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惯用java工具类(一)

热度：451   发布时间：2012-09-01 09:33:02.0
常用java工具类(一)

1.读取配置文件

EnvironmentConfig.java

Java代码 复制代码 收藏代码
  1. package com.billows.util;
  3. import java.io.*;
  4. import java.util.*;
  6. /**
  7. * java 读取配置（属性）文件
  8. * @author Billows.Van
  9. * billows.van@gmail.com
  10. */
  11. public class EnvironmentConfig {
  12. static EnvironmentConfig ec;// 创建对象ec
  13. private static Hashtable<String, Properties> register = new Hashtable<String, Properties>();// 静态对象初始化[在其它对象之前]
  15. private EnvironmentConfig() {
  16. super();
  17. }
  19. /**
  20. * 取得EnvironmentConfig的一个实例
  21. */
  22. public static EnvironmentConfig getInstance() {
  23. if (ec == null)
  24. ec = new EnvironmentConfig();// 创建EnvironmentConfig对象
  25. return ec;// 返回EnvironmentConfig对象
  26. }
  28. /**
  29. * 读取配置文件
  30. */
  31. public Properties getProperties(String fileName) {// 传递配置文件路径
  32. InputStream is = null;// 定义输入流is
  33. Properties p = null;
  34. try {
  35. p = (Properties) register.get(fileName);// 将fileName存于一个HashTable
  36. /**
  37. * 如果为空就尝试输入进文件
  38. */
  39. if (p == null) {
  40. try {
  41. is = new FileInputStream(fileName);// 创建输入流
  42. } catch (Exception e) {
  43. if (fileName.startsWith("/"))
  44. // 用getResourceAsStream()方法用于定位并打开外部文件。
  45. is = EnvironmentConfig.class.getResourceAsStream(fileName);
  46. else
  47. is = EnvironmentConfig.class.getResourceAsStream("/"+fileName);
  48. }
  49. p = new Properties();
  50. p.load(is);// 加载输入流
  51. register.put(fileName, p);// 将其存放于HashTable缓存
  52. is.close();// 关闭输入流
  53. }
  54. } catch (Exception e) {
  55. e.printStackTrace(System.out);
  56. }
  57. return p;// 返回Properties对象
  58. }
  60. /**
  61. * 此处插入方法描述。
  62. */
  63. public String getPropertyValue(String fileName, String strKey) {
  64. Properties p = getProperties(fileName);
  65. try {
  66. return (String) p.getProperty(strKey);
  67. } catch (Exception e) {
  68. e.printStackTrace(System.out);
  69. }
  70. return null;
  71. }
  72. } 
package com.billows.util;

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;
	}
}

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用法：

Java代码 复制代码 收藏代码
  1. EnvironmentConfig ec=EnvironmentConfig.getInstance();
  2. String driverClassName=ec.getPropertyValue("/config/jdbc.properties", "jdbc.driverClassName"); 
EnvironmentConfig ec=EnvironmentConfig.getInstance();
String driverClassName=ec.getPropertyValue("/config/jdbc.properties", "jdbc.driverClassName");

