SysProperties (H2 Database Engine wt-1.0.1 API)

java.lang.Object
- org.h2.engine.SysProperties

```
public class SysProperties
extends Object
```
The constants defined in this class are initialized from system properties. Some system properties are per machine settings, and others are as a last resort and temporary solution to work around a problem in the application or database engine. Also, there are system properties to enable features that are not yet fully tested or that are not backward compatible.
System properties can be set when starting the virtual machine:
```
 java -Dh2.baseDir=/temp
 
```
They can be set within the application, but this must be done before loading any classes of this database (before loading the JDBC driver):
```
 System.setProperty("h2.baseDir", "/temp");
 
```

字段概要

字段
限定符和类型	字段和说明
`static String`	`ALLOWED_CLASSES` System property `h2.allowedClasses` (default: *).
`static String`	`BIND_ADDRESS` System property `h2.bindAddress` (default: null).
`static String`	`BROWSER` System property `h2.browser` (default: null).
`static boolean`	`CHECK` System property `h2.check` (default: true).
`static boolean`	`CHECK2` System property `h2.check2` (default: false).
`static String`	`CLIENT_TRACE_DIRECTORY` System property `h2.clientTraceDirectory` (default: trace.db/).
`static int`	`COLLATOR_CACHE_SIZE` System property `h2.collatorCacheSize` (default: 32000).
`static int`	`CONSOLE_MAX_PROCEDURES_LIST_COLUMNS` System property `h2.consoleProcedureColumns` (default: 500).
`static int`	`CONSOLE_MAX_TABLES_LIST_COLUMNS` System property `h2.consoleTableColumns` (default: 500).
`static int`	`CONSOLE_MAX_TABLES_LIST_INDEXES` System property `h2.consoleTableIndexes` (default: 100).
`static boolean`	`CONSOLE_STREAM` System property `h2.consoleStream` (default: true).
`static int`	`CONSOLE_TIMEOUT` System property `h2.consoleTimeout` (default: 1800000).
`static int`	`DATASOURCE_TRACE_LEVEL` System property `h2.dataSourceTraceLevel` (default: 1).
`static int`	`DELAY_WRONG_PASSWORD_MAX` System property `h2.delayWrongPasswordMax` (default: 4000).
`static int`	`DELAY_WRONG_PASSWORD_MIN` System property `h2.delayWrongPasswordMin` (default: 250).
`static boolean`	`ENABLE_ANONYMOUS_TLS` System property `h2.enableAnonymousTLS` (default: true).
`static String`	`FILE_ENCODING` System property `file.encoding` (default: Cp1252).
`static String`	`FILE_SEPARATOR` System property `file.separator` (default: /).
`static String`	`H2_BROWSER` INTERNAL
`static String`	`H2_SCRIPT_DIRECTORY` INTERNAL
`static boolean`	`IMPLICIT_RELATIVE_PATH` System property `h2.implicitRelativePath` (default: true for version 1.3, false for version 1.4).
`static String`	`JAVA_OBJECT_SERIALIZER` System property `h2.javaObjectSerializer` (default: null).
`static String`	`JAVA_SPECIFICATION_VERSION` System property `java.specification.version`.
`static boolean`	`JAVA_SYSTEM_COMPILER` System property `h2.javaSystemCompiler` (default: true).
`static String`	`LINE_SEPARATOR` System property `line.separator` (default: \n).
`static int`	`LOB_CLIENT_MAX_SIZE_MEMORY` System property `h2.lobClientMaxSizeMemory` (default: 1048576).
`static int`	`LOB_FILES_PER_DIRECTORY` System property `h2.lobFilesPerDirectory` (default: 256).
`static boolean`	`lobCloseBetweenReads` System property `h2.lobCloseBetweenReads` (default: false).
`static int`	`MAX_FILE_RETRY` System property `h2.maxFileRetry` (default: 16).
`static int`	`MAX_MEMORY_ROWS` System property `h2.maxMemoryRows` (default: 40000 per GB of available RAM).
`static int`	`MAX_RECONNECT` System property `h2.maxReconnect` (default: 3).
`static long`	`MAX_TRACE_DATA_LENGTH` System property `h2.maxTraceDataLength` (default: 65535).
`static boolean`	`MODIFY_ON_WRITE` System property `h2.modifyOnWrite` (default: false).
`static boolean`	`NIO_CLEANER_HACK` System property `h2.nioCleanerHack` (default: false).
`static boolean`	`NIO_LOAD_MAPPED` System property `h2.nioLoadMapped` (default: false).
`static boolean`	`OBJECT_CACHE` System property `h2.objectCache` (default: true).
`static int`	`OBJECT_CACHE_MAX_PER_ELEMENT_SIZE` System property `h2.objectCacheMaxPerElementSize` (default: 4096).
`static int`	`OBJECT_CACHE_SIZE` System property `h2.objectCacheSize` (default: 1024).
`static boolean`	`OLD_STYLE_OUTER_JOIN` System property `h2.oldStyleOuterJoin` (default: true for version 1.3, false for version 1.4).
`static String`	`PG_DEFAULT_CLIENT_ENCODING` System property `h2.pgClientEncoding` (default: UTF-8).
`static String`	`PREFIX_TEMP_FILE` System property `h2.prefixTempFile` (default: h2.temp).
`static boolean`	`serializeJavaObject` System property `h2.serializeJavaObject` (default: true).
`static int`	`SERVER_CACHED_OBJECTS` System property `h2.serverCachedObjects` (default: 64).
`static int`	`SERVER_RESULT_SET_FETCH_SIZE` System property `h2.serverResultSetFetchSize` (default: 100).
`static int`	`SOCKET_CONNECT_RETRY` System property `h2.socketConnectRetry` (default: 16).
`static int`	`SOCKET_CONNECT_TIMEOUT` System property `h2.socketConnectTimeout` (default: 2000).
`static boolean`	`SORT_BINARY_UNSIGNED` System property `h2.sortBinaryUnsigned` (default: false with version 1.3, true with version 1.4).
`static boolean`	`SORT_NULLS_HIGH` System property `h2.sortNullsHigh` (default: false).
`static long`	`SPLIT_FILE_SIZE_SHIFT` System property `h2.splitFileSizeShift` (default: 30).
`static String`	`SYNC_METHOD` System property `h2.syncMethod` (default: sync).
`static boolean`	`THREAD_DEADLOCK_DETECTOR` System property `h2.threadDeadlockDetector` (default: false).
`static boolean`	`TRACE_IO` System property `h2.traceIO` (default: false).
`static String`	`URL_MAP` System property `h2.urlMap` (default: null).
`static boolean`	`USE_THREAD_CONTEXT_CLASS_LOADER` System property `h2.useThreadContextClassLoader` (default: false).
`static String`	`USER_HOME` System property `user.home` (empty string if not set).

