databaseinformation.java

hsqldb是100％java实现的数据库,是一个开放源代码的JAVA数据库 l 具有标准的SQL语法和JAVA接口 l HSQLDB可以自由使用和分发 l 非常简洁和快速的

//        "SYSTEM_DIRECT_SUPERTYPES",
//        "SYSTEM_DOMAIN_CONSTRAINTS",
//        "SYSTEM_DOMAINS",
//        "SYSTEM_ELEMENT_TYPES",
//        "SYSTEM_FIELDS",
//        "SYSTEM_FOREIGN_DATA_WRAPPER_OPTIONS",
//        "SYSTEM_FOREIGN_DATA_WRAPPERS",
//        "SYSTEM_FOREIGN_SERVER_OPTIONS",
//        "SYSTEM_FOREIGN_SERVERS",
//        "SYSTEM_FOREIGN_TABLE_OPTIONS",
//        "SYSTEM_FOREIGN_TABLES",
//        "SYSTEM_JAR_JAR_USAGE",
//        "SYSTEM_JARS",
//        "SYSTEM_KEY_COLUMN_USAGE",
//        "SYSTEM_METHOD_SPECIFICATION_PARAMETERS",
//        "SYSTEM_METHOD_SPECIFICATIONS",
//        "SYSTEM_MODULE_COLUMN_USAGE",
//        "SYSTEM_MODULE_PRIVILEGES",
//        "SYSTEM_MODULE_TABLE_USAGE",
//        "SYSTEM_MODULES",
//        "SYSTEM_PARAMETERS",
//        "SYSTEM_REFERENCED_TYPES",
//        "SYSTEM_REFERENTIAL_CONSTRAINTS",
//        "SYSTEM_ROLE_AUTHORIZATION_DESCRIPTORS", // boucherb@users 20050514 - implemented
//        "SYSTEM_ROLES",
//        "SYSTEM_ROUTINE_COLUMN_USAGE",
//        "SYSTEM_ROUTINE_JAR_USAGE",
//        "SYSTEM_ROUTINE_MAPPING_OPTIONS",
//        "SYSTEM_ROUTINE_MAPPINGS",
//        "SYSTEM_ROUTINE_PRIVILEGES",
//        "SYSTEM_ROUTINE_ROUTINE_USAGE",
//        "SYSTEM_ROUTINE_SEQUENCE_USAGE",
//        "SYSTEM_ROUTINE_TABLE_USAGE",
//        "SYSTEM_ROUTINES",
//        "SYSTEM_SCHEMATA",                       // boucherb@users 20050514 - implemented
//        "SYSTEM_SEQUENCES",                      // boucherb@users 20040107 - implemented
//        "SYSTEM_SQL_FEATURES",
//        "SYSTEM_SQL_IMPLEMENTATION_INFO",
//        "SYSTEM_SQL_LANGUAGES",
//        "SYSTEM_SQL_SIZING",
//        "SYSTEM_SQL_SIZING_PROFILES",
//        "SYSTEM_TABLE_CONSTRAINTS",              // boucherb@users 20040107 - implemented
//        "SYSTEM_TABLE_METHOD_PRIVILEGES",
//        "SYSTEM_TABLE_PRIVILEGES",
//        "SYSTEM_TABLES",
//        "SYSTEM_TRANSFORMS",
//        "SYSTEM_TRANSLATIONS",
//        "SYSTEM_TRIGGER_COLUMN_USAGE",
//        "SYSTEM_TRIGGER_ROUTINE_USAGE",
//        "SYSTEM_TRIGGER_SEQUENCE_USAGE",
//        "SYSTEM_TRIGGER_TABLE_USAGE",
//        "SYSTEM_TRIGGERED_UPDATE_COLUMNS",
//        "SYSTEM_TRIGGERS",
//        "SYSTEM_TYPE_JAR_USAGE",
//        "SYSTEM_USAGE_PRIVILEGES",               // boucherb@users 20040107 - implemented
//        "SYSTEM_USER_DEFINED_TYPE_PRIVILEGES",
//        "SYSTEM_USER_DEFINED_TYPES",
//        "SYSTEM_USER_MAPPING_OPTIONS",
//        "SYSTEM_USER_MAPPINGS",
//        "SYSTEM_USERS",
//        "SYSTEM_VIEW_COLUMN_USAGE",              // boucherb@users 20040107 - implemented
//        "SYSTEM_VIEW_ROUTINE_USAGE",             // boucherb@users 20040107 - implemented
//        "SYSTEM_VIEW_TABLE_USAGE",               // boucherb@users 20040107 - implemented
//        "SYSTEM_VIEWS", // boucherb@users 20030305 - implemented
    };

