Android studio实验：备份短信 能运行的实验代码是什么

以下是一个简单的备份短信的 Android Studio 实验代码示例：

import android.Manifest;
import android.content.ContentResolver;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.Telephony;
import android.util.Log;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends AppCompatActivity {
    private static final int PERMISSIONS_REQUEST_READ_SMS = 100;
    private static final int PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE = 101;
    private static final String SMS_BACKUP_FILE_NAME = "sms_backup.txt";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Check if we have read SMS permission
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_SMS)
                != PackageManager.PERMISSION_GRANTED) {
            // Request permission
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.READ_SMS},
                    PERMISSIONS_REQUEST_READ_SMS);
        } else {
            // Permission already granted
            backupSms();
        }
    }

    private void backupSms() {
        // Check if we have write external storage permission
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                != PackageManager.PERMISSION_GRANTED) {
            // Request permission
            ActivityCompat.requestPermissions(this,
                    new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                    PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE);
        } else {
            // Permission already granted
            ContentResolver contentResolver = getContentResolver();
            Cursor cursor = contentResolver.query(Uri.parse("content://sms/"), null, null, null, null);

            if (cursor == null) {
                Log.e("SMS Backup", "Cursor is null");
                Toast.makeText(this, "Failed to backup SMS", Toast.LENGTH_SHORT).show();
                return;
            }

            try {
                File backupFile = new File(Environment.getExternalStorageDirectory(), SMS_BACKUP_FILE_NAME);
                FileOutputStream fos = new FileOutputStream(backupFile);
                OutputStreamWriter writer = new OutputStreamWriter(fos);

                // Write header
                writer.write("Address,Date,Type,Body\n");

                // Loop through cursor and write to file
                while (cursor.moveToNext()) {
                    String address = cursor.getString(cursor.getColumnIndex(Telephony.Sms.ADDRESS));
                    long date = cursor.getLong(cursor.getColumnIndex(Telephony.Sms.DATE));
                    String type = cursor.getString(cursor.getColumnIndex(Telephony.Sms.TYPE));
                    String body = cursor.getString(cursor.getColumnIndex(Telephony.Sms.BODY));

                    writer.write(String.format(Locale.getDefault(), "%s,%s,%s,%s\n",
                            address, new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault()).format(new Date(date)),
                            type, body));
                }

                writer.close();
                fos.close();

                Toast.makeText(this, "SMS backup completed", Toast.LENGTH_SHORT).show();
            } catch (IOException e) {
                Log.e("SMS Backup", "Failed to backup SMS", e);
                Toast.makeText(this, "Failed to backup SMS", Toast.LENGTH_SHORT).show();
            } finally {
                cursor.close();
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
                                           @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case PERMISSIONS_REQUEST_READ_SMS:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    backupSms();
                } else {
                    Toast.makeText(this, "Read SMS permission required", Toast.LENGTH_SHORT).show();
                }
                break;
            case PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    backupSms();
                } else {
                    Toast.makeText(this, "Write external storage permission required", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }
}

代码中使用了两个常量 `PERMISSIONS_REQUEST_READ_SMS` 和 `PERMISSIONS_REQUEST_WRITE_EXTERNAL_STORAGE` 来表示请求权限的请求码，备份短信的文件名为 `SMS_BACKUP_FILE_NAME`。

需要注意的是，该代码中只备份了收到的短信，对于发送的短信需要另行处理。此外，还需要在 AndroidManifest.xml 文件中添加读取短信和写入外部存储器的权限声明：

<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />