MyBatis-HelloWorld_delete id="deleteempinfo" parametertype="com.examp-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_43775034/article/details/104564880

一、下载MyBatis

MyBatis将所有的项目托管到了github上，因此我们在github上搜索下载MyBatis下载
下载文件

二、创建对应的数据库表和JavaBean类

创建数据表：

CREATE TABLE tab1_employee（
	id 	INT(11) PRIMARY KEY AUTO_INCREMENT,
	last_name VARCHAR(255),
	gender CHAR(1),
	email VARCHAR(255)
）

创建对应的JavaBean类

package com.atorg.mybatis.bean;

import org.apache.ibatis.type.Alias;

@Alias("emp")
public class Employee {
	private Integer id;
	private String lastName; //注意此处与数据中的字段并不对应???
	private String email;
	private String gender;
	public Employee() {
		super();
	}
	public Employee(Integer id, String lastName, String email, String gender) {
		super();
		this.id = id;
		this.lastName = lastName;
		this.email = email;
		this.gender = gender;
	}
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	@Override
	public String toString() {
		return "Employee [id=" + id + ", lastName=" + lastName + ", email=" + email + ", gender=" + gender + "]";
	}
}

三、根据官方文档（下文按照官方文档的步骤实现一个"HelloWorld"）

官方文档在一开始下载的依赖和文档中有，如果没有可以到以下地址下载
官方文档下载链接提取码：hpaq 内附有Mybatis文档与依赖包

1.导入相关依赖

引入MyBatis的jar包,以及操作数据库驱动的jar包，为显示方便引入log4j日志包，引入log4j时必须要在类路径下放一个log4j.xml文件（在以上的链接中有这些jar包）

2.创建一个xml文件（全局配置文件）[ Building SqlSessionFactory from XML]

创建一个xml文件（mybatis-config.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">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">//数据源连向我们自己的数据库
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis_plus"/>
        <property name="username" value="root"/>
        <property name="password" value="1234567890"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
 <!--sql映射文件一定要注册在全局配置文件中(就是此文件中)-->
    <mapper resource="EmployeeMapper.xml"/>
  </mappers>
</configuration>

3.根据xml文件创建一个SqlSessionFactory对象

public class MyBatisTest {
    //此处的resource内容就是上面创建的xml文件的路径名
	public void test() throws IOException{
	   String resource = "mybatis-config.xml";
       InputStream inputStream = Resources.getResourceAsStream(resource); 
       SqlSessionFactory sqlSessionFactory =new SqlSessionFactoryBuilder().build(inputStream);
	}
}

4.获取sqlSession实例，能直接执行已经映射的sql语句

       SqlSession openSession = sqlSessionFactory.openSession();

5.用获取的sqlSession调用增删改查的方法 [Acquiring a SqlSession from SqlSessionFactory]

//第一个参数值为sql映射文件中**namespace+具体增删改查对应的唯一id的值**
//第二个参数是执行sql时传入的参数
openSession.selectOne(arg0,arg1);//查询
openSession.delete(arg0,arg1);//删除
openSession.update(arg0,arg1);//更新
openSession.insert(arg0,arg1);//插入
//第一个参数 *statement是一个唯一标识:Unique identifier matching the statement to use.
//第二个参数*parameter是执行sql语句的一个参数:A parameter object to pass to the statement.

6.创建sql映射的xml文件 [Exploring Mapped SQL Statements]

<?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="org.mybatis.example.BlogMapper">   
      <select id="selectEmp" resultType="com.atorg.mybatis.bean.Employee">
           select id,last_name lastName,gender,email from tab1_employee where id = #{id}       <!--给数据库变量起别名解决字段不匹配问题-->
       </select>
</mapper>

【namespace】:名称空间用来映射sql语句的类的全类名
【id】:为select的唯一标识，内容为具体方法的方法名
【resultType】:返回值类型，查询完成之后要返回的类型
【#{id}】:从传递过来的参数中取出id值

7.完整文件

mybatis-config.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">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED"><!--数据库连接池-->
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis_plus"/>
        <property name="username" value="root"/>
        <property name="password" value="1234567890"/>
      </dataSource>
    </environment>
  </environments>

  <mappers>
    <mapper resource="EmployeeMapper.xml"/>
  </mappers>
</configuration>

