无法为Eclipse项目创建可运行的jar

Question

I have created small java application in eclipse. Everything is working fine when I am creating runnable jar from IDE. but somehow I am not able to create it via terminal (fyi I am using Mac).

Following is my project directory structure

./bin (Contains all compiled classes)
./lib (Contains all the third party lib I am using lib1.jar,lib2.jr, lib3.jar)
./src (Contains my java class = myProject.java)
manifest.txt (Contains 2 line, first line is Main-Class:myProject and second line is empty)

Following is the command that I used for compiling my classes

javac -d bin -sourcepath src -cp lib/lib1.jar:lib/lib2.jar:lib/lib3.jar src/myProject.java

To create jar file I am using following command

jar cvfm myProject.jar manifest.txt bin/*.class lib/*.jar

When I run this command I am getting invalid header field. Following is complete error message.

java.io.IOException: invalid header field
    at java.util.jar.Attributes.read(Attributes.java:393)
    at java.util.jar.Manifest.read(Manifest.java:180)
    at java.util.jar.Manifest.<init>(Manifest.java:50)
    at sun.tools.jar.Main.run(Main.java:149)
    at sun.tools.jar.Main.main(Main.java:1147)

I am not sure where I am going wrong. Can anyone point what mistake I am making or whether do I need to some more stuff ?

Thanks in advance.

Answer 1

The JAR File Specification can be of help here.

I think the problem behind the “invalid header field” message is that the value of the header field must begin with whitespace; try manifest.txt containing

Main-Class: myProject

instead.

As for accessing the classes in the lib/*.jar files, Java won't find classes inside jar files inside jar files—you can actually skip specifying lib/*.jar on the jar command line.

Here are two possibilities:

• Add

   Class-Path: lib/lib1.jar lib/lib2.jar lib/lib3.jar 

  to manifest.txt . The disadvantage to this is that if you distribute your jar and the library jars are not at the correct relative paths, there will be a ClassNotFoundError.

• Unzip all the .class files from inside lib/*.jar into a temporary directory and add them to myProject.jar . The advantage to this is that the jar is completely self-contained; the disadvantage is that it is a larger file that is more complicated and takes more time to create. You could use a shell script along these lines:

   mkdir lib/expanded cd lib/expanded for J in ../*.jar; do unzip "${J}" rm -rf META-INF done zip -R ../../myProject.jar * cd .. && rm -rf expanded 

  The META-INF directory is deleted after extracting each lib/*.jar file so that unzip won't ask whether to overwrite, and so that it doesn't overwrite the manifest of myProject.jar .

Answer 2

Reading through the jar manfile, I guess you could try something like this:

jar cvmfe manifest.txt myProjecy.jar myProject bin/*.class lib/*.jar

Where myProject is your entry class name. If that doesn't work, try removing the -m option and manifest.txt completely, I guess the -e option should take of the MainClass entry anyway.