MyBatis框架零基础快速入门案例详解

mysql> create database ssm;
Query OK, 1 row affected (0.01 sec)
mysql> use ssm
Database changed
mysql> CREATE TABLE `student` (
    ->  `id` int(11) NOT NULL ,
    ->  `name` varchar(255) DEFAULT NULL,
    ->  `email` varchar(255) DEFAULT NULL,
    ->  `age` int(11) DEFAULT NULL,
    ->  PRIMARY KEY (`id`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
Query OK, 0 rows affected, 3 warnings (0.03 sec)

<dependencies>
 <dependency>
<groupId>junit</groupId>
 <artifactId>junit</artifactId>
 <version>4.11</version>
 <scope>test</scope>
</dependency>
 <dependency>
 <groupId>org.mybatis</groupId>
 <artifactId>mybatis</artifactId>
 <version>3.5.1</version>
</dependency>
 <dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <version>5.1.9</version>
 </dependency>
 </dependencies>

<build>
<resources>
 <resource>
 <directory>src/main/java</directory><!--所在的目录-->
 <includes><!--包括目录下的.properties,.xml 文件都会扫描到-->
 <include>**/*.properties</include>
 <include>**/*.xml</include>
 </includes>
 <filtering>false</filtering>
 </resource>
</resources>
 <plugins>
 <plugin>
 <artifactId>maven-compiler-plugin</artifactId>
 <version>3.1</version>
 <configuration>
 <source>1.8</source>
 <target>1.8</target>
 </configuration>
 </plugin>
 </plugins>
</build>

package com.bjpowernode.domain;
/** 
 * <p>Description: 实体类 </p> 
 * <p>Company: http://www.bjpowernode.com 
 */ 
public class Student {
 //属性名和列名一样 
 private Integer id;
 private String name;
 private String email;
 private Integer age;
 // set ,get , toString
}

package com.bjpowernode.dao;
import com.bjpowernode.domain.Student;
import java.util.List;
/* 
 * <p>Description: Dao 接口 </p> 
 * <p>Company: http://www.bjpowernode.com 
 */ 
public interface StudentDao {
 /*查询所有数据*/ 
 List<Student> selectStudents();
}

<?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：必须有值，自定义的唯一字符串 
 推荐使用：dao 接口的全限定名称 
--> 
<mapper namespace="com.Example.dao.StudentDao">
 <!-- 
 <select>: 查询数据， 标签中必须是 select 语句 
 id: sql 语句的自定义名称，推荐使用 dao 接口中方法名称， 
 使用名称表示要执行的 sql 语句 
 resultType: 查询语句的返回结果数据类型，使用全限定类名 
 --> 
 <select id="selectStudents" 
resultType="com.Example.domain.Student">
 <!--要执行的 sql 语句--> 
 select id,name,email,age from student
 </select>
</mapper>

<?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>
 <!--配置 mybatis 环境--> 
 <environments default="mysql">
 <!--id:数据源的名称--> 
 <environment id="mysql">
 <!--配置事务类型：使用 JDBC 事务（使用 Connection 的提交和回
滚）--> 
 <transactionManager type="JDBC"/>
 <!--数据源 dataSource：创建数据库 Connection 对象 
 type: POOLED 使用数据库的连接池 
 --> 
 <dataSource type="POOLED">
 <!--连接数据库的四个要素--> 
 <property name="driver" value="com.mysql.jdbc.Driver"/>
 <property name="url" 
value="jdbc:mysql://localhost:3306/ssm"/>
 <property name="username" value="root"/>
 <property name="password" value="123456"/>
 </dataSource>
 </environment>
 </environments>
 <mappers>
 <!--告诉 mybatis 要执行的 sql 语句的位置--> 
 <mapper resource="com/Example/dao/StudentDao.xml"/>
 </mappers>
</configuration>

/* 
* mybatis 入门 
*/ 
@Test
public void testStart() throws IOException {
 //1.mybatis 主配置文件 
 String config = "mybatis-config.xml";
 //2.读取配置文件 
 InputStream in = Resources.getResourceAsStream(config);
 //3.创建 SqlSessionFactory 对象,目的是获取 SqlSession 
 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
 //4.获取 SqlSession,SqlSession 能执行 sql 语句 
 SqlSession session = factory.openSession();
 //5.执行 SqlSession 的 selectList() 
 List<Student> studentList = 
session.selectList("com.bjpowernode.dao.StudentDao.selectStudents");
 //6.循环输出查询结果 
 studentList.forEach( student -> System.out.println(student));
 //7.关闭 SqlSession，释放资源 
 session.close();
}

<settings>
 <setting name="logImpl" value="STDOUT_LOGGING" />
</settings>

int insertStudent(Student student);

<insert id="insertStudent">
 insert into student(id,name,email,age) 
values(#{id},#{name},#{email},#{age})
</insert>

@Test
public void testInsert() throws IOException {
 //1.mybatis 主配置文件 
 String config = "mybatis-config.xml";
 //2.读取配置文件 
 InputStream in = Resources.getResourceAsStream(config);
 //3.创建 SqlSessionFactory 对象 
 SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
 //4.获取 SqlSession 
 SqlSession session = factory.openSession();
 //5.创建保存数据的对象 
 Student student = new Student();
 student.setId(1005);
 student.setName("张丽");
 student.setEmail("zhangli@163.com");
 student.setAge(20);
 //6.执行插入 insert 
 int rows = session.insert(
"com.bjpowernode.dao.StudentDao.insertStudent",student);
 //7.提交事务 
 session.commit();
 System.out.println("增加记录的行数:"+rows);
 //8.关闭 SqlSession 
 session.close();
}