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小百科  ›  Pointer (JNA API)
char offset string
慷慨大方的汤圆
3 年前 
public class Pointer




    

extends Object
An abstraction for a native pointer data type. A Pointer instance represents, on the Java side, a native pointer. The native pointer could be any type of native pointer. Methods such as write , read , getXXX , and setXXX , provide means to access memory underlying the native pointer.

While a constructor exists to create a Pointer from an integer value, it's not generally a good idea to be creating pointers that way.

Author:
Sheng Liang, originator, Todd Fast, suitability modifications, Timothy Wall, robust library loading
See Also:
Function

Method Summary

All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method and Description clear (long size)
Zero memory for the given number of bytes.
static Pointer createConstant (int peer)
Convenience constant, equivalent to (void*)CONSTANT .
static Pointer createConstant (long peer)
Convenience constant, equivalent to (void*)CONSTANT .
String dump (long offset, int size)
Dump memory for debugging purposes.
boolean equals ( Object o)
Compares this Pointer to the specified object.
getByte (long offset)
Indirect the native pointer as a pointer to byte .
byte[] getByteArray (long offset, int arraySize)
Read a native array of bytes of size arraySize from the given offset from this Pointer .
ByteBuffer getByteBuffer (long offset, long length)
Get a ByteBuffer mapped to the memory pointed to by the pointer, ensuring the buffer uses native byte order.
getChar (long offset)
Indirect the native pointer as a pointer to wchar_t .
char[] getCharArray (long offset, int arraySize)
Read a native array of wchar_t of size arraySize from the given offset from this Pointer .
double getDouble (long offset)
Indirect the native pointer as a pointer to double .
double[] getDoubleArray (long offset, int arraySize)
Read a native array of double of size arraySize from the given offset from this Pointer .
float getFloat (long offset)
Indirect the native pointer as a pointer to float .
float[] getFloatArray (long offset, int arraySize)
Read a native array of float of size arraySize from the given offset from this Pointer .
getInt (long offset)
Indirect the native pointer as a pointer to int .
int[] getIntArray (long offset, int arraySize)
Read a native array of int32 of size arraySize from the given offset from this Pointer .
getLong (long offset)
Indirect the native pointer as a pointer to long .
long[] getLongArray (long offset, int arraySize)
Read a native array of int64 of size arraySize from the given offset from this Pointer .
NativeLong getNativeLong (long offset)
Indirect the native pointer as a pointer to long .
Pointer getPointer (long offset)
Indirect the native pointer as a pointer to pointer.
Pointer [] getPointerArray (long offset)
Returns an array of Pointer .
Pointer [] getPointerArray (long offset, int arraySize)
Returns an array of Pointer of the requested size.
short getShort (long offset)
Indirect the native pointer as a pointer to short .
short[] getShortArray (long offset, int arraySize)
Read a native array of int16 of size arraySize from the given offset from this Pointer .
String getString (long offset)
Copy native memory to a Java String.
String getString (long offset, boolean wide)
Deprecated.
use getString(long,String) or getWideString(long) instead.
getStringArray (long offset, int length)
Returns an array of String based on a native array of char * , using the given array length.
String [] getStringArray (long offset, int length, boolean wide)
Deprecated.
use getStringArray(long,int,String) or getWideStringArray(long,int) instead.
String encoding)
Returns an array of String based on a native array of char* or wchar_t* based on the wide parameter, using the given array length.
String [] getStringArray (long offset, String encoding)
Returns an array of String based on a native array of char * , using the requested encoding.
(package private) Object getValue (long offset, Class type, Object currentValue) String getWideString (long offset)
Read a wide ( const wchar_t * ) string from memory.
String [] getWideStringArray (long offset) String [] getWideStringArray (long offset, int length) hashCode ()
Returns a hashcode for the native pointer represented by this Pointer object
indexOf (long offset, byte value)
Returns the offset of the given value in memory from the given offset, or -1 if the value is not found.
static long nativeValue ( Pointer p)
Read the native peer value.
static void nativeValue ( Pointer p, long value)
Set the native peer value.
read (long offset, byte[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, char[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, double[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, float[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, int[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, long[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, Pointer [] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
read (long offset, short[] buf, int index, int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
setByte (long offset, byte value)
Set value at location being pointed to.
setChar (long offset, char value)
Set value at location being pointed to.
setDouble (long offset, double value)
Set value at location being pointed to.
setFloat (long offset, float value)
Set value at location being pointed to.
setInt (long offset, int value)
Set value at location being pointed to.
setLong (long offset, long value)
Set value at location being pointed to.
setMemory (long offset, long length, byte value)
Write value to the requested bank of memory.
setNativeLong (long offset, NativeLong value)
Set value at location being pointed to.
setPointer (long offset, Pointer value)
Set value at location being pointed to.
setShort (long offset, short value)
Set value at location being pointed to.
setString (long offset, String value)
Copy bytes out of string value to the location being pointed to, using the encoding indicated by Native.getDefaultStringEncoding() .
setString (long offset, String value, boolean wide)
Deprecated.
use setWideString(long,String) instead.
setString (long offset, WString value)
Copy string value to the location being pointed to as a wide string ( wchar_t* ).
(package private) void setValue (long offset, Object value, Class type) setWideString (long offset, String value)
Copy string value to the location being pointed to as a wide string ( wchar_t* ).
Pointer share (long offset)
Provide a view of this memory using the given offset to calculate a new base address.
Pointer share (long offset, long sz)
Provide a view of this memory using the given offset to calculate a new base address, bounds-limiting the memory with the given size.
String toString () write (long offset, byte[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long offset, char[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long offset, double[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long offset, float[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long offset, int[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long offset, long[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
write (long bOff, Pointer [] buf, int index, int length)
Write the given array of Pointer to native memory.
write (long offset, short[] buf, int index, int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.

