错误：即使在添加CLASSPATH变量后，包javax.servlet.http也不存在

我正在尝试实现基本的HelloServlet.java程序。 但它似乎正在产生这些错误

HelloServlet.java:7: error: cannot find symbol
public class HelloServlet extends HttpServlet {
                                  ^
  symbol: class HttpServlet
HelloServlet.java:11: error: cannot find symbol
   public void init() throws ServletException {
                             ^
  symbol:   class ServletException
  location: class HelloServlet
HelloServlet.java:16: error: cannot find symbol
   public void doGet(HttpServletRequest request, HttpServletResponse response)
                     ^
  symbol:   class HttpServletRequest
  location: class HelloServlet
HelloServlet.java:16: error: cannot find symbol
   public void doGet(HttpServletRequest request, HttpServletResponse response)
                                                 ^
  symbol:   class HttpServletResponse
  location: class HelloServlet
HelloServlet.java:17: error: cannot find symbol
      throws ServletException, IOException {
             ^
  symbol:   class ServletException
  location: class HelloServlet
HelloServlet.java:3: error: package javax.servlet does not exist
import javax.servlet.*;
^
HelloServlet.java:4: error: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
7 errors

我已经为jar文件添加了类路径

nithinchandranp@b-40:~$ echo ${CLASSPATH}
/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/*
nithinchandranp@b-40:~$ 

现在我做错了什么？

---

请帮助..

编译java类时，可以使用

-cp

参数提供类所需的类路径/库。对于您的案例，您需要提供给

servlet api.jar

。您可以编译Servlet，如下所示：

---

javac-cp/usr/local/ceral/tomcat/9.0.6/libexec/lib/servlet-api.jar HelloServlet.java

编译java类时，可以使用

-cp

参数提供类所需的类路径/库。对于您的案例，您需要提供给

servlet api.jar

。您可以编译Servlet，如下所示：

---

javac-cp/usr/local/ceral/tomcat/9.0.6/libexec/lib/servlet-api.jar HelloServlet.java

这是我的错误

这就是我通过命令行创建类路径的方式

 export CLASSPATH=/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/*

我创建的目录不是ApacheTomcat，而是ApacheTomcat（中间有一个空格）

也许这就是CLASSPATH变量无法识别正确位置的原因

我将目录名改为ApacheTomcat（删除了空格）

现在，我在.bashrc文件中定义了CLASSPATH变量，如下所示：

#classpath
export CLASSPATH=/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/*

现在，当我执行echo${CLASSPATH}时，我得到了我提到的所有jar文件

nithinchandranp@b-40:~$ echo ${CLASSPATH}
/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/annotations-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-ant.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-ha.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-storeconfig.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-tribes.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/ecj-4.6.3.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/el-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jasper-el.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jasper.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jaspic-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jsp-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/servlet-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-coyote.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-dbcp.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-es.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-fr.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-ja.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-ru.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-jdbc.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-jni.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-util.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-util-scan.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-websocket.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/websocket-api.jar

---

这是我的一个错误

这就是我通过命令行创建类路径的方式

 export CLASSPATH=/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/*

我创建的目录不是ApacheTomcat，而是ApacheTomcat（中间有一个空格）

也许这就是CLASSPATH变量无法识别正确位置的原因

我将目录名改为ApacheTomcat（删除了空格）

现在，我在.bashrc文件中定义了CLASSPATH变量，如下所示：

#classpath
export CLASSPATH=/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/*

现在，当我执行echo${CLASSPATH}时，我得到了我提到的所有jar文件

nithinchandranp@b-40:~$ echo ${CLASSPATH}
/home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/annotations-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-ant.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-ha.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-storeconfig.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/catalina-tribes.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/ecj-4.6.3.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/el-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jasper-el.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jasper.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jaspic-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/jsp-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/servlet-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-api.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-coyote.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-dbcp.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-es.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-fr.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-ja.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-i18n-ru.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-jdbc.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-jni.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-util.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-util-scan.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/tomcat-websocket.jar /home/nithinchandranp/ApacheTomcat/apache-tomcat-8.5.34/lib/websocket-api.jar

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末尾带有*的类路径不适用于jar数据集。必须将每个jar放在类路径中。

末尾带有*的类路径不能用于jar数据集。你必须把每个jar放在你的类路径中。

你在哪里看到这些错误，你在使用IDE吗？不，我在终端工作，你在哪里看到这些错误，你在使用IDE吗？不，我在终端工作。当我检查Stackoverflow的其他问题时，我确实找到了编译java文件的方法。这对我来说很好。但是使用类路径要简单得多，对吗？就像我们不必在编译期间提及所有jar文件一样，当我检查Stackoverflow的其他问题时，我确实找到了编译java文件的方法。这对我来说很好。但是使用类路径要简单得多，对吗？就像我们不必在编译期间提及所有jar文件一样。就像我在回答中提到的，我使用了通配符（*）将所有jar文件包含在特定目录中，并且所有jar文件都添加到了类路径中。单独添加它并不是我在回答中提到的必要条件，我使用了通配符（*）来包含特定目录中的所有jar文件，并且所有jar文件都被添加到了类路径中