DataUtils (H2 Database Engine wt-1.0.1 API)

java.lang.Object
- org.h2.mvstore.DataUtils

```
public class DataUtils
extends Object
```
Utility methods

嵌套类概要

嵌套类
限定符和类型类和说明

static class DataUtils.MapEntry<K,V>
An entry of a map.

嵌套类
限定符和类型	类和说明
`static class`	`DataUtils.MapEntry<K,V>` An entry of a map.

字段概要

字段
限定符和类型	字段和说明
`static int`	`COMPRESSED_VAR_INT_MAX` The maximum integer that needs less space when using variable size encoding (only 3 bytes instead of 4).
`static long`	`COMPRESSED_VAR_LONG_MAX` The maximum long that needs less space when using variable size encoding (only 7 bytes instead of 8).
`static int`	`ERROR_BLOCK_NOT_FOUND` The block in the stream store was not found.
`static int`	`ERROR_CHUNK_NOT_FOUND` The application was trying to read data from a chunk that is no longer available.
`static int`	`ERROR_CLOSED` The object is already closed.
`static int`	`ERROR_FILE_CORRUPT` The file is corrupt or (for encrypted files) the encryption key is wrong.
`static int`	`ERROR_FILE_LOCKED` The file is locked.
`static int`	`ERROR_INTERNAL` An internal error occurred.
`static int`	`ERROR_READING_FAILED` An error occurred while reading from the file.
`static int`	`ERROR_SERIALIZATION` An error occurred when serializing or de-serializing.
`static int`	`ERROR_TOO_MANY_OPEN_TRANSACTIONS` There are too many open transactions.
`static int`	`ERROR_TRANSACTION_CORRUPT` The transaction store is corrupt.
`static int`	`ERROR_TRANSACTION_ILLEGAL_STATE` The transaction store is in an illegal state (for example, not yet initialized).
`static int`	`ERROR_TRANSACTION_LOCKED` An entry is still locked by another transaction.
`static int`	`ERROR_UNSUPPORTED_FORMAT` The file format is not supported.
`static int`	`ERROR_WRITING_FAILED` An error occurred when trying to write to the file.
`static Charset`	`LATIN` The ISO Latin character encoding format.
`static int`	`MAX_VAR_INT_LEN` The maximum length of a variable size int.
`static int`	`MAX_VAR_LONG_LEN` The maximum length of a variable size long.
`static int`	`PAGE_COMPRESSED` The bit mask for compressed pages (compression level fast).
`static int`	`PAGE_COMPRESSED_HIGH` The bit mask for compressed pages (compression level high).
`static int`	`PAGE_LARGE` The marker size of a very large page.
`static int`	`PAGE_MEMORY` The estimated number of bytes used per page object.
`static int`	`PAGE_MEMORY_CHILD` The estimated number of bytes used per child entry.
`static int`	`PAGE_TYPE_LEAF` The type for leaf page.
`static int`	`PAGE_TYPE_NODE` The type for node page.
`static Charset`	`UTF8` The UTF-8 character encoding format.

构造器概要

构造器
构造器和说明

DataUtils()

