Class ClassFileWriter

java.lang.Object
org.mozilla.classfile.ClassFileWriter

public class ClassFileWriter extends Object
ClassFileWriter

A ClassFileWriter is used to write a Java class file. Methods are provided to create fields and methods, and within methods to write Java bytecodes.

  • Field Details

    • ACC_PUBLIC

      public static final short ACC_PUBLIC
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    • ACC_PRIVATE

      public static final short ACC_PRIVATE
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    • ACC_PROTECTED

      public static final short ACC_PROTECTED
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    • ACC_STATIC

      public static final short ACC_STATIC
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    • ACC_FINAL

      public static final short ACC_FINAL
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    • ACC_SUPER

      public static final short ACC_SUPER
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    • ACC_SYNCHRONIZED

      public static final short ACC_SYNCHRONIZED
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    • ACC_VOLATILE

      public static final short ACC_VOLATILE
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    • ACC_TRANSIENT

      public static final short ACC_TRANSIENT
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    • ACC_NATIVE

      public static final short ACC_NATIVE
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    • ACC_ABSTRACT

      public static final short ACC_ABSTRACT
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    • itsSuperBlockStarts

      private int[] itsSuperBlockStarts
    • itsSuperBlockStartsTop

      private int itsSuperBlockStartsTop
    • SuperBlockStartsSize

      private static final int SuperBlockStartsSize
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    • itsJumpFroms

      private UintMap itsJumpFroms
    • LineNumberTableSize

      private static final int LineNumberTableSize
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    • ExceptionTableSize

      private static final int ExceptionTableSize
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    • MajorVersion

      private static final int MajorVersion
    • MinorVersion

      private static final int MinorVersion
    • GenerateStackMap

      private static final boolean GenerateStackMap
    • FileHeaderConstant

      private static final int FileHeaderConstant
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    • DEBUGSTACK

      private static final boolean DEBUGSTACK
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    • DEBUGLABELS

      private static final boolean DEBUGLABELS
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    • DEBUGCODE

      private static final boolean DEBUGCODE
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    • generatedClassName

      private String generatedClassName
    • itsExceptionTable

      private ExceptionTableEntry[] itsExceptionTable
    • itsExceptionTableTop

      private int itsExceptionTableTop
    • itsLineNumberTable

      private int[] itsLineNumberTable
    • itsLineNumberTableTop

      private int itsLineNumberTableTop
    • itsCodeBuffer

      private byte[] itsCodeBuffer
    • itsCodeBufferTop

      private int itsCodeBufferTop
    • itsConstantPool

      private ConstantPool itsConstantPool
    • itsCurrentMethod

      private ClassFileMethod itsCurrentMethod
    • itsStackTop

      private short itsStackTop
    • itsMaxStack

      private short itsMaxStack
    • itsMaxLocals

      private short itsMaxLocals
    • itsMethods

      private ObjArray itsMethods
    • itsFields

      private ObjArray itsFields
    • itsInterfaces

      private ObjArray itsInterfaces
    • itsFlags

      private short itsFlags
    • itsThisClassIndex

      private short itsThisClassIndex
    • itsSuperClassIndex

      private short itsSuperClassIndex
    • itsSourceFileNameIndex

      private short itsSourceFileNameIndex
    • MIN_LABEL_TABLE_SIZE

      private static final int MIN_LABEL_TABLE_SIZE
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    • itsLabelTable

      private int[] itsLabelTable
    • itsLabelTableTop

      private int itsLabelTableTop
    • MIN_FIXUP_TABLE_SIZE

      private static final int MIN_FIXUP_TABLE_SIZE
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    • itsFixupTable

      private long[] itsFixupTable
    • itsFixupTableTop

      private int itsFixupTableTop
    • itsVarDescriptors

      private ObjArray itsVarDescriptors
    • itsBootstrapMethods

      private ObjArray itsBootstrapMethods
    • itsBootstrapMethodsLength

      private int itsBootstrapMethodsLength
    • tmpCharBuffer

      private char[] tmpCharBuffer
  • Constructor Details

    • ClassFileWriter

      public ClassFileWriter(String className, String superClassName, String sourceFileName)
      Construct a ClassFileWriter for a class.
      Parameters:
      className - the name of the class to write, including full package qualification.
      superClassName - the name of the superclass of the class to write, including full package qualification.
      sourceFileName - the name of the source file to use for producing debug information, or null if debug information is not desired
  • Method Details

