Java工具类:读配置文件,jdbc,数据源,hsqldb随web启动的Listener
1.读取配置文件
方法一:
EnvironmentConfig.java
import java.io.*; import java.util.*; /** * java 读取配置（属性）文件 * @author pippo */ public class EnvironmentConfig { static EnvironmentConfig ec;// 创建对象ec private static Hashtable<String, Properties> register = new Hashtable<String, Properties>();// 静态对象初始化[在其它对象之前] private EnvironmentConfig() { super(); } /** * 取得EnvironmentConfig的一个实例 */ public static EnvironmentConfig getInstance() { if (ec == null) ec = new EnvironmentConfig();// 创建EnvironmentConfig对象 return ec;// 返回EnvironmentConfig对象 } /** * 读取配置文件 */ public Properties getProperties(String fileName) {// 传递配置文件路径 InputStream is = null;// 定义输入流is Properties p = null; try { p = (Properties) register.get(fileName);// 将fileName存于一个HashTable /** * 如果为空就尝试输入进文件 */ if (p == null) { try { is = new FileInputStream(fileName);// 创建输入流 } catch (Exception e) { if (fileName.startsWith("/")) // 用getResourceAsStream()方法用于定位并打开外部文件。 is = EnvironmentConfig.class.getResourceAsStream(fileName); else is = EnvironmentConfig.class.getResourceAsStream("/"+fileName); } p = new Properties(); p.load(is);// 加载输入流 register.put(fileName, p);// 将其存放于HashTable缓存 is.close();// 关闭输入流 } } catch (Exception e) { e.printStackTrace(System.out); } return p;// 返回Properties对象 } /** * 此处插入方法描述。 */ public String getPropertyValue(String fileName, String strKey) { Properties p = getProperties(fileName); try { return (String) p.getProperty(strKey); } catch (Exception e) { e.printStackTrace(System.out); } return null; } }
方法二:
public class TextInfo { private static Properties pro; public static String getText(String key){ if(pro==null){ try { pro = new Properties(); pro.load(ClassLoader.getSystemResourceAsStream("XX.properties")); } catch (IOException e) { return "资源无法读取"; } } return pro.getProperty(key); } }
2.Jdbc工具
JdbcUtil.java
import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * @author pippo * @version 创建时间：2008-4-30 上午10:53:09 类说明 */ public class JdbcUtil { static { try { EnvironmentConfig ec=EnvironmentConfig.getInstance(); String driverClassName=ec.getPropertyValue("/config/jdbc.properties", "jdbc.driverClassName"); Class.forName(driverClassName); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public static Connection getConnection() throws SQLException { Connection conn = null; EnvironmentConfig ec=EnvironmentConfig.getInstance(); String url=ec.getPropertyValue("/config/jdbc.properties", "jdbc.url"); String name=ec.getPropertyValue("/config/jdbc.properties", "jdbc.username"); String pwd=ec.getPropertyValue("/config/jdbc.properties", "jdbc.password"); conn = DriverManager.getConnection(url, name, pwd); return conn; } public static void release(Connection conn, PreparedStatement ps,ResultSet rs) { if (rs != null)try {rs.close();} catch (SQLException e) {e.printStackTrace();} if (ps != null) try {ps.close();} catch (SQLException e) {e.printStackTrace();} if (conn!= null)try {conn.close();} catch (SQLException e) {e.printStackTrace();} } public static void release(Object obj) { if (obj instanceof Connection) { Connection conn = (Connection) obj; if (conn != null) try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } if (obj instanceof PreparedStatement) { PreparedStatement ps = (PreparedStatement) obj; if (ps != null) try { ps.close(); } catch (SQLException e) { e.printStackTrace(); } } if (obj instanceof ResultSet) { ResultSet rs = (ResultSet) obj; if (rs != null) try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } } } }
3.java数据源
DBConnectionPool.java
import java.sql.Connection; import javax.naming.Context; import javax.naming.InitialContext; import javax.sql.DataSource; public class DBConnectionPool { public static Connection getConnection() throws Exception{ Context ctx = new InitialContext(); DataSource ds = (DataSource)ctx.lookup("java:comp/env/hsql"); // Context initContext = new InitialContext(); // Context envContext = (Context)initContext.lookup("java:/comp/env"); // DataSource ds = (DataSource)envContext.lookup("hsql"); return ds.getConnection( ); } } 4.hsqldb随web启动的Listener import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import org.apache.log4j.Logger; import org.hsqldb.Server; import com.billows.util.EnvironmentConfig; /** * 该listener随web服务启动 并同时启动hsql-server * @auth Billows.Van * [email protected] */ public class HsqlListener implements ServletContextListener { public static final Logger log = Logger.getLogger("HsqlListener"); private EnvironmentConfig ec=EnvironmentConfig.getInstance(); /**配置文件中的占位符，代表webapp发布后的根目录.*/ public static final String TOKEN = "${webapp.root}"; /** 等待数据库停止的最大时间.*/ public static final int WAIT_TIME = 1000; /**jdbc的url.*/ private String url; /**登陆用户名.*/ private String username; /**登陆密码.*/ private String password; /**处理context初始化事件. * @param sce ServletContextEvent */ public void contextInitialized(ServletContextEvent sce) { try { username = ec.getPropertyValue("/config/jdbc.properties", "jdbc.username"); password = ec.getPropertyValue("/config/jdbc.properties", "jdbc.password"); String databaseName = ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbname"); int port = Integer.parseInt(ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbport")); String hsqlPath = ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbpath"); // FIXME: 因为要用到getRealPath方法获得路径，在使用war包发布的时候会出现问题 if (hsqlPath.startsWith(TOKEN)) { String webappRoot = sce.getServletContext().getRealPath("/").replace("//", "/"); hsqlPath = hsqlPath.substring(TOKEN.length()); hsqlPath = webappRoot + hsqlPath; } String databasePath = hsqlPath + "/" + databaseName; url = "jdbc:hsqldb:hsql://localhost:" + port + "/" + databaseName; Server server = new Server(); server.setDatabaseName(0, databaseName); server.setDatabasePath(0, databasePath); server.setPort(port); server.setSilent(true); server.start(); Thread.sleep(WAIT_TIME); log.info("Hsqldb启动成功！"); } catch (Exception ex) { log.error("Hsqldb启动失败：" + ex); } } /** * 处理context销毁事件. * @param sce ServletContextEvent */ public void contextDestroyed(ServletContextEvent sce) { try { Class.forName("org.hsqldb.jdbcDriver"); Connection conn = null; Statement state = null; try { // 向数据库发送shutdown命令，关闭数据库 conn = DriverManager.getConnection(url, username, password); state = conn.createStatement(); state.executeUpdate("SHUTDOWN;"); try { Thread.sleep(WAIT_TIME); } catch (InterruptedException e) { e.printStackTrace(); } log.info("关闭hsqldb数据库成功！"); } catch (SQLException ex1) { log.error("关闭hsqldb数据库时出现异常：" + ex1); } finally { // 确保关闭Statement if (state != null) { try { state.close(); state = null; } catch (SQLException ex1) { log.error("关闭Statement时异常："+ex1); } } // 确保关闭Connection if (conn != null) { try { conn.close(); conn = null; } catch (SQLException ex1) { log.error("关闭Connection时异常："+ex1); } } } } catch (ClassNotFoundException ex) { log.error("HsqldbListener : contextDestoryed : error : " + ex); } } }