[JAVA]入門 JDBC 連線模板設定

在目前的專案Web設計上來說，可以分為

Web / Action / Facade / Service / Dao

這幾層 JDBC 是在 Dao 之下，由頁面上的操作決定使用哪一個

 Action，由Action 決定使用哪個Facade，然後再由Facade去呼

叫哪一個Service，由Service 去做一些與DB交換資料的動作。

而DB的交換資料看是使用各種FrameWork或使傳統的JDBC，

這邊僅就JDBC去做說明，直接看Code就可明白。

import java.sql.Connection;

import java.sql.DriverManager;

import org.apache.log4j.Logger;

/**

 *

 * @author Hsu

 */

public class TestDbUtil {

        private static final Logger logger = Logger.getLogger(TestDbUtil.class);

        //對應DB環境代碼

        public final int DB1=1;

        public final int DB2=2;

        public final int DB3=3;

        public final int DB4=4;

        //是否為測試階段

        //可將其寫在properties 中取出

        public final boolean SIT = true;

        //資料庫連線資料

        //可將其寫在properties 中取出

        private final String DB1_CONNECTION_STRING = "jdbc:oracle:thin:@10.1.1.1:1521:TEST";

        private final String DB1_ACCOUNT = "user";

        private final String DB1_PASSWORD = "password";

/**

 * 依照傳入代號選擇DB 連線階段

 * @param db

 * @return

 * @throws Exception

 */

public Connection getConnection(int db) throws Exception{

                Connection conn=null;

                String connStr = null;

                String connId=null;

                String connPwd=null;

                if (SIT){

                        logger.debug("SIT狀態!!");

                        switch(db){

                        case DB1:

                                connStr=DB1_CONNECTION_STRING;

                                connId=DB1_ACCOUNT;

                                connPwd=DB1_PASSWORD;

                                logger.debug("使用DB1連線資料");

                                break;

                        case DB2:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB2連線資料");

                                break;

                        case DB3:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB3連線資料");

                                break;

                        case DB4:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB4連線資料");

                                break;

                        }

                }else{

                        logger.debug("非SIT狀態!!");

                        switch(db){

                        case DB1:

                                connStr=DB1_CONNECTION_STRING;

                                connId=DB1_ACCOUNT;

                                connPwd=DB1_PASSWORD;

                                logger.debug("使用DB1連線資料");

                                break;

                        case DB2:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB2連線資料");

                                break;

                        case DB3:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB3連線資料");

                                break;

                        case DB4:

                                connStr="";

                                connId="";

                                connPwd="";

                                logger.debug("使用DB4連線資料");

                                break;

                        }

                }

                try {

                        /*

                         * 此處可設定為支援各種不同DB連線

                         * 亦可寫在 properties 並使用

                          File PROPERTY_FILE = new File("properties/XXX.properties");

              InputStream is= new FileInputStream(PROPERTY_FILE);

              Properties prop = new Properties();

              prop.load(is);

              HOME_DIRECTORY = prop.getProperty("HOME_DIRECTORY");

              來取出 各式資料

                         */

                        Class.forName("oracle.jdbc.driver.OracleDriver");

                        logger.debug("啟用XXX資料庫連線");

                        conn = DriverManager.getConnection(connStr, connId, connPwd);

                } catch (Exception e) {

                        e.printStackTrace();

                }

                return conn;                

        }

}

上面這一段程式碼就可以用在Dao端，產生各種不同的DB連線設定，

DB的連線設定可以存在properties中，不用因為改了連線設定就改

Code，當然getConnection也可以寫成static，可供直接呼叫，但為此

就會犧牲了程式上的靈活性，若您的DB連線很單純(如只有一個連線

環境)，那設定成static後會方便許多。

原文網址：http://kuoshenghsu.blogspot.tw/2014/11/java-jdbc.html