問題背景
在同一套系統(tǒng)中，要支持連接訪問各種流行的數(shù)據(jù)庫，以及同一數(shù)據(jù)庫的不同版本，例如，oracle9i、oracle10g、oracle11g、oracle12c、sqlserver2000、sqlserver2005、sqlserver2008、sqlserver2012等，其中就會碰到一些問題，就是不同的數(shù)據(jù)庫，數(shù)據(jù)庫驅(qū)動肯定不同，對于這個問題到好解決，只需要將相應(yīng)的驅(qū)動加入即可；然而對于同種數(shù)據(jù)庫，不同版本時，而且不同版本的數(shù)據(jù)庫驅(qū)動不僅不兼容，同時存在還會出現(xiàn)沖突，例如，能滿足sqlserver2000的驅(qū)動，就不能滿足sqlserver2012，而能滿足sqlserver2012的驅(qū)動，就不能滿足sqlserver2000。對于這種問題，面前能想到的解決方案就是動態(tài)加載數(shù)據(jù)庫驅(qū)動，當(dāng)用到某種數(shù)據(jù)庫時，就加載其對應(yīng)的數(shù)據(jù)庫驅(qū)動。
代碼實(shí)現(xiàn)
在此只例出核心代碼，就是動態(tài)加載數(shù)據(jù)庫驅(qū)動的類，只是此處暫時沒有考慮到數(shù)據(jù)庫連接池的問題，當(dāng)選擇動態(tài)加載數(shù)據(jù)庫驅(qū)動時，數(shù)據(jù)庫連接池需要自己實(shí)現(xiàn)，對于數(shù)據(jù)庫池的實(shí)現(xiàn)，后續(xù)會出一篇文章專門講解。
DynamicLoaderService
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package com.tongtongxue.dynamic.service.impl;import java.net.URL;import java.net.URLClassLoader;import java.sql.Connection;import java.sql.Driver;import java.sql.DriverManager;import java.util.HashMap;import java.util.Map;import java.util.Properties;import javax.annotation.PostConstruct;import org.springframework.stereotype.Service;import com.tongtongxue.dynamic.model.DataSourceInfo;import com.tongtongxue.dynamic.service.IDynamicLoaderService;/** * 動態(tài)加載JDBC數(shù)據(jù)庫驅(qū)動服務(wù)類 * * @author lzj * */@Servicepublic class DynamicLoaderService implements IDynamicLoaderService { // 保存數(shù)據(jù)庫連接信息 private Map>String, DataSourceInfo< dataSourceInfos = null; // 保存數(shù)據(jù)庫相應(yīng)驅(qū)動JAR的路徑 private Map>String, String< paths = null; // 緩存對應(yīng)的Driver對象 private Map>String, Driver< drivers = null; private URLClassLoader classLoader; /** * 初始化方法 * * @throws Exception */ @PostConstruct public void init() throws Exception { dataSourceInfos = new HashMap>String, DataSourceInfo<(); // 此處只已oracle9和oracle12為例，其它數(shù)據(jù)庫信息同理的方式增加即可 DataSourceInfo oracle9Info = new DataSourceInfo(); oracle9Info.setDriver("oracle.jdbc.driver.OracleDriver"); oracle9Info.setUrl("jdbc:oracle:thin:@192.168.0.101:1521:ORACLE"); oracle9Info.setUsername("system"); oracle9Info.setPassword("system"); dataSourceInfos.put("oracle9", oracle9Info); DataSourceInfo oracle12Info = new DataSourceInfo(); oracle12Info.setDriver("oracle.jdbc.driver.OracleDriver"); oracle12Info.setUrl("jdbc:oracle:thin:@192.168.0.102:1521:orcl"); oracle12Info.setUsername("system"); oracle12Info.setPassword("system"); dataSourceInfos.put("oracle12", oracle12Info); // 將數(shù)據(jù)庫對應(yīng)驅(qū)動jar放置容器中 paths = new HashMap>String, String<(); paths.put("oracle9", "/driver/ojdbc14.jar"); paths.put("oracle12", "/driver/ojdbc7.jar"); // 初始化drivers drivers = new HashMap>String, Driver<(); } @Override public Connection getConnection(String dbType) throws Exception { Connection conn = null; Driver driver = drivers.get(dbType); DataSourceInfo dataSourceInfo = dataSourceInfos.get(dbType); if (driver == null) { URL jarUrl = this.getClass().getResource(paths.get(dbType)); classLoader = new URLClassLoader(new URL[]{jarUrl}); Class>?< driverClass = classLoader.loadClass(dataSourceInfo.getDriver()); driver = (Driver) driverClass.newInstance(); drivers.put(dbType, driver); } // 注冊驅(qū)動 DriverManager.registerDriver(driver); Properties properties = new Properties(); properties.put("user", dataSourceInfo.getUsername()); properties.put("password", dataSourceInfo.getPassword()); conn = DriverManager.getConnection(dataSourceInfo.getUrl(), properties); // 卸載驅(qū)動 DriverManager.deregisterDriver(driver); return conn; }} |
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