ASMifierClassVisitor (Drools 4.0.0.11754MR2 API) - JBoss RULES 4.0.0.11754MR2 API 英文版文档

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org.drools.asm.util
Class ASMifierClassVisitor

java.lang.Object
  org.drools.asm.util.AbstractVisitor
      org.drools.asm.util.ASMifierAbstractVisitor
          org.drools.asm.util.ASMifierClassVisitor

All Implemented Interfaces:: ClassVisitor

public class ASMifierClassVisitor
extends ASMifierAbstractVisitor
implements ClassVisitor
extends ASMifierAbstractVisitor
implements ClassVisitor

A ClassVisitor 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 org.objectweb.asm.*;
 
 public class HelloDump implements Opcodes {
 
     public static byte[] dump() throws Exception {
 
         ClassWriter cw = new ClassWriter(false);
         FieldVisitor fv;
         MethodVisitor mv;
         AnnotationVisitor av0;
 
         cw.visit(49,
                 ACC_PUBLIC + ACC_SUPER,
                 "Hello",
                 null,
                 "java/lang/Object",
                 null);
 
         cw.visitSource("Hello.java", null);
 
         {
             mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
             mv.visitVarInsn(ALOAD, 0);
             mv.visitMethodInsn(INVOKESPECIAL,
                     "java/lang/Object",
                     "<init>",
                     "()V");
             mv.visitInsn(RETURN);
             mv.visitMaxs(1, 1);
             mv.visitEnd();
         }
         {
             mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC,
                     "main",
                     "([Ljava/lang/String;)V",
                     null,
                     null);
             mv.visitFieldInsn(GETSTATIC,
                     "java/lang/System",
                     "out",
                     "Ljava/io/PrintStream;");
             mv.visitLdcInsn("hello");
             mv.visitMethodInsn(INVOKEVIRTUAL,
                     "java/io/PrintStream",
                     "println",
                     "(Ljava/lang/String;)V");
             mv.visitInsn(RETURN);
             mv.visitMaxs(2, 1);
             mv.visitEnd();
         }
         cw.visitEnd();
 
         return cw.toByteArray();
     }
 }

where Hello is defined by:

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

Author:: Eric Bruneton, Eugene Kuleshov

Field Summary

protected PrintWriter pw
          The print writer to be used to print the class.

Fields inherited from class org.drools.asm.util.ASMifierAbstractVisitor

name

Fields inherited from class org.drools.asm.util.AbstractVisitor

buf, OPCODES, text, TYPES

Constructor Summary

ASMifierClassVisitor(PrintWriter pw)
          Constructs a new ASMifierClassVisitor object.

Method Summary

static void main(String[] args)
          Prints the ASM source code to generate the given class to the standard output.

void visit(int version, int access, String name, String signature, String superName, String[] interfaces)
          Visits the header of the class.

AnnotationVisitor visitAnnotation(String desc, boolean visible)
          Prints the ASM code that generates the given annotation.

void visitEnd()
          Prints the ASM code to end the visit.

FieldVisitor visitField(int access, String name, String desc, String signature, Object value)
          Visits a field of the class.

void visitInnerClass(String name, String outerName, String innerName, int access)
          Visits information about an inner class.

MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions)
          Visits a method of the class.

void visitOuterClass(String owner, String name, String desc)
          Visits the enclosing class of the class.

void visitSource(String file, String debug)
          Visits the source of the class.

Methods inherited from class org.drools.asm.util.ASMifierAbstractVisitor

visitAttribute

Methods inherited from class org.drools.asm.util.AbstractVisitor

appendString, getDefaultAttributes, getText

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.drools.asm.ClassVisitor

visitAttribute

Field Summary
`protected PrintWriter`	`pw` The print writer to be used to print the class.

Fields inherited from class org.drools.asm.util.ASMifierAbstractVisitor
`name`

Fields inherited from class org.drools.asm.util.AbstractVisitor
`buf, OPCODES, text, TYPES`

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

Method Summary
`static void`	`main(String[] args)` Prints the ASM source code to generate the given class to the standard output.
`void`	`visit(int version, int access, String name, String signature, String superName, String[] interfaces)` Visits the header of the class.
`AnnotationVisitor`	`visitAnnotation(String desc, boolean visible)` Prints the ASM code that generates the given annotation.
`void`	`visitEnd()` Prints the ASM code to end the visit.
`FieldVisitor`	`visitField(int access, String name, String desc, String signature, Object value)` Visits a field of the class.
`void`	`visitInnerClass(String name, String outerName, String innerName, int access)` Visits information about an inner class.
`MethodVisitor`	`visitMethod(int access, String name, String desc, String signature, String[] exceptions)` Visits a method of the class.
`void`	`visitOuterClass(String owner, String name, String desc)` Visits the enclosing class of the class.
`void`	`visitSource(String file, String debug)` Visits the source of the class.

Methods inherited from class org.drools.asm.util.ASMifierAbstractVisitor
`visitAttribute`

Methods inherited from class org.drools.asm.util.AbstractVisitor
`appendString, getDefaultAttributes, getText`

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

Methods inherited from interface org.drools.asm.ClassVisitor
`visitAttribute`

Field Detail

pw

protected final PrintWriter pw

The print writer to be used to print the class.

Constructor Detail

ASMifierClassVisitor

public ASMifierClassVisitor(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(String[] args)
                 throws 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:: Exception - if the class cannot be found, or if an IO exception occurs.