MyBatis 入门

首先导入所有依赖包

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Mybatis依赖文件 提取码: r3sa

Mysql JDBC 提取码: 9df6

1.在 src 目录下创建 Mybatis 配置文件 , 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>
    <environments default="development">
        <environment id="development">
            <!--使用jdbc事物-->
            <transactionManager type="JDBC">
            </transactionManager>
            <!--使用连接池连接数据库-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm_database"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
     <mappers>
        <!--这里是sql 语句的配置-->
         <mapper resource="mappar/Usermappar.xml"/>
     </mappers>
</configuration>

2. 在 src 目录下创建 mappar 包，包下在创建 Usermappar.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">

 <!--namespace 自己命名 -->
<mapper namespace="Usermappar">
     <!--id 根据业务需求命名最好   parameterType是指定占位符的类型  resultType是返回值类型这里填的的是User类-->
<!--需要注意的是User类中的字段要对应数据库中的表字段 -->
    <select id="selectUserById" parameterType="Integer" resultType="bean.User">
    select * from user where id = #{id}
  </select>
</mapper>

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User 类

package bean;

public class User {
   int id;
   String name;
   String age;

   public int getId() {
       return id;
   }

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

   public void setId(int id) {
       this.id = id;
   }

   public String getName() {
       return name;
   }

   public void setName(String name) {
       this.name = name;
   }

   public String getAge() {
       return age;
   }

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

   public User(int id, String name, String age) {
       this.id = id;
       this.name = name;
       this.age = age;
   }

   public User() {
   }
}

注意：实体类字段需和 数据库字段对应

3.编写测试用例，验证之前的配置是否成功

  @Test
    public void Test1() throws IOException {
        //读取配置文件
        String resource = "sqlMapConfig.xml";
        InputStream in= Resources.getResourceAsStream(resource);

        //需要sqlSessionfactoryBulider
        SqlSessionFactoryBuilder builder= new SqlSessionFactoryBuilder();

        //创建需要sqlSessionfactory
        SqlSessionFactory sessionFactory= builder.build(in);

        //生产一个sqlSession
        SqlSession sqlSession=sessionFactory.openSession();
        //操作数据库
        //第一个参数 要操作的sql语句  第二个sql 语句的占位符
        User user = sqlSession.selectOne("Usermappar.selectUserById",0);
        System.out.println(user.toString());
    }

运行之后

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ok ，成功