Mybatis實現數據的增刪改查（CRUD）

什麼是 MyBatis？

MyBatis 是支持普通 SQL 查詢，存儲過程和高級映射的優秀持久層框架。 MyBatis 消除了幾乎所有的 JDBC 代碼和參數的手工設置以及對結果集的檢索。MyBatis 可以使用簡單的XML 或註解用於配置和原始映射，將接口和 Java 的 POJO（Plain Old Java Objects，普通的Java對象）映射成數據庫中的記錄。

MyBatis下載：https://github.com/mybatis/mybatis-3/releases

Mybatis實例

對一個User表的CRUD操作：

User表：

-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(50) DEFAULT NULL,
  `userAge` int(11) DEFAULT NULL,
  `userAddress` varchar(200) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', 'summer', '30', 'shanghai');
INSERT INTO `user` VALUES ('2', 'test2', '22', 'suzhou');
INSERT INTO `user` VALUES ('3', 'test1', '29', 'some place');
INSERT INTO `user` VALUES ('4', 'lu', '28', 'some place');
INSERT INTO `user` VALUES ('5', 'xiaoxun', '27', 'nanjing');

在Src目錄下建一個mybatis的xml配置文件Configuration.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>
    <!-- mybatis別名定義 -->
    <typeAliases> 
        <typeAlias alias="User" type="com.mybatis.test.User"/> 
    </typeAliases> 

    <environments default="development">
        <environment id="development">
        <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis" />
            <property name="username" value="root"/>
            <property name="password" value="admin"/>
            </dataSource>
        </environment>
    </environments>
    
    <!-- mybatis的mapper文件，每個xml配置文件對應一個接口 -->
    <mappers>
        <mapper resource="com/mybatis/test/User.xml"/>
    </mappers>
</configuration>

定義User mappers的User.xml配置文件

<?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="com.mybatis.test.IUserOperation">

    <!-- select語句 -->
    <select id="selectUserByID" parameterType="int" resultType="User">
        select * from `user` where user.id = #{id}
    </select>
    
    <!-- 定義的resultMap，可以解決類的屬性名和數據庫列名不一致的問題-->
    <!-- <resultMap type="User" id="userResultMap">
        <id property="id" column="user_id"  />
        <result property="userName" column="user_userName"  />
        <result property="userAge" column="user_userAge"  />
        <result property="userAddress" column="user_userAddress"  />
    </resultMap> -->
    
    <!-- 返回list的select語句，注意 resultMap的值是指向前面定義好的 -->
    <!-- <select id="selectUsersByName" parameterType="string" resultMap="userResultMap">
        select * from user where user.userName = #{userName}
    </select> -->
    
    <select id="selectUsersByName" parameterType="string" resultType="User">
        select * from user where user.userName = #{userName}
    </select>
    
    <!--執行增加操作的SQL語句。id和parameterType分別與IUserOperation接口中的addUser方法的名字和參數類型一致。
    useGeneratedKeys設置爲"true"表明要MyBatis獲取由數據庫自動生成的主鍵；keyProperty="id"指定把獲取到的主鍵值注入到User的id屬性--> 
    <insert id="addUser" parameterType="User" 
        useGeneratedKeys="true" keyProperty="id"> 
        insert into user(userName,userAge,userAddress)  
             values(#{userName},#{userAge},#{userAddress})  
    </insert>
    
    <update id="updateUser" parameterType="User" >
        update user set userName=#{userName},userAge=#{userAge},userAddress=#{userAddress} where id=#{id}
    </update>
    
    <delete id="deleteUser" parameterType="int">
        delete from user where id=#{id}
    </delete>
    
</mapper>

配置文件實現了接口和SQL語句的映射關係。selectUsersByName採用了2種方式實現，註釋掉的也是一種實現，採用resultMap可以把屬性和數據庫列名映射關係定義好，property爲類的屬性，column是表的列名，也可以是表列名的別名！

User類的定義：

package com.mybatis.test;

public class User {
    
    private int id;
    private String userName;
    private int userAge;
    private String userAddress;
    
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getUserName() {
        return userName;
    }
    
    public void setUserName(String userName) {
        this.userName = userName;
    }
    
    public int getUserAge() {
        return userAge;
    }
    
    public void setUserAge(int userAge) {
        this.userAge = userAge;
    }
    
    public String getUserAddress() {
        return userAddress;
    }
    
    public void setUserAddress(String userAddress) {
        this.userAddress = userAddress;
    }
    
    @Override
    public String toString(){
        return this.userName+" "+this.userAge+" "+this.userAddress;
    }

}

IUserOperaton定義：

package com.mybatis.test;

import java.util.List;

public interface IUserOperation {
    
    public User selectUserByID(int id);
    
    public List<User> selectUsersByName(String userName);
    
    public void addUser(User user);
    
    public void updateUser(User user);
    
    public void deleteUser(int id);
    
}

IUserOperation爲操作接口，函數名和mybatis的xml配置文件中的操作id名對應。

測試類Test：

package com.mybatis.test;

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;

public class Test {

    private static SqlSessionFactory sqlSessionFactory;
    private static Reader reader;

    static {
        try {
            reader = Resources.getResourceAsReader("Configuration.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSession() {
        return sqlSessionFactory;
    }

    public void getUserByID(int userID) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            IUserOperation userOperation = session
                    .getMapper(IUserOperation.class);
            User user = userOperation.selectUserByID(userID);
            if (user != null) {
                System.out.println(user.getId() + ":" + user.getUserName()
                        + ":" + user.getUserAddress());
            }

        } finally {
            session.close();
        }
    }

    public void getUserList(String userName) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            IUserOperation userOperation = session
                    .getMapper(IUserOperation.class);
            List<User> users = userOperation.selectUsersByName(userName);
            for (User user : users) {
                System.out.println(user.getId() + ":" + user.getUserName()
                        + ":" + user.getUserAddress());
            }

        } finally {
            session.close();
        }
    }

    /**
     * 增加後要commit
     */
    public void addUser() {
        User user = new User();
        user.setUserAddress("place");
        user.setUserName("test_add");
        user.setUserAge(30);
        SqlSession session = sqlSessionFactory.openSession();
        try {
            IUserOperation userOperation = session
                    .getMapper(IUserOperation.class);
            userOperation.addUser(user);
            session.commit();
            System.out.println("新增用戶ID：" + user.getId());
        } finally {
            session.close();
        }
    }

    /**
     * 修改後要commit
     */
    public void updateUser() {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            IUserOperation userOperation = session
                    .getMapper(IUserOperation.class);
            User user = userOperation.selectUserByID(1);
            if (user != null) {
                user.setUserAddress("A new place");
                userOperation.updateUser(user);
                session.commit();
            }
        } finally {
            session.close();
        }
    }

    /**
     * 刪除後要commit.
     * 
     * @param id
     */
    public void deleteUser(int id) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
            IUserOperation userOperation = session
                    .getMapper(IUserOperation.class);
            userOperation.deleteUser(id);
            session.commit();
        } finally {
            session.close();
        }
    }

    public static void main(String[] args) {
        try {
            Test test = new Test();
            // test.getUserByID(1);
            // test.getUserList("test1");
            // test.addUser();
            // test.updateUser();
            // test.deleteUser(6);

        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

}

 

代碼下載：http://download.csdn.net/detail/luxiaoxun/8056559

 

參考：

http://www.mybatis.org/mybatis-3/zh/getting-started.html

http://legend2011.blog.51cto.com/3018495/d-5

http://mybatis.github.io/mybatis-3/zh/sqlmap-xml.html

 

作者：阿凡盧

出處：http://www.cnblogs.com/luxiaoxun/