MyBatis框架基础在eclipse中使用的最全教程_eclipse mbatis

作者：Cpp五条 | 2024-02-29 06:35:42

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eclipse mbatis

它封装了JDBC操作的繁琐操作，对JDBC进行了封装，它相比传统的JDBC访问数据库，性能更加优异，具有高度的灵活性、可优化性和易于维护等特点，我们只需要关注 sql语句本身，而不需要花费精力去处理加载驱动、创建连接、创建 statement 等繁杂的过程。

配置MyBatis

下载MyBatis包，下载地址https://github.com/mybatis/mybatis-3/releases
我下载的版本是3.5.5，下载后解压，解压之后的目录是这样的
找到lib目录，把lib目录里的jar包全部拷贝到java项目中
导入数据库驱动包，下载地址https://dev.mysql.com/downloads/connector/j/
这时候我们的工程目录下是这样的
找到我们刚才下载的Mybatis包，并解压
解压之后，进入这个目录mybatis-3.5.5/mybatis-3.5.5/org/apache/ibatis/builder/xml，找到如下两个文件
在Eclipse中配置mybatis-3-config.dtd和mybatis-3-mapper.dtd，目的是让后面的xml文件的时候有标签提示

在src目录下创建jdbc.properties


jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/你的数据库名?characterEncoding=UTF-8
jdbc.username=你的数据库登录账号
jdbc.password=你的数据库登录密码

在src目录下创建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">
 
<!-- 配置全局配置文件 -->
<configuration>
 
<!-- 引入jdbc.properties -->
<properties resource="jdbc.properties" />
 
	<environments default="develop">
 
		<!-- 配置开发环境和正式环境 -->
		<environment id="develop">
 
			<!-- 必须先配置事务管理方式 type：JDBC 把事务交给JDBC来管理 type：MANAGED 自己管理事务 -->
			<transactionManager type="JDBC"></transactionManager>
 
			<!-- 其次配置数据库连接池（数据源） POOLED:使用连接池（数据源），推荐 UNPOOLED:不使用 JNDI:已经过时 -->
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}" />
				<property name="url" value="${jdbc.url}"/>
				<property name="username" value="${jdbc.username}" />
				<property name="password" value="${jdbc.password}" />
			</dataSource>
 
		</environment>
 
		<!-- <environment id=""> </environment> -->
 
	</environments>
	<mappers>
		<mapper resource="com/tedu/pojo/EmpMapper.xml" />
	</mappers>
</configuration>

在src目录下创建log4j.properties，目的是让控制台看到日志


# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

然后在src目录下创建如下几个类
稍等我们来解释各个类的作用及含义，我在本地创建了一张表，如下：

People是一个简单的bean类


package com.tedu.pojo;
 
public class People {
	//声明私有属性
	private Integer id;		
	private String name;	
	private String gender;  
	private String birthday;	
	private String job;
	private String salary;
	private String bonus;
	private String home;
	private String pass;
	
	public String getPass() {
		return pass;
	}
	public void setPass(String pass) {
		this.pass = pass;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	public String getBirthday() {
		return birthday;
	}
	public void setBirthday(String birthday) {
		this.birthday = birthday;
	}
	public String getJob() {
		return job;
	}
	public void setJob(String job) {
		this.job = job;
	}
	public String getSalary() {
		return salary;
	}
	public void setSalary(String salary) {
		this.salary = salary;
	}
	public String getBonus() {
		return bonus;
	}
	public void setBonus(String bonus) {
		this.bonus = bonus;
	}
	public String getHome() {
		return home;
	}
	public void setHome(String home) {
		this.home = home;
	}
	//提供toString方法
	@Override
	public String toString() {
		return "Emp [id=" + id + ", name=" + name + ", job=" + job + ", salary=" + salary + "]";
	}
}

PeopleMapper.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现在配置的是包路径，以后这里配置成接口的全路径 -->
<mapper namespace="com.tedu.dao.PeopleMapper">
 
	<!-- 优化内容1:提取公共查询列的语句,需要的地方通过<include refid="columns"></include>来替换 -->
	<sql id="columns">id,name,salary</sql>
 
 
	<!-- 查询所有员工信息，返回list<People>集合， 查询结果返回java对象，再把这些对象封装到一个集合中，resultType指定结果类型。表示将查询结果封装到People对象中 -->
	<select id="selectAll" resultType="com.tedu.pojo.People">
		select
		<include refid="columns"></include>
		from people
	</select>
 