构造器
构造器和说明
`DataUtils()`

方法概要

所有方法静态方法具体方法
限定符和类型	方法和说明
`static StringBuilder`	`appendMap(StringBuilder buff, HashMap<String,?> map)` Append a map to the string builder, sorted by key.
`static void`	`appendMap(StringBuilder buff, String key, Object value)` Append a key-value pair to the string builder.
`static void`	`checkArgument(boolean test, String message, Object... arguments)` Throw an IllegalArgumentException if the argument is invalid.
`static void`	`copyExcept(Object src, Object dst, int oldSize, int removeIndex)` Copy the elements of an array, and remove one element.
`static void`	`copyWithGap(Object src, Object dst, int oldSize, int gapIndex)` Copy the elements of an array, with a gap.
`static int`	`encodeLength(int len)` Convert the length to a length code 0..31. 31 means more than 1 MB.
`static String`	`formatMessage(int errorCode, String message, Object... arguments)` Format an error message.
`static short`	`getCheckValue(int x)` Calculate a check value for the given integer.
`static int`	`getErrorCode(String m)` Get the error code from an exception message.
`static int`	`getFletcher32(byte[] bytes, int length)` Calculate the Fletcher32 checksum.
`static int`	`getPageChunkId(long pos)` Get the chunk id from the position.
`static int`	`getPageMaxLength(long pos)` Get the maximum length for the given code.
`static int`	`getPageOffset(long pos)` Get the offset from the position.
`static long`	`getPagePos(int chunkId, int offset, int length, int type)` Get the position of this page.
`static int`	`getPageType(long pos)` Get the page type from the position.
`static int`	`getVarIntLen(int x)` Get the length of the variable size int.
`static int`	`getVarLongLen(long x)` Get the length of the variable size long.
`static byte[]`	`newBytes(int len)` Create an array of bytes with the given size.
`static ConcurrentModificationException`	`newConcurrentModificationException(String message)` Create a new ConcurrentModificationException.
`static IllegalArgumentException`	`newIllegalArgumentException(String message, Object... arguments)` Create a new IllegalArgumentException.
`static IllegalStateException`	`newIllegalStateException(int errorCode, String message, Object... arguments)` Create a new IllegalStateException.
`static UnsupportedOperationException`	`newUnsupportedOperationException(String message)` Create a new UnsupportedOperationException.
`static int`	`parseHexInt(String x)` Parse an unsigned, hex long.
`static long`	`parseHexLong(String x)` Parse an unsigned, hex long.
`static HashMap<String,String>`	`parseMap(String s)` Parse a key-value pair list.
`static void`	`readFully(FileChannel file, long pos, ByteBuffer dst)` Read from a file channel until the buffer is full.
`static int`	`readHexInt(HashMap<String,? extends Object> map, String key, int defaultValue)` Read a hex int value from a map.
`static long`	`readHexLong(Map<String,? extends Object> map, String key, long defaultValue)` Read a hex long value from a map.
`static String`	`readString(ByteBuffer buff, int len)` Read a string.
`static int`	`readVarInt(ByteBuffer buff)` Read a variable size int.
`static long`	`readVarLong(ByteBuffer buff)` Read a variable size long.
`static void`	`writeFully(FileChannel file, long pos, ByteBuffer src)` Write to a file channel.
`static void`	`writeStringData(ByteBuffer buff, String s, int len)` Write characters from a string (without the length).
`static void`	`writeVarInt(ByteBuffer buff, int x)` Write a variable size int.
`static void`	`writeVarInt(OutputStream out, int x)` Write a variable size int.
`static void`	`writeVarLong(ByteBuffer buff, long x)` Write a variable size long.
`static void`	`writeVarLong(OutputStream out, long x)` Write a variable size long.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - ERROR_READING_FAILED
```
public static final int ERROR_READING_FAILED
```
    An error occurred while reading from the file.
    
    另请参阅:
    
    常量字段值
  - ERROR_WRITING_FAILED
```
public static final int ERROR_WRITING_FAILED
```
    An error occurred when trying to write to the file.
    
    另请参阅:
    
    常量字段值
  - ERROR_INTERNAL
```
public static final int ERROR_INTERNAL
```
    An internal error occurred. This could be a bug, or a memory corruption (for example caused by out of memory).
    
    另请参阅:
    
    常量字段值
  - ERROR_CLOSED
```
public static final int ERROR_CLOSED
```
    The object is already closed.
    
    另请参阅:
    
    常量字段值
  - ERROR_UNSUPPORTED_FORMAT
```
public static final int ERROR_UNSUPPORTED_FORMAT
```
    The file format is not supported.
    
    另请参阅:
    
    常量字段值
  - ERROR_FILE_CORRUPT
```
public static final int ERROR_FILE_CORRUPT
```
    The file is corrupt or (for encrypted files) the encryption key is wrong.
    
