如何在 Android 的 TextView 中打印完整的 logcat 历史记录？

Question

我正在使用 logcat 在我的 Android 应用程序中记录消息，我希望能够访问这些消息并将它们显示在 DialogFragment 的 TextView 中。消息列表非常不一致，每次打开和关闭对话框时都会发生变化。它会显示一次完整的历史记录，然后在下一次擦除时，有时会显示更多消息。每次打开对话框时，我可以做些什么来显示所有消息（用于运行）？我是在错误的时间运行该过程还是什么？或者缓冲区应该在其他地方处理吗？谢谢。

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.action_view_logs:
            // View Logs MenuItem tapped
            if (logsDialogFragment == null) {
                logsDialogFragment = new LogsDialogFragment();
            }
            logsDialogFragment.show(getFragmentManager(), "dialog");
            return true;
        case R.id.action_exit:
            // Exit MenuItem tapped
            finish();
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

---

public class LogsDialogFragment extends DialogFragment {

@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    Log.i(WifiDirectHandler.LOG_TAG, "Viewing Logs");
    AlertDialog.Builder dialogBuilder =  new  AlertDialog.Builder(getActivity())
        .setTitle(getString(R.string.title_logs))
        .setNegativeButton(getString(R.string.action_close),
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int whichButton) {
                    dialog.dismiss();
                }
            }
        );

    LayoutInflater i = getActivity().getLayoutInflater();
    View rootView = i.inflate(R.layout.fragment_logs_dialog, null);

    TextView logTextView = (TextView) rootView.findViewById(R.id.logTextView);
    logTextView.setMovementMethod(new ScrollingMovementMethod());

    try {
        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) {
            if (line.contains(WifiDirectHandler.LOG_TAG)){
                // Removes log tag and PID from the log line
                log.append(line.substring(line.indexOf(": ") + 2)).append("\n");
            }
        }
        logTextView.setText(log.toString());
    } catch (IOException e) {
    }

    dialogBuilder.setView(rootView);
    return dialogBuilder.create();
}
}

Answer 1

消息的 logcat 缓冲区不是很大，所以旧消息只会从 logcat 中删除，如果您需要完整的日志 - 将 logcat 消息保存到 sdcard 上的文件，然后从中读取信息。此方法会将所有当前消息保存到文件中：

public static void saveLogcatToFile(Context context) {
        String fileName = "yourlogname.log";
        File outputFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath() +
                "/YourAppName", fileName);
        try {
            @SuppressWarnings("unused")
            Process process = Runtime.getRuntime().exec("logcat -f "+outputFile.getAbsolutePath());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

上面的代码只是某个时间点的日志快照。如果您想连续写入日志，请使用带有 FileLogger 的 Java 日志记录并写入。

Answer 2

Please add permission in manifest for logcat <uses-permission android:name="android.permission.READ_LOGS" />

Answer 3

我最终将历史记录保存到一个成员变量中，并且每次打开对话框时只附加新的日志行。

public class LogsDialogFragment extends DialogFragment {

    private StringBuilder log = new StringBuilder();

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        // Sets the Layout for the UI
        LayoutInflater i = getActivity().getLayoutInflater();
        View rootView = i.inflate(R.layout.fragment_logs_dialog, null);

        TextView logTextView = (TextView) rootView.findViewById(R.id.logTextView);
        logTextView.setMovementMethod(new ScrollingMovementMethod());

        try {
            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) {
                if (line.contains(WifiDirectHandler.LOG_TAG)){
                    // Removes log tag and PID from the log line
                    log.append(line.substring(line.indexOf(": ") + 2)).append("\n");
                }
            }

            this.log.append(log.toString().replace(this.log.toString(), ""));
            logTextView.setText(this.log.toString());
        } catch (IOException e) {
            Log.e("wifiDirectHandler", "Failure reading logcat");
        }

        // Creates and returns the AlertDialog for the logs
        AlertDialog.Builder dialogBuilder =  new  AlertDialog.Builder(getActivity())
            .setTitle(getString(R.string.title_logs))
            .setNegativeButton(getString(R.string.action_close),
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int whichButton) {
                        dialog.dismiss();
                    }
                }
            ).setView(rootView);
        return dialogBuilder.create();
    }
}