     *  
     */  
    private String appId;
    private String appDesc;
    private String newestVersion;
    private String newestVersionDesc;
    private String url;  
    private String md5;

    public String getAppId() {
        return appId;
    }

    public void setAppId(String appId) {
        this.appId = appId;
    }

    public String getAppDesc() {
        return appDesc;
    }

    public void setAppDesc(String appDesc) {
        this.appDesc = appDesc;
    }

    public String getNewestVersion() {
        return newestVersion;
    }

    public void setNewestVersion(String newestVersion) {
        this.newestVersion = newestVersion;
    }

    public String getNewestVersionDesc() {
        return newestVersionDesc;
    }

    public void setNewestVersionDesc(String newestVersionDesc) {
        this.newestVersionDesc = newestVersionDesc;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getMd5() {
        return md5;
    }

    public void setMd5(String md5) {
        this.md5 = md5;
    }

    public String toString() {
        return "App [appId=" + appId + ", appDesc=" + appDesc
                + ", newestVersion=" + newestVersion + ", newestVersionDesc="
                + newestVersionDesc + ", url=" + url + ", md5=" + md5 + "]";
    }

}

这个类即代表一个表，类里面的变量可以直接设置为何表里面的字段一致，不一致就要在映射文件里面设置对应关系

3.在mapperXml下面写映射文件

<?xml version="1.0" encoding="UTF-8" ?>  
<!DOCTYPE mapper PUBLIC "-//mybatis.org/DTD Mapper 3.0" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="mapper.AppMapper">
    <resultMap type="App" id="appResultMap">
        <id property="appId" column="app_id"  />
        <result property="appDesc" column="app_desc"  />
        <result property="newestVersion" column="newest_version"  />
        <result property="newestVersionDesc" column="newest_version_desc"  />
        <result property="url" column="url"  />
        <result property="md5" column="md5"  />
    </resultMap>
    <!-- select语句 -->
    <select id="selectUserByID" parameterType="int"  resultMap="appResultMap">
        select * from app_t where app_t.app_id = #{appId}
    </select>
</mapper>

其中resultMap就设置了对应的关系，解决实体类的变量和数据库中字段不一致的问题

具体的sql语句也是在映射文件里面写，其中id代表的是对应的方法，parameterType就是传入变量的类型，resultMap就是返回的数据类型

4.在mapper下为每个实体类建立对应的接口，接口里面的方法和映射文件里面的id一一对应

package mapper;


import java.util.List;

import domain.App;


public interface AppMapper {

    public App selectUserByID(int id);

    public List<App> selectUsersByName(String userName);

    public void addUser(App user);

    public void updateUser(App user);

    public void deleteUser(int id);

}

5.编写数据库查询帮助类，用于返回数据库对象

package Deal;


import domain.App;
import mapper.AppMapper;
import org.apache.ibatis.session.SqlSession;

public class Test{

    public void getUserByID(int userID) {
        SqlSession session = SqlSessionHelper.getSessionFactory().openSession();
        try {
            AppMapper userOperation = session
                    .getMapper(AppMapper.class);
            App user = userOperation.selectUserByID(userID);
            if (user != null) {
                System.out.println(user.getAppDesc());
            }

        } finally {
            session.close();
        }
    }

    
    public static void main(String[] args) {
        try {
            Test test = new Test();
            test.getUserByID(1);
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }



}

数据库表如下，使用该教程之前需要先在数据库建立表

查询的是app_id,对应的app_desc

运行test，得到的接口也是3

6.附上demo工程，不清楚的同学可以参考一下

链接: https://pan.baidu.com/s/1dFqVtSX 密码: jb7j