	<!-- 新增数据 -->
	<update id="insert">insert into people
		values(null,'马化腾','男','1978-02-03','开淘宝的','500','700','河北',123)
	</update>
 
	<!-- 新增数据 -->
	<update id="insertdata">insert into people
		values(null,#{name},#{gender},#{birthday},#{job},#{salary},#{bonus},#{home},#{pass})
	</update>
 
	<!-- 修改数据 -->
	<update id="update">update people set salary='5000' where name='马云'
	</update>
 
	<!-- 修改数据 -->
	<update id="updatedata">update people set salary=#{salary} where name=#{name}
	</update>
 
	<!-- 删除数据 -->
	<update id="delete">delete from people where name='马化腾'</update>
 
	<!-- 删除数据 -->
	<update id="deletedata">delete from people where name=#{name}</update>
 
	<!-- 查询单个数据,必须指定类型 -->
	<select id="selectOne" resultType="com.tedu.pojo.">
		select
		<include refid="columns"></include>
		from people where
		id=#{id}
	</select>
 
	<!-- 查询特定条件区间的数据 -->
	<select id="selectOnly" resultType="com.tedu.pojo.People">
		select
		<include refid="columns"></include>
		from people where
		salary between #{smallSalary} and #{bigSalary}
	</select>
 
	<!-- 查询特定列的数据 -->
	<select id="selectSomeColumn" resultType="com.tedu.pojo.People">select ${columns} from
		people
	</select>
 
	<!-- 模糊查询 -->
	<select id="selectLikes" resultType="com.tedu.pojo.People">select ${columns} from
		people where name like '%${p_name}%'</select>
 
	<!-- 根据if标签进行条件查询 动态sql -->
	<select id="select_if" resultType="com.tedu.pojo.People">
		select * from people
		<if test="p_name!=null">where name like '%${p_name}%'</if>
	</select>
 
	<!-- where和if标签结合使用 动态sql -->
	<select id="select_where_if" resultType="com.tedu.pojo.People">
		select * from people
		<where>
			<if test="smallSalary!=null">salary>#{smallSalary}</if>
			<if test="bigSalary!=null">and
				salary<![CDATA[<]]>#{bigSalary}
			</if>
		</where>
	</select>
 
	<!-- set标签 动态sql -->
	<update id="update_set">
		update people
		<set>
			<if test="home!=null">home=#{home} where name=#{name}</if>
		</set>
	</update>
 
	<!-- foreach遍历 item="ids"表示接收参数的变量 -->
	<update id="delete_array">
		delete from people where id in
		<foreach collection="array" open="(" separator="," close=")"
			item="ids">#{ids}</foreach>
	</update>
</mapper>

PeopleMapper.java


package com.tedu.dao;
 
import java.util.List;
 
import com.tedu.pojo.People;
 
/**
 * 1，EmpMapper.xml对应的接口
 * 2，接口中的方法名要和EmpMapper.xml中查询语句的id保持相同
 * @author sujianda
 *
 */
public interface PeopleMapper {
	/**
	 * 查询所有信息
	 */
	public List<People> selectAll();
	
	/**
	 * 根据id查询某一个员工
	 */
	 public People selectOne(int id);
}

MyBatisInterfaceTest测试类


package com.tedu.mybatis;
 
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
 
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.tedu.dao.PeopleMapper;
import com.tedu.pojo.People;
 
public class MyBatisInterfaceTest {
	public static void main(String[] args) throws IOException {
		//读取核心配置文件sqlMapConfig.xml,getResourceAsStream获取资源作为流
		InputStream in=Resources.getResourceAsStream("sqlMapConfig.xml");
		
		//通过配置信息获取SqlSessionFactory对象
		SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
	
		//通过工厂获取SqlSession对象，session线程不安全
		SqlSession session=factory.openSession();
		
		//getMapper(EmpMapper.class)返回的是一个EmpMapper实例，得到empMapper实例之后，再调用selectAll
		PeopleMapper empMapper=session.getMapper(PeopleMapper.class);
		List<People>list=empMapper.selectAll();
		
		//输出信息
		for (People emp : list) {
			System.out.println(emp.toString());
		}
	}
	
	@Test
	public void selectOne() throws IOException {
		InputStream in=Resources.getResourceAsStream("sqlMapConfig.xml");
		SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(in);
		SqlSession session=factory.openSession();
		PeopleMapper empMapper=session.getMapper(PeopleMapper.class);
		People emp=empMapper.selectOne(1);
		System.out.println(emp.toString());
	}
}

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