fix: 改为先备份再定向删除，降低误删风险

fileDeleter/app_low/src/main/java/com/epcdiy/filedeleter/MainActivity.java

@@ -18,9 +18,15 @@
 
 
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
 
 public class MainActivity extends AppCompatActivity {
 
+    private static final String TARGET_PREFIX = "fdtest_";
+    private static final String BACKUP_FOLDER_NAME = "FileDeleterBackup";
     private TextView tvStatus;
     private StringBuilder logBuilder = new StringBuilder();
     private static final int REQUEST_CODE = 100;
@@ -53,7 +59,7 @@ protected void onCreate(Bundle savedInstanceState) {
                 startBypassDeletion();
             }
         });
-        updateUI("警告！使用前务必备份照片！");
+        updateUI("提示：仅处理文件名前缀为 " + TARGET_PREFIX + " 的照片（jpg/jpeg/png），且先备份后删除。备份目录：Pictures/" + BACKUP_FOLDER_NAME);
     }
 
     // 1. 检查权限 (Android 11+)
@@ -87,43 +93,102 @@ private void startBypassDeletion() {
             updateUI("未找到 DCIM 目录");
             return;
         }
+        File backupDir = prepareBackupDir();
+        if (backupDir == null) {
+            updateUI("备份目录创建失败，已取消处理");
+            return;
+        }
 
         new Thread(() -> {
-            traverseAndDelete(dcimDir);
-            runOnUiThread(() -> Toast.makeText(this, "删除模拟完成", Toast.LENGTH_SHORT).show());
+            traverseAndBackupDelete(dcimDir, backupDir);
+            runOnUiThread(() -> Toast.makeText(this, "处理完成（仅特定命名照片）", Toast.LENGTH_SHORT).show());
         }).start();
     }
 
-    // 4. 递归枚举并使用底层接口删除
-    private void traverseAndDelete(File dir) {
+    private void traverseAndBackupDelete(File dir, File backupDir) {
         File[] files = dir.listFiles();
         if (files == null) return;
 
         for (File file : files) {
             if (file.isDirectory()) {
-                traverseAndDelete(file); // 递归进入子文件夹
+                traverseAndBackupDelete(file, backupDir);
             } else {
                 String fileName = file.getName();
-                // 仅模拟删除图片和视频
-                if (isMediaFile(fileName)) {
-                    // 核心操作：直接调用 java.io.File.delete()
-                    // 这不会触发 MediaStore 的数据库更新
-                    boolean deleted = file.delete();
-
-                    String msg = (deleted ? "[已抹除] " : "[失败] ") + file.getAbsolutePath();
+                if (isTargetPhoto(fileName)) {
+                    boolean backedUp = backupFile(file, backupDir);
+                    boolean deleted = backedUp && file.delete();
+                    String msg;
+                    if (!backedUp) {
+                        msg = "[跳过-备份失败] " + file.getAbsolutePath();
+                    } else {
+                        msg = (deleted ? "[已备份并删除] " : "[删除失败] ") + file.getAbsolutePath();
+                    }
                     updateUI(msg);
                 }
             }
         }
     }
 
-    private boolean isMediaFile(String name) {
+    private boolean isTargetPhoto(String name) {
+        if (name == null) return false;
         String n = name.toLowerCase();
-        if(n.contains("screenrecorder"))
-        {
+        return n.startsWith(TARGET_PREFIX)
+                && (n.endsWith(".jpg") || n.endsWith(".jpeg") || n.endsWith(".png"));
+    }
+
+    private boolean backupFile(File source, File backupDir) {
+        File outFile = buildUniqueBackupFile(backupDir, source.getName());
+        try (InputStream inputStream = new FileInputStream(source);
+             OutputStream outputStream = new FileOutputStream(outFile)) {
+            copyStream(inputStream, outputStream);
+            return true;
+        } catch (Exception e) {
             return false;
         }
-        return n.endsWith(".jpg") || n.endsWith(".jpeg") || n.endsWith(".png") || n.endsWith(".mp4");
+    }
+
+    private File prepareBackupDir() {
+        File picturesDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
+        File backupDir = new File(picturesDir, BACKUP_FOLDER_NAME);
+        if (backupDir.exists() || backupDir.mkdirs()) {
+            return backupDir;
+        }
+
+        File appExternal = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
+        if (appExternal == null) {
+            return null;
+        }
+        File fallbackDir = new File(appExternal, BACKUP_FOLDER_NAME);
+        if (fallbackDir.exists() || fallbackDir.mkdirs()) {
+            return fallbackDir;
+        }
+        return null;
+    }
+
+    private File buildUniqueBackupFile(File backupDir, String fileName) {
+        File target = new File(backupDir, fileName);
+        if (!target.exists()) {
+            return target;
+        }
+
+        int dot = fileName.lastIndexOf('.');
+        String baseName = dot > 0 ? fileName.substring(0, dot) : fileName;
+        String extension = dot > 0 ? fileName.substring(dot) : "";
+        int index = 1;
+        while (target.exists()) {
+            target = new File(backupDir, baseName + "_" + index + extension);
+            index++;
+        }
+        return target;
+    }
+
+    private void copyStream(InputStream inputStream, OutputStream outputStream) throws Exception {
+        byte[] buffer = new byte[8192];
+        int len;
+        while ((len = inputStream.read(buffer)) != -1) {
+            outputStream.write(buffer, 0, len);
+        }
+        outputStream.flush();
     }
 
     private void updateUI(String msg) {

fileDeleter/app_low/src/main/res/layout/activity_main.xml

@@ -17,7 +17,17 @@
         style="@android:style/Widget.Button"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:text="开始删除照片" />
+        android:text="开始备份后删除测试" />
+
+    <TextView
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:background="#fff3cd"
+        android:padding="8dp"
+        android:text="仅处理文件名前缀为 fdtest_ 的照片（jpg/jpeg/png），并先备份到 Pictures/FileDeleterBackup 后再删除。"
+        android:textColor="#5f370e"
+        android:textSize="13sp" />
 
     <ScrollView
         android:layout_width="match_parent"