AbstractWindowedCursor.java revision 7ce745248d4de0e6543a559c93423df899832100 
1/*
2 * Copyright (C) 2006 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.database;
18
19/**
20 * A base class for Cursors that store their data in {@link CursorWindow}s.
21 * <p>
22 * Subclasses are responsible for filling the cursor window with data during
23 * {@link #onMove(int, int)}, allocating a new cursor window if necessary.
24 * During {@link #requery()}, the existing cursor window should be cleared and
25 * filled with new data.
26 * </p><p>
27 * If the contents of the cursor change or become invalid, the old window must be closed
28 * (because it is owned by the cursor) and set to null.
29 * </p>
30 */
31public abstract class AbstractWindowedCursor extends AbstractCursor {
32    /**
33     * The cursor window owned by this cursor.
34     */
35    protected CursorWindow mWindow;
36
37    @Override
38    public byte[] getBlob(int columnIndex) {
39        checkPosition();
40        return mWindow.getBlob(mPos, columnIndex);
41    }
42
43    @Override
44    public String getString(int columnIndex) {
45        checkPosition();
46        return mWindow.getString(mPos, columnIndex);
47    }
48
49    @Override
50    public void copyStringToBuffer(int columnIndex, CharArrayBuffer buffer) {
51        checkPosition();
52        mWindow.copyStringToBuffer(mPos, columnIndex, buffer);
53    }
54
55    @Override
56    public short getShort(int columnIndex) {
57        checkPosition();
58        return mWindow.getShort(mPos, columnIndex);
59    }
60
61    @Override
62    public int getInt(int columnIndex) {
63        checkPosition();
64        return mWindow.getInt(mPos, columnIndex);
65    }
66
67    @Override
68    public long getLong(int columnIndex) {
69        checkPosition();
70        return mWindow.getLong(mPos, columnIndex);
71    }
72
73    @Override
74    public float getFloat(int columnIndex) {
75        checkPosition();
76        return mWindow.getFloat(mPos, columnIndex);
77    }
78
79    @Override
80    public double getDouble(int columnIndex) {
81        checkPosition();
82        return mWindow.getDouble(mPos, columnIndex);
83    }
84
85    @Override
86    public boolean isNull(int columnIndex) {
87        checkPosition();
88        return mWindow.getType(mPos, columnIndex) == Cursor.FIELD_TYPE_NULL;
89    }
90
91    /**
92     * @deprecated Use {@link #getType}
93     */
94    @Deprecated
95    public boolean isBlob(int columnIndex) {
96        return getType(columnIndex) == Cursor.FIELD_TYPE_BLOB;
97    }
98
99    /**
100     * @deprecated Use {@link #getType}
101     */
102    @Deprecated
103    public boolean isString(int columnIndex) {
104        return getType(columnIndex) == Cursor.FIELD_TYPE_STRING;
105    }
106
107    /**
108     * @deprecated Use {@link #getType}
109     */
110    @Deprecated
111    public boolean isLong(int columnIndex) {
112        return getType(columnIndex) == Cursor.FIELD_TYPE_INTEGER;
113    }
114
115    /**
116     * @deprecated Use {@link #getType}
117     */
118    @Deprecated
119    public boolean isFloat(int columnIndex) {
120        return getType(columnIndex) == Cursor.FIELD_TYPE_FLOAT;
121    }
122
123    @Override
124    public int getType(int columnIndex) {
125        checkPosition();
126        return mWindow.getType(mPos, columnIndex);
127    }
128
129    @Override
130    protected void checkPosition() {
131        super.checkPosition();
132
133        if (mWindow == null) {
134            throw new StaleDataException("Attempting to access a closed CursorWindow." +
135                    "Most probable cause: cursor is deactivated prior to calling this method.");
136        }
137    }
138
139    @Override
140    public CursorWindow getWindow() {
141        return mWindow;
142    }
143
144    /**
145     * Sets a new cursor window for the cursor to use.
146     * <p>
147     * The cursor takes ownership of the provided cursor window; the cursor window
148     * will be closed when the cursor is closed or when the cursor adopts a new
149     * cursor window.
150     * </p><p>
151     * If the cursor previously had a cursor window, then it is closed when the
152     * new cursor window is assigned.
153     * </p>
154     *
155     * @param window The new cursor window, typically a remote cursor window.
156     */
157    public void setWindow(CursorWindow window) {
158        if (window != mWindow) {
159            closeWindow();
160            mWindow = window;
161        }
162    }
163
164    /**
165     * Returns true if the cursor has an associated cursor window.
166     *
167     * @return True if the cursor has an associated cursor window.
168     */
169    public boolean hasWindow() {
170        return mWindow != null;
171    }
172
173    /**
174     * Closes the cursor window and sets {@link #mWindow} to null.
175     * @hide
176     */
177    protected void closeWindow() {
178        if (mWindow != null) {
179            mWindow.close();
180            mWindow = null;
181        }
182    }
183}
184