Pointer 

public Pointer(long peer)
Create from native pointer. Don't use this unless you know what you're doing.

createConstant 

public static final Pointer createConstant(int peer)
Convenience constant, equivalent to (void*)CONSTANT . This version will avoid setting any of the high bits on 64-bit systems. 
public Pointer share(long offset,
                     long sz)
Provide a view of this memory using the given offset to calculate a new base address, bounds-limiting the memory with the given size.
Returns:
True if the other object is a Pointer , and the C pointers being pointed to by these objects are also equal. Returns false otherwise.

hashCode 

public int hashCode()
Returns a hashcode for the native pointer represented by this Pointer object
Overrides:
hashCode in class Object
Returns:
A hash code value for the represented native pointer 
public long indexOf(long offset,
                    byte value)
Returns the offset of the given value in memory from the given offset, or -1 if the value is not found.
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - byte array into which data is copied
index - array index from which to start copying
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - short array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - char array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - int array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - long array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - float array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - double array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying from memory pointed to by native pointer, into the specified array.
Parameters:
offset - byte offset from pointer from which data is copied
buf - Pointer array into which data is copied
index - array index to which data is copied
length - number of elements from native pointer that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - byte array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - short array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - char array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - int array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - long array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - float array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
int length)
Indirect the native pointer, copying into memory pointed to by native pointer, from the specified array.
Parameters:
offset - byte offset from pointer into which data is copied
buf - double array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied
Parameters:
bOff - byte offset from pointer into which data is copied
buf - Pointer array from which to copy
index - array index from which to start copying
length - number of elements from buf that must be copied

getByte 

public byte getByte(long offset)
Indirect the native pointer as a pointer to byte . This is equivalent to the expression *((jbyte *)((char *)Pointer + offset)) .
Parameters:
offset - offset from pointer to perform the indirection
Returns:
the byte value being pointed to

getChar 

public char getChar(long offset)
Indirect the native pointer as a pointer to wchar_t . This is equivalent to the expression *((wchar_t*)((char *)Pointer + offset)) .
Parameters:
offset - offset from pointer to perform the indirection
Returns:
the wchar_t value being pointed to

getShort 

public short getShort(long offset)
Indirect the native pointer as a pointer to short . This is equivalent to the expression *((jshort *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the short value being pointed to

getInt 

public int getInt(long offset)
Indirect the native pointer as a pointer to int . This is equivalent to the expression *((jint *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the int value being pointed to

getLong 

public long getLong(long offset)
Indirect the native pointer as a pointer to long . This is equivalent to the expression *((jlong *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the long value being pointed to

getNativeLong 

public NativeLong getNativeLong(long offset)
Indirect the native pointer as a pointer to long . This is equivalent to the expression *((long *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the long value being pointed to

getFloat 

public float getFloat(long offset)
Indirect the native pointer as a pointer to float . This is equivalent to the expression *((jfloat *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the float value being pointed to

getDouble 

public double getDouble(long offset)
Indirect the native pointer as a pointer to double . This is equivalent to the expression *((jdouble *)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
the double value being pointed to

getPointer 

public Pointer getPointer(long offset)
Indirect the native pointer as a pointer to pointer. This is equivalent to the expression *((void **)((char *)Pointer + offset)) .
Parameters:
offset - byte offset from pointer to perform the indirection
Returns:
a Pointer equivalent of the pointer value being pointed to, or null if the pointer value is NULL ; 
public ByteBuffer getByteBuffer(long offset,
                                long length)
Get a ByteBuffer mapped to the memory pointed to by the pointer, ensuring the buffer uses native byte order.
Parameters:
offset - byte offset from pointer to start the buffer
length - Length of ByteBuffer
Returns:
a direct ByteBuffer that accesses the memory being pointed to, 
public String getString(long offset,
                        boolean wide)
Deprecated. use getString(long,String) or getWideString(long) instead.
Copy native memory to a Java String. If wide is true, access the memory as an array of wchar_t , otherwise as an array of char , using the default platform encoding.
Parameters:
offset - byte offset from pointer to obtain the native string v * @param wide whether to convert from a wide or standard C string
Returns:
the String value being pointed to

