itVincent , 非常感謝您的回復.看到您的回復,我就作了一下測試.

我的測試代碼如下:

????????????? //InputStream in=LoginAction.class.getClassLoader().getResourceAsStream("com.yourcompany.struts.config.properties");

????????????? InputStream in=LoginAction.class.getClassLoader().getResourceAsStream("com//yourcompany//struts//config.properties");

?????????????

????????????? System.out.println("properties? in? is? :?? "+in);

????????????? Properties? p=new Properties();

????????????? try {

???????????????????? p.load(in);

???????????????????? String h=p.getProperty("JAVA_HOME");

???????????????????? System.out.println("JAVA_HOME?? :? --? "+h);??

????????????? } catch (IOException e1) {

???????????????????? e1.printStackTrace();

????????????? }

?

我是在一個 action 中寫的這段代碼 .

執行后的結果如下:（錯誤）

properties? in? is? :?? null

2006-10-24 20:36:59 org.apache.struts.action.RequestProcessor processExc

警告 : Unhandled Exception thrown: class java.lang.NullPointerException

?

頁面的錯誤是:

message

?

description The server encountered an internal error () that prevented it from fulfilling this request.

?

exception

?

javax.servlet.ServletException

?????? org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:523)

?????? org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)

?????? org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)

?????? org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)

?????? org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)

?????? javax.servlet.http.HttpServlet.service(HttpServlet.java:709)

?????? javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

?

?

root cause

?

java.lang.NullPointerException

?????? java.util.Properties$LineReader.readLine(Properties.java:365)

?????? java.util.Properties.load(Properties.java:293)

?????? com.yourcompany.struts.action.LoginAction.execute(LoginAction.java:134)

?????? org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)

?????? org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)

?????? org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)

?????? org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)

?????? javax.servlet.http.HttpServlet.service(HttpServlet.java:709)

?????? javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

?

?

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.

?

?????? 然后我又作了如下的測試：

????????????? InputStream in1=LoginAction.class.getClassLoader().getResourceAsStream("config.properties");

?????????????

????????????? System.out.println("properties? in? is? :?? "+in1);

????????????? Properties? p1=new Properties();

????????????? try {

???????????????????? p1.load(in1);

???????????????????? String h1=p1.getProperty("JAVA_HOME");

???????????????????? System.out.println("JAVA_HOME?? :? --? "+h1);

????????????? } catch (IOException e1) {

???????????????????? // TODO Auto-generated catch block

???????????????????? e1.printStackTrace();

????????????? }

執行后的結果如下：（正確）

properties? in? is? :?? java.io.ByteArrayInputStream@257b34

JAVA_HOME?? :? --? c:jdk

xml file? url? is? :? file:/D:/jakarta-tomcat-5.0.28/webapps/StrutsDemo/WEB-INF/

classes/config.xml

inputStream of the xml file? is? :? java.io.BufferedInputStream@ca5bff

reader?? :?? org.dom4j.io.SAXReader@1cd3dd7

document doc? is? :? org.dom4j.tree.DefaultDocument@13c4c09 [Document: name null

]

action? document? is? :? org.dom4j.tree.DefaultDocument@13c4c09 [Document: name

null]

note? List is : 1

java home? node? is? :? org.dom4j.tree.DefaultElement@f1f34a [Element: <java att

ributes: []/>]

the value of the java node? is? :? c:\jdk

?

兩次的結果不同點的分析：

?????? （主要看藍色的代碼部分，文件的存放位置的不同）

?????? 第一種方法，配置文件在 WEB-INF/classes/ com/yourcompany/struts/config.properties 目錄下放著。也就是在包目錄下。

?????? 第二種方法，配置文件在 WEB-INF/classes/ 目錄下存放。也就是根目錄下。

?????? 所以如果用第二種方法來讀第一種配置文件，就會出錯。

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以上是我的個人見解,歡迎批評指正.zhyiwww@163.com

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