EmployeeMapper.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">
<mapper namespace="com.atorg.mybatis.EmployeeMapper">
	<!-- 查询数据  -->
   <select id="selectEmp" resultType="com.atorg.mybatis.bean.Employee">
        select * from tab1_emp where id = #{id}
   </select>
   <!-- 插入数据  -->
   <insert id="addEmp" parameterType="com.atorg.mybatis.bean.Employee" useGeneratedKeys="true" keyProperty="id">
		insert into tab1_emp(last_name,email,gender) values(#{lastName},#{email},#{gender})
	</insert>
	
	<!-- 更新数据  -->
	<update id="updateEmp" parameterType="com.atorg.mybatis.bean.Employee">
		update tab1_emp 
		set last_name=#{lastName},email=#{email},gender=#{gender}
		where id =#{id}
	</update>
	<!-- 删除数据  -->
	<!-- public void deleteEmpByTd(Integer id);  -->
	<delete id="deleteEmp" parameterType="com.atorg.mybatis.bean.Employee">
		delete from tab1_emp where id=#{id}
	</delete>
</mapper>

log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
 
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
 
 <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
   <param name="Encoding" value="UTF-8" />
   <layout class="org.apache.log4j.PatternLayout">
    <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m  (%F:%L) \n" />
   </layout>
 </appender>
 <logger name="java.sql">
   <level value="debug" />
 </logger>
 <logger name="org.apache.ibatis">
   <level value="info" />
 </logger>
 <root>
   <level value="debug" />
   <appender-ref ref="STDOUT" />
 </root>
</log4j:configuration>

四、进行测试

测试类

package com.atorg.mybatis.test;

import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;
import com.atorg.mybatis.bean.Employee;

public class MyBatisTest {

	@Test
	public void test() throws IOException {
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		// 获取sqlsession实例，能直接执行已经映射的sql语句
		SqlSession session = sqlSessionFactory.openSession();
		try {
//			Object employee = session.selectOne("com.atorg.mybatis.EmployeeMapper.selectEmp", 5);
//			System.out.println(employee);
			
//			session.insert("com.atorg.mybatis.EmployeeMapper.addEmp", new Employee("Jack","Jack@qq.com","1"));
//			session.commit();
//			System.out.println("插入成功");
			
//			session.delete("com.atorg.mybatis.EmployeeMapper.deleteEmp", 5);
//			session.commit();
//			System.out.println("删除成功");
			
			session.update("com.atorg.mybatis.EmployeeMapper.updateEmp", new Employee(5,"lucy","lucy@qq.com","0"));
			session.commit();
			System.out.println("更新成功");
		} finally {
			session.close();
		}
	}
}

查看数据库原始状态

数据库原始数据
测试添加方法（ “Bob”,“Bob@163.com”,“0” ）

数据库添加的数据
测试查询方法（查询5号）
在这里插入图片描述
数据库信息
测试删除方法(删除5号)
控制台信息
数据库信息减少
测试跟新方法（更新1号【“Jack”,“Jack@git.com”,“1”】）

五、升级[Using an interface (e.g. BlogMapper.class) that properly describes the parameter and return value for a given statement]

使用上述代码可以实现对数据库的增删改查操作，但是我们在测试类中传入参数很麻烦，因此我们引进了接口式编程，我们可以创建一个接口，接口来描述我们给定的sql语句的参数和返回值

1.创建一个接口

package com.atorg.mybatis.dao;
import com.atorg.mybatis.bean.Employee;
public interface EmployeeMapper {
	
	public Employee getEmpByTd(Integer id);
	
	public void addEmp(Employee employee);
	
	public void updateEmp(Employee employee);
	
	public void deleteEmpByTd(Integer id);
}

mybatis提供一个特殊的功能，接口可以与配置文件进行动态绑定
【namespce】:指定为接口的全类名
【id】:增删改查标签的id指定为接口对应的方法名

2.此时的测试类（以查询为例其他类似）

	@Test
	public void test02() throws IOException{
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		// 获取sqlsession实例，能直接执行已经映射的sql语句
		SqlSession openSession = sqlSessionFactory.openSession();
		try{
		EmployeeMapper eMapper=openSession.getMapper(EmployeeMapper.class);
		Employee employee=eMapper.getEmpByTd(1);//直接调用接口的查询员工方法
		System.out.println(employee);
		}finally{
			openSession.close();
		}
	}