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 String`	`getBaseDir()` INTERNAL
`static String`	`getScriptDirectory()` System property `h2.scriptDirectory` (default: empty string).
`static void`	`setBaseDir(String dir)` INTERNAL

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
  - H2_SCRIPT_DIRECTORY
```
public static final String H2_SCRIPT_DIRECTORY
```
    INTERNAL
    
    另请参阅:
    
    常量字段值
  - H2_BROWSER
```
public static final String H2_BROWSER
```
    INTERNAL
    
    另请参阅:
    
    常量字段值
  - FILE_ENCODING
```
public static final String FILE_ENCODING
```
    System property file.encoding (default: Cp1252).
    It is usually set by the system and is the default encoding used for the RunScript and CSV tool.
  - FILE_SEPARATOR
```
public static final String FILE_SEPARATOR
```
    System property file.separator (default: /).
    It is usually set by the system, and used to build absolute file names.
  - JAVA_SPECIFICATION_VERSION
```
public static final String JAVA_SPECIFICATION_VERSION
```
    System property java.specification.version.
    It is set by the system. Examples: 1.4, 1.5, 1.6.
  - LINE_SEPARATOR
```
public static final String LINE_SEPARATOR
```
    System property line.separator (default: \n).
    It is usually set by the system, and used by the script and trace tools.
  - USER_HOME
```
public static final String USER_HOME
```
    System property user.home (empty string if not set).
    It is usually set by the system, and used as a replacement for ~ in file names.
  - ALLOWED_CLASSES
```
public static final String ALLOWED_CLASSES
```
    System property h2.allowedClasses (default: *).
    Comma separated list of class names or prefixes.
  - BROWSER
```
public static final String BROWSER
```
    System property h2.browser (default: null).
    The preferred browser to use. If not set, the default browser is used. For Windows, to use the Internet Explorer, set this property to 'explorer'. For Mac OS, if the default browser is not Safari and you want to use Safari, use: java -Dh2.browser="open,-a,Safari,%url" ....
  - ENABLE_ANONYMOUS_TLS
```
public static final boolean ENABLE_ANONYMOUS_TLS
```
    System property h2.enableAnonymousTLS (default: true).
    When using TLS connection, the anonymous cipher suites should be enabled.
  - BIND_ADDRESS
```
public static final String BIND_ADDRESS
```
    System property h2.bindAddress (default: null).
    The bind address to use.
  - CHECK
```
public static final boolean CHECK
```
    System property h2.check (default: true).
    Assertions in the database engine.
  - CHECK2
```
public static final boolean CHECK2
```
    System property h2.check2 (default: false).
    Additional assertions in the database engine.
  - CLIENT_TRACE_DIRECTORY
```
public static final String CLIENT_TRACE_DIRECTORY
```
    System property h2.clientTraceDirectory (default: trace.db/).
    Directory where the trace files of the JDBC client are stored (only for client / server).
  - COLLATOR_CACHE_SIZE
```
public static final int COLLATOR_CACHE_SIZE
```
    System property h2.collatorCacheSize (default: 32000).
    The cache size for collation keys (in elements). Used when a collator has been set for the database.
  - CONSOLE_MAX_TABLES_LIST_INDEXES
```
public static final int CONSOLE_MAX_TABLES_LIST_INDEXES
```
    System property h2.consoleTableIndexes (default: 100).
    Up to this many tables, the column type and indexes are listed.
  - CONSOLE_MAX_TABLES_LIST_COLUMNS
```
public static final int CONSOLE_MAX_TABLES_LIST_COLUMNS
```
    System property h2.consoleTableColumns (default: 500).
    Up to this many tables, the column names are listed.
  - CONSOLE_MAX_PROCEDURES_LIST_COLUMNS
```
public static final int CONSOLE_MAX_PROCEDURES_LIST_COLUMNS
```
