schemamanager.java

hsql是很有名的嵌入式数据库

/* Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
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 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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package org.hsqldb;

import org.hsqldb.HsqlNameManager.HsqlName;
import org.hsqldb.lib.ArrayUtil;
import org.hsqldb.lib.HsqlArrayList;
import org.hsqldb.lib.HashMappedList;
import org.hsqldb.lib.Iterator;
import org.hsqldb.lib.WrapperIterator;
import org.hsqldb.persist.Logger;

/**
 * Manages all SCHEMA related database objects
 *
 * @author fredt@users
 * @version  1.8.0
 * @since 1.8.0
 */
public class SchemaManager {

    static final String SYSTEM_SCHEMA      = "SYSTEM_SCHEMA";
    static final String DEFINITION_SCHEMA  = "DEFINITION_SCHEMA";
    static final String INFORMATION_SCHEMA = "INFORMATION_SCHEMA";
    static final String PUBLIC_SCHEMA      = "PUBLIC";
    static HsqlName INFORMATION_SCHEMA_HSQLNAME =
        HsqlNameManager.newHsqlSystemObjectName(INFORMATION_SCHEMA);
    static HsqlName SYSTEM_SCHEMA_HSQLNAME =
        HsqlNameManager.newHsqlSystemObjectName(SYSTEM_SCHEMA);
    Database       database;
    HsqlName       defaultSchemaHsqlName;
    HashMappedList schemaMap = new HashMappedList();

    SchemaManager(Database database) {

        this.database = database;

        Schema schema = new Schema(PUBLIC_SCHEMA, false);

        defaultSchemaHsqlName = schema.name;

        schemaMap.put(PUBLIC_SCHEMA, schema);
    }

    void createSchema(String name, boolean isQuoted) throws HsqlException {

        if (DEFINITION_SCHEMA.equals(name) || INFORMATION_SCHEMA.equals(name)
                || SYSTEM_SCHEMA.equals(name)) {
            throw Trace.error(Trace.INVALID_SCHEMA_NAME_NO_SUBCLASS);
        }

        Schema schema = new Schema(name, isQuoted);

        schemaMap.add(name, schema);
    }

    void dropSchema(String name, boolean cascade) throws HsqlException {

        Schema schema = (Schema) schemaMap.get(name);

        if (schema == null) {
            throw Trace.error(Trace.INVALID_SCHEMA_NAME_NO_SUBCLASS);
        }

        if (!cascade &&!schema.isEmpty()) {
            throw Trace.error(Trace.DEPENDENT_DATABASE_OBJECT_EXISTS);
        }

        Iterator tableIterator = schema.tablesIterator();

        while (tableIterator.hasNext()) {
            Table table = ((Table) tableIterator.next());

            database.getUserManager().removeDbObject(table.getName());
            table.drop();
        }

        Iterator sequenceIterator = schema.sequencesIterator();

        while (tableIterator.hasNext()) {
            NumberSequence sequence =
                ((NumberSequence) sequenceIterator.next());

            database.getUserManager().removeDbObject(sequence.getName());
        }

        schema.clearStructures();
        schemaMap.remove(name);

        if (defaultSchemaHsqlName.name.equals(name)) {
            if (schemaMap.isEmpty()) {
                schema = new Schema(PUBLIC_SCHEMA, false);
            } else {
                schema = (Schema) schemaMap.get(0);
            }

            defaultSchemaHsqlName = schema.name;

            schemaMap.put(defaultSchemaHsqlName.name, schema);
        }
    }

    void renameSchema(String name, String newName,
                      boolean isQuoted) throws HsqlException {

        Schema schema = (Schema) schemaMap.get(name);
        Schema exists = (Schema) schemaMap.get(newName);

        if (schema == null || exists != null
                || INFORMATION_SCHEMA.equals(newName)) {
            throw Trace.error(Trace.INVALID_SCHEMA_NAME_NO_SUBCLASS,
                              schema == null ? name
                                             : newName);
        }

        schema.name.rename(newName, isQuoted);

        int index = schemaMap.getIndex(name);

        schemaMap.set(index, newName, schema);
    }

    void clearStructures() {

        Iterator it = schemaMap.values().iterator();

        while (it.hasNext()) {
            Schema schema = (Schema) it.next();

            schema.clearStructures();
        }
    }

    public Iterator userSchemaNameIterator() {
        return schemaMap.keySet().iterator();
    }

