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TeamProject/other/07_210340159 周卢东_代码标注/tool/BackupUtils.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.
*/
package net.micode.notes.tool;
public class BackupUtils {
private static final String TAG = "BackupUtils";
// Singleton stuff
private static BackupUtils sInstance; //类里面为什么可以定义自身类的对象?
public static synchronized BackupUtils getInstance(Context context) {
//ynchronized 关键字,代表这个方法加锁,相当于不管哪一个线程例如线程A
//运行到这个方法时,都要检查有没有其它线程B或者C、 D等正在用这个方法(或者该类的其他同步方法)有的话要等正在使用synchronized方法的线程B或者C 、D运行完这个方法后再运行此线程A,没有的话,锁定调用者,然后直接运行。
//它包括两种用法synchronized 方法和 synchronized 块。
if (sInstance == null) {
//如果当前备份不存在,则新声明一个
sInstance = new BackupUtils(context);
}
return sInstance;
}
/**
* Following states are signs to represents backup or restore
* status
*/
// Currently, the sdcard is not mounted SD卡没有被装入手机
public static final int STATE_SD_CARD_UNMOUONTED = 0;
// The backup file not exist 备份文件夹不存在
public static final int STATE_BACKUP_FILE_NOT_EXIST = 1;
// The data is not well formated, may be changed by other programs 数据已被破坏,可能被修改
public static final int STATE_DATA_DESTROIED = 2;
// Some run-time exception which causes restore or backup fails 超时异常
public static final int STATE_SYSTEM_ERROR = 3;
// Backup or restore success 成功存储
public static final int STATE_SUCCESS = 4;
private TextExport mTextExport;
private BackupUtils(Context context) { //初始化函数
mTextExport = new TextExport(context);
}
private static boolean externalStorageAvailable() { //外部存储功能是否可用
return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
}
public int exportToText() {
return mTextExport.exportToText();
}
public String getExportedTextFileName() {
return mTextExport.mFileName;
}
public String getExportedTextFileDir() {
return mTextExport.mFileDirectory;
}
private static class TextExport {
private static final String[] NOTE_PROJECTION = {
NoteColumns.ID,
NoteColumns.MODIFIED_DATE,
NoteColumns.SNIPPET,
NoteColumns.TYPE
};
private static final int NOTE_COLUMN_ID = 0;
private static final int NOTE_COLUMN_MODIFIED_DATE = 1;
private static final int NOTE_COLUMN_SNIPPET = 2;
private static final String[] DATA_PROJECTION = {
DataColumns.CONTENT,
DataColumns.MIME_TYPE,
DataColumns.DATA1,
DataColumns.DATA2,
DataColumns.DATA3,
DataColumns.DATA4,
};
private static final int DATA_COLUMN_CONTENT = 0;
private static final int DATA_COLUMN_MIME_TYPE = 1;
private static final int DATA_COLUMN_CALL_DATE = 2;
private static final int DATA_COLUMN_PHONE_NUMBER = 4;
private final String [] TEXT_FORMAT;
private static final int FORMAT_FOLDER_NAME = 0;
private static final int FORMAT_NOTE_DATE = 1;
private static final int FORMAT_NOTE_CONTENT = 2;
private Context mContext;
private String mFileName;
private String mFileDirectory;
public TextExport(Context context) {
TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
mContext = context;
mFileName = ""; //为什么为空?
mFileDirectory = "";
}
private String getFormat(int id) { //获取文本的组成部分
return TEXT_FORMAT[id];
}
/**
* Export the folder identified by folder id to text
*/
private void exportFolderToText(String folderId, PrintStream ps) {
// Query notes belong to this folder 通过查询parent id是文件夹id的note来选出制定ID文件夹下的Note
Cursor notesCursor = mContext.getContentResolver().query(Notes.CONTENT_NOTE_URI,
NOTE_PROJECTION, NoteColumns.PARENT_ID + "=?", new String[] {
folderId
}, null);
if (notesCursor != null) {
if (notesCursor.moveToFirst()) {
do {
// Print note's last modified date ps里面保存有这份note的日期
ps.println(String.format(getFormat(FORMAT_NOTE_DATE), DateFormat.format(
mContext.getString(R.string.format_datetime_mdhm),
notesCursor.getLong(NOTE_COLUMN_MODIFIED_DATE))));
// Query data belong to this note
String noteId = notesCursor.getString(NOTE_COLUMN_ID);
exportNoteToText(noteId, ps); //将文件导出到text
} while (notesCursor.moveToNext());
}
notesCursor.close();
}
}
/**
* Export note identified by id to a print stream
*/
private void exportNoteToText(String noteId, PrintStream ps) {
Cursor dataCursor = mContext.getContentResolver().query(Notes.CONTENT_DATA_URI,
DATA_PROJECTION, DataColumns.NOTE_ID + "=?", new String[] {
noteId
}, null);
if (dataCursor != null) { //利用光标来扫描内容区别为callnote和note两种靠ps.printline输出
if (dataCursor.moveToFirst()) {
do {
String mimeType = dataCursor.getString(DATA_COLUMN_MIME_TYPE);
if (DataConstants.CALL_NOTE.equals(mimeType)) {
// Print phone number
String phoneNumber = dataCursor.getString(DATA_COLUMN_PHONE_NUMBER);
