添加注释

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

@@ -35,12 +35,23 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.PrintStream;
 
-
+/**
+ * BackupUtils 类提供笔记备份功能，支持将笔记导出为文本文件。
+ * 该类使用单例模式，通过 TextExport 内部类实现具体的导出逻辑。
+ * 导出过程会遍历所有文件夹和笔记，将它们按照特定格式保存到外部存储中。
+ */
 public class BackupUtils {
+    // 日志标签
     private static final String TAG = "BackupUtils";
-    // Singleton stuff
+    // 单例实例
     private static BackupUtils sInstance;
 
+    /**
+     * 获取 BackupUtils 的单例实例
+     * 
+     * @param context 应用上下文
+     * @return BackupUtils 实例
+     */
     public static synchronized BackupUtils getInstance(Context context) {
         if (sInstance == null) {
             sInstance = new BackupUtils(context);
@@ -49,43 +60,72 @@ public class BackupUtils {
     }
 
     /**
-     * Following states are signs to represents backup or restore
+     * 备份或恢复操作的状态码
-     * status
      */
-    // Currently, the sdcard is not mounted
+    // 当前SD卡未挂载
     public static final int STATE_SD_CARD_UNMOUONTED           = 0;
-    // The backup file not exist
+    // 备份文件不存在
     public static final int STATE_BACKUP_FILE_NOT_EXIST        = 1;
-    // The data is not well formated, may be changed by other programs
+    // 数据格式不正确，可能被其他程序修改
     public static final int STATE_DATA_DESTROIED               = 2;
-    // Some run-time exception which causes restore or backup fails
+    // 运行时异常导致备份或恢复失败
     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;
 
+    // 文本导出工具
     private TextExport mTextExport;
 
+    /**
+     * 私有构造函数，初始化文本导出工具
+     * 
+     * @param context 应用上下文
+     */
     private BackupUtils(Context context) {
         mTextExport = new TextExport(context);
     }
 
+    /**
+     * 检查外部存储是否可用
+     * 
+     * @return 如果外部存储已挂载返回true，否则返回false
+     */
     private static boolean externalStorageAvailable() {
         return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
     }
 
+    /**
+     * 将笔记导出为文本文件
+     * 
+     * @return 导出状态码
+     */
     public int exportToText() {
         return mTextExport.exportToText();
     }
 
+    /**
+     * 获取导出的文本文件名
+     * 
+     * @return 文件名
+     */
     public String getExportedTextFileName() {
         return mTextExport.mFileName;
     }
 
+    /**
+     * 获取导出的文本文件目录
+     * 
+     * @return 文件目录路径
+     */
     public String getExportedTextFileDir() {
         return mTextExport.mFileDirectory;
     }
 
+    /**
+     * 内部类，负责将笔记导出为文本文件
+     */
     private static class TextExport {
+        // 笔记查询投影，定义从笔记表中查询的列
         private static final String[] NOTE_PROJECTION = {
                 NoteColumns.ID,
                 NoteColumns.MODIFIED_DATE,
@@ -93,12 +133,12 @@ public class BackupUtils {
                 NoteColumns.TYPE
         };
 
+        // 笔记查询结果集中各列的索引
         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;
 
+        // 数据查询投影，定义从数据表中查询的列
         private static final String[] DATA_PROJECTION = {
                 DataColumns.CONTENT,
                 DataColumns.MIME_TYPE,
@@ -108,39 +148,56 @@ public class BackupUtils {
                 DataColumns.DATA4,
         };
 
+        // 数据查询结果集中各列的索引
         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;
 
+        // 文本格式数组，用于格式化导出的笔记内容
         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;
 
+        // 应用上下文
         private Context mContext;
+        // 导出的文件名
         private String mFileName;
+        // 导出的文件目录
         private String mFileDirectory;
 
+        /**
+         * 构造函数，初始化文本导出工具
+         * 
+         * @param context 应用上下文
+         */
         public TextExport(Context context) {
+            // 从资源文件中获取文本格式
             TEXT_FORMAT = context.getResources().getStringArray(R.array.format_for_exported_note);
             mContext = context;
             mFileName = "";
             mFileDirectory = "";
         }
 
+        /**
+         * 获取指定ID的文本格式
+         * 
+         * @param id 格式ID
+         * @return 格式字符串
+         */
         private String getFormat(int id) {
             return TEXT_FORMAT[id];
         }
 
         /**
-         * Export the folder identified by folder id to text
+         * 将指定文件夹下的所有笔记导出为文本
+         * 
+         * @param folderId 文件夹ID
+         * @param ps 输出流
          */
         private void exportFolderToText(String folderId, PrintStream ps) {
-            // Query notes belong to this folder
+            // 查询属于该文件夹的所有笔记
             Cursor notesCursor = mContext.getContentResolver().query(Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION, NoteColumns.PARENT_ID + "=?", new String[] {
                         folderId
@@ -149,11 +206,11 @@ public class BackupUtils {
             if (notesCursor != null) {
                 if (notesCursor.moveToFirst()) {
                     do {
-                        // Print note's last modified date
+                        // 打印笔记的最后修改日期
                         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
+                        // 查询属于该笔记的详细数据并导出
                         String noteId = notesCursor.getString(NOTE_COLUMN_ID);
                         exportNoteToText(noteId, ps);
                     } while (notesCursor.moveToNext());
@@ -163,9 +220,13 @@ public class BackupUtils {
         }
 
