ASMifierClassVisitor (Oracle Fusion Middleware Java API Reference for Oracle TopLink)

A PrintClassVisitor that prints the ASM code that generates the classes it visits. This class visitor can be used to quickly write ASM code to generate some given bytecode:

write the Java source code equivalent to the bytecode you want to generate;
compile it with javac;
make a ASMifierClassVisitor visit this compiled class (see the main method);
edit the generated source code, if necessary.

The source code printed when visiting the Hello class is the following:

 import oracle.toplink.libraries.asm.*;
 import java.io.FileOutputStream;

 public class Dump implements Constants {

 public static void main (String[] args) throws Exception {

 ClassWriter cw = new ClassWriter(false);
 CodeVisitor cv;

 cw.visit(ACC_PUBLIC + ACC_SUPER, "Hello", "java/lang/Object", null, "Hello.java");

 {
 cv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC, "main", "([Ljava/lang/String;)V", null, null);
 cv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;");
 cv.visitLdcInsn("hello");
 cv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V");
 cv.visitInsn(RETURN);
 cv.visitMaxs(2, 1);
 }
 {
 cv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
 cv.visitVarInsn(ALOAD, 0);
 cv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V");
 cv.visitInsn(RETURN);
 cv.visitMaxs(1, 1);
 }
 cw.visitEnd();

 FileOutputStream os = new FileOutputStream("Dumped.class");
 os.write(cw.toByteArray());
 os.close();
 }
 }

where Hello is defined by:

 public class Hello {

   public static void main (String[] args) {
     System.out.println("hello");
   }
 }

Constructor Summary
`ASMifierClassVisitor(java.io.PrintWriter pw)` Constructs a new `ASMifierClassVisitor` object.

Method Summary
`static void`	`main(java.lang.String[] args)` Prints the ASM source code to generate the given class to the standard output.
`void`	`visit(int version, int access, java.lang.String name, java.lang.String superName, java.lang.String[] interfaces, java.lang.String sourceFile)` Visits the header of the class.
`void`	`visitAttribute(Attribute attr)` Visits a non standard attribute of the class.
`void`	`visitEnd()` Visits the end of the class.
`void`	`visitField(int access, java.lang.String name, java.lang.String desc, java.lang.Object value, Attribute attrs)` Visits a field of the class.
`void`	`visitInnerClass(java.lang.String name, java.lang.String outerName, java.lang.String innerName, int access)` Visits information about an inner class.
`CodeVisitor`	`visitMethod(int access, java.lang.String name, java.lang.String desc, java.lang.String[] exceptions, Attribute attrs)` Visits a method of the class.

Methods inherited from class oracle.toplink.libraries.asm.util.PrintClassVisitor
`getDefaultAttributes`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

ASMifierClassVisitor

public ASMifierClassVisitor(java.io.PrintWriter pw)

Constructs a new ASMifierClassVisitor object.

Parameters:: pw - the print writer to be used to print the class.

Method Detail

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

Prints the ASM source code to generate the given class to the standard output.

Usage: ASMifierClassVisitor [-debug] <fully qualified class name or class file name>

Parameters:: args - the command line arguments.
Throws:: java.lang.Exception - if the class cannot be found, or if an IO exception occurs.