    另请参阅:
    
    常量字段值
  - ERROR_FILE_LOCKED
```
public static final int ERROR_FILE_LOCKED
```
    The file is locked.
    
    另请参阅:
    
    常量字段值
  - ERROR_SERIALIZATION
```
public static final int ERROR_SERIALIZATION
```
    An error occurred when serializing or de-serializing.
    
    另请参阅:
    
    常量字段值
  - ERROR_CHUNK_NOT_FOUND
```
public static final int ERROR_CHUNK_NOT_FOUND
```
    The application was trying to read data from a chunk that is no longer available.
    
    另请参阅:
    
    常量字段值
  - ERROR_BLOCK_NOT_FOUND
```
public static final int ERROR_BLOCK_NOT_FOUND
```
    The block in the stream store was not found.
    
    另请参阅:
    
    常量字段值
  - ERROR_TRANSACTION_CORRUPT
```
public static final int ERROR_TRANSACTION_CORRUPT
```
    The transaction store is corrupt.
    
    另请参阅:
    
    常量字段值
  - ERROR_TRANSACTION_LOCKED
```
public static final int ERROR_TRANSACTION_LOCKED
```
    An entry is still locked by another transaction.
    
    另请参阅:
    
    常量字段值
  - ERROR_TOO_MANY_OPEN_TRANSACTIONS
```
public static final int ERROR_TOO_MANY_OPEN_TRANSACTIONS
```
    There are too many open transactions.
    
    另请参阅:
    
    常量字段值
  - ERROR_TRANSACTION_ILLEGAL_STATE
```
public static final int ERROR_TRANSACTION_ILLEGAL_STATE
```
    The transaction store is in an illegal state (for example, not yet initialized).
    
    另请参阅:
    
    常量字段值
  - PAGE_TYPE_LEAF
```
public static final int PAGE_TYPE_LEAF
```
    The type for leaf page.
    
    另请参阅:
    
    常量字段值
  - PAGE_TYPE_NODE
```
public static final int PAGE_TYPE_NODE
```
    The type for node page.
    
    另请参阅:
    
    常量字段值
  - PAGE_COMPRESSED
```
public static final int PAGE_COMPRESSED
```
    The bit mask for compressed pages (compression level fast).
    
    另请参阅:
    
    常量字段值
  - PAGE_COMPRESSED_HIGH
```
public static final int PAGE_COMPRESSED_HIGH
```
    The bit mask for compressed pages (compression level high).
    
    另请参阅:
    
    常量字段值
  - MAX_VAR_INT_LEN
```
public static final int MAX_VAR_INT_LEN
```
    The maximum length of a variable size int.
    
    另请参阅:
    
    常量字段值
  - MAX_VAR_LONG_LEN
```
public static final int MAX_VAR_LONG_LEN
```
    The maximum length of a variable size long.
    
    另请参阅:
    
    常量字段值
  - COMPRESSED_VAR_INT_MAX
```
public static final int COMPRESSED_VAR_INT_MAX
```
    The maximum integer that needs less space when using variable size encoding (only 3 bytes instead of 4).
    
    另请参阅:
    
    常量字段值
  - COMPRESSED_VAR_LONG_MAX
```
public static final long COMPRESSED_VAR_LONG_MAX
```
    The maximum long that needs less space when using variable size encoding (only 7 bytes instead of 8).
    
    另请参阅:
    
    常量字段值
  - PAGE_MEMORY
```
public static final int PAGE_MEMORY
```
    The estimated number of bytes used per page object.
    
    另请参阅:
    
    常量字段值
  - PAGE_MEMORY_CHILD
```
public static final int PAGE_MEMORY_CHILD
```
    The estimated number of bytes used per child entry.
    
    另请参阅:
    
    常量字段值
  - PAGE_LARGE
```
public static final int PAGE_LARGE
```
    The marker size of a very large page.
    
