java中，類的static變量作為類變量，只需要被一次初始化，就可使用，但是，我在程序中遇到一個問題：

在web.xml中配置listener，服務器啟動時，ServletContextListen初始化數據源(DataSource)，第一次初始化成功，但是在Test類中，調用ConnectionManager.getConnection()時，DataSource卻為null，意味著ServletContextListen初始化數據源失敗了，大家幫忙解答下，到底什么原因造成的，謝謝！！！

以下是代碼：

package c3p0.connection;

import java.beans.PropertyVetoException;

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Properties;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class ConnectionManager {

private static DataSource data_source=null;;

private static Properties props=null;

private static String porps_name=null;

/**

* 創建數據庫連接池

* @return

*/

private static DataSource createDataSource(){

load();

data_source=initDB();

return data_source;

}

/**

* 加載配置文件

*/

private static void load(){

try {

props = new Properties();

InputStream in=Thread.currentThread().getContextClassLoader().getResourceAsStream(porps_name);

props.load(in);

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 初始化數據庫

*/

private static DataSource initDB(){

System.out.println("開始初始化數據源...");

ComboPooledDataSource pool_ds=new ComboPooledDataSource();

try {

pool_ds.setDriverClass(getProperty("c3p0.connection.driverClass"));

} catch (PropertyVetoException e) {

e.printStackTrace();

throw new RuntimeException("數據庫驅動加載失敗");

}

pool_ds.setJdbcUrl(getProperty("c3p0.connection.url"));

pool_ds.setUser(getProperty("c3p0.connection.user"));

pool_ds.setPassword(getProperty("c3p0.connection.password"));

pool_ds.setInitialPoolSize(Integer.parseInt(getProperty("c3p0.connection.initialPoolSize")));

pool_ds.setMaxPoolSize(Integer.parseInt(getProperty("c3p0.connection.maxPoolSize")));

pool_ds.setMinPoolSize(Integer.parseInt(getProperty("c3p0.connection.minPoolSize")));

pool_ds.setMaxIdleTime(Integer.parseInt(getProperty("c3p0.connection.maxIdleTime")));

pool_ds.setAcquireIncrement(Integer.parseInt(getProperty("c3p0.connection.acquireIncrement")));

pool_ds.setAcquireRetryAttempts(Integer.parseInt(getProperty("c3p0.connection.acquireRetryAttempts")));

pool_ds.setAcquireRetryDelay(Integer.parseInt(getProperty("c3p0.connection.acquireRetryDelay")));

pool_ds.setTestConnectionOnCheckout(Boolean.parseBoolean(getProperty("c3p0.connection.testConnectionOnCheckout")));

pool_ds.setTestConnectionOnCheckin(Boolean.parseBoolean(getProperty("c3p0.connection.testConnectionOnCheckin")));

pool_ds.setIdleConnectionTestPeriod(Integer.parseInt(getProperty("c3p0.connection.idleConnectionTestPeriod")));

pool_ds.setCheckoutTimeout(Integer.parseInt(getProperty("c3p0.connection.checkoutTimeout")));

pool_ds.setAutomaticTestTable(getProperty("c3p0.connection.automaticTestTable"));

System.out.println("數據源初始化完畢...");

return pool_ds;

}

/**

* 獲取c3p0連接池文件配置信息

* @param key

* @return

*/

private static String getProperty(String key){

if(key==null||"".equals(key)){

throw new NullPointerException("key不能為空!!!請檢查key的賦值!!!");

}

return props.getProperty(key);

}

public static Connection getConnection() throws SQLException{

data_source=(data_source==null) ? createDataSource() : data_source;

return data_source.getConnection();

}

public static void start(String porps_name) throws SQLException{

ConnectionManager.porps_name=porps_name;

Connection conn=getConnection();

conn.close();

}

public static void stop(){

data_source=null;

}

public static void release(Connection conn,PreparedStatement pstmt,ResultSet res){

try {

if(conn!=null){

conn.close();

}

if(pstmt!=null){

pstmt.close();

}

if(res!=null){

res.close();

}

} catch (SQLException e) {

e.printStackTrace();

}

}

}

package mystruts.listener;

import java.sql.SQLException;

import javax.servlet.ServletContextEvent;

import javax.servlet.ServletContextListener;

import c3p0.connection.ConnectionManager;

/**

* ServletContext 上下文監聽器

* 應用服務器一啟動就產生該對象，服務器關閉即銷毀

* 作用于全局，所有Servlet ,相當于靜態變量

* @author tianly

*

*/

public class ServletContextListen implements ServletContextListener {

/**

* web服務器關閉時執行

*/

@Override

public void contextDestroyed(ServletContextEvent event) {

/**

* 關閉數據源

*/

ConnectionManager.stop();

}

/**

* web服務器啟動時執行

*/

@Override

public void contextInitialized(ServletContextEvent event) {

/**

* 初始化數據源

*/

String db_url=event.getServletContext().getInitParameter("DataBaseConfig");

try {

ConnectionManager.start(db_url);

} catch (SQLException e) {

e.printStackTrace();

}

}

}

package test.c3p0;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import c3p0.connection.ConnectionManager;

import c3p0.util.DateUtil;

public class Test {

/**

* @param args

*/

public static void main(String[] args) {

String currdate=DateUtil.getDateTime();

Connection conn=null;

PreparedStatement pstmt=null;

ResultSet res=null;

try {

String sql="insert into userinfo(username,password,sex,regdate) values(?,?,?,?)";

String sql4ID="select LAST_INSERT_ID()";

conn=ConnectionManager.getConnection();

conn.setAutoCommit(false);

pstmt=conn.prepareStatement(sql);

pstmt.setString(1, "tly");

pstmt.setString(2, "tly");

pstmt.setInt(3, 0);

pstmt.setString(4, currdate);//mysql中無需進行日期格式轉換

pstmt.executeUpdate();

pstmt=conn.prepareStatement(sql4ID);

res=pstmt.executeQuery();

if(res.next()){

int ID=res.getInt(1);

System.out.println("ID："+ID);

}

conn.commit();

} catch (SQLException e) {

e.printStackTrace();

try {

conn.rollback();

} catch (SQLException e1) {

e1.printStackTrace();

}

}finally{

ConnectionManager.release(conn, pstmt, res);

}

}

}

mysystem

index.html

index.htm

index.jsp

default.html

default.htm

default.jsp

ActionDispatcher

mystruts.actionfilter.ActionDispatcher

ActionDispatcher

*.action

DataBaseConfig

c3p0/c3p0.properties

mystruts.listener.ServletContextListen

在Test類中，調用ConnectionManager.getConnection()時，DataSource卻為null，但我在debug時，跟蹤查看，發現DataSource是被初始化了，不知什么原因造成初始化失敗，請大家幫忙查看下，謝謝

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