好奇怪，我写在JSP里是对的，写在BEAN里就错了，怎么会事~~

楼上，怎么解决啊，我不太明白你的意思啊
我用的服务器是TOMCAT，你说的JNDI的配置是什么意思
以前我有个BEAN也是那样写的，而且正常使用呢~~

不过有些变动，原来的数据库连接池是配置的ROOT目录，现在配置的是自己建的虚拟目录
不知道会不会影响，至少我的JSP文件能运行啊~

<Context path="/bqll" docBase="bqll" debug="0" reloadable="true" crossContext="true">
          <Resource name="jdbc/xq" auth="Container" type="javax.sql.DataSource"/>
          <ResourceParams name="jdbc/xq" >

          <parameter>
              <name>factory</name>
              <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
          </parameter>

          <parameter>
              <name>driverClassName</name>
              <value>com.microsoft.jdbc.sqlserver.SQLServerDriver</value>
          </parameter>

          <parameter>
              <name>url</name>
              <value>jdbc:microsoft:sqlserver://10.0.0.80:2433;DatabaseName=DB_8760db</value>
          </parameter>

          <parameter>
              <name>username</name>
              <value>sa</value>
          </parameter>

          <parameter>
              <name>password</name>
              <value>sqlserver</value>
          </parameter>

          <parameter>
              <name>maxActive</name>
              <value>20</value>
          </parameter>

          <parameter>
              <name>maxIdle</name>
              <value>10</value>
          </parameter>

          <parameter>
              <name>maxWait</name>
              <value>-1</value>
          </parameter>

          </ResourceParams>

         </Context>这就是我在Server.xml里的配置，配置在JSP文件中正常使用~

很奇怪啊，楼主的应用服务器是什么，BEAN又是怎么运行的？以Tomcat应用服务器为例，在Tomcat启动的时候会向系统属性中添加一个属性（默认的web应用）：
System.setProperty(javax.naming.Context.INITIAL_CONTEXT_FACTORY,"org.apache.naming.java.javaURLContextFactory");
如果有了这个javax.naming.Context.INITIAL_CONTEXT_FACTORY项，在new InitalContext()的时候就不会报出楼主的错误。从异常信息：Need to specify class name in environmen
t or system property, or as an applet parameter, or in an application resource f
ile中可以看出，传递javax.naming.Context.INITIAL_CONTEXT_FACTORY参数的值的方式。

我有下面几个问题，麻烦楼主回答一下。1。目前你的JVM属性中有没有java.naming.factory.initial一项属性，利用System.getProperty()可以获取出属性来，这项属性是什么？
2。你的DataSource是如何构造出来的？目前Tomcat推荐的是：
InitialContext cxt = new InitialContext();
DataSource ds = (DataSource) cxt.lookup( "java:/comp/env/jdbc/TestDB" );
3。由于属性是Tomcat启动时加载的，如果没有属性，需要研究有没有什么类修改过这项属性。

好的，先谢谢，但你要完全明白我已经给出的信息~~out.println(System.getProperty());    //这样？？？要抱错啊DBConn文件如下：package dqh.DBConn;import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;public class GetConn
{
     public static synchronized Connection getConnection( ) throws Exception
     {
          try
          {
               Context initCtx = new javax.naming.InitialContext( );
               Context envCtx = ( Context ) initCtx.lookup( "java:comp/env" );
               DataSource ds = ( DataSource ) envCtx.lookup( "jdbc/xq" );
               return ds.getConnection( );
          }
          catch( SQLException e )
          {
               throw e;
          }
          catch( NamingException e )
          {
               throw e;
          }
     }
}

楼上的老兄，System.getProperty()是需要参数的：
System.getProperty("java.naming.factory.initial")，如果为null，那么你在这个web应用的jsp页面中肯定也无法获取到正确的InitialContext还是那句话，你的bean是怎么运行的？是采用jsp:useBean吗？如果是的话，在这个bean访问出错的web应用中，jsp页面能否正常获取到数据源？如果jsp页面也无法获取到数据源，报出同样的问题，说明你在conf\server.xml文件的配置出现了不同，在tomcat的context定义中，有一项属性useNaming，你是否设置为了false
<Context useNaming="false" />不知道这样解释是否清楚！

还是那句话，你的bean是怎么运行的？是采用jsp:useBean吗？如果是的话，在这个bean访问出错的web应用中，jsp页面能否正常获取到数据源？
-------------------------------------
能，我说的JSP能访问，就是同一WEB应用System.getProperty("java.naming.factory.initial")的结果是org.apache.naming.java.javaURLContextFactory

