程序包 org.beetl.ow2.asm

类 ClassWriter

java.lang.Object
org.beetl.ow2.asm.ClassVisitor
org.beetl.ow2.asm.ClassWriter
public class ClassWriter extends ClassVisitor
A ClassVisitor that generates classes in bytecode form. More precisely this visitor generates a byte array conforming to the Java class file format. It can be used alone, to generate a Java class "from scratch", or with one or more ClassReader and adapter class visitor to generate a modified class from one or more existing Java classes.
作者:
Eric Bruneton

  • 字段详细资料

    • COMPUTE_MAXS

      public static final int COMPUTE_MAXS
      Flag to automatically compute the maximum stack size and the maximum number of local variables of methods. If this flag is set, then the arguments of the visitMaxs method of the MethodVisitor returned by the visitMethod method will be ignored, and computed automatically from the signature and the bytecode of each method.
      另请参阅:

    • COMPUTE_FRAMES

      public static final int COMPUTE_FRAMES
      Flag to automatically compute the stack map frames of methods from scratch. If this flag is set, then the calls to the MethodVisitor.visitFrame(int, int, java.lang.Object[], int, java.lang.Object[]) method are ignored, and the stack map frames are recomputed from the methods bytecode. The arguments of the visitMaxs method are also ignored and recomputed from the bytecode. In other words, computeFrames implies computeMaxs.
      另请参阅:

  • 构造器详细资料

    • ClassWriter

      public ClassWriter(int flags)
      Constructs a new ClassWriter object.
      参数:
      flags - option flags that can be used to modify the default behavior of this class. See COMPUTE_MAXS, COMPUTE_FRAMES.

    • ClassWriter

      public ClassWriter(ClassReader classReader, int flags)
      Constructs a new ClassWriter object and enables optimizations for "mostly add" bytecode transformations. These optimizations are the following:
      • The constant pool from the original class is copied as is in the new class, which saves time. New constant pool entries will be added at the end if necessary, but unused constant pool entries won't be removed.
      • Methods that are not transformed are copied as is in the new class, directly from the original class bytecode (i.e. without emitting visit events for all the method instructions), which saves a lot of time. Untransformed methods are detected by the fact that the ClassReader receives MethodVisitor objects that come from a ClassWriter (and not from any other ClassVisitor instance).
      参数:
      classReader - the ClassReader used to read the original class. It will be used to copy the entire constant pool from the original class and also to copy other fragments of original bytecode where applicable.
      flags - option flags that can be used to modify the default behavior of this class. These option flags do not affect methods that are copied as is in the new class. This means that the maximum stack size nor the stack frames will be computed for these methods. See COMPUTE_MAXS, COMPUTE_FRAMES.

  • 方法详细资料

    • visit

      public final void visit(int version, int access, String name, String signature, String superName, String[] interfaces)
      从类复制的说明: ClassVisitor
      Visits the header of the class.
      覆盖:
      visit 在类中 ClassVisitor
      参数:
      version - the class version.
      access - the class's access flags (see Opcodes). This parameter also indicates if the class is deprecated.
      name - the internal className of the class (see getInternalName).
      signature - the signature of this class. May be null if the class is not a generic one, and does not extend or implement generic classes or interfaces.
      superName - the internal of className of the super class (see getInternalName). For interfaces, the super class is Object. May be null, but only for the Object class.
      interfaces - the internal names of the class's interfaces (see getInternalName). May be null.

    • visitSource

      public final void visitSource(String file, String debug)
      从类复制的说明: ClassVisitor
      Visits the srccode of the class.
      覆盖:
      visitSource 在类中 ClassVisitor
      参数:
      file - the className of the srccode file from which the class was compiled. May be null.
      debug - additional debug information to compute the correspondance between srccode and compiled elements of the class. May be null.

    • visitOuterClass

      public final void visitOuterClass(String owner, String name, String desc)
      从类复制的说明: ClassVisitor
      Visits the enclosing class of the class. This method must be called only if the class has an enclosing class.
      覆盖:
      visitOuterClass 在类中 ClassVisitor
      参数:
      owner - internal className of the enclosing class of the class.
      name - the className of the method that contains the class, or null if the class is not enclosed in a method of its enclosing class.
      desc - the descriptor of the method that contains the class, or null if the class is not enclosed in a method of its enclosing class.

    • visitAnnotation

      public final AnnotationVisitor visitAnnotation(String desc, boolean visible)
      从类复制的说明: ClassVisitor
      Visits an annotation of the class.
      覆盖:
      visitAnnotation 在类中 ClassVisitor
      参数:
      desc - the class descriptor of the annotation class.
      visible - true if the annotation is visible at runtime.
      返回:
      a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

    • visitTypeAnnotation

      public final AnnotationVisitor visitTypeAnnotation(int typeRef, TypePath typePath, String desc, boolean visible)
      从类复制的说明: ClassVisitor
      Visits an annotation on a type in the class signature.
      覆盖:
      visitTypeAnnotation 在类中 ClassVisitor
      参数:
      typeRef - a reference to the annotated type. The sort of this type reference must be CLASS_TYPE_PARAMETER, CLASS_TYPE_PARAMETER_BOUND or CLASS_EXTENDS. See TypeReference.
      typePath - the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.
      desc - the class descriptor of the annotation class.
      visible - true if the annotation is visible at runtime.
      返回:
      a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.

