mybatis入门

一、目录结构

二、代码

　　1、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>org.example</groupId>
    <artifactId>A01mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!--引入mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.1</version>
        </dependency>
        <!--引入mysql驱动包-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.11</version>
        </dependency>
        <!--引入log4j-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!--指定maven编译器版本-->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

　　2、mybatis.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>
    <!--指定别名后mapper文件resultType可以省略包名-->
    <typeAliases>
        <package name="com.wuxi.beans"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url"
                          value="jdbc:mysql://192.168.2.105:3306/ssm?characterEncoding=utf8&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <!--指定mapper文件位置-->
    <mappers>
        <package name="com.wuxi.daos"/>
    </mappers>
</configuration>

　　3、log4j.properties

log4j.logger.com.wuxi.daos=debug,console

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%d{HH:mm:ss}] %m%n

　　4、Student.java

package com.wuxi.beans;

public class Student {
    private Integer id;
    private String name;
    private Integer age;
    private Integer sex;

    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 == null ? null : name.trim();
    }

    public Integer getAge() {
        return age;
    }

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

    public Integer getSex() {
        return sex;
    }

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

    @Override
    public String toString() {
        return "Student:{id:" + id + ", name:" + name + ", age:" + age + ", sex:" + sex + "}";
    }
}

　　5、StudentMapper.java

package com.wuxi.daos;

import com.wuxi.beans.Student;

import java.util.List;
import java.util.Map;

public interface StudentMapper {
    Integer insertStudent(Student student);

    List<Student> selectAllStudent(Map map);
}

　　6、StudentMapper.xml（必须放在resources目录下。要放在java目录下需做下方pom.xml配置）

<?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.wuxi.daos.StudentMapper">
    <insert id="insertStudent">
        insert into student(name, age, sex) values(#{name}, #{age}, #{sex})
        <selectKey resultType="int" keyProperty="id" order="AFTER">
            select @@identity
        </selectKey>
    </insert>
    <select id="selectAllStudent" resultType="Student">
        select id, name, age, sex from student
        where name like #{student.name}
    </select>
</mapper>

<build>
    <resources>
        <!--
            src/main/java目录下的mapper.xml文件，需此配置才能打进包里
        -->
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
        </resource>
    </resources>
</build>

　　7、MybatisTest.java

package com.wuxi;

import com.wuxi.beans.Student;
import com.wuxi.daos.StudentMapper;
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.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MybatisTest {
    public static void main(String[] args) {
        SqlSession session = null;
        try {
            String resource = "mybatis.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            session = sqlSessionFactory.openSession();

            StudentMapper mapper = session.getMapper(StudentMapper.class);
/*
            // 增
            Student student = new Student();
            student.setName("林允儿");
            student.setAge(16);
            student.setSex(0);
            mapper.insertStudent(student);
            // student的id为插入时的id
            System.out.println(student);
*/
            // 模糊查询
            Map<String, Object> map = new HashMap<String, Object>();
            Student student = new Student();
            // %占位符不要写在mapper文件的sql中
            student.setName("%" + "美" + "%");
            map.put("student", student);
            // 使用map传参和ognl表达式
            List<Student> students = mapper.selectAllStudent(map);
            System.out.println(students);

            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (session != null) {
                session.close();
            }
        }
    }
}