小白入门：mybatis超简单方便的增删改查操作（idea2019）

配置pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>MYBATIS</groupId>
    <artifactId>MYBATIS</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.generator</groupId>
            <artifactId>mybatis-generator-core</artifactId>
            <version>1.3.7</version>
        </dependency>
    </dependencies>
    <build>
        <finalName>zsxt</finalName>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.7</version>
                <configuration>
                    <verbose>true</verbose>
                    <overwrite>true</overwrite>
                </configuration>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
    </build>


</project>

配置资源 generator.properties


连接数据库：view->tool windows->database


选择所要连接的数据库类型

填写账号密码和数据库

建立generatorConfig.xml文件
目的是为了自动生成mapper和数据库实体类

<?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE generatorConfiguration
    PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
   "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
</generatorConfiguration>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">

<generatorConfiguration>
    <!--导入属性配置-->
    <properties resource="generator.properties"></properties>

    <!--指定特定数据库的jdbc驱动jar包的位置-->
    <classPathEntry location="${jdbc.driverLocation}"/>

    <context id="default" targetRuntime="MyBatis3">

        <!-- optional，旨在创建class时，对注释进行控制 -->
        <commentGenerator type="com.example.demo.channellable.CommentGenerator">
            <!-- <property name="suppressDate" value="true" />
            <property name="suppressAllComments" value="true" /> -->
        </commentGenerator>

        <!--jdbc的数据库连接 -->
        <jdbcConnection
                driverClass="${jdbc.driverClass}"
                connectionURL="${jdbc.connectionURL}"
                userId="${jdbc.userId}"
                password="${jdbc.password}">
        </jdbcConnection>


        <!-- 非必需，类型处理器，在数据库类型和java类型之间的转换控制-->
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>


        <!-- Model模型生成器,用来生成含有主键key的类，记录类 以及查询Example类
            targetPackage     指定生成的model生成所在的包名
            targetProject     指定在该项目下所在的路径，如果没有该路径会自动生成
        -->
        <javaModelGenerator targetPackage="com.example.demo.model"
                            targetProject="src/main/java">

            <!-- 是否允许子包，即targetPackage.schemaName.tableName -->
            <property name="enableSubPackages" value="false"/>
            <!-- 是否对model添加 构造函数 -->
            <property name="constructorBased" value="true"/>
            <!-- 是否对类CHAR类型的列的数据进行trim操作 -->
            <property name="trimStrings" value="true"/>
            <!-- 建立的Model对象是否 不可改变  即生成的Model对象不会有 setter方法，只有构造方法 -->
            <property name="immutable" value="false"/>
        </javaModelGenerator>

        <!--在resources目录下的mapper文件，生成数据库的表对应的xml文件 -->
        <sqlMapGenerator targetPackage="mapper"
                         targetProject="src/main/resources">
            <property name="enableSubPackages" value="false"/>
        </sqlMapGenerator>

        <!-- 生成dao层的java代码
                type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象
                type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象
                type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口
                targetPackage填写自己想要存放dao的路径，如果没有该路径会自动生成
        -->
        <javaClientGenerator targetPackage="com.example.demo.dao"
                             targetProject="src/main/java" type="XMLMAPPER">
            <property name="enableSubPackages" value="false"/>
        </javaClientGenerator>

        <!-- 数据表名及实体类名称  -->

    <table tableName="t_user" domainObjectName="User"
           enableCountByExample="false" enableUpdateByExample="false"
           enableDeleteByExample="false" enableSelectByExample="false"
           selectByExampleQueryId="false"></table>
    
    </context>
</generatorConfiguration>

建立CommentGenerator，用于通过数据库注释生成实体类注释

package com.example.demo.channellable;

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.*;
import org.mybatis.generator.internal.DefaultCommentGenerator;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.Properties;

/**
 * @author wfr
 * @description:
 * @date 2019-10-12 15:04
 * @parem CommentGenerator
 */
public class CommentGenerator extends DefaultCommentGenerator {
    private Properties properties;
    private Properties systemPro;
    private boolean suppressDate;
    private boolean suppressAllComments;
    private String currentDateStr;

    public CommentGenerator() {
        super();
        this.properties = new Properties();
        this.systemPro = System.getProperties();
        this.suppressDate = false;
        this.suppressAllComments = false;
        this.currentDateStr = (new SimpleDateFormat("yyyy-MM-dd")).format(new Date());
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable,
                                IntrospectedColumn introspectedColumn) {
        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        field.addJavaDocLine("/**");
        sb.append(" * ");
        sb.append(introspectedColumn.getRemarks());
        sb.append("\n");
        sb.append("	* 列名:" + introspectedColumn.getActualColumnName() + " 类型:" + introspectedColumn.getJdbcTypeName()
                + "(" + introspectedColumn.getLength() + ")" + " 允许空:" + introspectedColumn.isNullable() + " 缺省值:"
                + introspectedColumn.getDefaultValue());
        field.addJavaDocLine(sb.toString());
        field.addJavaDocLine(" */");
    }

    public void addFieldComment(Field field, IntrospectedTable introspectedTable) {

    }

    public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {

        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        sb.append("/**");
        sb.append("\n");
        sb.append("	* ");
        sb.append("\n");
        sb.append("	* @author wfr" + "\n");//改为自己的名字
        if (!suppressDate) {

            sb.append("	* @date " + currentDateStr + "\n");

