ajc — compiler and bytecode weaver for the AspectJ and Java languages
ajc [
Options] [
file... | @
file... | -argfile
file... ]
The
ajc command compiles and weaves AspectJ and Java source and .class
files, producing .class files compliant with any Java VM (1.1 or later). It
combines compilation and bytecode weaving and supports incremental builds; you
can also weave bytecode at run-time using
"" >.
The arguments after the options specify the source file(s) to compile. To
specify source classes, use
-inpath (below). Files may be listed
directly on the command line or in a file. The
-argfile file and
@file forms are equivalent, and are interpreted as meaning all
the arguments listed in the specified file.
Note: You must explicitly pass
ajc all necessary sources. Be sure
to include the source not only for the aspects or pointcuts but also for any
affected types. Specifying all sources is necessary because, unlike javac, ajc
does not search the sourcepath for classes. (For a discussion of what affected
types might be required, see
The AspectJ Programming Guide,
Implementation Appendix ../progguide/implementation.html) .
To specify sources, you can list source files as arguments or use the options
-sourceroots or
-inpath. If there are multiple sources for any
type, the result is undefined since ajc has no way to determine which source
is correct. (This happens most often when users include the destination
directory on the inpath and rebuild.)
- -injars JarList
- deprecated: since 1.2, use -inpath, which also takes
directories.
- -inpath Path
- Accept as source bytecode any .class files in the The
output will include these classes, possibly as woven with any applicable
aspects. Path is a single argument containing a list of paths to zip files
or directories, delimited by the platform-specific path delimiter.
- -aspectpath Path
- Weave binary aspects from jar files and directories on path
into all sources. The aspects should have been output by the same version
of the compiler. When running the output classes, the run classpath should
contain all aspectpath entries. Path, like classpath, is a single argument
containing a list of paths to jar files, delimited by the platform-
specific classpath delimiter.
- -argfile File
- The file contains a line-delimited list of arguments. Each
line in the file should contain one option, filename, or argument string
(e.g., a classpath or inpath). Arguments read from the file are inserted
into the argument list for the command. Relative paths in the file are
calculated from the directory containing the file (not the current working
directory). Comments, as in Java, start with // and extend to the
end of the line. Options specified in argument files may override rather
than extending existing option values, so avoid specifying options like
-classpath in argument files unlike the argument file is the only
build specification. The form @file is the same as specifying
-argfile file.
- -outjar output.jar
- Put output classes in zip file output.jar.
- -outxml
- Generate aop.xml file for load-time weaving with default
name.
- -outxmlfile custom/aop.xml
- Generate aop.xml file for load-time weaving with custom
name.
- -incremental
- Run the compiler continuously. After the initial
compilation, the compiler will wait to recompile until it reads a newline
from the standard input, and will quit when it reads a 'q'. It will only
recompile necessary components, so a recompile should be much faster than
doing a second compile. This requires -sourceroots.
- -sourceroots DirPaths
- Find and build all .java or .aj source files under any
directory listed in DirPaths. DirPaths, like classpath, is a single
argument containing a list of paths to directories, delimited by the
platform- specific classpath delimiter. Required by -incremental.
- -crossrefs
- Generate a build .ajsym file into the output directory.
Used for viewing crosscutting references by tools like the AspectJ
Browser.
- -emacssym
- Generate .ajesym symbol files for emacs support
(deprecated).
- -Xlint
- Same as -Xlint:warning (enabled by default)
- -Xlint:{level}
- Set default level for messages about potential programming
mistakes in crosscutting code. {level} may be ignore, warning, or error.
This overrides entries in org/aspectj/weaver/XlintDefault.properties from
aspectjtools.jar, but does not override levels set using the -Xlintfile
option.
- -Xlintfile PropertyFile
- Specify properties file to set levels for specific
crosscutting messages. PropertyFile is a path to a Java .properties file
that takes the same property names and values as
org/aspectj/weaver/XlintDefault.properties from aspectjtools.jar, which it
also overrides.
