Posts
import javax.tools.*;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
import java.net.URI;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
/**
* Created by nanashi07 on 15/12/13.
*/
public class CompileOnFly {
public static void 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("package com.prhythm.output;");
out.println();
out.println("public class OutputImpl implements IOutput {");
out.println();
out.println(" public void printFor(String message) {");
out.println(" System.out.printf(\"Print from %s : %s%n\", getClass().getName(), message);");
out.println(" }");
out.println();
out.println("}");
out.close();
JavaFileObject file = new TextJavaObject("com.prhythm.output.OutputImpl", 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.out.printf("Code: %s%n", diagnostic.getCode());
System.out.printf("Kind: %s%n", diagnostic.getKind());
System.out.printf("Position: %s%n", diagnostic.getPosition());
System.out.printf("StartPosition: %s%n", diagnostic.getStartPosition());
System.out.printf("EndPosition: %s%n", diagnostic.getEndPosition());
System.out.printf("Source: %s%n", diagnostic.getSource());
System.out.printf("Message: %s%n", diagnostic.getMessage(null));
}
if (success) {
try {
URLClassLoader classLoader = URLClassLoader.newInstance(new URL[]{new File("").toURI().toURL()});
Class<?> outClass = Class.forName("com.prhythm.output.OutputImpl", true, classLoader);
Object outInstance = outClass.newInstance();
outClass.getDeclaredMethod("printFor", new Class[]{String.class}).invoke(outInstance, "Bruce");
} 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);
} catch (InstantiationException e) {
System.err.println("Initialize instance: " + e);
}
}
}
}
class TextJavaObject extends SimpleJavaFileObject {
final String code;
TextJavaObject(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;
}
}
Output:
Print from com.prhythm.output.OutputImpl : Bruce
