Flex provides a simple interface to the command-line compilers. For UNIX users, there is a shell script. For Windows users, there is an executable file. These files are located in the bin directory. You can also invoke the compilers using Java. This lets you integrate the compilers into Java-based projects (such as Ant) or other utilities.

The shell scripts and executable files for the command-line compilers wrap calls to the mxmlc.jar and compc.jar JAR files. To invoke the compilers from Java, you call the JAR files directly. For Flex SDK, the JAR files are located in the flex_install_dir/lib directory. For Flex Builder, they are located in the flex_builder_install_dir/sdks/sdk_version/lib.

To invoke a command in a JAR file, use the java command from the command line and specify the JAR file you want to execute with the jar option. You must also specify the value of the +flexlib option. This advanced option lets you set the root directory that is used by the compiler to locate the flex-config.xml file, among other files. You typically point it to your frameworks directory. From there, the compiler can detect the location of other configuration files.

The following example compiles MyApp.mxml into a SWF file using the JAR file to invoke the mxmlc compiler:

java -jar ../lib/mxmlc.jar +flexlib c:/flex_3_sdk/frameworks c:/flex3/MyApp.mxml

You pass all other options as you would when you open the command-line compilers. The following example sets the locale and source path when compiling MyApp:

java -jar ../lib/mxmlc.jar +flexlib c:/flex_3_sdk/frameworks -locale en_US -source-path locale/{locale} c:/flex3/MyApp.mxml