public class MyClass {
public static void main(String[] args) {
System.
out
.
println
("Hello world"
)
;
}
}
Nothing happens when I press Ctrl+Alt+L. I expect that it should format it to something like:
public class MyClass {
public static void main(String[] args) {
System.out.println("Hello world");
}
}
The code is already formatted according to the default style. If you want it formatted differently, change the configuration.
Related
I am creating a class like this:
class A{
A(A a){
...
}
A(){
A(null);
}
}
and my code looks like this:
TypeDefinition selfTypeDefinition = TypeDescription.Generic.Builder.rawType(TargetType.class).build();
Class c = new ByteBuddy().subclass(Object.class,ConstructorStrategy.Default.NO_CONSTRUCTORS).name("A").
defineConstructor(Modifier.PUBLIC).withParameters(selfTypeDefinition)
.intercept(MethodCall.invoke(Object.class.getConstructor())
.andThen(MethodCall.run(new Runnable() {
#Override
public void run() {
System.out.println("!!!!init A(A)");
}
})))
.defineConstructor(Modifier.PUBLIC).withParameters(new Type[0])
.intercept(MethodCall.invoke(ElementMatchers.isConstructor()
.and(ElementMatchers.takesArguments(selfTypeDefinition)))
.with(new Object[1])
.andThen(MethodCall.run(new Runnable() {
#Override
public void run() {
System.out.println("!!!!init A()");
}
})))
.make().load(Test.class.getClassLoader()).getLoaded();
The problem is I cannot pass TypeDefinition to ElementMatchers.takesArguments(). I have tried passing selfTypeDefinition.asErasure() but it does not work.
Just use selfTypeDefinition.asErasure() to represent a TypeDescription. Byte Buddy also supports matching generic type descriptions, but the matcher you are using expects an erasure format.
The code of my program to be attached is as below.
public class Foo {
}
public class TestEntry {
public TestEntry() {
}
public static void main(String[] args) throws Exception {
try
{
while(true)
{
System.out.println(new Foo().toString());
Thread.sleep(1000);
}
}
catch(Exception e)
{}
}
}
What I attempt to do is to make Foo.toString() returns 'test' by using the following agent.
public class InjectionAgent {
public InjectionAgent() {
}
public static void agentmain(String args, Instrumentation inst) throws Exception
{
System.out.println("agentmain Args:" + args);
new AgentBuilder.Default()
.type(ElementMatchers.named("Foo"))
.transform(new AgentBuilder.Transformer() {
#Override
public Builder<?> transform(Builder<?> arg0, TypeDescription arg1,
ClassLoader arg2, JavaModule arg3) {
return arg0.method(ElementMatchers.named("toString"))
.intercept(FixedValue.value("test"));
}
}).installOn(inst);
}
public static void premain(String args, Instrumentation inst) throws Exception
{
System.out.println("premain Args:" + args);
new AgentBuilder.Default()
.type(ElementMatchers.named("Foo"))
.transform(new AgentBuilder.Transformer() {
#Override
public Builder<?> transform(Builder<?> arg0, TypeDescription arg1,
ClassLoader arg2, JavaModule arg3) {
return arg0.method(ElementMatchers.named("toString"))
.intercept(FixedValue.value("test"));
}
}).installOn(inst);
}
}
I notice that, it was successful when I using -javaagent way, whereas attach way failed, here is code for attach.
public class Injection {
public Injection() {
}
public static void main(String[] args) throws AttachNotSupportedException, IOException, AgentLoadException, AgentInitializationException, InterruptedException {
VirtualMachine vm = null;
String agentjarpath = args[0];
vm = VirtualMachine.attach(args[1]);
vm.loadAgent(agentjarpath, "This is Args to the Agent.");
vm.detach();
}
}
I tried to add AgentBuilder.Listener.StreamWriting.toSystemOut() to the agent, after attaching, the output of TestEntry shows
[Byte Buddy] DISCOVERY Foo [sun.misc.Launcher$AppClassLoader#33909752, null, loaded=true]
[Byte Buddy] TRANSFORM Foo [sun.misc.Launcher$AppClassLoader#33909752, null, loaded=true]
[Byte Buddy] COMPLETE Foo [sun.misc.Launcher$AppClassLoader#33909752, null, loaded=true]
Foo#7f31245a
Foo#6d6f6e28
Foo#135fbaa4
Foo#45ee12a7
Foo#330bedb4
==================================Update=====================================
I defined a public method 'Bar' in Foo like this
public class Foo {
public String Bar()
{
return "Bar";
}
}
and then I was trying to make Foo.Bar() returns "modified" in the following way:
public static void agentmain(String args, Instrumentation inst) throws Exception
{
System.out.println("agentmain Args:" + args);
premain(args, inst);
new AgentBuilder.Default()
.with(RedefinitionStrategy.RETRANSFORMATION)
.disableClassFormatChanges()
.with(AgentBuilder.Listener.StreamWriting.toSystemOut())
.type(ElementMatchers.named("Foo"))
.transform(new AgentBuilder.Transformer() {
#Override
public Builder<?> transform(Builder<?> arg0, TypeDescription arg1,
ClassLoader arg2, JavaModule arg3) {
return arg0.visit(Advice.to(InjectionTemplate.class).on(ElementMatchers.named("Bar")));
}
})
.installOn(inst);
}
static class InjectionTemplate {
#Advice.OnMethodExit
static void exit(#Advice.Return String self) {
System.out.println(self.toString() + " " + self.getClass().toString());
self = new String("modified");
}
}
but I got this error:
java.lang.IllegalStateException: Cannot write to read-only parameter class java.lang.String at 1
any suggestions?
