导入数据至数据库时如何实现进度条功能？

Got it, let's get that progress bar working for your file import. Since you already have the total line count, we can use that to calculate real-time progress and keep your users informed. Here's a step-by-step adjustment to your code:

1. Update Your Dialog Layout #

First, add a horizontal progress bar and a progress text view to your import__dialog.xml to display progress:

<!-- Add these to your existing layout -->
<ProgressBar
    android:id="@+id/progress_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    style="@style/Widget.AppCompat.ProgressBar.Horizontal"
    android:max="100"
    android:visibility="gone"/>
<TextView
    android:id="@+id/tv_progress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="0%"
    android:layout_marginTop="8dp"
    android:visibility="gone"/>

2. Adjust Your Kotlin Code for Async Import & Progress Updates #

We'll use Kotlin Coroutines to handle heavy file/database work off the main thread, while updating the UI safely on the main thread. Here's the revised code with progress tracking:

// Add these properties at the top of your Activity/Fragment
private lateinit var progressBar: ProgressBar
private lateinit var progressText: TextView
private var totalLines = 0

private fun importDialog(type: Int, context: Context) {
    val builder = AlertDialog.Builder(this)
    val inflater = this.layoutInflater
    val view = inflater.inflate(R.layout.import__dialog, null)
    builder.setView(view)
    val dialog: AlertDialog = builder.create()
    dialog.window?.attributes?.windowAnimations = type
    dialog.setMessage(context.getString(R.string.open_master))
    
    lbl = view.findViewById(R.id.edit_master)
    lbl.text = noti.toString()
    
    // Initialize progress components
    progressBar = view.findViewById(R.id.progress_bar)
    progressText = view.findViewById(R.id.tv_progress)
    
    btnimport = view.findViewById(R.id.img_import)
    btnimport.setOnClickListener {
        val fileintent = Intent(Intent.ACTION_GET_CONTENT)
        fileintent.type = "text/*" // Fixed MIME type for txt/csv
        try {
            startActivityForResult(fileintent, requestcode)
            dialog.show()
        } catch (e: ActivityNotFoundException) {
            lbl.text = "No activity can handle picking a file. Showing alternatives."
        }
    }
    
    scan = view.findViewById<Button>(R.id.btn_scan)
    scan.setOnClickListener {
        // First calculate total lines before starting import
        calculateTotalLines()
        // Then start import with progress
        importWithProgress(this)
    }
    
    dialog.show()
}

// Helper function to calculate total lines (extracted from your existing logic)
private fun calculateTotalLines() {
    val cursor = contentResolver.openInputStream(android.net.Uri.parse(master_path)) ?: return
    try {
        val buffer = BufferedReader(InputStreamReader(cursor))
        buffer.readLine() // Skip header line
        totalLines = 0
        while (buffer.readLine() != null) {
            totalLines++
        }
    } catch (e: IOException) {
        e.printStackTrace()
        val d = Dialog(this)
        d.setTitle("Failed to count lines: ${e.message}")
        d.show()
    } finally {
        cursor.close()
    }
}

// Updated import function with progress tracking
private fun importWithProgress(context: Context) {
    // Show progress UI
    progressBar.visibility = View.VISIBLE
    progressText.visibility = View.VISIBLE
    
    // Launch coroutine for background work
    CoroutineScope(Dispatchers.IO).launch {
        val cursor = contentResolver.openInputStream(android.net.Uri.parse(master_path)) ?: return@launch
        val db = openOrCreateDatabase("database.db", Context.MODE_PRIVATE, null)
        val tableName = "Master"
        
        try {
            db.execSQL("delete from $tableName")
            val file = InputStreamReader(cursor)
            val buffer = BufferedReader(file)
            buffer.readLine() // Skip header
            val contentValues = ContentValues()
            
            db.beginTransaction()
            var currentLine = 0
            
            while (true) {
                val line = buffer.readLine() ?: break
                currentLine++
                