    System property h2.consoleProcedureColumns (default: 500).
    Up to this many procedures, the column names are listed.
  - CONSOLE_STREAM
```
public static final boolean CONSOLE_STREAM
```
    System property h2.consoleStream (default: true).
    H2 Console: stream query results.
  - CONSOLE_TIMEOUT
```
public static final int CONSOLE_TIMEOUT
```
    System property h2.consoleTimeout (default: 1800000).
    H2 Console: session timeout in milliseconds. The default is 30 minutes.
  - DATASOURCE_TRACE_LEVEL
```
public static final int DATASOURCE_TRACE_LEVEL
```
    System property h2.dataSourceTraceLevel (default: 1).
    The trace level of the data source implementation. Default is 1 for error.
  - DELAY_WRONG_PASSWORD_MIN
```
public static final int DELAY_WRONG_PASSWORD_MIN
```
    System property h2.delayWrongPasswordMin (default: 250).
    The minimum delay in milliseconds before an exception is thrown for using the wrong user name or password. This slows down brute force attacks. The delay is reset to this value after a successful login. Unsuccessful logins will double the time until DELAY_WRONG_PASSWORD_MAX. To disable the delay, set this system property to 0.
  - DELAY_WRONG_PASSWORD_MAX
```
public static final int DELAY_WRONG_PASSWORD_MAX
```
    System property h2.delayWrongPasswordMax (default: 4000).
    The maximum delay in milliseconds before an exception is thrown for using the wrong user name or password. This slows down brute force attacks. The delay is reset after a successful login. The value 0 means there is no maximum delay.
  - JAVA_SYSTEM_COMPILER
```
public static final boolean JAVA_SYSTEM_COMPILER
```
    System property h2.javaSystemCompiler (default: true).
    Whether to use the Java system compiler (ToolProvider.getSystemJavaCompiler()) if it is available to compile user defined functions. If disabled or if the system compiler is not available, the com.sun.tools.javac compiler is used if available, and "javac" (as an external process) is used if not.
  - lobCloseBetweenReads
```
public static boolean lobCloseBetweenReads
```
    System property h2.lobCloseBetweenReads (default: false).
    Close LOB files between read operations.
  - LOB_FILES_PER_DIRECTORY
```
public static final int LOB_FILES_PER_DIRECTORY
```
    System property h2.lobFilesPerDirectory (default: 256).
    Maximum number of LOB files per directory.
  - LOB_CLIENT_MAX_SIZE_MEMORY
```
public static final int LOB_CLIENT_MAX_SIZE_MEMORY
```
    System property h2.lobClientMaxSizeMemory (default: 1048576).
    The maximum size of a LOB object to keep in memory on the client side when using the server mode.
  - MAX_FILE_RETRY
```
public static final int MAX_FILE_RETRY
```
    System property h2.maxFileRetry (default: 16).
    Number of times to retry file delete and rename. in Windows, files can't be deleted if they are open. Waiting a bit can help (sometimes the Windows Explorer opens the files for a short time) may help. Sometimes, running garbage collection may close files if the user forgot to call Connection.close() or InputStream.close().
  - MAX_RECONNECT
```
public static final int MAX_RECONNECT
```
    System property h2.maxReconnect (default: 3).
    The maximum number of tries to reconnect in a row.
  - MAX_MEMORY_ROWS
```
public static final int MAX_MEMORY_ROWS
```
    System property h2.maxMemoryRows (default: 40000 per GB of available RAM).
    The default maximum number of rows to be kept in memory in a result set.
  - MAX_TRACE_DATA_LENGTH
```
public static final long MAX_TRACE_DATA_LENGTH
```
    System property h2.maxTraceDataLength (default: 65535).
    The maximum size of a LOB value that is written as data to the trace system.
  - MODIFY_ON_WRITE
```
public static final boolean MODIFY_ON_WRITE
```
    System property h2.modifyOnWrite (default: false).