    另请参阅:
    
    常量字段值
  - UTF8
```
public static final Charset UTF8
```
    The UTF-8 character encoding format.
  - LATIN
```
public static final Charset LATIN
```
    The ISO Latin character encoding format.
- 构造器详细资料
  - DataUtils
```
public DataUtils()
```
- 方法详细资料
  - getVarIntLen
```
public static int getVarIntLen(int x)
```
    Get the length of the variable size int.
    
    参数:
    
    x - the value
    
    返回:
    
    the length in bytes
  - getVarLongLen
```
public static int getVarLongLen(long x)
```
    Get the length of the variable size long.
    
    参数:
    
    x - the value
    
    返回:
    
    the length in bytes
  - readVarInt
```
public static int readVarInt(ByteBuffer buff)
```
    Read a variable size int.
    
    参数:
    
    buff - the source buffer
    
    返回:
    
    the value
  - readVarLong
```
public static long readVarLong(ByteBuffer buff)
```
    Read a variable size long.
    
    参数:
    
    buff - the source buffer
    
    返回:
    
    the value
  - writeVarInt
```
public static void writeVarInt(OutputStream out,
                               int x)
                        throws IOException
```
    Write a variable size int.
    
    参数:
    
    out - the output stream
    
    x - the value
    
    抛出:
    
    IOException
  - writeVarInt
```
public static void writeVarInt(ByteBuffer buff,
                               int x)
```
    Write a variable size int.
    
    参数:
    
    buff - the source buffer
    
    x - the value
  - writeStringData
```
public static void writeStringData(ByteBuffer buff,
                                   String s,
                                   int len)
```
    Write characters from a string (without the length).
    
    参数:
    
    buff - the target buffer (must be large enough)
    
    s - the string
    
    len - the number of characters
  - readString
```
public static String readString(ByteBuffer buff,
                                int len)
```
    Read a string.
    
    参数:
    
    buff - the source buffer
    
    len - the number of characters
    
    返回:
    
    the value
  - writeVarLong
```
public static void writeVarLong(ByteBuffer buff,
                                long x)
```
    Write a variable size long.
    
    参数:
    
    buff - the target buffer
    
    x - the value
  - writeVarLong
```
public static void writeVarLong(OutputStream out,
                                long x)
                         throws IOException
```
    Write a variable size long.
    
    参数:
    
    out - the output stream
    
    x - the value
    
    抛出:
    
    IOException
  - copyWithGap
```
public static void copyWithGap(Object src,
                               Object dst,
                               int oldSize,
                               int gapIndex)
```
    Copy the elements of an array, with a gap.
    
    参数:
    
    src - the source array
    
    dst - the target array
    
    oldSize - the size of the old array
    
    gapIndex - the index of the gap
  - copyExcept
```
public static void copyExcept(Object src,
                              Object dst,
                              int oldSize,
                              int removeIndex)
```
    Copy the elements of an array, and remove one element.
    
    参数:
    
    src - the source array
    
    dst - the target array
    
    oldSize - the size of the old array
    
    removeIndex - the index of the entry to remove
  - readFully
```
public static void readFully(FileChannel file,
                             long pos,
                             ByteBuffer dst)
```
    Read from a file channel until the buffer is full. The buffer is rewind after reading.
    
    参数:
    
    file - the file channel
    
    pos - the absolute position within the file
    
    dst - the byte buffer
    
    抛出:
    
    IllegalStateException - if some data could not be read
  - writeFully
```
public static void writeFully(FileChannel file,
                              long pos,
                              ByteBuffer src)
```
    Write to a file channel.
    
    参数:
    
    file - the file channel
    
    pos - the absolute position within the file
    
    src - the source buffer
  - encodeLength
```
public static int encodeLength(int len)
```
    Convert the length to a length code 0..31. 31 means more than 1 MB.
    
    参数:
    
    len - the length
    
    返回:
    
    the length code
  - getPageChunkId
```
public static int getPageChunkId(long pos)
```
    Get the chunk id from the position.
    
