第一个Mybatis程序的书写流程

第一个Mybatis

步骤：

1、工具类需要配置文件，所以需要到resources文件夹中写一个配置文件

<?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.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/nscrl/dao/StudentMapper.xml"/>
    </mappers>
</configuration>

2、写工具类

创建一个utils包，在包下创建一个utils工具类：

public class StudentUtils {
    
    

    private static SqlSessionFactory sqlSessionFactory;

    // 获取SQLSessionFactory对象
    static {
    
    
        try {
    
    
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
    }

    // 获取SQLSession的实例对象
    public static SqlSession getSqlSession(){
    
    
        return sqlSessionFactory.openSession();
    }
}

3、写实体类

创建一个实体类

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

    public Student() {
    
    
    }

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

    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 int getAge() {
    
    
        return age;
    }

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

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

4、写接口

写一个dao接口

public interface StudentDao {
    
    
    List<Student> getStudentList();
}

5、写接口的实现，XxxMapper.xml文件

<?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="com.nscrl.dao.StudentDao">
    <select id="getStudentList" resultType="com.nscrl.pojo.Student">
      select * from mybatis.student
  </select>
</mapper>

6、写test测试类

public class StudentDaoTest {
    
    
    @Test
    public void test(){
    
    
        // 获取sqlsession对象
        SqlSession sqlSession = StudentUtils.getSqlSession();

        StudentDao mapper = sqlSession.getMapper(StudentDao.class);

        List<Student> studentList = mapper.getStudentList();

        for (Student student : studentList) {
    
    
            System.out.println(student);
        }

        // 关闭SQLSession
        sqlSession.close();

    }
}

7、在maven文件中，写入导出失败处理的文件

为了处理可能出现的资源导出失败的问题，需要在pom.xml文件中加入下面配置：

<!-- 在build中配置resources, 来防止资源导出失败的问题 -->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>