    Only modify the database file when recovery is necessary, or when writing to the database. If disabled, opening the database always writes to the file (except if the database is read-only). When enabled, the serialized file lock is faster.
  - NIO_LOAD_MAPPED
```
public static final boolean NIO_LOAD_MAPPED
```
    System property h2.nioLoadMapped (default: false).
    If the mapped buffer should be loaded when the file is opened. This can improve performance.
  - NIO_CLEANER_HACK
```
public static final boolean NIO_CLEANER_HACK
```
    System property h2.nioCleanerHack (default: false).
    If enabled, use the reflection hack to un-map the mapped file if possible. If disabled, System.gc() is called in a loop until the object is garbage collected. See also http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4724038
  - OBJECT_CACHE
```
public static final boolean OBJECT_CACHE
```
    System property h2.objectCache (default: true).
    Cache commonly used values (numbers, strings). There is a shared cache for all values.
  - OBJECT_CACHE_MAX_PER_ELEMENT_SIZE
```
public static final int OBJECT_CACHE_MAX_PER_ELEMENT_SIZE
```
    System property h2.objectCacheMaxPerElementSize (default: 4096).
    The maximum size (precision) of an object in the cache.
  - OBJECT_CACHE_SIZE
```
public static final int OBJECT_CACHE_SIZE
```
    System property h2.objectCacheSize (default: 1024).
    The maximum number of objects in the cache. This value must be a power of 2.
  - OLD_STYLE_OUTER_JOIN
```
public static final boolean OLD_STYLE_OUTER_JOIN
```
    System property h2.oldStyleOuterJoin (default: true for version 1.3, false for version 1.4).
    Limited support for the old-style Oracle outer join with "(+)".
  - PG_DEFAULT_CLIENT_ENCODING
```
public static final String PG_DEFAULT_CLIENT_ENCODING
```
    System property h2.pgClientEncoding (default: UTF-8).
    Default client encoding for PG server. It is used if the client does not sends his encoding.
  - PREFIX_TEMP_FILE
```
public static final String PREFIX_TEMP_FILE
```
    System property h2.prefixTempFile (default: h2.temp).
    The prefix for temporary files in the temp directory.
  - SERVER_CACHED_OBJECTS
```
public static final int SERVER_CACHED_OBJECTS
```
    System property h2.serverCachedObjects (default: 64).
    TCP Server: number of cached objects per session.
  - SERVER_RESULT_SET_FETCH_SIZE
```
public static final int SERVER_RESULT_SET_FETCH_SIZE
```
    System property h2.serverResultSetFetchSize (default: 100).
    The default result set fetch size when using the server mode.
  - SOCKET_CONNECT_RETRY
```
public static final int SOCKET_CONNECT_RETRY
```
    System property h2.socketConnectRetry (default: 16).
    The number of times to retry opening a socket. Windows sometimes fails to open a socket, see bug http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6213296
  - SOCKET_CONNECT_TIMEOUT
```
public static final int SOCKET_CONNECT_TIMEOUT
```
    System property h2.socketConnectTimeout (default: 2000).
    The timeout in milliseconds to connect to a server.
  - SORT_BINARY_UNSIGNED
```
public static final boolean SORT_BINARY_UNSIGNED
```
    System property h2.sortBinaryUnsigned (default: false with version 1.3, true with version 1.4).
    Whether binary data should be sorted in unsigned mode (0xff is larger than 0x00).
  - SORT_NULLS_HIGH
```
public static final boolean SORT_NULLS_HIGH
```
    System property h2.sortNullsHigh (default: false).
    Invert the default sorting behavior for NULL, such that NULL is at the end of a result set in an ascending sort and at the beginning of a result set in a descending sort.
  - SPLIT_FILE_SIZE_SHIFT
```
public static final long SPLIT_FILE_SIZE_SHIFT
```
    System property h2.splitFileSizeShift (default: 30).