    • visitAttribute

      public final void visitAttribute(Attribute attr)
      从类复制的说明: ClassVisitor
      Visits a non standard attribute of the class.
      覆盖:
      visitAttribute 在类中 ClassVisitor
      参数:
      attr - an attribute.

    • visitInnerClass

      public final void visitInnerClass(String name, String outerName, String innerName, int access)
      从类复制的说明: ClassVisitor
      Visits information about an inner class. This inner class is not necessarily a member of the class being visited.
      覆盖:
      visitInnerClass 在类中 ClassVisitor
      参数:
      name - the internal className of an inner class (see getInternalName).
      outerName - the internal className of the class to which the inner class belongs (see getInternalName). May be null for not member classes.
      innerName - the (simple) className 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 final FieldVisitor visitField(int access, String name, String desc, String signature, Object value)
      从类复制的说明: ClassVisitor
      Visits a field of the class.
      覆盖:
      visitField 在类中 ClassVisitor
      参数:
      access - the field's access flags (see Opcodes). This parameter also indicates if the field is synthetic and/or deprecated.
      name - the field's className.
      desc - the field's descriptor (see Type).
      signature - the field's signature. May be null if the field's type does not use generic types.
      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.
      返回:
      a visitor to visit field annotations and attributes, or null if this class visitor is not interested in visiting these annotations and attributes.

    • visitMethod

      public final MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions)
      从类复制的说明: ClassVisitor
      Visits a method of the class. This method must return a new MethodVisitor instance (or null) each time it is called, i.e., it should not return a previously returned visitor.
      覆盖:
      visitMethod 在类中 ClassVisitor
      参数:
      access - the method's access flags (see Opcodes). This parameter also indicates if the method is synthetic and/or deprecated.
      name - the method's className.
      desc - the method's descriptor (see Type).
      signature - the method's signature. May be null if the method parameters, return type and exceptions do not use generic types.
      exceptions - the internal names of the method's exception classes (see getInternalName). May be null.
      返回:
      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.

    • visitEnd

      public final void visitEnd()
      从类复制的说明: 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.
      覆盖:
      visitEnd 在类中 ClassVisitor

    • toByteArray

      public byte[] toByteArray()
      Returns the bytecode of the class that was build with this class writer.
      返回:
      the bytecode of the class that was build with this class writer.

    • newConst

      public int newConst(Object cst)
      Adds a number or string constant to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      cst - the value of the constant to be added to the constant pool. This parameter must be an Integer, a Float, a Long, a Double or a String.
      返回:
      the index of a new or already existing constant item with the given value.

    • newUTF8

      public int newUTF8(String value)
      Adds an UTF8 string to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      value - the String value.
      返回:
      the index of a new or already existing UTF8 item.

    • newClass

      public int newClass(String value)
      Adds a class reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      value - the internal className of the class.
      返回:
      the index of a new or already existing class reference item.

    • newMethodType

      public int newMethodType(String methodDesc)
      Adds a method type reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      methodDesc - method descriptor of the method type.
      返回:
      the index of a new or already existing method type reference item.

    • newHandle

      public int newHandle(int tag, String owner, String name, String desc)
      Adds a handle to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      tag - the kind of this handle. Must be Opcodes.H_GETFIELD, Opcodes.H_GETSTATIC, Opcodes.H_PUTFIELD, Opcodes.H_PUTSTATIC, Opcodes.H_INVOKEVIRTUAL, Opcodes.H_INVOKESTATIC, Opcodes.H_INVOKESPECIAL, Opcodes.H_NEWINVOKESPECIAL or Opcodes.H_INVOKEINTERFACE.
      owner - the internal className of the field or method owner class.
      name - the className of the field or method.
      desc - the descriptor of the field or method.
      返回:
      the index of a new or already existing method type reference item.

    • newInvokeDynamic

      public int newInvokeDynamic(String name, String desc, Handle bsm, Object... bsmArgs)
      Adds an invokedynamic reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      name - className of the invoked method.
      desc - descriptor of the invoke method.
      bsm - the bootstrap method.
      bsmArgs - the bootstrap method constant arguments.
      返回:
      the index of a new or already existing invokedynamic reference item.

    • newField

      public int newField(String owner, String name, String desc)
      Adds a field reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      owner - the internal className of the field's owner class.
      name - the field's className.
      desc - the field's descriptor.
      返回:
      the index of a new or already existing field reference item.

    • newMethod

      public int newMethod(String owner, String name, String desc, boolean itf)
      Adds a method reference to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      owner - the internal className of the method's owner class.
      name - the method's className.
      desc - the method's descriptor.
      itf - true if owner is an interface.
      返回:
      the index of a new or already existing method reference item.

    • newNameType

      public int newNameType(String name, String desc)
      Adds a className and type to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      name - a className.
      desc - a type descriptor.
      返回:
      the index of a new or already existing className and type item.

    • getCommonSuperClass

      protected String getCommonSuperClass(String type1, String type2)
      Returns the common super type of the two given types. The default implementation of this method loads the two given classes and uses the java.lang.Class methods to find the common super class. It can be overridden to compute this common super type in other ways, in particular without actually loading any class, or to take into account the class that is currently being generated by this ClassWriter, which can of course not be loaded since it is under construction.
      参数:
      type1 - the internal className of a class.
      type2 - the internal className of another class.
      返回:
      the internal className of the common super class of the two given classes.