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yss__miui__notes/data_gtask 包代码注释_邹国涛/SqlData.java

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/*
* 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.
*/
/*用于支持小米便签最底层的数据库相关操作和sqlnote的关系上是子集关系即data是note的一个子集或者说是节点
SqlData就是所谓数据中的数据*/
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 {
// 功能得到类的简写名称存入字符串TAG中
// 实现调用getSimpleName ()函数来获取类的简写名称
private static final String TAG = SqlData.class.getSimpleName();
private static final int INVALID_ID = -99999;
//给mDataId设置初始值为-99999
//来自Notes类中定义的DataColumn中的一些常量
// 集合了interface DataColumns中所有SF常量
public static final String[] PROJECTION_DATA = new String[] {
DataColumns.ID, DataColumns.MIME_TYPE, DataColumns.CONTENT, DataColumns.DATA1,
DataColumns.DATA3
};
//下面五行的五个变量是作为SQL表中五列的编号
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;
//判断是否直接用Content生成是的话则为true否则的话为false
private boolean mIsCreate;
private long mDataId;
private String mDataMimeType;
private String mDataContent;
private long mDataContentData1;
private String mDataContentData3;
private ContentValues mDiffDataValues;
/* 功能:构造函数,用于初始化数据
参数注解mContentResolver用于获取ContentProvider提供的数据
参数注解: mIsCreate表示当前数据是用哪种方式创建的因为两种构造函数的参数是不同的 */
public SqlData(Context context) {
mContentResolver = context.getContentResolver();
mIsCreate = true;
mDataId = INVALID_ID; //mDataId置为初始值-99999前面已经叙述过
mDataMimeType = DataConstants.NOTE;
mDataContent = "";
mDataContentData1 = 0;
mDataContentData3 = "";
mDiffDataValues = new ContentValues();
}
/* 功能:构造函数,用于初始化数据
参数注解mContentResolver用于获取ContentProvider提供的数据
参数注解: mIsCreate表示当前数据是用哪种方式创建的因为两种构造函数的参数是不同的 */
public SqlData(Context context, Cursor c) {
mContentResolver = context.getContentResolver();
mIsCreate = false;
loadFromCursor(c);
mDiffDataValues = new ContentValues();
}
/* 功能:从光标处加载数据
从当前的光标处将五列的数据加载到该类的对象之中 */
private void loadFromCursor(Cursor c) {
mDataId = c.getLong(DATA_ID_COLUMN);
mDataMimeType = c.getString(DATA_MIME_TYPE_COLUMN);
mDataContent = c.getString(DATA_CONTENT_COLUMN);
mDataContentData1 = c.getLong(DATA_CONTENT_DATA_1_COLUMN);
mDataContentData3 = c.getString(DATA_CONTENT_DATA_3_COLUMN);
}
//功能:设置用于共享的数据,并提供异常抛出机制与处理机制
public void setContent(JSONObject js) throws JSONException {
//如果传入的JSONObject对象中有DataColumns.ID这一项则设置否则设为INVALID_ID使用格式
long dataId = js.has(DataColumns.ID) ? js.getLong(DataColumns.ID) : INVALID_ID;
if (mIsCreate || mDataId != dataId) {
mDiffDataValues.put(DataColumns.ID, dataId);
}
mDataId = dataId;
String dataMimeType = js.has(DataColumns.MIME_TYPE) ? js.getString(DataColumns.MIME_TYPE)
: DataConstants.NOTE;
if (mIsCreate || !mDataMimeType.equals(dataMimeType)) {
mDiffDataValues.put(DataColumns.MIME_TYPE, dataMimeType);
}
mDataMimeType = dataMimeType;
String dataContent = js.has(DataColumns.CONTENT) ? js.getString(DataColumns.CONTENT) : "";
if (mIsCreate || !mDataContent.equals(dataContent)) {
mDiffDataValues.put(DataColumns.CONTENT, dataContent);
}
mDataContent = dataContent;
long dataContentData1 = js.has(DataColumns.DATA1) ? js.getLong(DataColumns.DATA1) : 0;
if (mIsCreate || mDataContentData1 != dataContentData1) {
mDiffDataValues.put(DataColumns.DATA1, dataContentData1);
}
mDataContentData1 = dataContentData1;
String dataContentData3 = js.has(DataColumns.DATA3) ? js.getString(DataColumns.DATA3) : "";
if (mIsCreate || !mDataContentData3.equals(dataContentData3)) {
mDiffDataValues.put(DataColumns.DATA3, dataContentData3);
}
mDataContentData3 = dataContentData3;
}
//获取共享的数据内容,并提供异常抛出与处理机制
public JSONObject getContent() throws JSONException {
if (mIsCreate) {
Log.e(TAG, "it seems that we haven't created this in database yet");
return null;
}
//创建JSONObject对象将相关数据放入其中并返回。
JSONObject js = new JSONObject();
js.put(DataColumns.ID, mDataId);
js.put(DataColumns.MIME_TYPE, mDataMimeType);
js.put(DataColumns.CONTENT, mDataContent);
js.put(DataColumns.DATA1, mDataContentData1);
js.put(DataColumns.DATA3, mDataContentData3);
return js;
}
//功能commit函数用于把当前所做的修改保存到数据库
public void commit(long noteId, boolean validateVersion, long version) {
if (mIsCreate) {
if (mDataId == INVALID_ID && mDiffDataValues.containsKey(DataColumns.ID)) {
mDiffDataValues.remove(DataColumns.ID);
}
mDiffDataValues.put(DataColumns.NOTE_ID, noteId);
Uri uri = mContentResolver.insert(Notes.CONTENT_DATA_URI, mDiffDataValues);
try {
mDataId = Long.valueOf(uri.getPathSegments().get(1));
} catch (NumberFormatException e) {
Log.e(TAG, "Get note id error :" + e.toString());
throw new ActionFailureException("create note failed");
}
} else {
if (mDiffDataValues.size() > 0) {
int result = 0;
if (!validateVersion) {
result = mContentResolver.update(ContentUris.withAppendedId(
Notes.CONTENT_DATA_URI, mDataId), mDiffDataValues, null, null);
} 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)
});
}
if (result == 0) {
Log.w(TAG, "there is no update. maybe user updates note when syncing");
}
}
}
mDiffDataValues.clear();
mIsCreate = false;
}
//获取当前Id
public long getId() {
return mDataId;
}
}