        }

        List<Parameter> parameters = method.getParameters();

        for (Parameter parameter : parameters) {

            sb.append("	* @param " + parameter.getName() + "\n");

        }

        sb.append("	* @return " + method.getReturnType());
        sb.append("\n" + "	*/");
        method.addJavaDocLine(sb.toString());
    }

    public void addGetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {

    }

    public void addSetterComment(Method method, IntrospectedTable introspectedTable,
                                 IntrospectedColumn introspectedColumn) {

    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {

        super.addClassComment(innerClass, introspectedTable, markAsDoNotDelete);
    }

    public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {

    }

    public void addModelClassComment(TopLevelClass topLevelClass, IntrospectedTable introspectedTable) {

        if (suppressAllComments) {
            return;
        }
        StringBuilder sb = new StringBuilder();
        sb.append("/**");
        sb.append("\n");
        sb.append("* ");
        sb.append("\n");
        sb.append("* @author wfr" + "\n");//改为自己的名字
        if (!suppressDate) {

            sb.append("* @date " + currentDateStr + "\n");

        }
        sb.append("* 数据表" + introspectedTable.getFullyQualifiedTableNameAtRuntime() + "映射bean，由Mybaits自动生成工具生成");
        sb.append("\n" + "*/");
        topLevelClass.addJavaDocLine(sb.toString());

    }

}

建立MyBatisGeneratorRun类，用于运行generatorConfig.xml

package com.example.demo.channellable;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

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

/**
 * @author wfr
 * @description:
 * @date 2019-10-12 15:49
 * @parem MyBatisGeneratorRun
 */
public class MyBatisGeneratorRun {
    public static void main(String[] args) throws Exception{
        MyBatisGeneratorRun app = new MyBatisGeneratorRun();

        System.out.println(app.getClass().getResource("/").getPath());
        app.generator();
        System.out.println(System.getProperty("user.dir"));
    }

    public void generator() throws Exception{

        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream("generatorConfig.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(resourceAsStream);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);

        for(String warning:warnings){
            System.out.println(warning);
        }
    }
}

配置mapper文件

<?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>

</configuration>

<?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>
    <!--导入属性配置-->
    <properties resource="generator.properties"></properties>
    <!--配置文件-->
    <environments default="mysql">
        <environment id="mysql">

            <transactionManager type="JDBC"></transactionManager>

            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driverClass}"/>
                <property name="url" value="${jdbc.connectionURL}"/>
                <property name="username" value="${jdbc.userId}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--生成映射xml所在的目录，默认是在resource目录的mapper下-->
        <mapper resource="mapper/CartMapper.xml"></mapper>
    </mappers>
</configuration>

运行MyBatisGeneratorRun 后，前期准备就完成了
然后就可以通过测试来检查了
找到自动生成的mapper类右击，生成测试类

package com.example.demo.dao;

import com.example.demo.model.Cart;
import com.example.demo.model.User;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;

import static org.junit.Assert.*;

public class CartMapperTest {


    @Test
    public void deleteByPrimaryKey() throws Exception{
        InputStream inputStream= Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建工厂
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂创建会话
        SqlSession openSession=factory.openSession();

        openSession.delete("com.example.demo.dao.CartMapper.deleteByPrimaryKey",10);
        //提交事务
        openSession.commit();//重点，如果没有openSession.commit();就插入数据库失败

        openSession.close();
    }

    @Test
    public void insert() throws Exception{
        InputStream inputStream= Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建工厂
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂创建会话
        SqlSession openSession=factory.openSession();
        Cart cart= new Cart(null, 2, 1, 1, null);
        //两种写法
        openSession.insert("com.example.demo.dao.CartMapper.insert",cart);
//        openSession.getMapper(CartMapper.class).insert(cart);
        //提交事务
        openSession.commit();//重点，如果没有openSession.commit();就插入数据库失败
        openSession.close();
        System.out.println(cart);
    }

    @Test
    public void insertSelective() throws Exception{

    }

    @Test
    public void selectByPrimaryKey() throws Exception{

        InputStream inputStream= Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建工厂
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂创建会话
        SqlSession openSession=factory.openSession();
        //第一个参数：所调用的sql语句：namespace+‘.’+SqlID
        //第二个参数：传入的参数
        Cart cart=openSession.getMapper(CartMapper.class).selectByPrimaryKey(1);
        System.out.println(cart);
        openSession.close();
    }

    @Test
    public void updateByPrimaryKeySelective() throws Exception{

    }

    @Test
    public void updateByPrimaryKey() throws Exception{
        InputStream inputStream= Resources.getResourceAsStream("SqlMapConfig.xml");
        //创建工厂
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(inputStream);
        //通过工厂创建会话
        SqlSession openSession=factory.openSession();
        Cart cart= new Cart(9, 2, 4, 1, null);
        //两种写法
        openSession.update("com.example.demo.dao.CartMapper.updateByPrimaryKey",cart);

        openSession.commit();//重点，如果没有openSession.commit();就插入数据库失败
        openSession.close();
        System.out.println(cart);
    }
}