    参数:
    
    pos - the position
    
    返回:
    
    the chunk id
  - getPageMaxLength
```
public static int getPageMaxLength(long pos)
```
    Get the maximum length for the given code. For the code 31, PAGE_LARGE is returned.
    
    参数:
    
    pos - the position
    
    返回:
    
    the maximum length
  - getPageOffset
```
public static int getPageOffset(long pos)
```
    Get the offset from the position.
    
    参数:
    
    pos - the position
    
    返回:
    
    the offset
  - getPageType
```
public static int getPageType(long pos)
```
    Get the page type from the position.
    
    参数:
    
    pos - the position
    
    返回:
    
    the page type (PAGE_TYPE_NODE or PAGE_TYPE_LEAF)
  - getPagePos
```
public static long getPagePos(int chunkId,
                              int offset,
                              int length,
                              int type)
```
    Get the position of this page. The following information is encoded in the position: the chunk id, the offset, the maximum length, and the type (node or leaf).
    
    参数:
    
    chunkId - the chunk id
    
    offset - the offset
    
    length - the length
    
    type - the page type (1 for node, 0 for leaf)
    
    返回:
    
    the position
  - getCheckValue
```
public static short getCheckValue(int x)
```
    Calculate a check value for the given integer. A check value is mean to verify the data is consistent with a high probability, but not meant to protect against media failure or deliberate changes.
    
    参数:
    
    x - the value
    
    返回:
    
    the check value
  - appendMap
```
public static StringBuilder appendMap(StringBuilder buff,
                                      HashMap<String,?> map)
```
    Append a map to the string builder, sorted by key.
    
    参数:
    
    buff - the target buffer
    
    map - the map
    
    返回:
    
    the string builder
  - appendMap
```
public static void appendMap(StringBuilder buff,
                             String key,
                             Object value)
```
    Append a key-value pair to the string builder. Keys may not contain a colon. Values that contain a comma or a double quote are enclosed in double quotes, with special characters escaped using a backslash.
    
    参数:
    
    buff - the target buffer
    
    key - the key
    
    value - the value
  - parseMap
```
public static HashMap<String,String> parseMap(String s)
```
    Parse a key-value pair list.
    
    参数:
    
    s - the list
    
    返回:
    
    the map
    
    抛出:
    
    IllegalStateException - if parsing failed
  - getFletcher32
```
public static int getFletcher32(byte[] bytes,
                                int length)
```
    Calculate the Fletcher32 checksum.
    
    参数:
    
    bytes - the bytes
    
    length - the message length (if odd, 0 is appended)
    
    返回:
    
    the checksum
  - checkArgument
```
public static void checkArgument(boolean test,
                                 String message,
                                 Object... arguments)
```
    Throw an IllegalArgumentException if the argument is invalid.
    
    参数:
    
    test - true if the argument is valid
    
    message - the message
    
    arguments - the arguments
    
    抛出:
    
    IllegalArgumentException - if the argument is invalid
  - newIllegalArgumentException
```
public static IllegalArgumentException newIllegalArgumentException(String message,
                                                                   Object... arguments)
```
    Create a new IllegalArgumentException.
    
    参数:
    
    message - the message
    
    arguments - the arguments
    
    返回:
    
    the exception
  - newUnsupportedOperationException
```
public static UnsupportedOperationException newUnsupportedOperationException(String message)
```
    Create a new UnsupportedOperationException.
    
    参数:
    
    message - the message
    
    返回:
    
    the exception
  - newConcurrentModificationException
```
public static ConcurrentModificationException newConcurrentModificationException(String message)
```
    Create a new ConcurrentModificationException.
    
    参数:
    
    message - the message
    
    返回:
    
    the exception
  - newIllegalStateException
```
public static IllegalStateException newIllegalStateException(int errorCode,
                                                             String message,
                                                             Object... arguments)
```
    Create a new IllegalStateException.
    
    参数:
    
    errorCode - the error code
    
    message - the message
    
    arguments - the arguments
    
    返回:
    
    the exception
  - formatMessage
```
public static String formatMessage(int errorCode,
                                   String message,
                                   Object... arguments)
```
    Format an error message.
    
