MiNote/gtask/data/SqlData.java

/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * 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 net.micode.notes.gtask.data;

 import android.content.ContentResolver;
 import android.content.ContentUris;
 import android.content.ContentValues;
 import android.content.Context;
 import android.database.Cursor;
 import android.net.Uri;
 import android.util.Log;
 
 import net.micode.notes.data.Notes;
 import net.micode.notes.data.Notes.DataColumns;
 import net.micode.notes.data.Notes.DataConstants;
 import net.micode.notes.data.Notes.NoteColumns;
 import net.micode.notes.data.NotesDatabaseHelper.TABLE;
 import net.micode.notes.gtask.exception.ActionFailureException;
 
 import org.json.JSONException;
 import org.json.JSONObject;
 
 public class SqlData {
     private static final String TAG = SqlData.class.getSimpleName(); // 用于日志记录的标签
 
     private static final int INVALID_ID = -99999; // 无效ID常量
 
     // 数据库列的投影
     public static final String[] PROJECTION_DATA = new String[] {
             DataColumns.ID, DataColumns.MIME_TYPE, DataColumns.CONTENT, DataColumns.DATA1,
             DataColumns.DATA3
     };
 
     // 数据库列索引
     public static final int DATA_ID_COLUMN = 0;
     public static final int DATA_MIME_TYPE_COLUMN = 1;
     public static final int DATA_CONTENT_COLUMN = 2;
     public static final int DATA_CONTENT_DATA_1_COLUMN = 3;
     public static final int DATA_CONTENT_DATA_3_COLUMN = 4;
 
     private ContentResolver mContentResolver; // 内容解析器，用于与内容提供者交互
 
     private boolean mIsCreate; // 标识是否为新创建的数据
 
     private long mDataId; // 数据ID
     private String mDataMimeType; // 数据MIME类型
     private String mDataContent; // 数据内容
     private long mDataContentData1; // 数据内容的附加信息1
     private String mDataContentData3; // 数据内容的附加信息3
 
     private ContentValues mDiffDataValues; // 存储数据变化的内容值
 
     // 构造函数，初始化新数据
     public SqlData(Context context) {
         mContentResolver = context.getContentResolver(); // 获取内容解析器
         mIsCreate = true; // 标记为新创建
         mDataId = INVALID_ID; // 初始化ID为无效值
         mDataMimeType = DataConstants.NOTE; // 默认MIME类型为NOTE
         mDataContent = ""; // 初始化内容为空
         mDataContentData1 = 0; // 初始化附加信息1为0
         mDataContentData3 = ""; // 初始化附加信息3为空
         mDiffDataValues = new ContentValues(); // 初始化内容值对象
     }
 
     // 构造函数，初始化已有数据
     public SqlData(Context context, Cursor c) {
         mContentResolver = context.getContentResolver(); // 获取内容解析器
         mIsCreate = false; // 标记为已有数据
         loadFromCursor(c); // 从Cursor加载数据
         mDiffDataValues = new ContentValues(); // 初始化内容值对象
     }
 
     // 从Cursor加载数据
     private void loadFromCursor(Cursor c) {
         mDataId = c.getLong(DATA_ID_COLUMN); // 获取数据ID
         mDataMimeType = c.getString(DATA_MIME_TYPE_COLUMN); // 获取MIME类型
         mDataContent = c.getString(DATA_CONTENT_COLUMN); // 获取内容
         mDataContentData1 = c.getLong(DATA_CONTENT_DATA_1_COLUMN); // 获取附加信息1
         mDataContentData3 = c.getString(DATA_CONTENT_DATA_3_COLUMN); // 获取附加信息3
     }
 
     // 设置内容，从JSON对象中提取数据
     public void setContent(JSONObject js) throws JSONException {
         long dataId = js.has(DataColumns.ID) ? js.getLong(DataColumns.ID) : INVALID_ID; // 获取ID
         if (mIsCreate || mDataId != dataId) {
             mDiffDataValues.put(DataColumns.ID, dataId); // 更新ID
         }
         mDataId = dataId;
 
