backup部分注释

Notes-master/src/net/micode/notes/tool/BackupUtils.java

@@ -35,10 +35,10 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.PrintStream;
 
-
+//笔记备份工具类
 public class BackupUtils {
     private static final String TAG = "BackupUtils";
-    // Singleton stuff
+    // Singleton stuff 单例模式
     private static BackupUtils sInstance;
 
     public static synchronized BackupUtils getInstance(Context context) {
@@ -47,23 +47,34 @@ public class BackupUtils {
         }
         return sInstance;
     }
+    // 备份和恢复功能
+   //定义备份或恢复数据时可能遇到的状态码。
+ 
+public class BackupState {
+
+    //当前SD未挂载
+   
+    public static final int STATE_SD_CARD_UNMOUNTED           = 0;
+    
+    //备份文件不存在
      
-    /**
-     * Following states are signs to represents backup or restore
-     * status
-     */
-    // Currently, the sdcard is not mounted
-    public static final int STATE_SD_CARD_UNMOUONTED           = 0;
-    // The backup file not exist
     public static final int STATE_BACKUP_FILE_NOT_EXIST        = 1;
-    // The data is not well formated, may be changed by other programs
+    
-    public static final int STATE_DATA_DESTROIED               = 2;
+    // 数据格式不正确，可能被其他程序更改
-    // Some run-time exception which causes restore or backup fails
+    
+    public static final int STATE_DATA_DESTROYED               = 2;
+    
+    //运行时异常导致恢复或备份失败
+
     public static final int STATE_SYSTEM_ERROR                 = 3;
-    // Backup or restore success
+    
+    // 备份或恢复成功
+    
     public static final int STATE_SUCCESS                      = 4;
     
+    // 用于导出文件的目录
     private TextExport mTextExport;
+}
 
     private BackupUtils(Context context) {
         mTextExport = new TextExport(context);
@@ -84,7 +95,7 @@ public class BackupUtils {
     public String getExportedTextFileDir() {
         return mTextExport.mFileDirectory;
     }
-
+    // 笔记备份类
     private static class TextExport {
         private static final String[] NOTE_PROJECTION = {
                 NoteColumns.ID,
@@ -92,7 +103,7 @@ public class BackupUtils {
                 NoteColumns.SNIPPET,
                 NoteColumns.TYPE
         };
-
+        //定义Note数据表中各列对应的索引常量。
         private static final int NOTE_COLUMN_ID = 0;
 
         private static final int NOTE_COLUMN_MODIFIED_DATE = 1;
@@ -124,28 +135,26 @@ public class BackupUtils {
         private Context mContext;
         private String mFileName;
         private String mFileDirectory;
-
+        // 备份和恢复功能       
         public TextExport(Context context) {
             TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
             mContext = context;
             mFileName = "";
             mFileDirectory = "";
         }
-
+        //同上
         private String getFormat(int id) {
             return TEXT_FORMAT[id];
         }
 