    • getClassName

      public final String getClassName()
    • addInterface

      public void addInterface(String interfaceName)
      Add an interface implemented by this class.

      This method may be called multiple times for classes that implement multiple interfaces.

      Parameters:
      interfaceName - a name of an interface implemented by the class being written, including full package qualification.
    • setFlags

      public void setFlags(short flags)
      Set the class's flags.

      Flags must be a set of the following flags, bitwise or'd together: ACC_PUBLIC ACC_PRIVATE ACC_PROTECTED ACC_FINAL ACC_ABSTRACT TODO: check that this is the appropriate set

      Parameters:
      flags - the set of class flags to set
    • getSlashedForm

      static String getSlashedForm(String name)
    • classNameToSignature

      public static String classNameToSignature(String name)
      Convert Java class name in dot notation into "Lname-with-dots-replaced-by-slashes;" form suitable for use as JVM type signatures.
    • addField

      public void addField(String fieldName, String type, short flags)
      Add a field to the class.
      Parameters:
      fieldName - the name of the field
      type - the type of the field using ...
      flags - the attributes of the field, such as ACC_PUBLIC, etc. bitwise or'd together
    • addField

      public void addField(String fieldName, String type, short flags, int value)
      Add a field to the class.
      Parameters:
      fieldName - the name of the field
      type - the type of the field using ...
      flags - the attributes of the field, such as ACC_PUBLIC, etc. bitwise or'd together
      value - an initial integral value
    • addField

      public void addField(String fieldName, String type, short flags, long value)
      Add a field to the class.
      Parameters:
      fieldName - the name of the field
      type - the type of the field using ...
      flags - the attributes of the field, such as ACC_PUBLIC, etc. bitwise or'd together
      value - an initial long value
    • addField

      public void addField(String fieldName, String type, short flags, double value)
      Add a field to the class.
      Parameters:
      fieldName - the name of the field
      type - the type of the field using ...
      flags - the attributes of the field, such as ACC_PUBLIC, etc. bitwise or'd together
      value - an initial double value
    • addVariableDescriptor

      public void addVariableDescriptor(String name, String type, int startPC, int register)
      Add Information about java variable to use when generating the local variable table.
      Parameters:
      name - variable name.
      type - variable type as bytecode descriptor string.
      startPC - the starting bytecode PC where this variable is live, or -1 if it does not have a Java register.
      register - the Java register number of variable or -1 if it does not have a Java register.
    • startMethod

      public void startMethod(String methodName, String type, short flags)
      Add a method and begin adding code.

      This method must be called before other methods for adding code, exception tables, etc. can be invoked.

      Parameters:
      methodName - the name of the method
      type - a string representing the type
      flags - the attributes of the field, such as ACC_PUBLIC, etc. bitwise or'd together
    • stopMethod

      public void stopMethod(short maxLocals)
      Complete generation of the method.

      After this method is called, no more code can be added to the method begun with startMethod.

