在Ubuntu中编译Servlet返回错误

Question

I am attempting to compile source code to be used in a webapp. I know things in Ubuntu are not like things in Windows and that setting classpath permanently is not a good thing to do so I decided to set the flag temporarily. Here is my command in terminal:

littlejavachild@ubuntu:~/LittleJavaChild/ServletProjects/beerV1$ javac -cp "/usr/share/tomcat7/servlet-api.jar" -d classes src/com/example/*.java

What I am trying to achieve is:

compile all the .java files in the package com.example

send the .class files directly to the appropriate directories

copy the classes folder to the WEB-INF folder

Despite setting the classpath I get the errors:

src/com/example/ListenerTester.java:3: error: package javax.servlet does not exist
import javax.servlet.*;
^
src/com/example/ListenerTester.java:4: error: package javax.servlet.http does not exist
import javax.servlet.http.*;
^
src/com/example/ListenerTester.java:7: error: cannot find symbol
public class ListenerTester extends HttpServlet{
                                    ^
  symbol: class HttpServlet
src/com/example/ListenerTester.java:8: error: cannot find symbol
    public void doGet(HttpServletRequest request,
                      ^
  symbol:   class HttpServletRequest
  location: class ListenerTester
src/com/example/ListenerTester.java:9: error: cannot find symbol
                HttpServletResponse response) throws IOException, ServletException {
                ^
  symbol:   class HttpServletResponse
  location: class ListenerTester
src/com/example/ListenerTester.java:9: error: cannot find symbol
                HttpServletResponse response) throws IOException, ServletException {
                                                                  ^
  symbol:   class ServletException
  location: class ListenerTester
src/com/example/MyServletContextListener.java:2: error: package javax.servlet does not exist
import javax.servlet.*;
^
src/com/example/MyServletContextListener.java:4: error: cannot find symbol
public class MyServletContextListener implements ServletContextListener{
                                                 ^
  symbol: class ServletContextListener
src/com/example/MyServletContextListener.java:5: error: cannot find symbol
    public void contextInitialized(ServletContextEvent event){
                                   ^
  symbol:   class ServletContextEvent
  location: class MyServletContextListener
src/com/example/MyServletContextListener.java:12: error: cannot find symbol
    public void contextDestroyed(ServletContextEvent event){
                                 ^
  symbol:   class ServletContextEvent
  location: class MyServletContextListener
src/com/example/ListenerTester.java:14: error: cannot find symbol
        Dog dog = (Dog) getServletContext().getAttribute("dog");
                        ^
  symbol:   method getServletContext()
  location: class ListenerTester
src/com/example/MyServletContextListener.java:6: error: cannot find symbol
        ServletContext sc = event.getServletContext();
        ^
  symbol:   class ServletContext
  location: class MyServletContextListener  

---

I know these errors occur when the classpath is not set properly. Please help me with this. Tell me what is wrong and how do I go about correcting it and how to avoid it in future.

Update with -verbose

[search path for class files: /usr/lib/jvm/java-7-openjdk-i386/jre/lib/resources.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/rt.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/sunrsasign.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jsse.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jce.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/charsets.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/netx.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/plugin.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/rhino.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/jfr.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/classes,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/localedata.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/sunjce_provider.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/dnsns.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/java-atk-wrapper.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/pulse-java.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/sunpkcs11.jar,/usr/lib/jvm/java-7-openjdk-i386/jre/lib/ext/z ipfs.jar,.,/usr/share/tomcat7/servlet-api.jar]

Answer 1

Split the task in bits, and let's just try to compile the java files first. Later check for how to move the class file.

The error indeed says that it didn't find the required class, so the jar isn't added correctly to the classpath. Check this

javac -classpath .:/usr/share/tomcat7/servlet-api.jar src/com/example/*.java

Ensure the jar is present at the given location. Also try running this from the src folder and giving the path as com/example/*.java

Answer 2

I would try using -classpath and not -cp . The Ubuntu man page for javac does not indicate a -cp option. You can also add -verbose to get more output from javac .

Note: The javac implementation on my mac disagrees, but I'm not on an ubuntu machine atm.