帮我看看这两种运行方式有什么不同

yingShisscWang 2012-01-02 09:34:59

我在tomcat里配了一个数据库连接池，我用两种方式去调用下面这段代码。第一种，我直接用main方法调用，第二种我在jsp
页面里面调用<%out.println(GetConnectionTest.show()%>。第二种成功了，但是第一种却显示没有找到源，下面是代码和错误信息：





package test;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;



import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

import javax.sql.DataSource;



public class GetConnectionTest {

	public static void main(String[] args) {  

		GetConnectionTest.show();

    }  

	

	public  static String show(){

		 InitialContext ctx;  

	        PreparedStatement pstmt = null;  

	        Connection conn = null;  

	        String sql = "select * from user"; 

	        String show = null;

	        try {  

	            ctx = new InitialContext();  

	            /* 

	             * 在下面的字符串"java:comp/env/jdbc/course"中，*"java:comp/env/"是不变的， 

	             * 而"jdbc/course"大家应该还记得自己之前起的数据源名称吧！ 

	             */  

	            //DataSource ds = (DataSource) ctx.lookup("java:comp/env/jdbc/TestDB");  

	            Context context = (Context)ctx.lookup("java:comp/env/");

	            DataSource ds = (DataSource)context.lookup("jdbc/TestDB");

	            conn = ds.getConnection();  

	            System.out.println("got conn");

	            pstmt = conn.prepareStatement(sql);  

	            ResultSet rs = pstmt.executeQuery(); 

	            rs.last();

	            System.out.println("row:" + rs.getRow());

	            rs.first();

	            show = rs.getString(2) +"||" +rs.getInt(3);

	            

	        } catch (NamingException e) {  

	            e.printStackTrace();  

	        } catch (SQLException e) {  

	            e.printStackTrace();  

	        } 

	        return show;

	}

}



javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file:  java.naming.factory.initial

	at javax.naming.spi.NamingManager.getInitialContext(Unknown Source)

	at javax.naming.InitialContext.getDefaultInitCtx(Unknown Source)

	at javax.naming.InitialContext.getURLOrDefaultInitCtx(Unknown Source)

	at javax.naming.InitialContext.lookup(Unknown Source)

	at test.GetConnectionTest.show(GetConnectionTest.java:30)

	at test.GetConnectionTest.main(GetConnectionTest.java:14)

...全文