mybatis入门-查询所有

实现mybatis查询一张表中的所有数据
1.新创建一个maven
2.在pom文件中导入mybatis依赖，mysql依赖，junit测试依赖，在setting中设置本地仓库
<dependencies>
<dependency>
<groupId>mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.26</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
</dependencies>
3.在网上下载mybatis核心配置文件，映射配置文件
核心配置文件：配置数据库，映射文件路径
<?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>
<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/book"></property>
<property name="username" value="root"></property>
<property name="password" value="root"></property>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="UserMapper.xml"></mapper>
</mappers>
</configuration>
映射文件：namespace，id都是作为标识的作用
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="userMapper">
<select id="findAll" resultType="com.shuai.dao.book">
select * from p;
</select>

</mapper>
4.实体类创建 book这里就不写了属性与数据库的字段名一一对应
5..测试，selectList下面定义的就是mapper文件namespace，id标识的内容
import com.shuai.dao.book;
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.InputStream;
import java.util.List;

public class test {

@Test
public void findAllTest(){
    InputStream inputStream=this.getClass().getClassLoader().getResourceAsStream("Config.xml");
    SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
    SqlSession sqlSession=sqlSessionFactory.openSession();
    List<book> bookList= sqlSession.selectList("userMapper.findAll");
    for (book book : bookList) {
        System.out.println(book);
    }
}

}
值得一提的是mysql1.8版本以上，mysql导入依赖的时候版本要一致，配置文件驱动要改一下，url后面也要添加一个参数：

<?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>
    <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://localhost:3306/mypeople?serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="3041"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="peopleM.xml"/>
    </mappers>
</configuration>