iBATIS初體驗－Jemmy Walker

有別於JPA等ORM產品，iBATIS是直接把SQL Mapping作為一組input/output，而SQL字串則定義在XML檔。對全新專案開發時可能不是最佳選擇，但對中小型專案全新開發，或是接手舊系統的維護卻是比JPA較好的選擇。

iBATIS下載是自Apache網站，目前最新版本2.3.3.720，只需引進一個Jar檔(當然還要有應對的JDBC Driver)。

和JPA類似的，config檔似乎比程式還要吃重。

SqlMapConfig.xml (不一定叫這個名字)

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE sqlMapConfig PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN"
"http://ibatis.apache.org/dtd/sql-map-config-2.dtd">

</sqlMapConfig>

SqlMap.xml

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE sqlMap PUBLIC "-//ibatis.apache.org//DTD SQL Map 2.0//EN"
"http://ibatis.apache.org/dtd/sql-map-2.dtd">

<sqlMap>
        <select id="getAllUsers" parameterClass="string" resultClass="hashmap">
                SELECT * FROM USER_ACCOUNT WHERE GROUPNAME = #groupName#
        </select>
</sqlMap>

Main.java測試主程式

import com.ibatis.sqlmap.client.*;
import com.ibatis.common.resources.Resources;

import java.io.Reader;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
           String resource = "./sql-map-config.xml";
           Reader reader = Resources.getResourceAsReader(resource);
           SqlMapClient sqlMap = SqlMapClientBuilder.buildSqlMapClient(reader);
           List list = sqlMap.queryForList("getAllUsers", "EMPLOYEE"); // 對映到SqlMap.xml的getAllUsers
           System.out.println("Selected " + list.size() + " records!");
           for (int i=0; i<list.size(); i++) {
               System.out.println(list.get(i));
           }
           Map accountMap = sqlMap.queryForMap("getAllUsers", "EMPLOYEE", "USERID");
           System.out.println(accountMap.toString());
           accountMap = sqlMap.queryForMap("getAllUsers", "EMPLOYEE", "USERID", "GROUPNAME");
           System.out.println(accountMap.toString());
    }
}