Compiling in Memory
I am reading a book Java 6 Platform Revealed which describes using of Compiler API. Unfortunately Compiler API was changed during development of Mustang.
This sample stopped to work although I renamed names of classes into new ones.
I am able to compile the source of HelloWorld class, but I don't know how to invoke a new instance of this successfully compiled class (I get permanent ClassNotFoundException).
How to get it work?
Thank you for your help
Cavity
PS. I don't want to use extern files (as described here http://javainsel.blogspot.com/2006/03/example-for-using-java-6-compiler-api.html), I would like to make it as fast as possible (=in memory).
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Java SE 6 final
import javax.tools.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
import java.net.URI;
import java.util.Arrays;
publicclass CompileSource{
private CompileSource(){
}
publicstaticvoid main(String args[])throws IOException{
JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
DiagnosticCollector<JavaFileObject> diagnostics =
new DiagnosticCollector<JavaFileObject>();
StringWriter writer =new StringWriter();
PrintWriter out =new PrintWriter(writer);
out.println("public class HelloWorld {");
out.println(" public static void main(String args[]) {");
out.println("System.out.println(\"Hello, World\");");
out.println(" }");
out.println("}");
out.close();
JavaFileObject file =
new JavaSourceFromString("HelloWorld", writer.toString());
Iterable<?extends JavaFileObject> compilationUnits =
Arrays.asList(file);
JavaCompiler.CompilationTask task = compiler.getTask(
null, null, diagnostics, null, null, compilationUnits);
boolean success = task.call();
for (Diagnostic diagnostic : diagnostics.getDiagnostics())
System.console().printf(
"Code: %s%n" +
"Kind: %s%n" +
"Position: %s%n" +
"Start Position: %s%n" +
"End Position: %s%n" +
"Source: %s%n" +
"Message: %s%n",
diagnostic.getCode(), diagnostic.getKind(),
diagnostic.getPosition(), diagnostic.getStartPosition(),
diagnostic.getEndPosition(), diagnostic.getSource(),
diagnostic.getMessage(null));
System.out.println("Success: " + success);
if (success){
try{
System.out.println("--Output--");
Class.forName("HelloWorld").getDeclaredMethod("main",
new Class[]{String[].class}).invoke(null,new Object[]{null});
System.out.println("--Output--");
}catch (ClassNotFoundException e){
System.err.println("Class not found: " + e);
}catch (NoSuchMethodException e){
System.err.println("No such method: " + e);
}catch (IllegalAccessException e){
System.err.println("Illegal access: " + e);
}catch (InvocationTargetException e){
System.err.println("Invocation target: " + e);
}
}
}
staticpublicclass JavaSourceFromStringextends SimpleJavaFileObject{
final String code;
JavaSourceFromString(String name, String code){
super(URI.create(
"string:///" + name.replace('.','/') + Kind.SOURCE.extension),
Kind.SOURCE);
this.code = code;
}
@Override
public CharSequence getCharContent(boolean ignoreEncodingErrors){
return code;
}
}
}
Message was edited by:
Cavity