    /** Map: table name => table id */
    protected static final IntValueHashMap sysTableNamesMap;

    static {
        sysTableNamesMap = new IntValueHashMap(47);

        for (int i = 0; i < sysTableNames.length; i++) {
            sysTableNamesMap.put(sysTableNames[i], i);
        }
    }

    static int getSysTableID(String token) {
        return sysTableNamesMap.get(token, -1);
    }

    /** Database for which to produce tables */
    protected final Database database;

    /**
     * Simple object-wide flag indicating that all of this object's cached
     * data is dirty.
     */
    protected boolean isDirty = true;

    /**
     * state flag -- if true, contentful tables are to be produced, else
     * empty (surrogate) tables are to be produced.  This allows faster
     * database startup where user views reference system tables and faster
     * system table structural reflection for table metadata.
     */
    protected boolean withContent = false;

    /**
     * Factory method retuns the fullest system table producer
     * implementation available.  This instantiates implementations beginning
     * with the most complete, finally choosing an empty table producer
     * implemenation (this class) if no better instance can be constructed.
     * @param db The Database object for which to produce system tables
     * @return the fullest system table producer
     *      implementation available
     * @throws HsqlException never - required by constructor
     */
    static final DatabaseInformation newDatabaseInformation(Database db)
    throws HsqlException {

        Class clazz = null;

        try {
            clazz = Class.forName("org.hsqldb.DatabaseInformationFull");
        } catch (Exception e) {
            try {
                clazz = Class.forName("org.hsqldb.DatabaseInformationMain");
            } catch (Exception e2) {}
        }

        try {
            Class[]     ctorParmTypes = new Class[]{ Database.class };
            Object[]    ctorParms     = new Object[]{ db };
            Constructor ctor = clazz.getDeclaredConstructor(ctorParmTypes);

            return (DatabaseInformation) ctor.newInstance(ctorParms);
        } catch (Exception e) {}

        return new DatabaseInformation(db);
    }

    /**
     * Constructs a new DatabaseInformation instance which knows the names of
     * all system tables (isSystemTable()) but simpy returns null for all
     * getSystemTable() requests. <p>
     *
     * @param db The Database object for which to produce system tables
     * @throws HsqlException never (required for descendents)
     */
    DatabaseInformation(Database db) throws HsqlException {
        database = db;
    }

    /**
     * Tests if the specified name is that of a system table. <p>
     *
     * @param name the name to test
     * @return true if the specified name is that of a system table
     */
    final boolean isSystemTable(String name) {
        return sysTableNamesMap.containsKey(name);
    }

    /**
     * Retrieves a table with the specified name whose content may depend on
     * the execution context indicated by the session argument as well as the
     * current value of <code>withContent</code>. <p>
     *
     * @param session the context in which to produce the table
     * @param name the name of the table to produce
     * @throws HsqlException if a database access error occurs
     * @return a table corresponding to the name and session arguments, or
     *      <code>null</code> if there is no such table to be produced
     */
    Table getSystemTable(Session session, String name) throws HsqlException {
        return null;
    }

    /**
     * Controls caching of all tables produced by this object. <p>
     *
     * Subclasses are free to ignore this, since they may choose an
     * implementation that does not dynamically generate and/or cache
     * table content on an as-needed basis. <p>
     *
     * If not ignored, this call indicates to this object that all cached
     * table data may be dirty, requiring a complete cache clear at some
     * point.<p>
     *
     * Subclasses are free to delay cache clear until next getSystemTable().
     * However, subclasses may have to be aware of additional methods with
     * semantics similar to getSystemTable() and act accordingly (e.g.
     * clearing earlier than next invocation of getSystemTable()).
     */
    final void setDirty() {
        isDirty = true;
    }

    /**
     * Switches this table producer between producing empty (surrogate)
     * or contentful tables. <p>
     *
     * @param withContent if true, then produce contentful tables, else
     *        produce emtpy (surrogate) tables
     */
    final void setWithContent(boolean withContent) {
        this.withContent = withContent;
    }
}