MyBatis练习——使用MyBatis查询所有职员信息

一时失言乱红尘 2023-01-13 04:21 75阅读 0赞

### 实现要求： ###

使用MyBatis查询所有职员信息

![20210419214405794.png][]

create table employee(	
    	id int not null auto_increment,
    	name varchar(255) not null,
    	gender varchar(2) null,
    	position varchar(255) null, -- 岗位
    	nationality varchar(255) null, -- 国籍
    	primary key(id)
    );

### 实现思路： ###

在上一个项目基础上，在src/main/resources下面创建MyBatis的配置文件mybatis-config.xml。

![20210419205613689.png][]

**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>
    	
    	<typeAliases>
    		<package name="jack.mybatis.simple.model" />
    	</typeAliases>
    	<environments default="development">
    		
    		<environment id="development">
    			<transactionManager type="JDBC">
    				
    				<property name="" value="" />
    			</transactionManager>
    			
    			<dataSource type="UNPOOLED">
    				
    				<property name="driver" value="com.mysql.jdbc.Driver" />
    				<property name="url" value="jdbc:mysql://localhost:3306/db_mybatis" />
    				<property name="username" value="root" />
    				<property name="password" value="root" />
    			</dataSource>
    		</environment>
    	</environments>
    	
    	<mappers>
    		<mapper resource="jack/mybatis/simple/mapper/EmployeeMapper.xml" />
    	</mappers>
    </configuration>

在src/main/java下创建一个基础的包jack.mybatis.simple，在这个包下面再创建model包。根据数据库表employee，在model包下创建实体类Employee。

![20210419210227678.png][]

**Employee.java**

package jack.mybatis.simple.model;
    
    public class Employee {
    	private int id;
    	private String name;
    	private String gender;
    	private String position;
    	private String nationality;
    	public int getId() {
    		return id;
    	}
    	public void setId(int 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 getPosition() {
    		return position;
    	}
    	public void setPosition(String position) {
    		this.position = position;
    	}
    	public String getNationality() {
    		return nationality;
    	}
    	public void setNationality(String nationality) {
    		this.nationality = nationality;
    	}
    	public Employee(int id, String name, String gender, String position, String nationality) {
    		super();
    		this.id = id;
    		this.name = name;
    		this.gender = gender;
    		this.position = position;
    		this.nationality = nationality;
    	}
    	public Employee() {
    		super();
    	}
    	@Override
    	public String toString() {
    		return "Employee [id=" + id + ", name=" + name + ", gender=" + gender + ", position=" + position
    				+ ", nationality=" + nationality + "]";
    	}
    	
    }

在src/main/resources下面创建jack/mybatis/simple/mapper目录，再在该目录下面创建与实体类Employee对应的映射文件EmployeeMapper.xml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="jack.mybatis.simple.model">
    	<select id="selectAll" resultMap="Employee">
    		select * from employee
    	</select>
    </mapper>

配置Log4j。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg5MzkwMg_size_16_color_FFFFFF_t_70][]

# 全局配置
    log4j.rootLogger=ERROR, stdout
    # MyBatis日志配直
    log4j.logger.mapper=TRACE
    # 控制台输出配置
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

编写测试代码查询所有职员的信息。

package test;
    
    import java.io.IOException;
    import java.io.Reader;
    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.BeforeClass;
    import org.junit.Test;
    
    import jack.mybatis.simple.model.Employee;
    
    public class EmployeeTest {
    	private static SqlSessionFactory sqlSessionFactory;
    
    	/* 完成mybatis配置的加载，创建得到SqlSessionFactory */
    	@BeforeClass
    	public static void init() {
    		try {
    			Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
    			sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
    			reader.close();
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    
    	/* 获取SqlSession对象，用于调用方法得到数据 */
    	@Test
    	public void testSelectAll() {
    		SqlSession sqlSession = sqlSessionFactory.openSession();
    		try {
    			List<Employee> selectList = sqlSession.selectList("selectAll");
    			for (Employee employee : selectList) {
    				System.out.println(employee.toString());
    			}
    		} finally {
    			// 不要忘记关闭sqlSession
    			sqlSession.close();
    		}
    	}
    }

[20210419214405794.png]: /images/20221022/ad0396fdf1344679a298218e5e9e6cf1.png
[20210419205613689.png]: /images/20221022/57f7c52eb4c84b98bd3c962846516efc.png
[20210419210227678.png]: /images/20221022/e313d6f981504968a43c098aaae828f9.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDg5MzkwMg_size_16_color_FFFFFF_t_70]: /images/20221022/f5976ce798774d8ea256dc686e5ac2ac.png