I am experimenting with the Rhino java engine, which I want to embed in a project of mine. I made a Scriptable object scope which defines the global functions print, printLine, log, logLine in JavaScript. I can pull all data printed and logged by these functions by calling pullOutput, which returns a pair of all printed Output and logged Output. I have tested these functions and everything works as expected, but one thing.
When I give as argument for my log functions a new line, the string doesn't contain a new line char
but just "\n". For example the following code:
Context context;
try {
context = Context.enter();
TemplateScope scope = TemplateScope.init(context);
context.evaluateString(scope, "log(\"test\" + \"\\n\");", "test source", 1, null);
Pair<String, String> result = scope.pullOutput();
System.out.println("log is: " + result.b);
} finally {
Context.exit();
}
gives:
out is:
log is: test\n
Which is obviously not what I am expecting.
The complete code is here:
https://gist.github.com/4139978
Already fixed it. Another library overwrote my own rhino version with an old version and introduced this bug.
Related
Currently, I am trying to read the console output of my program when there is a method call. How it works is, my Java program calls the JNI wrapper to invoke the C++ method call. My C++ is using std::cout. The payload.invoke will invoke my c++ library API. Inside the c++ API there are a few cout statements. That is the statement I want to read it as a variable in Java.
The current PrintStream only supports out, print, println and printf.Each time when there is a method call, there are bunch of logs being printed out in command prompt. Now, I would like my java program to read those output which my C++ prints out.
This is my current Java code:
public void execute() {
try {
Matcher m = Pattern.compile("([^()]*)[(]([^()]*)[)]").matcher(getPayloadString());
m.find();
boolean passed;
if (m.group(2).isEmpty()) {
// this is where it invoke the method
passed = (boolean) payload.invoke(testcase);
System.out.println("Boolean is: " + passed + "\n");
}else {
passed = (boolean) payload.invoke(testcase, ObjectCreator.convertParameters(m.group(2)));
System.out.println("Boolean2 is: " + passed + "\n");
}
String output = passed ? "PASS" : "FAIL";
// I want to use the console output string variable here -> xxxx
TestCase.printResult(payload.getName(), output, m.group(2), xxxx, "");
} catch (Exception ex) {
ex.printStackTrace();
}
}
Are there any ways to do it? Previously I tried using one of the tutorial from here. but that seems not working. Can someone help me out with this please. Thanks in advance.
If you have full control of the .cpp codebase it is possible for you to change the std::cout to become a ostream& instead.
By referencing a base class you can easily switch the implementation.
Do a JNI-Stream whichh extends the ostream& and just overwrite the operators you need to send JNI wrapped callbacks to java.
Then depending on if you run native or Java style use your JNI-Stream instead of the std::cout.
I would do something as seen in the link below to package and send the data to Java:
JNI - How to callback from C++ or C to Java?
that is my 2 cents.
Read carefully the JNI tutorial.
https://www.baeldung.com/jni
Follow the tutorial.
Basically you need to create a java class with a static block to load the C++ library:
static {
System.loadLibrary("native");
}
Then you can create your own static java method and invoke a method on the library.
If what you need is read the output from a system call, it's a different matter.
This can help you:
Java Runtime.getRuntime(): getting output from executing a command line program
My intentions are to ask the user to write down some code in a TextArea, then see if that code compiles, and if it does, print out the results to another TextArea, which acts like a console.
Edit:Solving this via online compilers is the priority.
To accomplish this, I've tried using online compilers (i.e. compilerjava.net) and used the library HtmlUnit, but the library came in with a lot of errors, especially when reading the JavaScript code and returned me pages of 'warnings' that increase the compile & run time for about 20 seconds. I will leave the code below with explanations if anyone has intentions about trying to fix it.
I've also tried using the JavaCompiler interface, which did succeed in compiling, but under the conditions that I have provided the exact location of the .java file, which is something I have to create using the information I get from the TextArea. So again, a dead end.