      Parameters:
      maxLocals - the maximum number of local variable slots (a.k.a. Java registers) used by the method
    • add

      public void add(int theOpCode)
      Add the single-byte opcode to the current method.
      Parameters:
      theOpCode - the opcode of the bytecode
    • add

      public void add(int theOpCode, int theOperand)
      Add a single-operand opcode to the current method.
      Parameters:
      theOpCode - the opcode of the bytecode
      theOperand - the operand of the bytecode
    • addLoadConstant

      public void addLoadConstant(int k)
      Generate the load constant bytecode for the given integer.
      Parameters:
      k - the constant
    • addLoadConstant

      public void addLoadConstant(long k)
      Generate the load constant bytecode for the given long.
      Parameters:
      k - the constant
    • addLoadConstant

      public void addLoadConstant(float k)
      Generate the load constant bytecode for the given float.
      Parameters:
      k - the constant
    • addLoadConstant

      public void addLoadConstant(double k)
      Generate the load constant bytecode for the given double.
      Parameters:
      k - the constant
    • addLoadConstant

      public void addLoadConstant(String k)
      Generate the load constant bytecode for the given string.
      Parameters:
      k - the constant
    • add

      public void add(int theOpCode, int theOperand1, int theOperand2)
      Add the given two-operand bytecode to the current method.
      Parameters:
      theOpCode - the opcode of the bytecode
      theOperand1 - the first operand of the bytecode
      theOperand2 - the second operand of the bytecode
    • add

      public void add(int theOpCode, String className)
    • add

      public void add(int theOpCode, String className, String fieldName, String fieldType)
    • addInvoke

      public void addInvoke(int theOpCode, String className, String methodName, String methodType)
    • addInvokeDynamic

      public void addInvokeDynamic(String methodName, String methodType, ClassFileWriter.MHandle bsm, Object... bsmArgs)
    • addPush

      public void addPush(int k)
      Generate code to load the given integer on stack.
      Parameters:
      k - the constant
    • addPush

      public void addPush(boolean k)
    • addPush

      public void addPush(long k)
      Generate code to load the given long on stack.
      Parameters:
      k - the constant
    • addPush

      public void addPush(double k)
      Generate code to load the given double on stack.
      Parameters:
      k - the constant
    • addPush

      public void addPush(String k)
      Generate the code to leave on stack the given string even if the string encoding exeeds the class file limit for single string constant
      Parameters:
      k - the constant
    • isUnderStringSizeLimit

      public boolean isUnderStringSizeLimit(String k)
      Check if k fits limit on string constant size imposed by class file format.
      Parameters:
      k - the string constant
    • addIStore

      public void addIStore(int local)
      Store integer from stack top into the given local.
      Parameters:
      local - number of local register
    • addLStore

      public void addLStore(int local)
      Store long from stack top into the given local.
      Parameters:
      local - number of local register
    • addFStore

      public void addFStore(int local)
      Store float from stack top into the given local.
      Parameters:
      local - number of local register
    • addDStore

      public void addDStore(int local)
      Store double from stack top into the given local.
      Parameters:
      local - number of local register
    • addAStore

      public void addAStore(int local)
      Store object from stack top into the given local.
      Parameters:
      local - number of local register
    • addILoad

      public void addILoad(int local)
      Load integer from the given local into stack.
      Parameters:
      local - number of local register
    • addLLoad

      public void addLLoad(int local)
      Load long from the given local into stack.
      Parameters:
      local - number of local register
    • addFLoad

      public void addFLoad(int local)
      Load float from the given local into stack.
      Parameters:
      local - number of local register
    • addDLoad

      public void addDLoad(int local)
      Load double from the given local into stack.
      Parameters:
      local - number of local register
    • addALoad

      public void addALoad(int local)
      Load object from the given local into stack.
      Parameters:
      local - number of local register
    • addLoadThis

      public void addLoadThis()
      Load "this" into stack.
    • xop

      private void xop(int shortOp, int op, int local)
    • addTableSwitch

      public int addTableSwitch(int low, int high)
    • markTableSwitchDefault

      public final void markTableSwitchDefault(int switchStart)
    • markTableSwitchCase

      public final void markTableSwitchCase(int switchStart, int caseIndex)
    • markTableSwitchCase

      public final void markTableSwitchCase(int switchStart, int caseIndex, int stackTop)
    • setTableSwitchJump