    The maximum file size of a split file is 1L << x.
  - SYNC_METHOD
```
public static final String SYNC_METHOD
```
    System property h2.syncMethod (default: sync).
    What method to call when closing the database, on checkpoint, and on CHECKPOINT SYNC. The following options are supported: "sync" (default): RandomAccessFile.getFD().sync(); "force": RandomAccessFile.getChannel().force(true); "forceFalse": RandomAccessFile.getChannel().force(false); "": do not call a method (fast but there is a risk of data loss on power failure).
  - TRACE_IO
```
public static final boolean TRACE_IO
```
    System property h2.traceIO (default: false).
    Trace all I/O operations.
  - THREAD_DEADLOCK_DETECTOR
```
public static final boolean THREAD_DEADLOCK_DETECTOR
```
    System property h2.threadDeadlockDetector (default: false).
    Detect thread deadlocks in a background thread.
  - IMPLICIT_RELATIVE_PATH
```
public static final boolean IMPLICIT_RELATIVE_PATH
```
    System property h2.implicitRelativePath (default: true for version 1.3, false for version 1.4).
    If disabled, relative paths in database URLs need to be written as jdbc:h2:./test instead of jdbc:h2:test.
  - URL_MAP
```
public static final String URL_MAP
```
    System property h2.urlMap (default: null).
    A properties file that contains a mapping between database URLs. New connections are written into the file. An empty value in the map means no redirection is used for the given URL.
  - USE_THREAD_CONTEXT_CLASS_LOADER
```
public static final boolean USE_THREAD_CONTEXT_CLASS_LOADER
```
    System property h2.useThreadContextClassLoader (default: false).
    Instead of using the default class loader when deserializing objects, the current thread-context class loader will be used.
  - serializeJavaObject
```
public static boolean serializeJavaObject
```
    System property h2.serializeJavaObject (default: true).
    If true, values of type OTHER will be stored in serialized form and have the semantics of binary data for all operations (such as sorting and conversion to string).
    If false, the objects will be serialized only for I/O operations and a few other special cases (for example when someone tries to get the value in binary form or when comparing objects that are not comparable otherwise).
    If the object implements the Comparable interface, the method compareTo will be used for sorting (but only if objects being compared have a common comparable super type). Otherwise the objects will be compared by type, and if they are the same by hashCode, and if the hash codes are equal, but objects are not, the serialized forms (the byte arrays) are compared.
    The string representation of the values use the toString method of object.
    In client-server mode, the server must have all required classes in the class path. On the client side, this setting is required to be disabled as well, to have correct string representation and display size.
    In embedded mode, no data copying occurs, so the user has to make defensive copy himself before storing, or ensure that the value object is immutable.
  - JAVA_OBJECT_SERIALIZER
```
public static final String JAVA_OBJECT_SERIALIZER
```
    System property h2.javaObjectSerializer (default: null).
    The JavaObjectSerializer class name for java objects being stored in column of type OTHER. It must be the same on client and server to work correctly.
- 方法详细资料
  - setBaseDir
```
public static void setBaseDir(String dir)
```
    INTERNAL
  - getBaseDir
```
public static String getBaseDir()
```
    INTERNAL
  - getScriptDirectory
```
public static String getScriptDirectory()
```
    System property h2.scriptDirectory (default: empty string).
    Relative or absolute directory where the script files are stored to or read from.
    