-        /**
+        // 导出笔记到文本
-         * Export the folder identified by folder id to text
-         */
         private void exportFolderToText(String folderId, PrintStream ps) {
             // Query notes belong to this folder
             Cursor notesCursor = mContext.getContentResolver().query(Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION, NoteColumns.PARENT_ID + "=?", new String[] {
                         folderId
                     }, null);
-
+            // 查询笔记
             if (notesCursor != null) {
                 if (notesCursor.moveToFirst()) {
                     do {
@@ -161,22 +170,21 @@ public class BackupUtils {
                 notesCursor.close();
             }
         }
-
+        // 导出笔记到文本
-        /**
-         * 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);
-
+            // 查询笔记数据                            
             if (dataCursor != null) {
                 if (dataCursor.moveToFirst()) {
-                    do {
+                    do {// 开始遍历笔记数据
+                        // 获取当前行的MIME类型
                         String mimeType = dataCursor.getString(DATA_COLUMN_MIME_TYPE);
                         if (DataConstants.CALL_NOTE.equals(mimeType)) {
-                            // Print phone number
+                            // 处理电话笔记：打印电话号码、通话日期和附件位置
+                            // 获取并打印电话号码
                             String phoneNumber = dataCursor.getString(DATA_COLUMN_PHONE_NUMBER);
                             long callDate = dataCursor.getLong(DATA_COLUMN_CALL_DATE);
                             String location = dataCursor.getString(DATA_COLUMN_CONTENT);
@@ -185,16 +193,17 @@ public class BackupUtils {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         phoneNumber));
                             }
-                            // Print call date
+                            // 获取并打印通话日期
                             ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT), DateFormat
                                     .format(mContext.getString(R.string.format_datetime_mdhm),
                                             callDate)));
-                            // Print call attachment location
+                            // 获取并打印附件位置（如果存在）
                             if (!TextUtils.isEmpty(location)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         location));
                             }
                         } else if (DataConstants.NOTE.equals(mimeType)) {
+                            // 处理普通笔记：打印笔记内容（如果非空）
                             String content = dataCursor.getString(DATA_COLUMN_CONTENT);
                             if (!TextUtils.isEmpty(content)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
@@ -203,9 +212,11 @@ public class BackupUtils {
                         }
                     } while (dataCursor.moveToNext());
                 }
+                // 关闭数据游标
                 dataCursor.close();
             }
             // print a line separator between note
+        
             try {
                 ps.write(new byte[] {
                         Character.LINE_SEPARATOR, Character.LETTER_NUMBER
@@ -214,56 +225,61 @@ public class BackupUtils {
                 Log.e(TAG, e.toString());
             }
         }
-
+        // 导出笔记到文本
-        /**
-         * Note will be exported as text which is user readable
-         */
         public int exportToText() {
             if (!externalStorageAvailable()) {
                 Log.d(TAG, "Media was not mounted");
                 return STATE_SD_CARD_UNMOUONTED;
             }
-
+            // 错误输出
             PrintStream ps = getExportToTextPrintStream();
             if (ps == null) {
                 Log.e(TAG, "get print stream error");
                 return STATE_SYSTEM_ERROR;
             }
             // First export folder and its notes
+
+            // 查询文件夹
             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);
-
+            // 遍历文件夹    
-            if (folderCursor != null) {
+             if (folderCursor != null) {
                 if (folderCursor.moveToFirst()) {
                     do {
-                        // Print folder's name
+                        // 获取并处理当前文件夹的名称
                         String folderName = "";
+                        // 判断当前文件夹是否为通话记录文件夹，据此设置不同的文件夹名称
                         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);
                         }
+                        // 如果文件夹名称不为空，则打印到文本
                         if (!TextUtils.isEmpty(folderName)) {
                             ps.println(String.format(getFormat(FORMAT_FOLDER_NAME), folderName));
                         }
+                        // 获取并导出当前文件夹的详细信息到文本
                         String folderId = folderCursor.getString(NOTE_COLUMN_ID);
                         exportFolderToText(folderId, ps);
                     } while (folderCursor.moveToNext());
                 }
+                // 关闭文件夹游标
                 folderCursor.close();
             }
             
+            // Export trash folder
+
             // Export notes in root's folder
             Cursor noteCursor = mContext.getContentResolver().query(
                     Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION,
                     NoteColumns.TYPE + "=" + +Notes.TYPE_NOTE + " AND " + NoteColumns.PARENT_ID
                             + "=0", null, null);
-
+            //  遍历笔记
             if (noteCursor != null) {
                 if (noteCursor.moveToFirst()) {
                     do {
@@ -285,6 +301,7 @@ public class BackupUtils {
         /**
          * Get a print stream pointed to the file {@generateExportedTextFile}
          */
+        // 获取打印流
         private PrintStream getExportToTextPrintStream() {
             File file = generateFileMountedOnSDcard(mContext, R.string.file_path,
                     R.string.file_name_txt_format);
@@ -294,7 +311,9 @@ public class BackupUtils {
             }
             mFileName = file.getName();
             mFileDirectory = mContext.getString(R.string.file_path);
+            
             PrintStream ps = null;
+            // 创建文件输出流
             try {
                 FileOutputStream fos = new FileOutputStream(file);
                 ps = new PrintStream(fos);
@@ -312,6 +331,8 @@ public class BackupUtils {
     /**
      * Generate the text file to store imported data
      */
+
+    // 生成文件
     private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
         StringBuilder sb = new StringBuilder();
         sb.append(Environment.getExternalStorageDirectory());
@@ -322,21 +343,26 @@ public class BackupUtils {
                 DateFormat.format(context.getString(R.string.format_date_ymd),
                         System.currentTimeMillis())));
         File file = new File(sb.toString());
-
+        // 创建文件
-        try {
+       try {
+            // 检查目录是否存在，不存在则创建目录
             if (!filedir.exists()) {
                 filedir.mkdir();
             }
+            // 检查文件是否存在，不存在则创建文件
             if (!file.exists()) {
                 file.createNewFile();
             }
             return file;
         } catch (SecurityException e) {
+            // 处理安全异常
             e.printStackTrace();
         } catch (IOException e) {
+            // 处理IO异常
             e.printStackTrace();
         }
 
+        // 遇到异常返回null
         return null;
     }
 }