2.Jdbc工具

JdbcUtil.java

Java代码 复制代码 收藏代码
  1. package com.billows.util;
  3. import java.sql.Connection;
  4. import java.sql.DriverManager;
  5. import java.sql.PreparedStatement;
  6. import java.sql.ResultSet;
  7. import java.sql.SQLException;
  9. /**
  10. * @author Billows.Van haidii@126.com
  11. * @version 创建时间：2008-4-30 上午10:53:09 类说明
  12. */
  13. public class JdbcUtil {
  14. static {
  15. try {
  16. EnvironmentConfig ec=EnvironmentConfig.getInstance();
  17. String driverClassName=ec.getPropertyValue("/config/jdbc.properties", "jdbc.driverClassName");
  18. Class.forName(driverClassName);
  19. } catch (ClassNotFoundException e) {
  20. e.printStackTrace();
  21. }
  22. }
  24. public static Connection getConnection() throws SQLException {
  25. Connection conn = null;
  26. EnvironmentConfig ec=EnvironmentConfig.getInstance();
  27. String url=ec.getPropertyValue("/config/jdbc.properties", "jdbc.url");
  28. String name=ec.getPropertyValue("/config/jdbc.properties", "jdbc.username");
  29. String pwd=ec.getPropertyValue("/config/jdbc.properties", "jdbc.password");
  30. conn = DriverManager.getConnection(url, name, pwd);
  31. return conn;
  32. }
  34. public static void release(Connection conn, PreparedStatement ps,ResultSet rs) {
  35. if (rs != null)try {rs.close();} catch (SQLException e) {e.printStackTrace();}
  36. if (ps != null) try {ps.close();} catch (SQLException e) {e.printStackTrace();}
  37. if (conn!= null)try {conn.close();} catch (SQLException e) {e.printStackTrace();}
  38. }
  40. public static void release(Object obj) {
  41. if (obj instanceof Connection) {
  42. Connection conn = (Connection) obj;
  43. if (conn != null)
  44. try {
  45. conn.close();
  46. } catch (SQLException e) {
  47. e.printStackTrace();
  48. }
  49. }
  50. if (obj instanceof PreparedStatement) {
  51. PreparedStatement ps = (PreparedStatement) obj;
  52. if (ps != null)
  53. try {
  54. ps.close();
  55. } catch (SQLException e) {
  56. e.printStackTrace();
  57. }
  58. }
  59. if (obj instanceof ResultSet) {
  60. ResultSet rs = (ResultSet) obj;
  61. if (rs != null)
  62. try {
  63. rs.close();
  64. } catch (SQLException e) {
  65. e.printStackTrace();
  66. }
  67. }
  68. }
  69. } 
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();
				}
		}
	}
}

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3.java数据源

DBConnectionPool.java

Java代码 复制代码 收藏代码
  1. package com.billows.util;
  3. import java.sql.Connection;
  5. import javax.naming.Context;
  6. import javax.naming.InitialContext;
  7. import javax.sql.DataSource;
  9. public class DBConnectionPool {
  10. public static Connection getConnection() throws Exception{
  11. Context ctx = new InitialContext();
  12. DataSource ds = (DataSource)ctx.lookup("java:comp/env/hsql");
  13. // Context initContext = new InitialContext();
  14. // Context envContext = (Context)initContext.lookup("java:/comp/env");
  15. // DataSource ds = (DataSource)envContext.lookup("hsql");
  16. return ds.getConnection( );
  17. }
  18. } 
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