- -help
- Emit information on compiler options and usage
- -version
- Emit the version of the AspectJ compiler
- -classpath Path
- Specify where to find user class files. Path is a single
argument containing a list of paths to zip files or directories, delimited
by the platform-specific path delimiter.
- -bootclasspath Path
- Override location of VM's bootclasspath for purposes of
evaluating types when compiling. Path is a single argument containing a
list of paths to zip files or directories, delimited by the
platform-specific path delimiter.
- -extdirs Path
- Override location of VM's extension directories for
purposes of evaluating types when compiling. Path is a single argument
containing a list of paths to directories, delimited by the
platform-specific path delimiter.
- -d Directory
- Specify where to place generated .class files. If not
specified, Directory defaults to the current working dir.
- -target [1.1 to 1.5]
- Specify classfile target setting (1.1 to 1.5, default is
1.2)
- -1.3
- Set compliance level to 1.3 This implies -source 1.3 and
-target 1.1.
- -1.4
- Set compliance level to 1.4 (default) This implies -source
1.4 and -target 1.2.
- -1.5
- Set compliance level to 1.5. This implies -source 1.5 and
-target 1.5.
- -source [1.3|1.4|1.5]
- Toggle assertions (1.3, 1.4, or 1.5 - default is 1.4). When
using -source 1.3, an assert() statement valid under Java 1.4 will result
in a compiler error. When using -source 1.4, treat assert as a
keyword and implement assertions according to the 1.4 language spec. When
using -source 1.5, Java 5 language features are permitted.
- -nowarn
- Emit no warnings (equivalent to '-warn:none') This does not
suppress messages generated by declare warning or Xlint.
- -warn: items
- Emit warnings for any instances of the comma-delimited list
of questionable code (eg '-warn:unusedLocals,deprecation'):
constructorName method with constructor name
packageDefaultMethod attempt to override package-default method
deprecation usage of deprecated type or member
maskedCatchBlocks hidden catch block
unusedLocals local variable never read
unusedArguments method argument never read
unusedImports import statement not used by code in file
none suppress all compiler warnings
-warn:none does not suppress messages generated by
declare warning
or
Xlint.
- -deprecation
- Same as -warn:deprecation
- -noImportError
- Emit no errors for unresolved imports
- -proceedOnError
- Keep compiling after error, dumping class files with
problem methods
- -g:[lines,vars,source]
- debug attributes level, that may take three forms:
-g all debug info ('-g:lines,vars,source')
-g:none no debug info
-g:{items} debug info for any/all of [lines, vars, source], e.g.,
-g:lines,source
- -preserveAllLocals
- Preserve all local variables during code generation (to
facilitate debugging).
- -referenceInfo
- Compute reference information.
- -encoding format
- Specify default source encoding format. Specify custom
encoding on a per file basis by suffixing each input source file/folder
name with '[encoding]'.
- -verbose
- Emit messages about accessed/processed compilation units
- -showWeaveInfo
- Emit messages about weaving
- -log file
- Specify a log file for compiler messages.
- -progress
- Show progress (requires -log mode).
- -time
- Display speed information.
- -noExit
- Do not call System.exit(n) at end of compilation (n=0 if no
error)
- -repeat N
- Repeat compilation process N times (typically to do
performance analysis).
- -XterminateAfterCompilation
- Causes compiler to terminate before weaving
- -XaddSerialVersionUID
- Causes the compiler to calculate and add the
SerialVersionUID field to any type implementing Serializable that is
affected by an aspect. The field is calculated based on the class before
weaving has taken place.
- -Xreweavable[:compress]
- (Experimental - deprecated as now default) Runs weaver in
reweavable mode which causes it to create woven classes that can be
rewoven, subject to the restriction that on attempting a reweave all the
types that advised the woven type must be accessible.
- -XnoInline
- (Experimental) do not inline around advice
- -XincrementalFile file
- (Experimental) This works like incremental mode, but using
a file rather than standard input to control the compiler. It will
recompile each time file is changed and and halt when file is deleted.
- -XserializableAspects
- (Experimental) Normally it is an error to declare aspects
Serializable. This option removes that restriction.