getString 

public String getString(long offset)
Copy native memory to a Java String. The encoding used is obtained form Native.getDefaultStringEncoding() .
Parameters:
offset - byte offset from pointer to start reading bytes
Returns:
the String value being pointed to 
public String getString(long offset,
                        String encoding)
Copy native memory to a Java String using the requested encoding.
Parameters:
offset - byte offset from pointer to obtain the native string
encoding - the desired encoding
Returns:
the String value being pointed to 
public byte[] getByteArray(long offset,
                           int arraySize)
Read a native array of bytes of size arraySize from the given offset from this Pointer . 
public char[] getCharArray(long offset,
                           int arraySize)
Read a native array of wchar_t of size arraySize from the given offset from this Pointer . 
public short[] getShortArray(long offset,
                             int arraySize)
Read a native array of int16 of size arraySize from the given offset from this Pointer . 
public int[] getIntArray(long offset,
                         int arraySize)
Read a native array of int32 of size arraySize from the given offset from this Pointer . 
public long[] getLongArray(long offset,
                           int arraySize)
Read a native array of int64 of size arraySize from the given offset from this Pointer . 
public float[] getFloatArray(long offset,
                             int arraySize)
Read a native array of float of size arraySize from the given offset from this Pointer . 
public double[] getDoubleArray(long offset,
                               int arraySize)
Read a native array of double of size arraySize from the given offset from this Pointer .

getPointerArray 

public Pointer[] getPointerArray(long offset)
Returns an array of Pointer . The array length is determined by a NULL-valued terminating element.

getStringArray 

public String[] getStringArray(long offset)

Returns an array of String based on a native array of char * . The array length is determined by a NULL-valued terminating element. The strings are decoded using the encoding returned by Native.getDefaultStringEncoding() . 

public String[] getStringArray(long offset,
                               String encoding)
Returns an array of String based on a native array of char * , using the requested encoding. The array length is determined by a NULL-valued terminating element. 
public String[] getStringArray(long offset,
                               int length)

Returns an array of String based on a native array of char * , using the given array length. The strings are decoded using the encoding returned by Native.getDefaultStringEncoding() . 

public String[] getStringArray(long offset,
                               boolean wide)
Deprecated. use getStringArray(long,String) or getWideStringArray(long) instead.
Returns an array of String based on a native array of char* or wchar_t* based on the wide parameter. The array length is determined by a NULL-valued terminating element.
int length, boolean wide)
Deprecated. use getStringArray(long,int,String) or getWideStringArray(long,int) instead.
Returns an array of String based on a native array of char* or wchar_t* based on the wide parameter, using the given array length.
String encoding)
Returns an array of String based on a native array of char* or wchar_t* based on the wide parameter, using the given array length.
Parameters:
offset -
length -
encoding - 
public void setByte(long offset,
                    byte value)
Set value at location being pointed to. This is equivalent to the expression *((jbyte *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - byte value to set 
public void setShort(long offset,
                     short value)
Set value at location being pointed to. This is equivalent to the expression *((jshort *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - short value to set 
public void setChar(long offset,
                    char value)
Set value at location being pointed to. This is equivalent to the expression *((wchar_t *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - char value to set 
public void setInt(long offset,
                   int value)
Set value at location being pointed to. This is equivalent to the expression *((jint *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - int value to set 
public void setLong(long offset,
                    long value)
Set value at location being pointed to. This is equivalent to the expression *((jlong *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - long value to set 
public void setNativeLong(long offset,
                          NativeLong value)
Set value at location being pointed to. This is equivalent to the expression *((long *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - long value to set 
public void setFloat(long offset,
                     float value)
Set value at location being pointed to. This is equivalent to the expression *((jfloat *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - float value to set 
public void setDouble(long offset,
                      double value)
Set value at location being pointed to. This is equivalent to the expression *((jdouble *)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - double value to set 
public void setPointer(long offset,
                       Pointer value)
Set value at location being pointed to. This is equivalent to the expression *((void **)((char *)Pointer + offset)) = value .
Parameters:
offset - byte offset from pointer at which value must be set
value - Pointer holding the actual pointer value to set, which may be null to indicate a NULL pointer.
boolean wide)
Deprecated. use setWideString(long,String) instead.
Copy string value to the location being pointed to.
Parameters:
offset - byte offset from pointer at which characters in value must be set
value - java.lang.String value to set
wide - whether to write the native string as an array of wchar_t . If false, writes as a NUL-terminated array of char using the encoding indicated by Native.getDefaultStringEncoding() . 
public void setWideString(long offset,
                          String value)
Copy string value to the location being pointed to as a wide string ( wchar_t* ).
Parameters:
offset - byte offset from pointer at which characters in value must be set
value - java.lang.String value to set 
public void setString(long offset,
                      WString value)
Copy string value to the location being pointed to as a wide string ( wchar_t* ).
Parameters:
offset - byte offset from pointer at which characters in value must be set
value - WString value to set 
public void setString(long offset,
                      String value)
Copy bytes out of string value to the location being pointed to, using the encoding indicated by Native.getDefaultStringEncoding() .
Parameters:
offset - byte offset from pointer at which characters in value must be set
value - java.lang.String value to set
String encoding)
Copy string value to the location being pointed to, using the requested encoding.
Parameters:
offset - byte offset from pointer at which characters in value must be set
value - java.lang.String value to set
encoding - desired encoding
 
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