         /**
-         * Export note identified by id to a print stream
+         * 将指定ID的笔记导出为文本
+         * 
+         * @param noteId 笔记ID
+         * @param ps 输出流
          */
         private void exportNoteToText(String noteId, PrintStream ps) {
+            // 查询笔记的详细数据
             Cursor dataCursor = mContext.getContentResolver().query(Notes.CONTENT_DATA_URI,
                     DATA_PROJECTION, DataColumns.NOTE_ID + "=?", new String[] {
                         noteId
@@ -176,7 +237,7 @@ public class BackupUtils {
                     do {
                         String mimeType = dataCursor.getString(DATA_COLUMN_MIME_TYPE);
                         if (DataConstants.CALL_NOTE.equals(mimeType)) {
-                            // Print phone number
+                            // 处理通话记录类型的笔记
                             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 +246,17 @@ public class BackupUtils {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         phoneNumber));
                             }
-                            // Print call date
+                            // 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
+                            // 打印通话附件位置
                             if (!TextUtils.isEmpty(location)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
                                         location));
                             }
                         } else if (DataConstants.NOTE.equals(mimeType)) {
+                            // 处理普通文本类型的笔记
                             String content = dataCursor.getString(DATA_COLUMN_CONTENT);
                             if (!TextUtils.isEmpty(content)) {
                                 ps.println(String.format(getFormat(FORMAT_NOTE_CONTENT),
@@ -205,7 +267,7 @@ public class BackupUtils {
                 }
                 dataCursor.close();
             }
-            // print a line separator between note
+            // 在笔记之间打印分隔符
             try {
                 ps.write(new byte[] {
                         Character.LINE_SEPARATOR, Character.LETTER_NUMBER
@@ -216,20 +278,25 @@ public class BackupUtils {
         }
 
         /**
-         * Note will be exported as text which is user readable
+         * 将所有笔记导出为用户可读的文本文件
+         * 
+         * @return 导出状态码
          */
         public int exportToText() {
+            // 检查外部存储是否可用
             if (!externalStorageAvailable()) {
                 Log.d(TAG, "Media was not mounted");
                 return STATE_SD_CARD_UNMOUONTED;
             }
 
+            // 获取导出文件的打印流
             PrintStream ps = getExportToTextPrintStream();
             if (ps == null) {
                 Log.e(TAG, "get print stream error");
                 return STATE_SYSTEM_ERROR;
             }
-            // First export folder and its notes
+            
+            // 首先导出文件夹及其笔记
             Cursor folderCursor = mContext.getContentResolver().query(
                     Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION,
@@ -240,7 +307,7 @@ public class BackupUtils {
             if (folderCursor != null) {
                 if (folderCursor.moveToFirst()) {
                     do {
-                        // Print folder's name
+                        // 打印文件夹名称
                         String folderName = "";
                         if(folderCursor.getLong(NOTE_COLUMN_ID) == Notes.ID_CALL_RECORD_FOLDER) {
                             folderName = mContext.getString(R.string.call_record_folder_name);
@@ -257,7 +324,7 @@ public class BackupUtils {
                 folderCursor.close();
             }
 
-            // Export notes in root's folder
+            // 导出根文件夹中的笔记
             Cursor noteCursor = mContext.getContentResolver().query(
                     Notes.CONTENT_NOTE_URI,
                     NOTE_PROJECTION,
@@ -270,7 +337,7 @@ public class BackupUtils {
                         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
+                        // 查询属于该笔记的详细数据并导出
                         String noteId = noteCursor.getString(NOTE_COLUMN_ID);
                         exportNoteToText(noteId, ps);
                     } while (noteCursor.moveToNext());
@@ -283,9 +350,12 @@ public class BackupUtils {
         }
 
         /**
-         * Get a print stream pointed to the file {@generateExportedTextFile}
+         * 获取指向导出文本文件的打印流
+         * 
+         * @return 打印流对象，如果创建失败则返回null
          */
         private PrintStream getExportToTextPrintStream() {
+            // 生成外部存储上的文件
             File file = generateFileMountedOnSDcard(mContext, R.string.file_path,
                     R.string.file_name_txt_format);
             if (file == null) {
@@ -310,13 +380,20 @@ public class BackupUtils {
     }
 
     /**
-     * Generate the text file to store imported data
+     * 在外部存储上生成用于存储导入数据的文本文件
+     * 
+     * @param context 应用上下文
+     * @param filePathResId 文件路径资源ID
+     * @param fileNameFormatResId 文件名格式资源ID
+     * @return 生成的文件对象，如果创建失败则返回null
      */
     private static File generateFileMountedOnSDcard(Context context, int filePathResId, int fileNameFormatResId) {
         StringBuilder sb = new StringBuilder();
+        // 构建文件路径
         sb.append(Environment.getExternalStorageDirectory());
         sb.append(context.getString(filePathResId));
         File filedir = new File(sb.toString());
+        // 构建文件名（包含时间戳）
         sb.append(context.getString(
                 fileNameFormatResId,
                 DateFormat.format(context.getString(R.string.format_date_ymd),
@@ -324,9 +401,11 @@ public class BackupUtils {
         File file = new File(sb.toString());
 
         try {
+            // 确保目录存在
             if (!filedir.exists()) {
                 filedir.mkdir();
             }
+            // 确保文件存在
             if (!file.exists()) {
                 file.createNewFile();
             }
@@ -340,5 +419,3 @@ public class BackupUtils {
         return null;
     }
 }
-
-