在应用程序中以编程方式读取logcat

Question

我想阅读并回应我的应用程序中的logcat日志.

我找到了以下代码:

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) {
    log.append(line);
  }
  TextView tv = (TextView)findViewById(R.id.textView1);
  tv.setText(log.toString());
  } 
catch (IOException e) {}

此代码确实返回在应用程序启动之前所做的logcat日志 -

但是有可能连续监听甚至新的logcat日志吗？

Answer 1

只需删除上面代码中的"-d"标志,即可继续阅读日志.

"-d"标志指示logcat显示日志内容并退出.如果删除该标志,logcat将不会终止并继续发送添加到其中的任何新行.

请记住,如果设计不正确,可能会阻止您的应用程序.

祝好运.

Answer 2

随着协同程序和官方的生命周期livedata-KTX和生命周期-视图模型- KTX库，它的简单这样的：

class LogCatViewModel : ViewModel() {
    fun logCatOutput() = liveData(viewModelScope.coroutineContext + Dispatchers.IO) {
        Runtime.getRuntime().exec("logcat -c")
        Runtime.getRuntime().exec("logcat")
                .inputStream
                .bufferedReader()
                .useLines { lines -> lines.forEach { line -> emit(line) }
        }
    }
}

用法

val logCatViewModel by viewModels<LogCatViewModel>()

logCatViewModel.logCatOutput().observe(this, Observer{ logMessage ->
    logMessageTextView.append("$logMessage\n")
})

Answer 3

您可以使用此方法清除您的logcat,我将其用于在将logcat写入文件后清除,以避免重复的行:

public void clearLog(){
     try {
         Process process = new ProcessBuilder()
         .command("logcat", "-c")
         .redirectErrorStream(true)
         .start();
    } catch (IOException e) {
    }
}

Answer 4

根据 @user1185087 的回答，没有 ViewModel 的简单解决方案可能是：

在 IO 线程上启动作业：

// Custom scope for collecting logs on IO threads.
val scope = CoroutineScope(Job() + Dispatchers.IO)

val job = scope.launch {
    Runtime.getRuntime().exec("logcat -c") // Clear logs
    Runtime.getRuntime().exec("logcat") // Start to capture new logs
        .inputStream 
        .bufferedReader()
        .useLines { lines ->
            // Note that this forEach loop is an infinite loop until this job is cancelled.
            lines.forEach { newLine ->
                // Check whether this job is cancelled, since a coroutine must
                // cooperate to be cancellable.
                ensureActive()  
                // TODO: Write newLine into a file or buffer or anywhere appropriate              
            }
        }
}

从主线程取消作业：

MainScope().launch {
    // Cancel the job and wait for its completion on main thread.
    job.cancelAndJoin()
    job = null // May be necessary
    // TODO: Anything else you may want to clean up
}

如果您想在后台线程上连续收集应用程序的新日志，此解决方案应该足够了。

Answer 5

这是一个快速组合/插入，可用于捕获所有当前或所有新的（自上次请求以来）日志项。

您应该修改/扩展它，因为您可能想要返回连续流而不是 LogCapture。

Android LogCat“手册”：https://developer.android.com/studio/command-line/logcat.html

import android.util.Log;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.Stack;

/**
* Created by triston on 6/30/17.
*/

public class Logger {

  // http://www.java2s.com/Tutorial/Java/0040__Data-Type/SimpleDateFormat.htm
  private static final String ANDROID_LOG_TIME_FORMAT = "MM-dd kk:mm:ss.SSS";
  private static SimpleDateFormat logCatDate = new SimpleDateFormat(ANDROID_LOG_TIME_FORMAT);

  public static String lineEnding = "\n";
  private final String logKey;

  private static List<String> logKeys = new ArrayList<String>();

  Logger(String tag) {
    logKey = tag;
    if (! logKeys.contains(tag)) logKeys.add(logKey);
  }

  public static class LogCapture {
    private String lastLogTime = null;
    public final String buffer;
    public final List<String> log, keys;
    LogCapture(String oLogBuffer, List<String>oLogKeys) {
      this.buffer = oLogBuffer;
      this.keys = oLogKeys;
      this.log = new ArrayList<>();
    }
    private void close() {
      if (isEmpty()) return;
      String[] out = log.get(log.size() - 1).split(" ");
      lastLogTime = (out[0]+" "+out[1]);
    }
    private boolean isEmpty() {
      return log.size() == 0;
    }
    public LogCapture getNextCapture() {
      LogCapture capture = getLogCat(buffer, lastLogTime, keys);
      if (capture == null || capture.isEmpty()) return null;
      return capture;
    }
    public String toString() {
      StringBuilder output = new StringBuilder();
      for (String data : log) {
        output.append(data+lineEnding);
      }
      return output.toString();
    }
  }