         String dataMimeType = js.has(DataColumns.MIME_TYPE) ? js.getString(DataColumns.MIME_TYPE)
                 : DataConstants.NOTE; // 获取MIME类型
         if (mIsCreate || !mDataMimeType.equals(dataMimeType)) {
             mDiffDataValues.put(DataColumns.MIME_TYPE, dataMimeType); // 更新MIME类型
         }
         mDataMimeType = dataMimeType;
 
         String dataContent = js.has(DataColumns.CONTENT) ? js.getString(DataColumns.CONTENT) : ""; // 获取内容
         if (mIsCreate || !mDataContent.equals(dataContent)) {
             mDiffDataValues.put(DataColumns.CONTENT, dataContent); // 更新内容
         }
         mDataContent = dataContent;
 
         long dataContentData1 = js.has(DataColumns.DATA1) ? js.getLong(DataColumns.DATA1) : 0; // 获取附加信息1
         if (mIsCreate || mDataContentData1 != dataContentData1) {
             mDiffDataValues.put(DataColumns.DATA1, dataContentData1); // 更新附加信息1
         }
         mDataContentData1 = dataContentData1;
 
         String dataContentData3 = js.has(DataColumns.DATA3) ? js.getString(DataColumns.DATA3) : ""; // 获取附加信息3
         if (mIsCreate || !mDataContentData3.equals(dataContentData3)) {
             mDiffDataValues.put(DataColumns.DATA3, dataContentData3); // 更新附加信息3
         }
         mDataContentData3 = dataContentData3;
     }
 
     // 获取内容，返回JSON对象
     public JSONObject getContent() throws JSONException {
         if (mIsCreate) {
             Log.e(TAG, "it seems that we haven't created this in database yet"); // 如果未创建，记录错误
             return null;
         }
         JSONObject js = new JSONObject(); // 创建JSON对象
         js.put(DataColumns.ID, mDataId); // 添加ID
         js.put(DataColumns.MIME_TYPE, mDataMimeType); // 添加MIME类型
         js.put(DataColumns.CONTENT, mDataContent); // 添加内容
         js.put(DataColumns.DATA1, mDataContentData1); // 添加附加信息1
         js.put(DataColumns.DATA3, mDataContentData3); // 添加附加信息3
         return js; // 返回JSON对象
     }
 
     // 提交数据到数据库
     public void commit(long noteId, boolean validateVersion, long version) {
         if (mIsCreate) {
             if (mDataId == INVALID_ID && mDiffDataValues.containsKey(DataColumns.ID)) {
                 mDiffDataValues.remove(DataColumns.ID); // 如果ID无效，移除ID
             }
 
             mDiffDataValues.put(DataColumns.NOTE_ID, noteId); // 添加笔记ID
             Uri uri = mContentResolver.insert(Notes.CONTENT_DATA_URI, mDiffDataValues); // 插入数据
             try {
                 mDataId = Long.valueOf(uri.getPathSegments().get(1)); // 获取新插入数据的ID
             } catch (NumberFormatException e) {
                 Log.e(TAG, "Get note id error :" + e.toString()); // 记录错误
                 throw new ActionFailureException("create note failed"); // 抛出异常
             }
         } else {
             if (mDiffDataValues.size() > 0) {
                 int result = 0;
                 if (!validateVersion) {
                     result = mContentResolver.update(ContentUris.withAppendedId(
                             Notes.CONTENT_DATA_URI, mDataId), mDiffDataValues, null, null); // 更新数据
                 } else {
                     result = mContentResolver.update(ContentUris.withAppendedId(
                             Notes.CONTENT_DATA_URI, mDataId), mDiffDataValues,
                             " ? in (SELECT " + NoteColumns.ID + " FROM " + TABLE.NOTE
                                     + " WHERE " + NoteColumns.VERSION + "=?)", new String[] {
                                     String.valueOf(noteId), String.valueOf(version)
                             }); // 带版本验证的更新
                 }
                 if (result == 0) {
                     Log.w(TAG, "there is no update. maybe user updates note when syncing"); // 记录警告
                 }
             }
         }
 
         mDiffDataValues.clear(); // 清空差异数据
         mIsCreate = false; // 标记为非创建状态
     }
 
     // 获取数据ID
     public long getId() {
         return mDataId; // 返回数据ID
     }
 }