How to wildcard include JAR files when compiling?

问题

I have the following in a java file (MyRtmpClient.java):

import org.apache.mina.common.ByteBuffer;

and ByteBuffer is inside a JAR file (with the proper directory structure of course). That jar file and others I need are in the same directory as the .java file.

Then I compile with the line:

javac -cp ".;*.jar" MyRtmpClient.java

But I get the error:

MyRtmpClient.java:3: package org.apache.mina.common does not exist import org.apache.mina.common.ByteBuffer;

How can I include jar files in my project?

回答1:

your command line is correct, but there are some considerations:

you must have javac >= 1.6, because only in that version the compiler parses the "*" as various JAR files.
you must be running Windows, because ";" is the path separator for that operating system only (it doesn't work on Unix, the path separator on Unix is ":").

I'm assuming that the JAR file has the proper directory structure as you stated.

回答2:

javac does not understand *.jar in the classpath argument. You need to explicitly specify each jar. e.g.

javac -cp ".;mina.jar" MyRtmpClient.java

回答3:

In javac JDK 6 and above You could use (note lack of .jar):

javac -cp ".;*" MyRtmpClient.java

to quote javac - Java programming language compiler

As a special convenience, a class path element containing a basename of * is considered equivalent to specifying a list of all the files in the directory with the extension .jar or .JAR.

For example, if directory foo contains a.jar and b.JAR, then the class path element foo/* is expanded to A.jar;b.JAR, except that the order of jar files is unspecified. All jar files in the specified directory, even hidden ones, are included in the list. A classpath entry consisting simply of * expands to a list of all the jar files in the current directory.

回答4:

In your case, I think JAVAC can not found jars file.

Please try:

PROJECT_PATH
- lib\a.jar
- src\package\b.java

cd @PROJECT_PATH

javac -classpath lib\a.jar src\package\b.java

回答5:

If you have utilities find and tr at your disposal (e.g. you're working Linux), you could do:

javac -cp .:`find * -name "*.jar" | tr "\n" ":"` MyRtmpClient.java

All jar files in the current directory and all it's sub-directories will be added (shell command lists all jar files and puts colons as separators between them).

Explanation:

pair of the backticks ( ` ) denote shell commands to be executed,
find * -name "*.jar" finds and lists all jar files in hierarchy whose root is current folder,
vertical bar ( | ) is pipe; connects output of find to the input of next command,
tr "\n" ":" replaces all newline characters with colon characters.

回答6:

Probably below syntax will work on windows dos command

javac -cp ".;first.jar;second.jar;third.jar" MyRtmpClient.java

回答7:

In Java 8, the option ".;*" etc. which are mentioned above did not seem to work. I tried and found that : javac -cp '<location of jars>/*' MyRtmpClient.java

works:

<location of jar> can be /usr/local/classes/* or /home/developer/MyProject/*