  /**
   * Get a list of the known log keys
   * @return copy only
   */
  public static List<String> getLogKeys() {
    return logKeys.subList(0, logKeys.size() - 1);
  }

  /**
   * Platform: Android
   * Get the logcat output in time format from a buffer for this set of static logKeys.
   * @param oLogBuffer logcat buffer ring
   * @return A log capture which can be used to make further captures.
   */
  public static LogCapture getLogCat(String oLogBuffer) { return getLogCat(oLogBuffer, null, getLogKeys()); }

  /**
   * Platform: Android
   * Get the logcat output in time format from a buffer for a set of log-keys; since a specified time.
   * @param oLogBuffer logcat buffer ring
   * @param oLogTime time at which to start capturing log data, or null for all data
   * @param oLogKeys logcat tags to capture
   * @return A log capture; which can be used to make further captures.
   */
  public static LogCapture getLogCat(String oLogBuffer, String oLogTime, List<String> oLogKeys) {
    try {

      List<String>sCommand = new ArrayList<String>();
      sCommand.add("logcat");
      sCommand.add("-bmain");
      sCommand.add("-vtime");
      sCommand.add("-s");
      sCommand.add("-d");

      sCommand.add("-T"+oLogTime);

      for (String item : oLogKeys) sCommand.add(item+":V"); // log level: ALL
      sCommand.add("*:S"); // ignore logs which are not selected

      Process process = new ProcessBuilder().command(sCommand).start();

      BufferedReader bufferedReader = new BufferedReader(
        new InputStreamReader(process.getInputStream()));

      LogCapture mLogCapture = new LogCapture(oLogBuffer, oLogKeys);
      String line = "";

      long lLogTime = logCatDate.parse(oLogTime).getTime();
      if (lLogTime > 0) {
        // Synchronize with "NO YEAR CLOCK" @ unix epoch-year: 1970
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date(oLogTime));
        calendar.set(Calendar.YEAR, 1970);
        Date calDate = calendar.getTime();
        lLogTime = calDate.getTime();
      }

      while ((line = bufferedReader.readLine()) != null) {
        long when = logCatDate.parse(line).getTime();
        if (when > lLogTime) {
          mLogCapture.log.add(line);
          break; // stop checking for date matching
        }
      }

      // continue collecting
      while ((line = bufferedReader.readLine()) != null) mLogCapture.log.add(line);

      mLogCapture.close();
      return mLogCapture;
    } catch (Exception e) {
      // since this is a log reader, there is nowhere to go and nothing useful to do
      return null;
    }
  }

  /**
   * "Error"
   * @param e
   */
  public void failure(Exception e) {
    Log.e(logKey, Log.getStackTraceString(e));
  }

  /**
   * "Error"
   * @param message
   * @param e
   */
  public void failure(String message, Exception e) {
    Log.e(logKey, message, e);
  }

  public void warning(String message) {
    Log.w(logKey, message);
  }

  public void warning(String message, Exception e) {
    Log.w(logKey, message, e);
  }

  /**
   * "Information"
   * @param message
   */
  public void message(String message) {
    Log.i(logKey, message);
  }

  /**
   * "Debug"
   * @param message a Message
   */
  public void examination(String message) {
    Log.d(logKey, message);
  }

  /**
   * "Debug"
   * @param message a Message
   * @param e An failure
   */
  public void examination(String message, Exception e) {
    Log.d(logKey, message, e);
  }

}

在执行活动日志记录的项目中：

Logger log = new Logger("SuperLog");
// perform logging methods

当您想捕获通过“Logger”记录的所有内容时

LogCapture capture = Logger.getLogCat("main");

当您饿了并且想吃更多原木时

LogCapture nextCapture = capture.getNextCapture();

您可以将捕获作为字符串获取

String captureString = capture.toString();

或者您可以使用以下命令获取捕获的日志项

String logItem = capture.log.get(itemNumber);

没有确切的静态方法来捕获外部日志键，但仍然有一种方法

LogCapture foreignCapture = Logger.getLogCat("main", null, foreignCaptureKeyList);

使用上述方法还可以让您调用Logger.this.nextCapture外国捕获。