记录MyBatis连接数据库以及操纵数据库

员工信息的增删改查

为了增加记忆，写下的，如有不足，请多指教。

一、建立数据库ems,创建一个emp表。

create table emp(
				id int primary key auto_increment,
				name varchar(32),
				gender int,
				salary decimal(10,2),
				dept_id int,
				dept_name varchar(32),
				remark varchar(32),
				deleted tinyint(1) default 0
);
drop table emp;
desc emp;
select * from emp;
insert into emp (name,gender,salary,dept_id,dept_name,remark) values  ('陈赫',1,8000,3,'文艺部','演员');

二、在eclipse中，新建一个java项目emsMyBatis，右击项目名，新建一个文件夹lib,将mybatis-3.4.5.jar和mysql-cconnector-java-5.1.25-bin.jar这两个jar包放到lib文件夹中，选中这两个jar包，右击→Build Path→Add to Build Path.

三、配置MyBtis文件,右击src,新建一个MyBatis.xml文件,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>
 		<!-- 配置环境 -->
 	<environments default="env">
 		<environment id="env">
 			<!-- 事务管理 -->
 			<transactionManager type="JDBC"/>
 			<!-- 数据源 -->
 			<dataSource type="POOLED">
 				<property name="driver" value="com.mysql.jdbc.Driver"/>
 				<!-- 只需改一处：ems数据库名称 -->
 				<property name="url" value="jdbc:mysql://localhost:3306/ems?characterEncoding=UTF-8"/>
 				<property name="username" value="root"/>
				<property name="password" value="123456"/>
 			</dataSource>
 		</environment>
 	</environments>
 	<!-- 映射 -->
 	<mappers>
 		<!-- 一会写 -->
 		<mapper resource=""/>
 	</mappers>
 </configuration>

四、创建工具类Util,右击src→package,创建一个Util包，创建DbUtil类。

1、先敲上如下代码，导包后如下：

2、抛异常后，敲上如下代码：

package util;

import java.io.IOException;
import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class DbUtil {
	public static SqlSession getSqlSession() {
		SqlSession session=null;
		try {
			Reader reader=Resources.getResourceAsReader("MyBatis.xml");
			SqlSessionFactoryBuilder build=new SqlSessionFactoryBuilder();
			SqlSessionFactory factory=build.build(reader);
			session=factory.openSession(true);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return session;
		
	}
}

五、新建一个包entity，包中有emp.java实体类，实体类有私有成员，以及getter和setter方法。

package entity;

public class Emp {
	private Integer id;
	private String name;
	private Integer gender;
	private double salary;
	private Integer dept_id;
	private String dept_name;
	private String remark;
	private boolean deleted;
	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 Integer getGender() {
		return gender;
	}
	public void setGender(Integer gender) {
		this.gender = gender;
	}
	public double getSalary() {
		return salary;
	}
	public void setSalary(double salary) {
		this.salary = salary;
	}
	public Integer getDept_id() {
		return dept_id;
	}
	public void setDept_id(Integer dept_id) {
		this.dept_id = dept_id;
	}
	public String getDept_name() {
		return dept_name;
	}
	public void setDept_name(String dept_name) {
		this.dept_name = dept_name;
	}
	public String getRemark() {
		return remark;
	}
	public void setRemark(String remark) {
		this.remark = remark;
	}
	public boolean isDeleted() {
		return deleted;
	}
	public void setDeleted(boolean deleted) {
		this.deleted = deleted;
	}
	@Override
	public String toString() {
		return "Emp [id=" + id + ", name=" + name + ", gender=" + gender + ", salary=" + salary + ", dept_id=" + dept_id
				+ ", dept_name=" + dept_name + ", remark=" + remark + ", deleted=" + deleted + "]";
	}
	
}

六、创建一个mapper包，包中有EmpMapper.java接口，接口中写方法。

package mapper;

import java.util.List;

import entity.Emp;

public interface EmpMapper {
	List<Emp> findAll();
	Emp findById(Integer id);
	void add();
	void delete(Integer id);
	void update(Emp emp);
	
}

七、创建一个aql包，包中有EmpMapper.xml文件，用来写sql语句。

配置文件+sql语句：

<?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="mapper.EmpMapper">
	<select id="findAll" resultType="entity.Emp">
		select * from emp
	</select>
	<select id="findById" resultType="entity.Emp">
		select * from emp where id=#{id}
	</select>
	<insert id="add">
		insert into emp (name,gender,salary,dept_id,dept_name,remark) values (#{name},#{gender},#{salary},#{dept_id},#{dept_name},#{remark})
	</insert>
	<delete id="delete">
		delete from emp where id=#{id}
	</delete>
	<update id="update">
		update emp set name=#{name},gender=#{gender},salary=#{salary},dept_id=#{dept_id}  dept_name=#{dept_name},remark=#{remark}
	</update>
</mapper>

写完这个后，还记得MyBatis.xml配置文件中的映射mapper吗？

八、创建test包，新建SelectTest测试类。

package test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import entity.Emp;
import mapper.EmpMapper;
import util.DbUtil;

public class SelectTest {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		SqlSession session=DbUtil.getSqlSession();
		EmpMapper empMapper=session.getMapper(EmpMapper.class);
		List<Emp> emp=empMapper.findAll();
		for(Emp e:emp) {
			System.out.println(e);
		}
	}

}