Mybatis入門

配置jar包
接下來以查詢所有商品信息功能爲例，學習Mybatis框架實現步驟
1.準備domin實體類的材料，user和product

package com.itheima.domain;
import java.util.Date;
public class User {
    private int id;
    private String username;
    private String gender;
    private Date birthday;
    private String address;
    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 getGender() {
        return gender;
    }
    public void setGender(String gender) {
        this.gender = gender;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", gender='" + gender + '\'' +
                ", birthday=" + birthday +
                ", address='" + address + '\'' +
                '}';
    }
}

package com.itheima.domain;
public class Product {
    private int id;
    private String name;
    private double price;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public double getPrice() {
        return price;
    }
    public void setPrice(double price) {
        this.price = price;
    }
    @Override
    public String toString() {
        return "Product{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}

Mybatis實現步驟：
1.創建構造類對象
1.通過構建類對象調用build(通過類加載器讀取配置文件的流對象)方法創建工廠對象
2.由工廠對象創建sqlSession類對象，sqlSession類對象調用selectList（sql配置）方法

package com.itheima;
import com.itheima.domain.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.util.List;
/**
 * Hello world!
 */
public class App {
    public static void main(String[] args) {
        //創建sqlSessionFactoryBuilder
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //創建sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = builder.build(App.class.getClassLoader().getResourceAsStream("SqlMapConfig.xml"));
       //創建sqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //調用方法
        List<User> users = sqlSession.selectList("user" + "." + "findAll");
        System.out.println(users);
    }
}

配置文件內容如下
SqlMapConfig.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>
    <typeAliases >
        <package name="com.itheima.domain"></package>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/heima349_mybatis?characterEncoding=utf8" />
                <property name="username" value="root" />
                <property name="password" value="123" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"></mapper>
    </mappers>
</configuration>    

UserMapper.xml

<?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="user">
    <select id="findAll" resultType="user">
      select * from user
    </select>
</mapper>