DatabaseUtils.InsertHelper backup

DatabaseUtils.java

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.mpme.lib.util;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteProgram;
import android.database.sqlite.SQLiteStatement;
import android.util.Log;

import java.util.HashMap;
import java.util.Map;

/**
 * Static utility methods for dealing with databases and {@link Cursor}s.
 */
public class DatabaseUtils {

    private static final String TAG = "DatabaseUtils";

    private static final boolean DEBUG = false;

    public static void bindObjectToProgram(SQLiteProgram prog, int index,
                                           Object value) {
        if (value == null) {
            prog.bindNull(index);
        } else if (value instanceof Double || value instanceof Float) {
            prog.bindDouble(index, ((Number)value).doubleValue());
        } else if (value instanceof Number) {
            prog.bindLong(index, ((Number)value).longValue());
        } else if (value instanceof Boolean) {
            Boolean bool = (Boolean)value;
            if (bool) {
                prog.bindLong(index, 1);
            } else {
                prog.bindLong(index, 0);
            }
        } else if (value instanceof byte[]){
            prog.bindBlob(index, (byte[]) value);
        } else {
            prog.bindString(index, value.toString());
        }
    }

    /**
     * This class allows users to do multiple inserts into a table using
     * the same statement.
     * <p>
     * This class is not thread-safe.
     * </p>
     *
     */
    public static class InsertHelper {
        private final SQLiteDatabase mDb;
        private final String mTableName;
        private HashMap<String, Integer> mColumns;
        private String mInsertSQL = null;
        private SQLiteStatement mInsertStatement = null;
        private SQLiteStatement mReplaceStatement = null;
        private SQLiteStatement mPreparedStatement = null;

        /**
         * {@hide}
         *
         * These are the columns returned by sqlite's "PRAGMA
         * table_info(...)" command that we depend on.
         */
        public static final int TABLE_INFO_PRAGMA_COLUMNNAME_INDEX = 1;

        /**
         * This field was accidentally exposed in earlier versions of the platform
         * so we can hide it but we can't remove it.
         *
         * @hide
         */
        public static final int TABLE_INFO_PRAGMA_DEFAULT_INDEX = 4;

        /**
         * @param db the SQLiteDatabase to insert into
         * @param tableName the name of the table to insert into
         */
        public InsertHelper(SQLiteDatabase db, String tableName) {
            mDb = db;
            mTableName = tableName;
        }

        private void buildSQL() throws SQLException {
            StringBuilder sb = new StringBuilder(128);
            sb.append("INSERT INTO ");
            sb.append(mTableName);
            sb.append(" (");

            StringBuilder sbv = new StringBuilder(128);
            sbv.append("VALUES (");

            int i = 1;
            Cursor cur = null;
            try {
                cur = mDb.rawQuery("PRAGMA table_info(" + mTableName + ")", null);
                mColumns = new HashMap<String, Integer>(cur.getCount());
                while (cur.moveToNext()) {
                    String columnName = cur.getString(TABLE_INFO_PRAGMA_COLUMNNAME_INDEX);
                    String defaultValue = cur.getString(TABLE_INFO_PRAGMA_DEFAULT_INDEX);

                    mColumns.put(columnName, i);
                    sb.append("'");
                    sb.append(columnName);
                    sb.append("'");

                    if (defaultValue == null) {
                        sbv.append("?");
                    } else {
                        sbv.append("COALESCE(?, ");
                        sbv.append(defaultValue);
                        sbv.append(")");
                    }

                    sb.append(i == cur.getCount() ? ") " : ", ");
                    sbv.append(i == cur.getCount() ? ");" : ", ");
                    ++i;
                }
            } finally {
                if (cur != null) cur.close();
            }

            sb.append(sbv);

            mInsertSQL = sb.toString();
            if (DEBUG) Log.v(TAG, "insert statement is " + mInsertSQL);
        }

        private SQLiteStatement getStatement(boolean allowReplace) throws SQLException {
            if (allowReplace) {
                if (mReplaceStatement == null) {
                    if (mInsertSQL == null) buildSQL();
                    // chop "INSERT" off the front and prepend "INSERT OR REPLACE" instead.
                    String replaceSQL = "INSERT OR REPLACE" + mInsertSQL.substring(6);
                    mReplaceStatement = mDb.compileStatement(replaceSQL);
                }
                return mReplaceStatement;
            } else {
                if (mInsertStatement == null) {
                    if (mInsertSQL == null) buildSQL();
                    mInsertStatement = mDb.compileStatement(mInsertSQL);
                }
                return mInsertStatement;
            }
        }

