Mybatis总结：mybatis的搭建

Posted 2020-10-15

1. mybatis：它抽象了大量的jdbc代码，并提供了一个简单易用的API和数据库交互。
2. mybatis的优势：它消除了大量jdbc冗余的代码、它可以接受SQL语句。
3. mybatis的jar包：核心包只有一个mybatis-3.x.0.jar
4. mybatis框架需要的两种文件：
   1. 配置文件：

功能：主要放与数据库连接相关的信息

命名规则：mybatis-config.xml

位置：src下

1. 映射文件：

功能：主要放SQL语句

命名规则：XxxMapper.xml（Xxx一般是JavaBean的类名）

位置：src下

1. Mybatis的映射接口

   它与映射文件XxxMapper.xml中的SQL语句进行映射。

功能：它是调用SQL语句执行的接口。

命名规则：接口中的方法名字要与xml文件定义的SQL映射语句的名称相同。

同时我们不需要去实现该接口,因为mybatis中提供了相应的方式在运行期间动态生成该接口的实现类对象(动态代理技术)。

1. Mybatis中的SqlSession接口和SqlSessionFactory接口

SqlSession接口：它实现的对象是mybatis中最重要的一个对象，我们可以使用该对象动态的获得XxxMapper.java接口的实现对象，然后就可以调用到XxxMapper.java接口中方法映射的sql语句。

SqlSessionFactroy接口：它是专门负责生产sqlSession对象的。

 

Mybatis搭建实例：

第一步：导包：

     mybatis-3.3.0.jar    ojdbc14.jar

      junit-4.7.jar        log4j-1.2.17.jar

第二步：在src下创建配置文件mybatis-config.xml和映射文件XxxMapper.xml。

Mybaties-config.xml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>
    <typeAliases>
        <typeAlias type="com.zzuli.bean.Student" alias="Student" />
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="oracle.jdbc.driver.OracleDriver" /> 
                <property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:XE" /> 
                <property name="username" value="sahe" />
                <property name="password" value="sahe" />
            </dataSource>
        </environment>
    </environments>                
<mappers>
    <mapper resource="com/zzuli/Mapper/StudentMapper.xml"/>
</mappers>                
</configuration>

 XxxMapper.xml映射文件：

<?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.zzuli.Mapper.StudentMapper">
<resultMap type="Student" id="StudentResult">
    <id property="stuId" column="stud_id" />
    <result property="name" column="name" />
    <result property="email" column="email" />
    <result property="dob" column="dob" />
</resultMap>
<select id="findAllStudents" resultMap="StudentResult">
    SELECT * FROM STUDENTS
</select>
<select id="findStudentById" parameterType="int" resultType="Student">
    SELECT STUD_ID AS STUDID,NAME,EMAIL,DOB
    FROM STUDENTS
    WHERE
    STUD_ID=#{id}
</select>
<insert id="insertStudent" parameterType="Student"> 
    INSERT INTO
    STUDENTS(STUD_ID,NAME,EMAIL,DOB) 
    VALUES(#{stuId},#{name},#{email},#{dob}) 
</insert>
</mapper>

第三步：创建Student对象

package com.zzuli.bean;
import java.util.Date;
public class Student {
      private int stuId;
      private String name;
      private String email;
      private Date dob;
      public Student(int stuId, String name, String email, Date dob) {
          super();
          this.stuId = stuId;
          this.name = name;
          this.email = email;
          this.dob = dob;
      }
      public Student(){}
    public int getStuId() {
        return stuId;
    }
    public void setStuId(int stuId) {
        this.stuId = stuId;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public Date getDob() {
        return dob;
    }
    public void setDob(Date dob) {
        this.dob = dob;
    }
    @Override
    public String toString() {
        return "Student [stuId=" + stuId + ", name=" + name + ", email=" + email + ", dob=" + dob + "]";
    }
      
}
第四步：创建XxxMappeer.java接口
       package com.zzuli.Mapper
import java.util.List;
import com.zzuli.bean.Student;

public interface StudentMapper {
         List<Student> findAllStudents(); 
         Student findStudentById(Integer id); 
         void insertStudent(Student student);
}

第五步：创建test测试

  import com.zzuli.Mapper.StudentMapper;
import com.zzuli.bean.Student;

public class StudentMapperTest {
     @Test
     public void  testStudnet(){
        try {
            InputStream inputs = 
                    Resources.getResourceAsStream("mybaties-config.xml");
            SqlSessionFactory sqlSessionFactory = 
                    new SqlSessionFactoryBuilder().build(inputs);
            SqlSession session = sqlSessionFactory.openSession();
            StudentMapper mapper = session.getMapper(StudentMapper.class);
            Student student = new Student(1,"tom","[email protected]",new Date());
            mapper.insertStudent(student);
            session.commit();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
     }
}

对mybatis的一些基本封装

 public class MyBatisSqlSessionFactory {
     private static SqlSessionFactory sqlSessionFactory;
     public static SqlSessionFactory getSqlSessionFactory(){
         InputStream inputStream = null;
         try {
            inputStream = Resources.getResourceAsStream("mybaties-config.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
         } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            throw new RuntimeException(e.getCause());
         }
         return sqlSessionFactory;
     }
     public static SqlSession openSession() { 
            return openSession(false); 
     }
     public static SqlSession openSession(boolean autoCommit) { 
            return getSqlSessionFactory().openSession(autoCommit); 
     }
}