Java代码 复制代码 收藏代码
  1. package com.billows.util;
  3. import java.sql.Connection;
  4. import java.sql.DriverManager;
  5. import java.sql.SQLException;
  6. import java.sql.Statement;
  8. import javax.servlet.ServletContextEvent;
  9. import javax.servlet.ServletContextListener;
  11. import org.apache.log4j.Logger;
  12. import org.hsqldb.Server;
  14. import com.billows.util.EnvironmentConfig;
  15. /**
  16. * 该listener随web服务启动 并同时启动hsql-server
  17. * @auth Billows.Van
  18. * billows.van@gmail.com
  19. */
  20. public class HsqlListener implements ServletContextListener {
  21. public static final Logger log = Logger.getLogger("HsqlListener");
  22. private EnvironmentConfig ec=EnvironmentConfig.getInstance();
  23. /**配置文件中的占位符，代表webapp发布后的根目录.*/
  24. public static final String TOKEN = "${webapp.root}";
  25. /** 等待数据库停止的最大时间.*/
  26. public static final int WAIT_TIME = 1000;
  27. /**jdbc的url.*/
  28. private String url;
  29. /**登陆用户名.*/
  30. private String username;
  31. /**登陆密码.*/
  32. private String password;
  33. /**处理context初始化事件.
  34. * @param sce ServletContextEvent
  35. */
  36. public void contextInitialized(ServletContextEvent sce) {
  37. try {
  38. username = ec.getPropertyValue("/config/jdbc.properties", "jdbc.username");
  39. password = ec.getPropertyValue("/config/jdbc.properties", "jdbc.password");
  40. String databaseName = ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbname");
  41. int port = Integer.parseInt(ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbport"));
  42. String hsqlPath = ec.getPropertyValue("/config/jdbc.properties", "jdbc.dbpath");
  44. // 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
  45. if (hsqlPath.startsWith(TOKEN)) {
  46. String webappRoot = sce.getServletContext().getRealPath("/").replace("\\", "/");
  47. hsqlPath = hsqlPath.substring(TOKEN.length());
  48. hsqlPath = webappRoot + hsqlPath;
  49. }
  50. String databasePath = hsqlPath + "/" + databaseName;
  51. url = "jdbc:hsqldb:hsql://localhost:" + port + "/" + databaseName;
  52. Server server = new Server();
  53. server.setDatabaseName(0, databaseName);
  54. server.setDatabasePath(0, databasePath);
  55. server.setPort(port);
  56. server.setSilent(true);
  57. server.start();
  58. Thread.sleep(WAIT_TIME);
  59. log.info("Hsqldb启动成功！");
  60. } catch (Exception ex) {
  61. log.error("Hsqldb启动失败：" + ex);
  62. }
  63. }
  65. /**
  66. * 处理context销毁事件.
  67. * @param sce ServletContextEvent
  68. */
  69. public void contextDestroyed(ServletContextEvent sce) {
  70. try {
  71. Class.forName("org.hsqldb.jdbcDriver");
  72. Connection conn = null;
  73. Statement state = null;
  74. try {
  75. // 向数据库发送shutdown命令，关闭数据库
  76. conn = DriverManager.getConnection(url, username, password);
  77. state = conn.createStatement();
  78. state.executeUpdate("SHUTDOWN;");
  79. try {
  80. Thread.sleep(WAIT_TIME);
  81. } catch (InterruptedException e) {
  82. e.printStackTrace();
  83. }
  84. log.info("关闭hsqldb数据库成功！");
  85. } catch (SQLException ex1) {
  86. log.error("关闭hsqldb数据库时出现异常：" + ex1);
  87. } finally {
  88. // 确保关闭Statement
  89. if (state != null) {
  90. try {
  91. state.close();
  92. state = null;
  93. } catch (SQLException ex1) {
  94. log.error("关闭Statement时异常："+ex1);
  95. }
  96. }
  97. // 确保关闭Connection
  98. if (conn != null) {
  99. try {
  100. conn.close();
  101. conn = null;
  102. } catch (SQLException ex1) {
  103. log.error("关闭Connection时异常："+ex1);
  104. }
  105. }
  106. }
  107. } catch (ClassNotFoundException ex) {
  108. log.error("HsqldbListener : contextDestoryed : error : " + ex);
  109. }
  110. }
  111. } 
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

Properties代码 复制代码 收藏代码
  1. jdbc.driverClassName=org.hsqldb.jdbcDriver
  2. jdbc.url=jdbc:hsqldb:hsql://localhost:9990/billows
  3. jdbc.dbname=billows
  4. jdbc.dbport=9990
  5. jdbc.dbpath=${webapp.root}/hsqldb
  6. jdbc.username=sa
  7. jdbc.password=
  8. jdbc.max_connections=30 
jdbc.driverClassName=org.hsqldb.jdbcDriver
jdbc.url=jdbc:hsqldb:hsql://localhost:9990/billows
jdbc.dbname=billows
jdbc.dbport=9990
jdbc.dbpath=${webapp.root}/hsqldb
jdbc.username=sa
jdbc.password=
jdbc.max_connections=30

在web.xml中添加以下代码即可

Xml代码 复制代码 收藏代码
  1. <listener>
  2. <listener-class>com.billows.util.HsqlListener</listener-class>
  3. </listener> 
<listener>
	<listener-class>com.billows.util.HsqlListener</listener-class>
</listener>

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