- -XnotReweavable
- (Experimental) Create class files that can't be
subsequently rewoven by AspectJ.
- -Xajruntimelevel:1.2, ajruntimelevel:1.5
- (Experimental) Allows code to be generated that targets a
1.2 or a 1.5 level AspectJ runtime (default 1.5)
ajc accepts source files with either the
.java extension or the
.aj extension. We normally use
.java for all of our files in an
AspectJ system -- files that contain aspects as well as files that contain
classes. However, if you have a need to mechanically distinguish files that
use AspectJ's additional functionality from those that are pure Java we
recommend using the
.aj extension for those files.
We'd like to discourage other means of mechanical distinction such as naming
conventions or sub-packages in favor of the
.aj extension.
- •
- Filename conventions are hard to enforce and lead to
awkward names for your aspects. Instead of TracingAspect.java we
recommend using Tracing.aj (or just Tracing.java)
instead.
- •
- Sub-packages move aspects out of their natural place in a
system and can create an artificial need for privileged aspects. Instead
of adding a sub-package like aspects we recommend using the
.aj extension and including these files in your existing packages
instead.
AspectJ is a compatible extension to the Java programming language. The AspectJ
compiler adheres to the
The Java Language Specification, Second
Edition (BOOK) http://java.sun.com/docs/books/jls/index.html and
to the
The Java Virtual Machine Specification, Second
Edition (BOOK) http://java.sun.com/docs/books/vmspec/index.html
and runs on any Java 2 compatible platform. The code it generates runs on any
Java 1.1 or later compatible platform. For more information on compatibility
with Java and with previous releases of AspectJ, see
"" >.
A simple example
Compile two files:
ajc HelloWorld.java Trace.java
An example using -argfile/@
To avoid specifying file names on the command line, list source files in a
line-delimited text argfile. Source file paths may be absolute or relative to
the argfile, and may include other argfiles by @-reference. The following file
sources.lst contains absolute and relative files and @-references:
Gui.java
/home/user/src/Library.java
data/Repository.java
data/Access.java
@../../common/common.lst
@/home/user/src/lib.lst
view/body/ArrayView.java
Compile the files using either the -argfile or @ form:
ajc -argfile sources.lst
ajc @sources.lst
Argfiles are also supported by jikes and javac, so you can use the files in
hybrid builds. However, the support varies:
- •
- Only ajc accepts command-line options
- •
- Jikes and Javac do not accept internal @argfile references.
- •
- Jikes and Javac only accept the @file form on the command
line.
An example using -inpath and -aspectpath
Bytecode weaving using -inpath: AspectJ 1.2 supports weaving .class files in
input zip/jar files and directories. Using input jars is like compiling the
corresponding source files, and all binaries are emitted to output. Although
Java-compliant compilers may differ in their output, ajc should take as input
any class files produced by javac, jikes, eclipse, and, of course, ajc.
Aspects included in -inpath will be woven into like other .class files, and
they will affect other types as usual.
Aspect libraries using -aspectpath: AspectJ 1.1 supports weaving from read-only
libraries containing aspects. Like input jars, they affect all input; unlike
input jars, they themselves are not affected or emitted as output. Sources
compiled with aspect libraries must be run with the same aspect libraries on
their classpath.
The following example builds the tracing example in a command-line environment;
it creates a read-only aspect library, compiles some classes for use as input
bytecode, and compiles the classes and other sources with the aspect library.
The tracing example is in the AspectJ distribution
({aspectj}/doc/examples/tracing). This uses the following files:
aspectj1.1/
bin/
ajc
lib/
aspectjrt.jar
examples/
tracing/
Circle.java
ExampleMain.java
lib/
AbstractTrace.java
TraceMyClasses.java
notrace.lst
Square.java
tracelib.lst
tracev3.lst
TwoDShape.java
version3/
Trace.java
TraceMyClasses.java
Below, the path separator is taken as ";", but file separators are
"/". All commands are on one line. Adjust paths and commands to your
environment as needed.