                // Your existing line parsing logic (kept as-is)
                val article_array = ArrayList<String>()
                var desc_array = ArrayList<String>()
                var price_array = ArrayList<String>()
                var isbn_array = ArrayList<String>()
                var total_array = ArrayList<String>()
                
                for(i in 0..12){
                    val article = line[i].toString().replace(" ","")
                    article_array.add(article)
                }
                for(i in 13..62){
                    val desc = line[i].toString()
                    desc_array.add(desc)
                }
                for(i in 63..70){
                    val price = line[i].toString().replace(" ","")
                    price_array.add(price)
                }
                for(i in 71..line.length-1){
                    val isbn = line[i].toString().replace(" ","")
                    isbn_array.add(isbn)
                }
                
                val article_list = article_array.toString().replace(", ","").replace("[","").replace("]","").replace("\n","")
                val desc_list = desc_array.toString().replace(", ","").replace("[","").replace("]","").replace("\n","")
                val price_list = price_array.toString().replace(", ","").replace("[","").replace("]","").replace("\n","")
                val isbn_list:String = isbn_array.toString().replace(", ","").replace("[","").replace("]","").replace("\n","")
                
                total_array.add(article_list)
                total_array.add(desc_list)
                total_array.add(price_list)
                total_array.add(isbn_list)
                
                val article=total_array[0].toString()
                val desc=total_array[1].toString()
                val price=total_array[2].toString()
                val isbn=total_array[3].toString()
                
                contentValues.put("article", article)
                contentValues.put("description", desc)
                contentValues.put("price", price)
                contentValues.put("isbn", isbn)
                
                db.insert(tableName, null, contentValues)
                
                // Calculate progress and update UI on main thread
                val progress = (currentLine.toFloat() / totalLines * 100).toInt()
                withContext(Dispatchers.Main) {
                    progressBar.progress = progress
                    progressText.text = "$progress%"
                }
            }
            
            db.setTransactionSuccessful()
            withContext(Dispatchers.Main) {
                // Hide progress and show success message
                progressBar.visibility = View.GONE
                progressText.visibility = View.GONE
                val d = Dialog(context)
                d.setTitle("Import completed successfully!")
                d.show()
            }
        } catch (e: IOException) {
            if (db.inTransaction()) db.endTransaction()
            withContext(Dispatchers.Main) {
                progressBar.visibility = View.GONE
                progressText.visibility = View.GONE
                val d = Dialog(context)
                d.setTitle("Import failed: ${e.message}")
                d.show()
            }
        } catch (ex: Exception) {
            if (db.inTransaction()) db.endTransaction()
            withContext(Dispatchers.Main) {
                progressBar.visibility = View.GONE
                progressText.visibility = View.GONE
                val d = Dialog(context)
                d.setTitle("Import failed: ${ex.message}")
                d.show()
            }
        } finally {
            db.close()
            cursor.close()
        }
    }
}

// Updated onActivityResult with better error handling
@SuppressLint("MissingSuperCall")
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    if (data == null) return
    if (requestCode == requestcode && resultCode == Activity.RESULT_OK) {
        val filepath = data.data ?: return
        master_path = filepath.toString()
        lbl.text = filepath.toString()
    } else {
        val d = Dialog(this)
        d.setTitle("Only CSV/TXT files allowed or operation cancelled")
        d.show()
    }
}

Key Changes Made: #

• Added progress UI components: A horizontal progress bar and text view to display real-time import percentage.
• Separated line counting: Extracted total line calculation into its own function to run before starting the import.
• Kotlin Coroutines: Moved file reading and database operations to a background thread (Dispatchers.IO) to avoid blocking the main thread, and used Dispatchers.Main to safely update the UI.
• Real-time progress updates: Calculated progress percentage after each line is imported and refreshed the UI immediately.
• Resource cleanup: Added close() calls for cursors and databases to prevent memory leaks.

A quick side note: Your current line parsing uses line[i] to split characters, which might not work well for standard CSV files (which use delimiters like commas). If you're working with proper CSV data, consider using a library like OpenCSV to handle parsing more reliably—but that's a separate improvement!

内容的提问来源于stack exchange，提问作者kinesis