org.objectweb.asm.util
Class TraceClassVisitor

java.lang.Object
  extended by org.objectweb.asm.util.PrintClassVisitor
      extended by org.objectweb.asm.util.TraceClassVisitor
All Implemented Interfaces:
ClassVisitor

public class TraceClassVisitor
extends PrintClassVisitor

A PrintClassVisitor that prints a disassembled view of the classes it visits. This class visitor can be used alone (see the main method) to disassemble a class. It can also be used in the middle of class visitor chain to trace the class that is visited at a given point in this chain. This may be uselful for debugging purposes.

The trace printed when visiting the Hello class is the following:

 // compiled from Hello.java
 public class Hello {

   public static main ([Ljava/lang/String;)V
     GETSTATIC java/lang/System out Ljava/io/PrintStream;
     LDC "hello"
     INVOKEVIRTUAL java/io/PrintStream println (Ljava/lang/String;)V
     RETURN
     MAXSTACK = 2
     MAXLOCALS = 1

   public <init> ()V
     ALOAD 0
     INVOKESPECIAL java/lang/Object <init> ()V
     RETURN
     MAXSTACK = 1
     MAXLOCALS = 1

 }
 
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  ClassVisitor cv
          The ClassVisitor to which this visitor delegates calls.
 
Fields inherited from class org.objectweb.asm.util.PrintClassVisitor
buf, pw, text
 
Constructor Summary
TraceClassVisitor(ClassVisitor cv, PrintWriter pw)
          Constructs a new TraceClassVisitor object.
 
Method Summary
static void main(String[] args)
          Prints a disassembled view of the given class to the standard output.
 void visit(int version, int access, String name, String superName, String[] interfaces, 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, String name, String desc, Object value, Attribute attrs)
          Visits a field of the class.
 void visitInnerClass(String name, String outerName, String innerName, int access)
          Visits information about an inner class.
 CodeVisitor visitMethod(int access, String name, String desc, String[] exceptions, Attribute attrs)
          Visits a method of the class.
 
Methods inherited from class org.objectweb.asm.util.PrintClassVisitor
getDefaultAttributes
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

cv

protected final ClassVisitor cv
The ClassVisitor to which this visitor delegates calls. May be null.

Constructor Detail

TraceClassVisitor

public TraceClassVisitor(ClassVisitor cv,
                         PrintWriter pw)
Constructs a new TraceClassVisitor object.

Parameters:
cv - the class visitor to which this adapter must delegate calls. May be null.
pw - the print writer to be used to print the class.
Method Detail

main

public static void main(String[] args)
                 throws Exception
Prints a disassembled view of the given class to the standard output.

Usage: TraceClassVisitor [-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.

visit

public void visit(int version,
                  int access,
                  String name,
                  String superName,
                  String[] interfaces,
                  String sourceFile)
Description copied from interface: ClassVisitor
Visits the header of the class.

Parameters:
version - the class version.
access - the class's access flags (see Constants). This parameter also indicates if the class is deprecated.
name - the internal name of the class (see getInternalName).
superName - the internal of name of the super class (see getInternalName). For interfaces, the super class is Object. May be null, but only for the java.lang.Object class.
interfaces - the internal names of the class's interfaces (see getInternalName). May be null.
sourceFile - the name of the source file from which this class was compiled. May be null.

visitInnerClass

public void visitInnerClass(String name,
                            String outerName,
                            String innerName,
                            int access)
Description copied from interface: ClassVisitor
Visits information about an inner class. This inner class is not necessarily a member of the class being visited.

Parameters:
name - the internal name of an inner class (see getInternalName).
outerName - the internal name of the class to which the inner class belongs (see getInternalName). May be null.
innerName - the (simple) name of the inner class inside its enclosing class. May be null for anonymous inner classes.
access - the access flags of the inner class as originally declared in the enclosing class.

visitField

public void visitField(int access,
                       String name,
                       String desc,
                       Object value,
                       Attribute attrs)
Description copied from interface: ClassVisitor
Visits a field of the class.

Parameters:
access - the field's access flags (see Constants). This parameter also indicates if the field is synthetic and/or deprecated.
name - the field's name.
desc - the field's descriptor (see Type).
value - the field's initial value. This parameter, which may be null if the field does not have an initial value, must be an Integer, a Float, a Long, a Double or a String (for int, float, long or String fields respectively). This parameter is only used for static fields. Its value is ignored for non static fields, which must be initialized through bytecode instructions in constructors or methods.
attrs - the non standard method attributes, linked together by their next field. May be null.

visitMethod

public CodeVisitor visitMethod(int access,
                               String name,
                               String desc,
                               String[] exceptions,
                               Attribute attrs)
Description copied from interface: ClassVisitor
Visits a method of the class. This method must return a new CodeVisitor instance (or null) each time it is called, i.e., it should not return a previously returned visitor.

Parameters:
access - the method's access flags (see Constants). This parameter also indicates if the method is synthetic and/or deprecated.
name - the method's name.
desc - the method's descriptor (see Type).
exceptions - the internal names of the method's exception classes (see getInternalName). May be null.
attrs - the non standard method attributes, linked together by their next field. May be null.
Returns:
an object to visit the byte code of the method, or null if this class visitor is not interested in visiting the code of this method.

visitAttribute

public void visitAttribute(Attribute attr)
Description copied from interface: ClassVisitor
Visits a non standard attribute of the class. This method must visit only the first attribute in the given attribute list.

Parameters:
attr - a non standard class attribute. Must not be null.

visitEnd

public void visitEnd()
Description copied from interface: ClassVisitor
Visits the end of the class. This method, which is the last one to be called, is used to inform the visitor that all the fields and methods of the class have been visited.

Specified by:
visitEnd in interface ClassVisitor
Overrides:
visitEnd in class PrintClassVisitor