<%@ page import="dqh.news.NewsBean" %>然后
NewsBean nb=new NewsBean()
这样用的

我无法重现你的现象，我也没有办法找到新的解决办法，下面是我对JDK这部分代码的研究，请你根据下面的步骤自己来判断一下到底问题在哪里，很抱歉！1。查看类javax.naming.InitialContext的构造方法，new InitialContext()方法，里面执行init(null);
2。查看InitialContext.init(Hashtable)方法，下面是代码：
protected void init(Hashtable environment) throws NamingException {
myProps = ResourceManager.getInitialEnvironment(environment); if (myProps.get(Context.INITIAL_CONTEXT_FACTORY) != null) {
    // user has specified initial context factory; try to get it
    getDefaultInitCtx();
}
    }
3。从上面的代码可以看出，一定是从getDefaultInitCtx()方法调用进去的，否则defaultInitCtx属性将为null，不会出现楼主遇到的异常。
4。下面是getDefaultInitCtx()方法
protected Context getDefaultInitCtx() throws NamingException{
if (!gotDefault) {
    defaultInitCtx = NamingManager.getInitialContext(myProps);
    gotDefault = true;
}
if (defaultInitCtx == null)
    throw new NoInitialContextException(); return defaultInitCtx;
    }
调用了NamingManager.getInitialContext()方法。
5。下面是NamingManager.getInitialContext()方法：
public static Context getInitialContext(Hashtable env)
throws NamingException {
InitialContextFactory factory; InitialContextFactoryBuilder builder = getInitialContextFactoryBuilder();
if (builder == null) {
    // No factory installed, use property
    // Get initial context factory class name     String className = env != null ?
        (String)env.get(Context.INITIAL_CONTEXT_FACTORY) : null;
    if (className == null) {
NoInitialContextException ne = new NoInitialContextException(
    "Need to specify class name in environment or system " +
    "property, or as an applet parameter, or in an " +
    "application resource file:  " +
    Context.INITIAL_CONTEXT_FACTORY);
throw ne;
    }     try {
factory = (InitialContextFactory)
    helper.loadClass(className).newInstance();
    } catch(Exception e) {
NoInitialContextException ne =
    new NoInitialContextException(
"Cannot instantiate class: " + className);
ne.setRootCause(e);
throw ne;
    }
} else {
    factory = builder.createInitialContextFactory(env);
} return factory.getInitialContext(env);
    }
异常出现了，就是从env中没有找到Context.INITIAL_CONTEXT_FACTORY对应的类名。
6。现在回来看历史代码，env=myProps，也就是关系到ResourceManager.getInitialEnvironment(environment);方法，其中的environment=null。
7。下面是ResourceManager.getInitialEnvironment(Hashtable)方法，也是我们分析的重点：
public static Hashtable getInitialEnvironment(Hashtable env)
    throws NamingException
    {
String[] props = VersionHelper.PROPS; // system/applet properties
if (env == null) {
    env = new Hashtable(11);
}
Applet applet = (Applet)env.get(Context.APPLET); //applet肯定是null // Merge property values from env param, applet params, and system
// properties.  The first value wins:  there's no concatenation of
// colon-separated lists.
// Read system properties by first trying System.getProperties(),
// and then trying System.getProperty() if that fails.  The former
// is more efficient due to fewer permission checks.
//
String[] jndiSysProps = helper.getJndiProperties();
for (int i = 0; i < props.length; i++) {
    Object val = env.get(props[i]);
    if (val == null) { //肯定进入这个分支
if (applet != null) { //肯定不进入这个分支
    val = applet.getParameter(props[i]);
}
if (val == null) { //肯定进入这个分支
    // Read system property.
    val = (jndiSysProps != null)
? jndiSysProps[i]
: helper.getJndiProperty(i);
}
if (val != null) {
    env.put(props[i], val);
}
    }
} // Merge the above with the values read from all application
// resource files.  Colon-separated lists are concatenated.
mergeTables(env, getApplicationResources());
return env;
    }
下面是我个人的一下观察：
VersionHelper：
final static String[] PROPS = new String[] {
javax.naming.Context.INITIAL_CONTEXT_FACTORY,
javax.naming.Context.OBJECT_FACTORIES,
javax.naming.Context.URL_PKG_PREFIXES,
javax.naming.Context.STATE_FACTORIES,
javax.naming.Context.PROVIDER_URL,
javax.naming.Context.DNS_URL,
// The following shouldn't create a runtime dependence on ldap package.
javax.naming.ldap.LdapContext.CONTROL_FACTORIES
    };
所以问题的关键就是谁实现了VersionHelper，但是由于JSP页面和你的类都会进入相同的逻辑代码（也就是同一个Web应用，默认的versionHelper的实现也是一个），所以我也不知道，你的问题到底出现在了哪里？而且我自己的代码例子中也没有出现楼主的现象。