        /**
         * Performs an insert, adding a new row with the given values.
         *
         * @param values the set of values with which  to populate the
         * new row
         * @param allowReplace if true, the statement does "INSERT OR
         *   REPLACE" instead of "INSERT", silently deleting any
         *   previously existing rows that would cause a conflict
         *
         * @return the row ID of the newly inserted row, or -1 if an
         * error occurred
         */
        private long insertInternal(ContentValues values, boolean allowReplace) {
            // Start a transaction even though we don't really need one.
            // This is to help maintain compatibility with applications that
            // access InsertHelper from multiple threads even though they never should have.
            // The original code used to lock the InsertHelper itself which was prone
            // to deadlocks.  Starting a transaction achieves the same mutual exclusion
            // effect as grabbing a lock but without the potential for deadlocks.
            mDb.beginTransactionNonExclusive();
            try {
                SQLiteStatement stmt = getStatement(allowReplace);
                stmt.clearBindings();
                if (DEBUG) Log.v(TAG, "--- inserting in table " + mTableName);
                for (Map.Entry<String, Object> e: values.valueSet()) {
                    final String key = e.getKey();
                    int i = getColumnIndex(key);
                    DatabaseUtils.bindObjectToProgram(stmt, i, e.getValue());
                    if (DEBUG) {
                        Log.v(TAG, "binding " + e.getValue() + " to column " +
                                i + " (" + key + ")");
                    }
                }
                long result = stmt.executeInsert();
                mDb.setTransactionSuccessful();
                return result;
            } catch (SQLException e) {
                Log.e(TAG, "Error inserting " + values + " into table  " + mTableName, e);
                return -1;
            } finally {
                mDb.endTransaction();
            }
        }

        /**
         * Returns the index of the specified column. This is index is suitagble for use
         * in calls to bind().
         * @param key the column name
         * @return the index of the column
         */
        public int getColumnIndex(String key) {
            getStatement(false);
            final Integer index = mColumns.get(key);
            if (index == null) {
                throw new IllegalArgumentException("column '" + key + "' is invalid");
            }
            return index;
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, double value) {
            mPreparedStatement.bindDouble(index, value);
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, float value) {
            mPreparedStatement.bindDouble(index, value);
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, long value) {
            mPreparedStatement.bindLong(index, value);
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, int value) {
            mPreparedStatement.bindLong(index, value);
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, boolean value) {
            mPreparedStatement.bindLong(index, value ? 1 : 0);
        }

        /**
         * Bind null to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         */
        public void bindNull(int index) {
            mPreparedStatement.bindNull(index);
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, byte[] value) {
            if (value == null) {
                mPreparedStatement.bindNull(index);
            } else {
                mPreparedStatement.bindBlob(index, value);
            }
        }

        /**
         * Bind the value to an index. A prepareForInsert() or prepareForReplace()
         * without a matching execute() must have already have been called.
         * @param index the index of the slot to which to bind
         * @param value the value to bind
         */
        public void bind(int index, String value) {
            if (value == null) {
                mPreparedStatement.bindNull(index);
            } else {
                mPreparedStatement.bindString(index, value);
            }
        }

        /**
         * Performs an insert, adding a new row with the given values.
         * If the table contains conflicting rows, an error is
         * returned.
         *
         * @param values the set of values with which to populate the
         * new row
         *
         * @return the row ID of the newly inserted row, or -1 if an
         * error occurred
         */
        public long insert(ContentValues values) {
            return insertInternal(values, false);
        }

        /**
         * Execute the previously prepared insert or replace using the bound values
         * since the last call to prepareForInsert or prepareForReplace.
         *
         * <p>Note that calling bind() and then execute() is not thread-safe. The only thread-safe
         * way to use this class is to call insert() or replace().
         *
         * @return the row ID of the newly inserted row, or -1 if an
         * error occurred
         */
        public long execute() {
            if (mPreparedStatement == null) {
                throw new IllegalStateException("you must prepare this inserter before calling "
                        + "execute");
            }
            try {
                if (DEBUG) Log.v(TAG, "--- doing insert or replace in table " + mTableName);
                return mPreparedStatement.executeInsert();
            } catch (SQLException e) {
                Log.e(TAG, "Error executing InsertHelper with table " + mTableName, e);
                return -1;
            } finally {
                // you can only call this once per prepare
                mPreparedStatement = null;
            }
        }

        /**
         * Prepare the InsertHelper for an insert. The pattern for this is:
         * <ul>
         * <li>prepareForInsert()
         * <li>bind(index, value);
         * <li>bind(index, value);
         * <li>...
         * <li>bind(index, value);
         * <li>execute();
         * </ul>
         */
        public void prepareForInsert() {
            mPreparedStatement = getStatement(false);
            mPreparedStatement.clearBindings();
        }

        /**
         * Prepare the InsertHelper for a replace. The pattern for this is:
         * <ul>
         * <li>prepareForReplace()
         * <li>bind(index, value);
         * <li>bind(index, value);
         * <li>...
         * <li>bind(index, value);
         * <li>execute();
         * </ul>
         */
        public void prepareForReplace() {
            mPreparedStatement = getStatement(true);
            mPreparedStatement.clearBindings();
        }

        /**
         * Performs an insert, adding a new row with the given values.
         * If the table contains conflicting rows, they are deleted
         * and replaced with the new row.
         *
         * @param values the set of values with which to populate the
         * new row
         *
         * @return the row ID of the newly inserted row, or -1 if an
         * error occurred
         */
        public long replace(ContentValues values) {
            return insertInternal(values, true);
        }

        /**
         * Close this object and release any resources associated with
         * it.  The behavior of calling <code>insert()</code> after
         * calling this method is undefined.
         */
        public void close() {
            if (mInsertStatement != null) {
                mInsertStatement.close();
                mInsertStatement = null;
            }
            if (mReplaceStatement != null) {
                mReplaceStatement.close();
                mReplaceStatement = null;
            }
            mInsertSQL = null;
            mColumns = null;
        }
    }


}