常用java工具类(一)
1.读取配置文件EnvironmentConfig.java
import java.io.*;import java.util.*;/** * java 读取配置（属性）文件 * @author Billows.Van* billows.van@gmail.com */public class EnvironmentConfig {static EnvironmentConfig ec;// 创建对象ecprivate 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isProperties 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);elseis = 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;}}
用法：
EnvironmentConfig ec=EnvironmentConfig.getInstance();String driverClassName=ec.getPropertyValue("/config/jdbc.properties", "jdbc.driverClassName");
2.Jdbc工具
JdbcUtil.java
package com.billows.util;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;/** * @author Billows.Van haidii@126.com * @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
package com.billows.util;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
package com.billows.util;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* billows.van@gmail.com */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); } }}
其中， jdbc.properties内容为
jdbc.driverClassName=org.hsqldb.jdbcDriverjdbc.url=jdbc:hsqldb:hsql://localhost:9990/billowsjdbc.dbname=billowsjdbc.dbport=9990jdbc.dbpath=${webapp.root}/hsqldbjdbc.username=sajdbc.password=jdbc.max_connections=30
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