      public void setTableSwitchJump(int switchStart, int caseIndex, int jumpTarget)
      Set a jump case for a tableswitch instruction. The jump target should be marked as a super block start for stack map generation.
    • acquireLabel

      public int acquireLabel()
    • markLabel

      public void markLabel(int label)
    • markLabel

      public void markLabel(int label, short stackTop)
    • markHandler

      public void markHandler(int theLabel)
    • getLabelPC

      public int getLabelPC(int label)
    • addLabelFixup

      private void addLabelFixup(int label, int fixupSite)
    • fixLabelGotos

      private void fixLabelGotos()
    • getCurrentCodeOffset

      public int getCurrentCodeOffset()
      Get the current offset into the code of the current method.
      Returns:
      an integer representing the offset
    • getStackTop

      public short getStackTop()
    • setStackTop

      public void setStackTop(short n)
    • adjustStackTop

      public void adjustStackTop(int delta)
    • addToCodeBuffer

      private void addToCodeBuffer(int b)
    • addToCodeInt16

      private void addToCodeInt16(int value)
    • addReservedCodeSpace

      private int addReservedCodeSpace(int size)
    • addExceptionHandler

      public void addExceptionHandler(int startLabel, int endLabel, int handlerLabel, String catchClassName)
    • addLineNumberEntry

      public void addLineNumberEntry(short lineNumber)
    • arrayTypeToName

      private static char arrayTypeToName(int type)
      Convert a newarray operand into an internal type.
    • classDescriptorToInternalName

      private static String classDescriptorToInternalName(String descriptor)
      Convert a class descriptor into an internal name.

      For example, descriptor Ljava/lang/Object; becomes java/lang/Object.

    • descriptorToInternalName

      private static String descriptorToInternalName(String descriptor)
      Convert a non-method type descriptor into an internal type.
      Parameters:
      descriptor - the simple type descriptor to convert
    • createInitialLocals

      private int[] createInitialLocals()
      Compute the initial local variable array for the current method.

      Creates an array of the size of the method's max locals, regardless of the number of parameters in the method.

    • write

      public void write(OutputStream oStream) throws IOException
      Write the class file to the OutputStream.
      Parameters:
      oStream - the stream to write to
      Throws:
      IOException - if writing to the stream produces an exception
    • getWriteSize

      private int getWriteSize()
    • toByteArray

      public byte[] toByteArray()
      Get the class file as array of bytesto the OutputStream.
    • putInt64

      static int putInt64(long value, byte[] array, int offset)
    • badStack

      private static void badStack(int value)
    • sizeOfParameters

      private static int sizeOfParameters(String pString)
    • putInt16

      static int putInt16(int value, byte[] array, int offset)
    • putInt32

      static int putInt32(int value, byte[] array, int offset)
    • opcodeLength

      private static int opcodeLength(int opcode, boolean wide)
      Size of a bytecode instruction, counting the opcode and its operands.

      This is different from opcodeCount, since opcodeCount counts logical operands.

    • opcodeCount

      private static int opcodeCount(int opcode)
      Number of operands accompanying the opcode.
    • stackChange

      private static int stackChange(int opcode)
      The effect on the operand stack of a given opcode.
    • bytecodeStr

      private static String bytecodeStr(int code)
    • getCharBuffer

      final char[] getCharBuffer(int minimalSize)
    • addSuperBlockStart

      private void addSuperBlockStart(int pc)
      Add a pc as the start of super block.

      A pc is the beginning of a super block if: - pc == 0 - it is the target of a branch instruction - it is the beginning of an exception handler - it is directly after an unconditional jump

    • finalizeSuperBlockStarts

      private void finalizeSuperBlockStarts()
      Sort the list of recorded super block starts and remove duplicates.

      Also adds exception handling blocks as block starts, since there is no explicit control flow to these. Used for stack map table generation.