Android 开发：使用 Java 代码获取和保存系统日志到 SD 卡

您可以使用以下代码来获取系统日志并将其保存到 SD 卡：

import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Environment;
import android.util.Log;

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

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

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_WRITE_STORAGE = 112;
    private static final String TAG = 'SystemLog';

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

        // 检查和请求存储权限
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_WRITE_STORAGE);
            } else {
                captureSystemLog();
            }
        } else {
            captureSystemLog();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_WRITE_STORAGE && grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            captureSystemLog();
        }
    }

    private void captureSystemLog() {
        try {
            // 创建保存日志的文件
            String fileName = 'system_log_' + new SimpleDateFormat('yyyyMMdd_HHmmss', Locale.getDefault()).format(new Date()) + '.txt';
            File logFile = new File(Environment.getExternalStorageDirectory(), fileName);
            if (!logFile.exists()) {
                logFile.createNewFile();
            }

            // 执行命令获取系统日志
            Process process = Runtime.getRuntime().exec('logcat -d');
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
            StringBuilder log = new StringBuilder();
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                log.append(line);
                log.append('
');
            }

            // 将日志写入文件
            FileOutputStream fileOutputStream = new FileOutputStream(logFile);
            fileOutputStream.write(log.toString().getBytes());
            fileOutputStream.close();

            Log.d(TAG, 'System log captured and saved to ' + logFile.getAbsolutePath());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

请确保您已经在 AndroidManifest.xml 文件中声明了存储权限：

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

这段代码使用 Runtime.getRuntime().exec('logcat -d') 命令来获取系统日志，并将其保存到以当前时间命名的文本文件中，该文件将被保存在 SD 卡的根目录下。