[Java知识库]Mybatis

一：实体类

package domian;

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

    public Student() {
    }

    public Student(Integer id, String name, Integer age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    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;
    }

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

二：mapper层

package mapper;

import domian.Student;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface StudentMapper {
    List<Student> selectAll();

    List<Student> selectnameorage(@Param("p1") String name ,@Param("p2") Integer age);

    List<Student> selectnameandage(Student stu);

    List<Student> selectageandname(List<Integer> ids);
}

三：sevrver层

package service;

import domian.Student;

import java.util.List;

public interface StudentService {
    List<Student> SelectAll();

    List<Student> selectnameorage(String name,Integer age);
    List<Student> selectnameandage(Student stu);

    List<Student> selectageandname(List<Integer> ids);
}

实现类

package service;

import domian.Student;
import mapper.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.IOException;
import java.io.InputStream;
import java.util.List;

public class StudentServices implements StudentService {
    @Override
    public List<Student> SelectAll() {
        InputStream is = null;
        SqlSession sqlSession = null;
        List<Student> list = null;
        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");
            SqlSessionFactory build = new SqlSessionFactoryBuilder().build(is);

            sqlSession = build.openSession(true);
            StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
            list = mapper.selectAll();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is!=null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (sqlSession!=null){
                sqlSession.close();
            }

        }


        return list;
    }

    @Override
    public List<Student> selectnameorage(String name, Integer age) {
        InputStream is = null;
        SqlSession sqlSession = null;
        List<Student> list = null;
        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");
            SqlSessionFactory build = new SqlSessionFactoryBuilder().build(is);

            sqlSession = build.openSession(true);
            StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
            list = mapper.selectnameorage(name, age);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is!=null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (sqlSession!=null){
                sqlSession.close();
            }
    }

    return list;
    }

    @Override
    public List<Student> selectnameandage(Student stu) {
        InputStream is = null;
        SqlSession sqlSession = null;
        List<Student> list = null;
        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");
            SqlSessionFactory build = new SqlSessionFactoryBuilder().build(is);

            sqlSession = build.openSession(true);
            StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
            list = mapper.selectnameandage(stu);


        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is!=null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (sqlSession!=null){
                sqlSession.close();
            }
    }
    return list;
}

    @Override
    public List<Student> selectageandname(List<Integer> ids) {
        InputStream is = null;
        SqlSession sqlSession = null;
        List<Student> list = null;
        try {
            is = Resources.getResourceAsStream("MyBatisConfig.xml");
            SqlSessionFactory build = new SqlSessionFactoryBuilder().build(is);

            sqlSession = build.openSession(true);
            StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);

            list = mapper.selectageandname(ids);



        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is!=null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (sqlSession!=null){
                sqlSession.close();
            }
        }
        return list;
    }
}

配置文件：

全局配置

<?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>
//加载数据源的配置

    <properties resource="jdbc.properties"/>

//起别名
    <typeAliases>
        <typeAlias type="domian.Student" alias="student"/>
        <!--<package name="com.itheima.bean"/>-->
    </typeAliases>


    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

//加载sql语句的配置文件
    <mappers>
        <mapper resource="StudentMapper.xml"/>
    </mappers>
</configuration>

数据源? jdbc.properties文件

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/da1
username=root
password=root

编写sql文件

<?xml version="1.0" encoding="UTF-8" ?>
<!--MyBatis的DTD约束-->
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="mapper.StudentMapper">
    <select id="selectAll" resultType="student">
        select * from student
    </select>

    <select id="selectnameorage" resultType="student">
        select * from student where name = #{p1} or age =#{p2}
    </select>

    <!--多条件查询-->
    <select id="selectnameandage" resultType="student" parameterType="student">
        select * from student
        <where>
            <if test="age!=null">
                age=#{age}
            </if>
            <if test="name!=null">
              and name=#{name}
            </if>
        </where>
    </select>

    <select id="selectageandname" resultType="student" parameterType="list">
        select * from student
        <where>
            <foreach collection="list" open="id in (" close=")"  separator="," item="id">
                id=#{id}
            </foreach>
        </where>
    </select>
</mapper>

引入jar包：

?