I decided to come back to online compilers, since if I can manage to just return the data from the compiled program, I am set. The only issue is I haven't yet found an online compiler that allows a user to access its fields via Java code ( since its something too specific). I would appreciate any help on this if anyone can provide a way to send and retrieve data from an online compiler.
Here is the code using the HtmlUnit library, on the site 'compilerjava.net'. It is so close to working that the only 2 issues I have is that,
1) Run-time is too long.
2) I cannot access the console output of the code. Reasoning is that, when you hit 'compile', the output text-area's text turns into "executing". After a few seconds, it turns into the output of the code. When I try to access it, the data I retrieve is always "executing" and not the desired output. Here is the code;
public class Test {
public static void main(String[] args) {
try {
// Prevents the program to print thousands of warning codes.
java.util.logging.Logger.getLogger("com.gargoylesoftware").setLevel(java.util.logging.Level.OFF);
java.util.logging.Logger.getLogger("org.apache.http").setLevel(java.util.logging.Level.OFF);
// Initializes the web client and yet again stops some warning codes.
WebClient webClient = new WebClient( BrowserVersion.CHROME);
webClient.getOptions().setThrowExceptionOnFailingStatusCode( false);
webClient.getOptions().setThrowExceptionOnScriptError( false);
webClient.getOptions().setJavaScriptEnabled( true);
webClient.getOptions().setCssEnabled( true);
// Gets the html page, which is the online compiler I'm using.
HtmlPage page = webClient.getPage("https://www.compilejava.net/");
// Succesfully finds the form which has the required buttons etc.
List<HtmlForm> forms = page.getForms();
HtmlForm form = forms.get( 0);
// Finds the textarea which will hold the code.
HtmlTextArea textArea = form.getTextAreaByName( "code");
// Finds the textarea which will hold the result of the compilation.
HtmlTextArea resultArea = page.getHtmlElementById( "execsout");
// Finds the compile button.
HtmlButtonInput button = form.getInputByName( "compile");
System.out.println( button.getValueAttribute());
// Simple code to run.
textArea.setText( "public class HelloWorld\n" +
"{\n" +
" // arguments are passed using the text field below this editor\n" +
" public static void main(String[] args)\n" +
" {\n" +
" System.out.print( \"Hello\");\n" +
" }\n" +
"}");
// Compiles.
button.click();
// Result of the compilation.
System.out.println( resultArea.getText());
} catch ( Exception e) {
e.printStackTrace();
}
}
}
As I said, this final code System.out.println( resultArea.getText()); prints out "executing", which implies that I have succeeded in pressing the compile button on the webpage via code.
So after this long wall of text, I'm either looking for a way to fix the code I presented, which is so darn close to my answer but not quite, or just an entirely different solution to the problem I presented at the beginning.
P.S. Maven is the last hope.
I embed jruby script engine into my java program by using javax.script.ScriptEngineManager
I made some jruby code that end with do ~ end block,
after running all code, NullPointerException occured.
but code ends with any other statement, no exception occurs.
version : 1.7.19
Caused by: java.lang.NullPointerException
at org.jruby.embed.variable.Argv.updateARGV(Argv.java:169)
at org.jruby.embed.variable.Argv.retrieve(Argv.java:158)
at org.jruby.embed.variable.VariableInterceptor.retrieve(VariableInterceptor.java:154)
at org.jruby.embed.internal.BiVariableMap.retrieve(BiVariableMap.java:378)
at org.jruby.embed.internal.EmbedEvalUnitImpl.run(EmbedEvalUnitImpl.java:124)
in ARGV.java updateARGV
if (vars.containsKey((Object)name)) {
var = vars.getVariable((RubyObject)receiver.getRuntime().getTopSelf(), name);
var.setRubyObject(argv);
vars.getVariable returned null because of isReceiverIdentical return false
in BiVariableMap.java
if (var.isReceiverIdentical(receiver)) {
return var;
}
In isReceiverIdentical, this method just compare receiver with BiVariable's receiver usgin '=='.
Is this jruby bug? Or do I have to do something for this?
If you need more information about this problem, plz comment it!
