一個使用MyBatis將數據庫表中的一列內容放到List的例子

個人電腦操做系統版本爲Win7旗艦版（ServicePack1），Oracle版本爲Oracle11g

程序使用的jar包有：mybatis-3.2.2.jar、ojdbc14-10.2.0.2.0.jar

本例中使用的配置文件mybatis-config.xml，能夠參見個人另外一篇Blog《一個簡單的MyBatis鏈接Oracle數據庫的例子》（http://my.oschina.net/Tsybius2014/blog/626206）

如今Oracle數據庫中創建一個新表RANK_LIST並插入一些數據，SQL以下：

CREATE TABLE RANK_LIST
(
    ID NUMBER(12,0) PRIMARY KEY,
    COMPETITION VARCHAR2(20) NOT NULL,
    RANK NUMBER(5, 0) NOT NULL,
    NAME VARCHAR(20) NOT NULL,
    INPUT_DATE NUMBER(10,0) DEFAULT TO_NUMBER(TO_CHAR(sysdate,'yyyymmdd')),
    INPUT_TIME NUMBER(10,0) DEFAULT TO_NUMBER(TO_CHAR(sysdate,'hh24miss'))
);


INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (1, 'COMP1', 1, 'TSYBIUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (2, 'COMP1', 2, 'GALATEA');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (3, 'COMP1', 3, 'GAIUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (4, 'COMP1', 4, 'JULIA');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (5, 'COMP2', 1, 'TSYBIUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (6, 'COMP2', 2, 'GAIUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (7, 'COMP2', 3, 'MARCUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (8, 'COMP3', 1, 'QUINTUS');
INSERT INTO RANK_LIST (ID, COMPETITION, RANK, NAME) VALUES (9, 'COMP3', 2, 'MARCUS');

COMMIT;
/

這個表中，ID爲主鍵，COMPETITION爲賽事，RANK爲選手在這項賽事中取得的名次，NAME爲選手的姓名。從PL/SQL中看到的RANK_LIST表內容以下：

如今要將得到了名次的選手按字母順序正序取出，main函數調用代碼以下：

import java.io.InputStream;
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;

/**
 * MyBatis使用測試
 * @author Tsybius2014
 * @date 2016年3月14日
 * @time 下午10:55:12
 * @remark
 *
 */
public class MyBatisTest {
    public static void main(String[] args) {
        
        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            SqlSession session = sqlSessionFactory.openSession();
            try {
                RankListMapper mapper = session.getMapper(RankListMapper.class);

                List<String> productList = mapper.getWinnerList();
                System.out.println(productList);
                
            } finally {
                session.close();
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

RankListMapper.java代碼以下：

import java.util.List;

public interface RankListMapper {
    /** 獲取在RANK_LIST表中榜上有名者的列表 */
    List<String> getWinnerList();
}

RankListMapper.xml代碼以下：

<?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="RankListMapper">
    <select id="getWinnerList" resultType="java.lang.String" >
        SELECT NAME FROM RANK_LIST GROUP BY NAME ORDER BY NAME
    </select>
</mapper>

上面的main函數，執行結果爲：

[GAIUS, GALATEA, JULIA, MARCUS, QUINTUS, TSYBIUS]

END