一、下載MyBatis
MyBatis將所有的項目託管到了github上,因此我們在github上搜索下載MyBatis下載
二、創建對應的數據庫表和JavaBean類
創建數據表:
CREATE TABLE tab1_employee(
id INT(11) PRIMARY KEY AUTO_INCREMENT,
last_name VARCHAR(255),
gender CHAR(1),
email VARCHAR(255)
)
創建對應的JavaBean類
package com.atorg.mybatis.bean;
import org.apache.ibatis.type.Alias;
@Alias("emp")
public class Employee {
private Integer id;
private String lastName; //注意此處與數據中的字段並不對應???
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、根據官方文檔(下文按照官方文檔的步驟實現一個"HelloWorld")
官方文檔在一開始下載的依賴和文檔中有,如果沒有可以到以下地址下載
官方文檔下載鏈接 提取碼:hpaq 內附有Mybatis文檔與依賴包
1.導入相關依賴
引入MyBatis的jar包,以及操作數據庫驅動的jar包,爲顯示方便引入log4j日誌包,引入log4j時必須要在類路徑下放一個log4j.xml文件(在以上的鏈接中有這些jar包)
2.創建一個xml文件(全局配置文件)[ Building SqlSessionFactory from XML]
創建一個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">//數據源連向我們自己的數據庫
<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映射文件一定要註冊在全局配置文件中(就是此文件中)-->
<mapper resource="EmployeeMapper.xml"/>
</mappers>
</configuration>
3.根據xml文件創建一個SqlSessionFactory對象
public class MyBatisTest {
//此處的resource內容就是上面創建的xml文件的路徑名
public void test() throws IOException{
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory =new SqlSessionFactoryBuilder().build(inputStream);
}
}
4.獲取sqlSession實例,能直接執行已經映射的sql語句
SqlSession openSession = sqlSessionFactory.openSession();
5.用獲取的sqlSession調用增刪改查的方法 [Acquiring a SqlSession from SqlSessionFactory]
//第一個參數值爲sql映射文件中**namespace+具體增刪改查對應的唯一id的值**
//第二個參數是執行sql時傳入的參數
openSession.selectOne(arg0,arg1);//查詢
openSession.delete(arg0,arg1);//刪除
openSession.update(arg0,arg1);//更新
openSession.insert(arg0,arg1);//插入
//第一個參數 *statement是一個唯一標識:Unique identifier matching the statement to use.
//第二個參數*parameter是執行sql語句的一個參數:A parameter object to pass to the statement.
6.創建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} <!--給數據庫變量起別名解決字段不匹配問題-->
</select>
</mapper>
【namespace】:名稱空間用來映射sql語句的類的全類名
【id】:爲select的唯一標識,內容爲具體方法的方法名
【resultType】:返回值類型,查詢完成之後要返回的類型
【#{id}】:從傳遞過來的參數中取出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"><!--數據庫連接池-->
<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">
<!-- 查詢數據 -->
<select id="selectEmp" resultType="com.atorg.mybatis.bean.Employee">
select * from tab1_emp where id = #{id}
</select>
<!-- 插入數據 -->
<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>
<!-- 更新數據 -->
<update id="updateEmp" parameterType="com.atorg.mybatis.bean.Employee">
update tab1_emp
set last_name=#{lastName},email=#{email},gender=#{gender}
where id =#{id}
</update>
<!-- 刪除數據 -->
<!-- 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、進行測試
測試類
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);
// 獲取sqlsession實例,能直接執行已經映射的sql語句
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","[email protected]","1"));
// session.commit();
// System.out.println("插入成功");
// session.delete("com.atorg.mybatis.EmployeeMapper.deleteEmp", 5);
// session.commit();
// System.out.println("刪除成功");
session.update("com.atorg.mybatis.EmployeeMapper.updateEmp", new Employee(5,"lucy","[email protected]","0"));
session.commit();
System.out.println("更新成功");
} finally {
session.close();
}
}
}
查看數據庫原始狀態
測試添加方法( “Bob”,“[email protected]”,“0” )
測試查詢方法(查詢5號)
測試刪除方法(刪除5號)
測試跟新方法(更新1號【“Jack”,“[email protected]”,“1”】)
五、升級[Using an interface (e.g. BlogMapper.class) that properly describes the parameter and return value for a given statement]
使用上述代碼可以實現對數據庫的增刪改查操作,但是我們在測試類中傳入參數很麻煩,因此我們引進了接口式編程,我們可以創建一個接口,接口來描述我們給定的sql語句的參數和返回值
1.創建一個接口
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提供一個特殊的功能,接口可以與配置文件進行動態綁定
【namespce】:指定爲接口的全類名
【id】:增刪改查標籤的id指定爲接口對應的方法名
2.此時的測試類(以查詢爲例其他類似)
@Test
public void test02() throws IOException{
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
// 獲取sqlsession實例,能直接執行已經映射的sql語句
SqlSession openSession = sqlSessionFactory.openSession();
try{
EmployeeMapper eMapper=openSession.getMapper(EmployeeMapper.class);
Employee employee=eMapper.getEmpByTd(1);//直接調用接口的查詢員工方法
System.out.println(employee);
}finally{
openSession.close();
}
}
【getMapper】:會爲接口自動創建一個代理對象,用得到的代理對象去調用接口的增刪改查放方法
查詢結果