MyBatis概念

MyBatis的前身就是iBatis,本是apache的一個開源項目，2010年這個項目由apahce sofeware foundation 遷移到了google code，並且改名為MyBatis。

MyBatis是一個數據持久層(ORM)框架。

MyBatis是把實體類和sql語句之間建立了映射關系，而Hibernate在實體類和數據庫之間建立了映射關系。

總體來說 MyBatis 主要完成兩件事情

1. 根據 JDBC 規範建立與數據庫的連接；
2. 通過Annotaion/XML+JAVA反射技術，實現 Java 對象與關系數據庫之間相互轉化。

MyBatis的優點

1. 基於SQL語法，簡單易學。
2. 能了解底層組裝過程。
3. SQL語句封裝在配置文件中，便於統一管理與維護，降低了程序的耦合度。
4. 程序調試方便。

MyBatis層次結構

MyBatis安裝（環境配置）*.* 例子是最好的筆記

1. 準配需要的jar包:mybatis-3.2.6.jar和mysql-connector-java-5.1.11-bin.jar

　　2.創建mybatis-config.xml，並配置數據庫環境

 1 <?xml version="1.0" encoding="UTF-8" ?>
 2 <!DOCTYPE configuration
 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
 
 4 "http://mybatis.org/dtd/mybatis-3-config.dtd">
 5 <configuration>
 6     <!-- 環境 -->
 7     <environments default="developments">
 8         <environment id="mysql">
 9             <transactionManager type="JDBC"></transactionManager>
10             <dataSource 
 
type="POOLED">
11                 <property name="driver" value="com.mysql.jdbc.Driver"/>
12                 <property name="url" value="jdbc:mysql://127.0.0.1:3306/mydbone"/>
13                 <property name="username" value="root" />
14                 <property name="password" value="199751hwl" />
15             </dataSource>
16         </environment>
17     </environments>
18     
19 </configuration>

　　3.創建一個實體Person.java

package com.model.system;

public class Person {

    private Integer persId;
    private String persName;
    private String persSex;
    private String persHobby;
    
    
    public Person() {}

    public Person(Integer persId, String persName, String persSex, String persHobby) {
        super();
        this.persId = persId;
        this.persName = persName;
        this.persSex = persSex;
        this.persHobby = persHobby;
    }

    public Integer getPersId() {
        return persId;
    }

    public void setPersId(Integer persId) {
        this.persId = persId;
    }

    public String getPersName() {
        return persName;
    }

    public void setPersName(String persName) {
        this.persName = persName;
    }

    public String getPersSex() {
        return persSex;
    }

    public void setPersSex(String persSex) {
        this.persSex = persSex;
    }

    public String getpersHobby() {
        return persHobby;
    }

    public void setpersHobby(String persHobby) {
        this.persHobby = persHobby;
    }

    @Override
    public String toString() {
        return "Person [persId=" + persId + ", persName=" + persName + ", persSex=" + persSex + ", persHobby="
                + persHobby + "]";
    }
    
}

　　4.為實體配置對應的映射文件Person.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.model.system.Person">
    <resultMap type="com.model.system.Person" id="person">
        <result column="persId" property="persId" />
        <result column="persName" property="persName" />
        <result column="persSex" property="persSex" />
        <result column="persHobby" property="persHobby" />
    </resultMap>
    
    <!-- 查詢用戶通過用戶ID -->
    <select id="queryPersonByPersonId" parameterType="java.lang.Integer"
        resultMap="person">
        select * from person where persId = #{persId}
    </select>
    
    <!-- 添加用戶通過用戶ID -->
    <select id="insertPerson" parameterType="java.lang.String"
        resultMap="person">
        INSERT INTO person(persName,persSex,persHobby) VALUE (#{persName},#{persSex},#{persHobby})
    </select>
</mapper>

　　5.在mybatis-config.xml，添加User.xml映射文件

1 <!-- 添加映射文件 -->
2     <mappers>
3         <mapper resource="com/mapper/system/Person.xml" />
4     </mappers>

　　6. 調用類（測試類）

 1 package com;
 2 
 3 import java.io.IOException;
 4 import java.io.Reader;
 5 
 6 import org.apache.ibatis.io.Resources;
 7 import org.apache.ibatis.session.SqlSession;
 8 import org.apache.ibatis.session.SqlSessionFactory;
 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder;
10 
11 import com.model.system.Person;
12 
13 public class TestQueryPersonById {
14 
15     public static void main(String[] args) throws IOException {
16         
17         // 從XML中創建SqlSessionFactory
18         String resource = "mybatis-config.xml";
19         
20         Reader reader = Resources.getResourceAsReader(resource);
21         SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(reader, "mysql");
22         // 獲取session
23         SqlSession session = ssf.openSession();
24         
25         Person person = session.selectOne("com.model.system.Person.queryPersonByPersonId", 1);
26         // 通過命名空間查找sql
27         System.out.println(person);
28     }
29 }

MyBatis概念和”安裝“