I got ScriptEngine(engine) from ScriptEngineManager and set some java instance and method like this
engine.put("this", console);
engine.eval("$command = $this.java_method :command, [java.lang.String]");
here is my test ruby code. result and tab is java object
that has some method return String and list.
result = $command.call "something to pass"
puts result.getMessage
tabular = result.getData
tabular.each do |tab|
rows = tab.getRows
rows.each do |row|
puts row
end
puts tab.getColumnNames
end
I had created ruby type object in my java code by creating new Ruby object...
This causes checking fail in updateARGV because a receiver that register variable in BiVariableMap and another receiver that update variable are different.
So, I got a Ruby object from new ScriptingContainer(from it we can always get a same Ruby object if local context is singleton) and used it to create new ruby type object in my java code.
Reference: https://github.com/jruby/jruby/wiki/RedBridge#Singleton
I'm using tuProlog to integrate Prolog with Java, to do so I have defined a prolog.pl file with the following code:
go:-write('hello world!'),nl.
Then, in my Java project I Have the Main Class that invokes this:
Prolog engine = new Prolog();
Theory theory = new Theory(new FileInputStream("prolog.pl"));
try {
engine.setTheory(theory);
} catch (InvalidTheoryException ex) {
}
SolveInfo solution = engine.solve("go.");
if (solution.isSuccess()) {
System.out.println(solution.getSolution());
}
This code should output 'hello world', however, it outputs 'go', any ideas of why this behavior?
Finally found that the behavior was not erratic at all :)
The solution is to add this code just before calling the Solve Method.
engine.addOutputListener(new OutputListener() {
#Override
public void onOutput(OutputEvent e) {
finalResult += e.getMsg();
}
});
finalResult is just a Global variable that contains the returned String produced by Prolog Write instruction.
Your solution it's (correctly) the succeded Prolog query (go/0), what you expect ('hello world!') it's the output of a builtin, as such you should inspect the 'stdout' of your Java engine.
Otherwise, code your program to 'return' info in variables.
go(X) :- X = 'hello world!'.
Then tuProlog will provide the methods to access instanced variables.
I don't know about tuProlog/Java, but when calling Swi-Prolog from PHP, I must put 'halt' as the final statement of the predicate to tell Prolog to exit and return control back to php.
go:-write('hello world!'),nl, halt.
I am embedding some javascript in a Java application using Rhino. I am following the example on the Rhino website, executing a script by calling the Context's evaluateString method and passing the actual script in as a String.
I have a whole bunch of existing javascript code that I would like to make use of. I don't want to concatenate it all into an enormous String and pass it in to evaluateString. I would rather be able to load the code in so that I can call it from the code that I do pass into evaluateString (kind of like the AddCode method works in Microsoft's scripting control). I would like to add code like I can currently add variables by using the ScriptableObject.putProperty method.
Is there a way to do this? Can someone provide a code snippet or a link to the documentation. Thanks!
From the documentation and examples it looks like references to previously evaluated objects are controlled by scopes.
Context context = Context.enter();
try {
ScriptableObject scope = context.initStandardObjects();
Object out = Context.javaToJS(System.out, scope);
ScriptableObject.putProperty(scope, "out", out);
context.evaluateString(scope,
"function foo() { out.println('Hello, World!'); }", "<1>", 1, null);
context
.evaluateString(scope, "function bar() { foo(); }", "<2>", 1, null);
context.evaluateString(scope, "bar();", "<3>", 1, null);
} finally {
Context.exit();
}
(Rhino 1.7 release 2)
I know some people use Rhino directly to get the latest version, but the Java 6 implementation can evaluate scripts like this:
ScriptEngine engine = new ScriptEngineManager().getEngineByExtension("js");
engine.eval("function foo() { println('Hello, World!'); }");
engine.eval("function bar() { foo(); }");
engine.eval("bar();");
In my code I had that need (utility scripts and such), and I just simply concatenated them together in a giant StringBuilder and evaled it (Java 6). Its the only way since javascript can't do (without Java wrapper objects) otherJSScript.someUsefulFunction().