Setup the path, classpath, and current directory:
cd examples
export ajrt=../lib/aspectjrt.jar
export CLASSPATH="$ajrt"
export PATH="../bin:$PATH"
Build a read-only tracing library:
ajc -argfile tracing/tracelib.lst -outjar tracelib.jar
Build the application with tracing in one step:
ajc -aspectpath tracelib.jar -argfile tracing/notrace.lst -outjar tracedapp.jar
Run the application with tracing:
java -classpath "$ajrt;tracedapp.jar;tracelib.jar" tracing.ExampleMain
Build the application with tracing from binaries in two steps:
- •
- (a) Build the application classes (using javac for
demonstration's sake):
mkdir classes
javac -d classes tracing/*.java
jar cfM app.jar -C classes .
- •
- (b) Build the application with tracing:
ajc -inpath app.jar -aspectpath tracelib.jar -outjar tracedapp.jar
Run the application with tracing (same as above):
java -classpath "$ajrt;tracedapp.jar;tracelib.jar" tracing.ExampleMain
Run the application without tracing:
java -classpath "app.jar" tracing.ExampleMain
The AspectJ compiler is implemented completely in Java and can be called as a
Java class. The only interface that should be considered public are the public
methods in
org.aspectj.tools.ajc.Main. E.g.,
main(String[] args)
takes the the standard
ajc command line arguments. This means that an
alternative way to run the compiler is
java org.aspectj.tools.ajc.Main [
option...]
[
file...]
To access compiler messages programmatically, use the methods
setHolder(IMessageHolder holder) and/or
run(String[] args,
IMessageHolder holder).
ajc reports each message to the holder
using
IMessageHolder.handleMessage(..). If you just want to collect the
messages, use
MessageHandler as your
IMessageHolder. For
example, compile and run the following with
aspectjtools.jar on the
classpath:
import org.aspectj.bridge.*;
import org.aspectj.tools.ajc.Main;
import java.util.Arrays;
public class WrapAjc {
public static void main(String[] args) {
Main compiler = new Main();
MessageHandler m = new MessageHandler();
compiler.run(args, m);
IMessage[] ms = m.getMessages(null, true);
System.out.println("messages: " + Arrays.asList(ms));
}
}
Unlike traditional java compilers, the AspectJ compiler may in certain cases
generate classfiles from multiple source files. Unfortunately, the original
Java class file format does not support multiple SourceFile attributes. In
order to make sure all source file information is available, the AspectJ
compiler may in some cases encode multiple filenames in the SourceFile
attribute. When the Java VM generates stack traces, it uses this attribute to
specify the source file.
(The AspectJ 1.0 compiler also supports the .class file extensions of JSR-45.
These permit compliant debuggers (such as jdb in Java 1.4.1) to identify the
right file and line even given many source files for a single class. JSR-45
support is planned for ajc in AspectJ 1.1, but is not in the initial release.
To get fully debuggable .class files, use the -XnoInline option.)
Probably the only time you may see this format is when you view stack traces,
where you may encounter traces of the format
java.lang.NullPointerException
at Main.new$constructor_call37(Main.java;SynchAspect.java[1k]:1030)
where instead of the usual
File:LineNumber
format, you see
File0;File1[Number1];File2[Number2] ... :LineNumber
In this case, LineNumber is the usual offset in lines plus the "start
line" of the actual source file. That means you use LineNumber both to
identify the source file and to find the line at issue. The number in
[brackets] after each file tells you the virtual "start line" for
that file (the first file has a start of 0).
In our example from the null pointer exception trace, the virtual start line is
1030. Since the file SynchAspect.java "starts" at line 1000 [1k],
the LineNumber points to line 30 of SynchAspect.java.
So, when faced with such stack traces, the way to find the actual source
location is to look through the list of "start line" numbers to find
the one just under the shown line number. That is the file where the source
location can actually be found. Then, subtract that "start line"
from the shown line number to find the actual line number within that file.
In a class file that comes from only a single source file, the AspectJ compiler
generates SourceFile attributes consistent with traditional Java compilers.