mybatis知识点总结(mybatis入门菜鸟教程)

开发准备细节分析IDEA 模板创建工具类mybaits文档

创建maven 文件


pom 文件导入依赖：

        
            org.mybatis
            mybatis
            3.5.9
        

        
            mysql
            mysql-connector-java
            8.0.28
        

        
            log4j
            log4j
            1.2.17
        

        
            junit
            junit
            4.13.1
            test
        

    
     

        
            
                src/main/java
                
                    ***.xml
                
                false
            
        
    

创建日志文件，可不创：

log4j.rootLogger = debug,console

log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss} % -5p %c{1}:%L -%m%n

创建mybatis mapper文件：

创建DAO 接口 ，每一个接口一个mapper文件来操作数据库

package dao;

import domain.Student;

import java.util.List;

public interface StudentDao {

    //查询一个学生
    Student selectStudentById(Integer id);
    int insertStudent(Student student); //int 表示添加的函数
    List selectStudents();

}

对应的mapper文件，一般创建在同一个文件夹下。

    
        select * from student where id=1001
    

    
        insert into student values(#{id},#{name},#{age},#{email})
    

    
        select * from student
    

创建数据库类：student

package domain;

public class Student {

    private Integer id;
    private String name;
    private Integer age;
    private String email;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", age=" + age +
                ", email='" + email + ''' +
                '}';
    }
}

使用工具如navicat 创建数据库
id int pk,name varchar(255),email varchar(255),age int;测试 数据库的连接

import domain.Student;
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.Test;
import utils.MyBatisUtil;


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

public class MyTest {
    @Test
    public void testSlectStudentById() throws IOException {
        //调用mybatis中的sql方法
        String config = "mybatis.xml";
        //获取输入流
        InputStream inputStream = Resources.getResourceAsStream(config);
        //使用SQLSessionFactoryBuilder 创建 sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        try (SqlSession session = sqlSessionFactory.openSession()) {

            //            s = namespace+'.'+"select|delele|update|insert" 标签的id属性值
            String sqlid = "dao.StudentDao"+"."+"selectStudentById";

            Student student = (Student) session.selectOne(sqlid,"1001");
//            占位符：传递给 #{xxx}
            System.out.println("student = " + student);

            session.close();
        }
    }

    @Test
    public void testInsert() throws IOException {
        //调用mybatis中的sql方法
        String config = "mybatis.xml";
        //获取输入流
        InputStream inputStream = Resources.getResourceAsStream(config);
        //使用SQLSessionFactoryBuilder 创建 sqlSessionFactory

        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        try (SqlSession session = sqlSessionFactory.openSession()) {

            //            s = namespace+'.'+"select|delele|update|insert" 标签的id属性值
            String sqlid = "dao.StudentDao"+"."+"insertStudent";

//            也可以在这里传入Student对象 需要在xml文件中使用#{属性名} 来获取属性的值。
            Student student = new Student();
            student.setAge(20);
            student.setEmail("123456@qq.com");
            student.setId(1003);
            student.setName("wenjunze");
            int rows = session.insert(sqlid,student);
//            占位符：传递给 #{xxx}
            System.out.println("rows = " + rows);
            //需要手工提交事务
            session.commit();
            session.close();
        }

    }
}

package utils;

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 java.io.IOException;
import java.io.InputStream;

// 工具类 创建SqlSession 对象
public class MyBatisUtil {
    private static SqlSessionFactory factory = null;
    static{
        String config="mybatis.xml";
        try {
            InputStream inputStream = Resources.getResourceAsStream(config);
             factory = new SqlSessionFactoryBuilder().build(inputStream);

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //创建方法，获取Sqlsession 的对象
    public static SqlSession getSqlSession(){
        SqlSession session =null;
        if(factory != null){
            session = factory.openSession();
        }
        return session;
    }
}

测试：

@Test
    public void utilsTest() {
        SqlSession session = MyBatisUtil.getSqlSession();
        String sqid = "dao.StudentDao"+"."+"selectStudents";
        List student = session.selectList(sqid);
        for (Student student1 : student) {
            System.out.println("student1 = " + student1);
        }
        session.close();


    }