long callDate = dataCursor.getLong(DATA_COLUMN_CALL_DATE);
String location = dataCursor.getString(DATA_COLUMN_CONTENT);
if (!TextUtils.isEmpty(phoneNumber)) { //判断是否为空字符
ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
phoneNumber));
}
// Print call date
ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT), DateFormat
.format(mContext.getString(R.string.format_datetime_mdhm),
callDate)));
// Print call attachment location
if (!TextUtils.isEmpty(location)) {
ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
location));
}
} else if (DataConstants.NOTE.equals(mimeType)) {
String content = dataCursor.getString(DATA_COLUMN_CONTENT);
if (!TextUtils.isEmpty(content)) {
ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
content));
}
}
} while (dataCursor.moveToNext());
}
dataCursor.close();
}
// print a line separator between note
try {
ps.write(new byte[] {
Character.LINE_SEPARATOR, Character.LETTER_NUMBER
});
} catch (IOException e) {
Log.e(TAG, e.toString());
}
}
/**
* Note will be exported as text which is user readable
*/
public int exportToText() { //总函数调用上面的exportFolder和exportNote
if (!externalStorageAvailable()) {
Log.d(TAG, "Media was not mounted");
return STATE_SD_CARD_UNMOUONTED;
}
PrintStream ps = getExportToTextPrintStream();
if (ps == null) {
Log.e(TAG, "get print stream error");
return STATE_SYSTEM_ERROR;
}
// First export folder and its notes 导出文件夹,就是导出里面包含的便签
Cursor folderCursor = mContext.getContentResolver().query(
Notes.CONTENT_NOTE_URI,
NOTE_PROJECTION,
"(" + NoteColumns.TYPE + "=" + Notes.TYPE_FOLDER + " AND "
+ NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER + ") OR "
+ NoteColumns.ID + "=" + Notes.ID_CALL_RECORD_FOLDER, null, null);
if (folderCursor != null) {
if (folderCursor.moveToFirst()) {
do {
// Print folder's name
String folderName = "";
if(folderCursor.getLong(NOTE_COLUMN_ID) == Notes.ID_CALL_RECORD_FOLDER) {
folderName = mContext.getString(R.string.call_record_folder_name);
} else {
folderName = folderCursor.getString(NOTE_COLUMN_SNIPPET);
}
if (!TextUtils.isEmpty(folderName)) {
ps.println(String.format(getFormat(FORMAT_FOLDER_NAME), folderName));
}
String folderId = folderCursor.getString(NOTE_COLUMN_ID);
exportFolderToText(folderId, ps);
} while (folderCursor.moveToNext());
}
folderCursor.close();
}
// Export notes in root's folder 将根目录里的便签导出(由于不属于任何文件夹,因此无法通过文件夹导出来实现这一部分便签的导出)
Cursor noteCursor = mContext.getContentResolver().query(
Notes.CONTENT_NOTE_URI,
NOTE_PROJECTION,
NoteColumns.TYPE + "=" + +Notes.TYPE_NOTE + " AND " + NoteColumns.PARENT_ID
+ "=0", null, null);
if (noteCursor != null) {
if (noteCursor.moveToFirst()) {
do {
ps.println(String.format(getFormat(FORMAT_NOTE_DATE), DateFormat.format(
mContext.getString(R.string.format_datetime_mdhm),
noteCursor.getLong(NOTE_COLUMN_MODIFIED_DATE))));
// Query data belong to this note
String noteId = noteCursor.getString(NOTE_COLUMN_ID);
exportNoteToText(noteId, ps);
} while (noteCursor.moveToNext());
}
noteCursor.close();
}
ps.close();
return STATE_SUCCESS;
}
/**
* Get a print stream pointed to the file {@generateExportedTextFile}
*/
private PrintStream getExportToTextPrintStream() {
File file = generateFileMountedOnSDcard(mContext, R.string.file_path,
R.string.file_name_txt_format);
if (file == null) {
Log.e(TAG, "create file to exported failed");
return null;
}
mFileName = file.getName();
mFileDirectory = mContext.getString(R.string.file_path);
PrintStream ps = null;
try {
FileOutputStream fos = new FileOutputStream(file);
ps = new PrintStream(fos); //将ps输出流输出到特定的文件目的就是导出到文件而不是直接输出
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
} catch (NullPointerException e) {
e.printStackTrace();
return null;
}
return ps;
}
}
/**
* Generate the text file to store imported data
*/
private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
StringBuilder sb = new StringBuilder();
sb.append(Environment.getExternalStorageDirectory()); //外部SD卡的存储路径
sb.append(context.getString(filePathResId)); //文件的存储路径
File filedir = new File(sb.toString()); //filedir应该就是用来存储路径信息
sb.append(context.getString(
fileNameFormatResId,
DateFormat.format(context.getString(R.string.format_date_ymd),
System.currentTimeMillis())));
File file = new File(sb.toString());
try { //如果这些文件不存在,则新建
if (!filedir.exists()) {
filedir.mkdir();
}
if (!file.exists()) {
file.createNewFile();
}
return file;
} catch (SecurityException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// try catch 异常处理
return null;
}
}