    返回:
    
    the current value

类 SysProperties

字段概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

H2_SCRIPT_DIRECTORY

H2_BROWSER

FILE_ENCODING

FILE_SEPARATOR

JAVA_SPECIFICATION_VERSION

LINE_SEPARATOR

USER_HOME

ALLOWED_CLASSES

BROWSER

ENABLE_ANONYMOUS_TLS

BIND_ADDRESS

CHECK

CHECK2

CLIENT_TRACE_DIRECTORY

COLLATOR_CACHE_SIZE

CONSOLE_MAX_TABLES_LIST_INDEXES

CONSOLE_MAX_TABLES_LIST_COLUMNS

CONSOLE_MAX_PROCEDURES_LIST_COLUMNS

CONSOLE_STREAM

CONSOLE_TIMEOUT

DATASOURCE_TRACE_LEVEL

DELAY_WRONG_PASSWORD_MIN

DELAY_WRONG_PASSWORD_MAX

JAVA_SYSTEM_COMPILER

lobCloseBetweenReads

LOB_FILES_PER_DIRECTORY

LOB_CLIENT_MAX_SIZE_MEMORY

MAX_FILE_RETRY

MAX_RECONNECT

MAX_MEMORY_ROWS

MAX_TRACE_DATA_LENGTH

MODIFY_ON_WRITE

NIO_LOAD_MAPPED

NIO_CLEANER_HACK

OBJECT_CACHE

OBJECT_CACHE_MAX_PER_ELEMENT_SIZE

OBJECT_CACHE_SIZE

OLD_STYLE_OUTER_JOIN

PG_DEFAULT_CLIENT_ENCODING

PREFIX_TEMP_FILE

SERVER_CACHED_OBJECTS

SERVER_RESULT_SET_FETCH_SIZE

SOCKET_CONNECT_RETRY

SOCKET_CONNECT_TIMEOUT

SORT_BINARY_UNSIGNED

SORT_NULLS_HIGH

SPLIT_FILE_SIZE_SHIFT

SYNC_METHOD

TRACE_IO

THREAD_DEADLOCK_DETECTOR

IMPLICIT_RELATIVE_PATH

URL_MAP

USE_THREAD_CONTEXT_CLASS_LOADER

serializeJavaObject

JAVA_OBJECT_SERIALIZER

方法详细资料

setBaseDir

getBaseDir

getScriptDirectory