我看了一下，是JDK中的VersionHelper12实现了VersionHelper接口，下面是代码，希望对楼主有所帮助：
final class VersionHelper12 extends VersionHelper {    private boolean getSystemPropsFailed = false;    VersionHelper12() {} // Disallow external from creating one of these.    public Class loadClass(String className) throws ClassNotFoundException {
ClassLoader cl = getContextClassLoader();
return Class.forName(className, true, cl);
    }    /**
      * Package private.
      */
    Class loadClass(String className, ClassLoader cl)
throws ClassNotFoundException {
return Class.forName(className, true, cl);
    }    /**
     * @param className A non-null fully qualified class name.
     * @param codebase A non-null, space-separated list of URL strings.
     */
    public Class loadClass(String className, String codebase)
throws ClassNotFoundException, MalformedURLException {
ClassLoader cl; ClassLoader parent = getContextClassLoader();
cl = URLClassLoader.newInstance(getUrlArray(codebase), parent); return Class.forName(className, true, cl);
    }    String getJndiProperty(final int i) {
return (String) AccessController.doPrivileged(
    new PrivilegedAction() {
public Object run() {
    try {
return System.getProperty(PROPS[i]);
    } catch (SecurityException e) {
return null;
    }
        }
    }
);
    }    String[] getJndiProperties() {
if (getSystemPropsFailed) {
    return null; // after one failure, don't bother trying again
}
Properties sysProps = (Properties) AccessController.doPrivileged(
    new PrivilegedAction() {
public Object run() {
    try {
return System.getProperties();
    } catch (SecurityException e) {
getSystemPropsFailed = true;
return null;
    }
}
    }
);
if (sysProps == null) {
    return null;
}
String[] jProps = new String[PROPS.length];
for (int i = 0; i < PROPS.length; i++) {
    jProps[i] = sysProps.getProperty(PROPS[i]);
}
return jProps;
    }    InputStream getResourceAsStream(final Class c, final String name) {
return (InputStream) AccessController.doPrivileged(
    new PrivilegedAction() {
public Object run() {
            return c.getResourceAsStream(name);
        }
    }
);
    }    InputStream getJavaHomeLibStream(final String filename) {
return (InputStream) AccessController.doPrivileged(
    new PrivilegedAction() {
public Object run() {
    try {
String javahome = System.getProperty("java.home");
if (javahome == null) {
    return null;
}
String pathname = javahome + java.io.File.separator +
    "lib" + java.io.File.separator + filename;
return new java.io.FileInputStream(pathname);
    } catch (Exception e) {
return null;
    }
}
    }
);
    }    NamingEnumeration getResources(final ClassLoader cl, final String name)
    throws IOException
    {
Enumeration urls;
try {
    urls = (Enumeration) AccessController.doPrivileged(
new PrivilegedExceptionAction() {
    public Object run() throws IOException {
return (cl == null)
    ? ClassLoader.getSystemResources(name)
    : cl.getResources(name);
    }
}
    );
} catch (PrivilegedActionException e) {
    throw (IOException)e.getException();
}
return new InputStreamEnumeration(urls);
    }    ClassLoader getContextClassLoader() {
return (ClassLoader) AccessController.doPrivileged(
    new PrivilegedAction() {
public Object run() {
    return Thread.currentThread().getContextClassLoader();
}
    }
);
    }
    /**
     * Given an enumeration of URLs, an instance of this class represents
     * an enumeration of their InputStreams.  Each operation on the URL
     * enumeration is performed within a doPrivileged block.
     * This is used to enumerate the resources under a foreign codebase.
     * This class is not MT-safe.
     */
    class InputStreamEnumeration implements NamingEnumeration { private final Enumeration urls; private Object nextElement = null; InputStreamEnumeration(Enumeration urls) {
    this.urls = urls;
} /*
* Returns the next InputStream, or null if there are no more.
* An InputStream that cannot be opened is skipped.
*/
private Object getNextElement() {
    return AccessController.doPrivileged(
new PrivilegedAction() {
    public Object run() {
while (urls.hasMoreElements()) {
    try {
return ((URL)urls.nextElement()).openStream();
    } catch (IOException e) {
// skip this URL
    }
}
return null;
    }
}
    );
} public boolean hasMore() {
    if (nextElement != null) {
return true;
    }
    nextElement = getNextElement();
    return (nextElement != null);
} public boolean hasMoreElements() {
    return hasMore();
} public Object next() {
    if (hasMore()) {
Object res = nextElement;
nextElement = null;
return res;
    } else {
throw new NoSuchElementException();
    }
} public Object nextElement() {
    return next();
} public void close() {
}
    }
}

TO:bison_java(Java野牛) (
我解决了，非常感谢你的，至于原因嘛，我说出来都觉得丢脸！
1：我写了个MAIN函数去测试那个BEAN，它怎么可能调用TOMCAT的配置嘛，就等于运行一个JAVA文件
2：调用BEAN的JSP文件有两个错误，一少写个new Bean(....)的new，第2，我有个构造参数是int
结果，我忘记转换了气死我了，还烦恼了我两天
等会就结帖~，分太少，望谅解~

调试易

好奇怪，我写在JSP里是对的，写在BEAN里就错了，怎么会事~~

解决方案 »