It does not seem like you are using redefinition for your agent. You can activate it using:
new AgentBuilder.Default()
.with(RedefinitionStrategy.RETRANSFORMATION)
.disableClassFormatChanges();
The last part is required on most JVMs (with the notable exception of the dynamic code evolution VM, a custom build of HotSpot). It tells Byte Buddy to not add fields or methods, what most VMs do not support.
In this case, it is no longer possible to invoke the original implementation of a method what is however not required for your FixedValue. Typically, users of Byte Buddy take advantage of Advice when creating an agent that applies dynamic transformations of classes.
I was wondering if with MethodDecorator it's possible to have the passed parameter during the OnException... that would be great since if I can catch an exception I can also have the passed parameter values
Consider this piece of code
static void Main(string[] args)
{
Worker worker = new Worker();
worker.DoWork(6);
}
[AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor | AttributeTargets.Assembly | AttributeTargets.Module)]
public class LoggableAttribute : Attribute, IMethodDecorator
{
public void OnEntry(System.Reflection.MethodBase method)
{
var args = method.GetParameters();
var arguments = method.GetGenericArguments();
}
public void OnExit(System.Reflection.MethodBase method)
{
}
public void OnException(System.Reflection.MethodBase method, Exception exception)
{
}
}
and
public class Worker
{
[Loggable]
public void DoWork(int i )
{
}
}
I wish to have 6 on the OnEntry/Nor OnException
Thanks
I know this is an old question, but in case someone stumbles upon this like I did, you can add an Init method and capture the argument values there.
e.g:
public class LoggableAttribute : Attribute, IMethodDecorator
{
private object[] arguments;
public void Init(object instance, MethodBase method, object[] args) {
this.arguments = args;
}
public void OnEntry()
{
// this.arguments[0] would be 6 when calling worker.DoWork(6);
}
}
Check out the example on https://github.com/Fody/MethodDecorator
Why isn't this working for me?
public class Band {
public void addMember(Musician musician) {
musicians.add(musician);
System.out.println("Muscian: " + musician + "was successfully added");
}
}
public static void main(String[] args) {
Band Beatles = new Band("Beatles");
Beatles.addMember("John Lennon");
}
public class Musician {
private String name;
public Musician(String name, Instrument instrument) {
this.name = name;
Instrument Guitar = instrument;
}
public void play() {
}
}
Beatles.addMember("John Lennon");
should be
Beatles.addMember(new Musician("John Lennon", new Instrument(new Guitar()));
I suspect, without seeing your actual Instrument class, based on your comment that this line should work.
The problem is that you are treating some objects as Strings. You need to create the object out of the class that defines it first.
I have a problem with changing public static variables in Hadoop.
I am trying to pass some values as arguments to the jar file from command line.
here is my code:
public class MyClass {
public static long myvariable1 = 100;
public static class Map extends Mapper<Object, Text, Text, Text> {
public static long myvariabl2 = 200;
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
}
}
public static class Reduce extends Reducer<Text, Text, Text, Text> {
public void reduce(Text key, Iterable<Text> values, Context context)
throws IOException, InterruptedException {
}
}
public static void main(String[] args) throws Exception {
col_no = Long.parseLong(args[0]);
Map.myvariable1 = Long.parseLong(args[1]);
Map.myvariable2 = Long.parseLong(args[1]);
other stuff here
}
}
But it is not working, myvariable1 & myvaribale2 always have 100 & 200.
I use Hadoop 0.20.203 with Ubuntu 10.04
What you can do to get the same behavior is to store your variables in the Configuration you use to launch the job.
public static class Map extends Mapper<Object, Text, Text, Text> {
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
Configuration conf = context.getConfiguration();
String var2String = conf.get("myvariable2");
long myvariable2 = Long.parseLong(var2String);
//etc.
}
}
public static void main(String[] args) throws Exception {
col_no = Long.parseLong(args[0]);
String myvariable1 = args[1];
String myvariable2 = args[1];
// add values to configuration
Configuration conf = new Configuration();
conf.set("myvariable1", myvariable1);
conf.set("myvariable2", myvariable2);
//other stuff here
}