    参数:
    
    errorCode - the error code
    
    message - the message
    
    arguments - the arguments
    
    返回:
    
    the formatted message
  - getErrorCode
```
public static int getErrorCode(String m)
```
    Get the error code from an exception message.
    
    参数:
    
    m - the message
    
    返回:
    
    the error code, or 0 if none
  - newBytes
```
public static byte[] newBytes(int len)
```
    Create an array of bytes with the given size. If this is not possible because not enough memory is available, an OutOfMemoryError with the requested size in the message is thrown.
    This method should be used if the size of the array is user defined, or stored in a file, so wrong size data can be distinguished from regular out-of-memory.
    
    参数:
    
    len - the number of bytes requested
    
    返回:
    
    the byte array
    
    抛出:
    
    OutOfMemoryError - if the allocation was too large
  - readHexLong
```
public static long readHexLong(Map<String,? extends Object> map,
                               String key,
                               long defaultValue)
```
    Read a hex long value from a map.
    
    参数:
    
    map - the map
    
    key - the key
    
    defaultValue - if the value is null
    
    返回:
    
    the parsed value
    
    抛出:
    
    IllegalStateException - if parsing fails
  - parseHexLong
```
public static long parseHexLong(String x)
```
    Parse an unsigned, hex long.
    
    参数:
    
    x - the string
    
    返回:
    
    the parsed value
    
    抛出:
    
    IllegalStateException - if parsing fails
  - parseHexInt
```
public static int parseHexInt(String x)
```
    Parse an unsigned, hex long.
    
    参数:
    
    x - the string
    
    返回:
    
    the parsed value
    
    抛出:
    
    IllegalStateException - if parsing fails
  - readHexInt
```
public static int readHexInt(HashMap<String,? extends Object> map,
                             String key,
                             int defaultValue)
```
    Read a hex int value from a map.
    
    参数:
    
    map - the map
    
    key - the key
    
    defaultValue - if the value is null
    
    返回:
    
    the parsed value
    
    抛出:
    
    IllegalStateException - if parsing fails

类 DataUtils

嵌套类概要

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

ERROR_READING_FAILED

ERROR_WRITING_FAILED

ERROR_INTERNAL

ERROR_CLOSED

ERROR_UNSUPPORTED_FORMAT

ERROR_FILE_CORRUPT

ERROR_FILE_LOCKED

ERROR_SERIALIZATION

ERROR_CHUNK_NOT_FOUND

ERROR_BLOCK_NOT_FOUND

ERROR_TRANSACTION_CORRUPT

ERROR_TRANSACTION_LOCKED

ERROR_TOO_MANY_OPEN_TRANSACTIONS

ERROR_TRANSACTION_ILLEGAL_STATE

PAGE_TYPE_LEAF

PAGE_TYPE_NODE

PAGE_COMPRESSED

PAGE_COMPRESSED_HIGH

MAX_VAR_INT_LEN

MAX_VAR_LONG_LEN

COMPRESSED_VAR_INT_MAX

COMPRESSED_VAR_LONG_MAX

PAGE_MEMORY

PAGE_MEMORY_CHILD

PAGE_LARGE

UTF8

LATIN

构造器详细资料

DataUtils

方法详细资料

getVarIntLen

getVarLongLen

readVarInt

readVarLong

writeVarInt

writeVarInt

writeStringData

readString

writeVarLong

writeVarLong

copyWithGap

copyExcept

readFully

writeFully

encodeLength

getPageChunkId

getPageMaxLength

getPageOffset

getPageType

getPagePos

getCheckValue

appendMap

appendMap

parseMap

getFletcher32

checkArgument

newIllegalArgumentException

newUnsupportedOperationException

newConcurrentModificationException

newIllegalStateException

formatMessage

getErrorCode

newBytes

readHexLong

parseHexLong

parseHexInt

readHexInt