    HsqlName toSchemaHsqlName(String name) {

        Schema schema = (Schema) schemaMap.get(name);

        return schema == null ? null
                              : schema.name;
    }

    HsqlName getDefaultSchemaHsqlName() {
        return defaultSchemaHsqlName;
    }

    public String getDefaultSchemaName() {
        return defaultSchemaHsqlName.name;
    }

    boolean schemaExists(String name) {

        if (INFORMATION_SCHEMA.equals(name)) {
            return true;
        }

        return schemaMap.containsKey(name);
    }

    /**
     * If schemaName is null, return the current schema name, else return
     * the HsqlName object for the schema. If schemaName does not exist,
     * throw.
     */
    HsqlName getSchemaHsqlName(String name) throws HsqlException {

        if (name == null) {
            return defaultSchemaHsqlName;
        }

        if (name.equals(INFORMATION_SCHEMA)) {
            return INFORMATION_SCHEMA_HSQLNAME;
        }

        Schema schema = ((Schema) schemaMap.get(name));

        if (schema == null) {
            throw Trace.error(Trace.INVALID_SCHEMA_NAME_NO_SUBCLASS, name);
        }

        return schema.name;
    }

    /**
     * Same as above, but return string
     */
    String getSchemaName(String name) throws HsqlException {
        return getSchemaHsqlName(name).name;
    }

    /**
     * Iterator includes INFORMATION_SCHEMA
     */
    Iterator fullSchemaNamesIterator() {
        return new WrapperIterator(new WrapperIterator(INFORMATION_SCHEMA),
                                   schemaMap.keySet().iterator());
    }

    /**
     * is a schema read-only
     */
    public boolean isSystemSchema(HsqlName schema) {

        return (INFORMATION_SCHEMA_HSQLNAME.equals(schema) || SYSTEM_SCHEMA_HSQLNAME.equals(schema))
               ? true
               : false;
    }

    public Iterator tablesIterator(String schema) {

        Schema temp = (Schema) schemaMap.get(schema);

        return temp.tablesIterator();
    }

    public Iterator allTablesIterator() {

        Iterator schemas = userSchemaNameIterator();
        Iterator tables  = new WrapperIterator();

        while (schemas.hasNext()) {
            String   name = (String) schemas.next();
            Iterator t    = tablesIterator(name);

            tables = new WrapperIterator(tables, t);
        }

        return tables;
    }

    Iterator sequenceIterator(String schema) {

        Schema temp = (Schema) schemaMap.get(schema);

        return temp.sequencesIterator();
    }

    public Iterator allSequencesIterator() {

        Iterator it        = schemaMap.values().iterator();
        Iterator sequences = new WrapperIterator();

        while (it.hasNext()) {
            Schema temp = (Schema) it.next();

            sequences = new WrapperIterator(sequences,
                                            temp.sequencesIterator());
        }

        return sequences;
    }

    /**
     *  Returns an HsqlArrayList containing references to all non-system
     *  tables and views. This includes all tables and views registered with
     *  this Database.
     */
    public HsqlArrayList getAllTables() {

        Iterator      schemas   = userSchemaNameIterator();
        HsqlArrayList alltables = new HsqlArrayList();

        while (schemas.hasNext()) {
            String         name    = (String) schemas.next();
            HashMappedList current = getTables(name);

            alltables.addAll(current.values());
        }

        return alltables;
    }

    public HashMappedList getTables(String schema) {

        Schema temp = (Schema) schemaMap.get(schema);

        return temp.tableList;
    }

    /**
     * @throws HsqlException if exists.
     */
    void checkUserViewNotExists(Session session, String viewName,
                                String schema) throws HsqlException {

        boolean exists =
            database.schemaManager.findUserTable(session, viewName, schema)
            != null;

        if (exists) {
            throw Trace.error(Trace.VIEW_ALREADY_EXISTS, viewName);
        }
    }

    /**
     * @throws HsqlException if exists
     */
    void checkUserTableNotExists(Session session, String tableName,
                                 String schema) throws HsqlException {

        boolean exists = findUserTable(session, tableName, schema) != null;

        if (exists) {
            throw Trace.error(Trace.TABLE_ALREADY_EXISTS, tableName);
        }
    }

    /**
     *  Retruns the specified user-defined table or view visible within the
     *  context of the specified Session, or any system table of the given
     *  name. It excludes any temp tables created in other Sessions.
     *  Throws if the table does not exist in the context.
     */
    public Table getTable(Session session, String name,
                          String schema) throws HsqlException {

        Table t = findUserTable(session, name, schema);

        if (t == null) {
            if (!"INFORMATION_SCHEMA".equals(schema)) {
                throw Trace.error(Trace.TABLE_NOT_FOUND);
            }

            if (database.dbInfo != null) {
                t = database.dbInfo.getSystemTable(session, name);
            }
        }

        if (t == null) {
            throw Trace.error(Trace.TABLE_NOT_FOUND, name);
        }