Mybatis学习笔记之---环境搭建

Mybatis环境搭建

（一）环境搭建

（1）第一步：创建maven工程并导入jar包

<dependencies>
  <dependency>
    <groupId>junitgroupId>
    <artifactId>junitartifactId>
    <version>4.11version>
  dependency>
  <dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>5.1.41version>
  dependency>
  <dependency>
    <groupId>org.mybatisgroupId>
    <artifactId>mybatisartifactId>
    <version>3.4.6version>
  dependency>

dependencies>

 

（2）第二步：创建实体类和dao的接口

（3）第三步：创建Mybatis的主配置文件SqlMapperConfig.xml

xml version="1.0" encoding="UTF-8" ?>

DOCTYPEconfiguration

        PUBLIC"-//mybatis.org//DTD Config 3.0//EN"

        "http://mybatis.org/dtd/mybatis-3-config.dtd">



<configuration>

    

    <environments default="mysql">

        

        <environment id="mysql">

            

            <transactionManager type="JDBC">transactionManager>

            

            <dataSource type="POOLED">

                

                <property name="driver" value="com.mysql.jdbc.Driver">property>

                <property name="url" value="jdbc:mysql://localhost:3306/zml?useUnicode=true&characterEncoding=utf-8">property>

                <property name="username" value="root">property>

                <property name="password" value="root">property>

            dataSource>

            

        environment>

    environments>

    

<mappers>

    <mapper resource="dao/UserDao.xml">mapper>

mappers>

configuration>

 

（4）第四步：创建映射配置文件UserDao.xml

xml version="1.0" encoding="UTF-8" ?>

DOCTYPEmapper

        PUBLIC"-//mybatis.org//DTD Mapper 3.0//EN"

        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="dao.UserDao">

    <select id="findAll" resultType="entity.Users">

        select * from users;

    select>

mapper>
 

 

（二）环境搭建的注意事项

（1）创建UserDao.xml和UserDao.java时名称是为了和我们之前的知识保持-致。在Mybatis中它把持久层的操作接口名称和映射文件也叫做:Mapper所以:UserDao和UserMapper是一样的

（2）在idea中创建目录的时候，它和包是不一样的包在创建时:com.itheina.dao它是三级结构目录在创建时:com.itheima.dao是一级目录

（3）mybatis的映射配置文件位置必须和dao接口的包结构相同

（4）映射配置文件的mapper标签namespace属性的取值必须是dao接口的全限定类名

（5）映射配置文件的操作配置(select)，id属性的取值必须是dao接口的方法名，当我们遵从了第三，四，五点之后，我们在开发中就无须再写dao的实现类

（三）第一个Mybatis实例

 

（1）第一步：

pom.xml

<dependencies>
  <dependency>
    <groupId>junitgroupId>
    <artifactId>junitartifactId>
    <version>4.11version>
  dependency>
  <dependency>
    <groupId>mysqlgroupId>
    <artifactId>mysql-connector-javaartifactId>
    <version>5.1.41version>
  dependency>
  <dependency>
    <groupId>org.mybatisgroupId>
    <artifactId>mybatisartifactId>
    <version>3.4.6version>
  dependency>

dependencies>

 

（2）第二步：

Users.java

package entity;



public class Users {

    private int id;

    private String username;

    private String password;



    public int getId() {

        return id;

    }



    public void setId(int id) {

        this.id = id;

    }



    public String getUsername() {

        return username;

    }



    public void setUsername(String username) {

        this.username = username;

    }



    public String getPassword() {

        return password;

    }



    public void setPassword(String password) {

        this.password = password;

    }



    @Override

    public String toString() {

        return "Users{" +

                "id=" + id +

                ", username='" + username + '\'' +

                ", password='" + password + '\'' +

                '}';

    }

}

 

UserDao.java

package dao;



import entity.Users;



import java.util.List;



public interface UserDao {

     List findAll();

}

 

（3）第三步：

SqlMapperConfig.xml

xml version="1.0" encoding="UTF-8" ?>

DOCTYPEconfiguration

        PUBLIC"-//mybatis.org//DTD Config 3.0//EN"

        "http://mybatis.org/dtd/mybatis-3-config.dtd">



<configuration>

    

    <environments default="mysql">

        

        <environment id="mysql">

            

            <transactionManager type="JDBC">transactionManager>

            

            <dataSource type="POOLED">

                

                <property name="driver" value="com.mysql.jdbc.Driver">property>

                <property name="url" value="jdbc:mysql://localhost:3306/zml?useUnicode=true&characterEncoding=utf-8">property>

                <property name="username" value="root">property>

                <property name="password" value="root">property>

            dataSource>

            

        environment>

    environments>

    

<mappers>

    <mapper resource="dao/UserDao.xml">mapper>

mappers>

configuration>

 

（4）第四步

UserDao.xml

xml version="1.0" encoding="UTF-8" ?>

DOCTYPEmapper

        PUBLIC"-//mybatis.org//DTD Mapper 3.0//EN"

        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="dao.UserDao">

    <select id="findAll" resultType="entity.Users">

        select * from users;

    select>

mapper>

 

（5）第五步：创建测试类

UserTest.java

package test;



import dao.UserDao;

import entity.Users;

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 java.io.IOException;

import java.io.InputStream;

import java.util.List;



public class UserTest {

    @Test

    public void findall() throws IOException {

        //1.读取配置文件

        InputStream in= Resources.getResourceAsStream("SqlMapperConfig.xml");

        //2.创建SqlSessionFactory工厂

        SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();

        SqlSessionFactory factory=builder.build(in);

        //3.使用工厂生产SqlSession对象

        SqlSession session=factory.openSession();

        //4.使用SqlSession创建dao接口的代理对象

        UserDao UserDaoImpl=session.getMapper(UserDao.class);

        //5.使用代理对象执行方法

        List users=UserDaoImpl.findAll();

        for(Users u:users){

            System.out.println(u);

        }

        //6.释放资源

        session.close();

        in.close();

    }

}