本文介绍了如何利用logcat的AndroidRuntime异常信息，并通过自定义的LogCatReader类将错误日志写入Android设备的SD卡上。作者遇到的问题是，adb logcat命令在Windows上有效，但在Android设备上无法正常工作。他们希望只记录导致应用程序执行ANR的AndroidRuntime错误，而不是依赖于Log.d, Log.e等常规日志输出。"
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当我浏览到Android的SDK文件夹下我platform-tools文件夹，我能够执行一些操作，所以我可以从LogCat充分利用logcat的AndroidRuntime异常和写入文件
得到输出，如该命令实例
adb logcat AndroidRuntime:E *:E
这将列出带有标记AndroidRuntime的消息。为了测试这个我在onResume方法去除super.onResume()，输出会是这个样子在我的命令行窗口，在Win7：
到目前为止好，这是我想要的信息的类型登录。我在我的应用程序的方法，看起来像这样：
public class LogCatReader {
// constants
private static final String CR = "\r\n";
private static final String END_OF_DATE_TIME = "): ";
private static final int DEFAULT_SEARCH_START_INDEX = 0;
// member variables
private StringBuilder mLog;
private LogThread mLogThread = null;
private String mLastLogReadToken = "";
private String mLogCommand = "";
private String mProcess = "";
private int mStringCapacity;
private File mFileTarget = null;
// constructor
public LogCatReader(String command, int capacity, String process) {
mLogCommand = command;
mStringCapacity = capacity;
mProcess = process;
}
// returns complete logcat buffer
// note: takes about 1.5sec to finish
synchronized public StringBuilder getLogComplete() {
try {
// capacity should be about 25% bigger than buffer size since the
// buffer is compressed
mLog = new StringBuilder(mStringCapacity);
// command to capture log
Process process = Runtime.getRuntime().exec(mLogCommand);
BufferedReader bufferedReader = new BufferedReader(
new InputStreamReader(process.getInputStream()));
String line;
while ((line = bufferedReader.readLine()) != null) {
// append() is costly if capacity needs to be increased, be sure
// to reserve enough in the first place
mLog.append(line + CR);
}
} catch (IOException e) {
}
return mLog;
}
public String getLogUpdatesOnly() {
String strReturn = "";
StringBuilder sbLog = getLogComplete();
try {
int iStartindex = DEFAULT_SEARCH_START_INDEX;
// if there exists a token from a previous search then use that
if (mLastLogReadToken.length() > 0) {
iStartindex = sbLog.indexOf(mLastLogReadToken);
// if string not found then start at beginning
if (iStartindex == -1) {
// start search at beginning of log
iStartindex = DEFAULT_SEARCH_START_INDEX;
}
}
int iEndindex = sbLog.length();
// if token is found then move index to the next line
if (iStartindex > DEFAULT_SEARCH_START_INDEX) {
iStartindex = sbLog.indexOf(CR, iStartindex);
if (iStartindex != -1) {
iStartindex += CR.length();
} else {
// return an empty string
iStartindex = iEndindex;
}
}
// grab the data between the start and end indices
strReturn = sbLog.substring(iStartindex, iEndindex);
// grab date/time token for next search
iStartindex = sbLog.lastIndexOf(END_OF_DATE_TIME);
if (iStartindex != -1) {
iEndindex = iStartindex;
iStartindex = sbLog.lastIndexOf(CR, iEndindex);
iStartindex += CR.length();
if (iStartindex == -1) {
// read from beginning
iStartindex = 0;
}
mLastLogReadToken = sbLog.substring(iStartindex, iEndindex);
}
} catch (Exception e) {
strReturn = "";
}
return strReturn;
}
public void startPeriodicLogCatReader(int timePeriod, String logfilename) {
if (mLogThread == null) {
mLogThread = new LogThread(timePeriod, logfilename);
mLogThread.start();
}
}
public void stopPeriodicLogCatReader() {
if (mLogThread != null) {
mLogThread.interrupt();
mLogThread = null;
}
}
private class LogThread extends Thread {
private boolean mInterrupted;
private int mTimePeriod;// in seconds
private String mLogref;
private BufferedWriter mBuffWriter = null;
public boolean mPauseLogCollection = false;
// constructor: logfilename is optional - pass null to not use
public LogThread(int timePeriod, String logfilename) {
mTimePeriod = timePeriod;
if (logfilename != null) {
File fLogFolder = new File(
Environment.getExternalStorageDirectory() + "/SteriaFITMobile/CoreLogging");
if (fLogFolder.exists() == false) {
if (fLogFolder.mkdirs() == false) {
Log.e("LogCatReader",
"Could not create "
+ fLogFolder.getAbsolutePath());
}
}
mFileTarget = new File(
Environment.getExternalStorageDirectory() + "/SteriaFITMobile/CoreLogging",
logfilename);
if (mFileTarget.exists() == false) {
try {
// file doesn't yet exist - create a fresh one !
mFileTarget.createNewFile();
} catch (IOException e) {
e.printStackTrace();
mFileTarget = null;
}
}
}
}
@Override
public void interrupt() {
mInterrupted = true;
super.interrupt();
}
@Override
public void run() {
super.run();
// initialization
mInterrupted = false;
// set up storage
if (mFileTarget != null) {
try {
mBuffWriter = new BufferedWriter(new FileWriter(
mFileTarget, true), 10240);
} catch (IOException e) {
e.printStackTrace();
}
}
while ((mInterrupted == false) && (mBuffWriter != null)) {
if (mPauseLogCollection == false) {
// read log updates
mLogref = mProcess + ": " + getLogUpdatesOnly();
// save log updates to file
try {
mBuffWriter.append(mLogref);
mBuffWriter.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
if (!mInterrupted) {
try {
sleep(mTimePeriod * 1000);
} catch (InterruptedException e) {
}
}
}
if (mBuffWriter != null) {
try {
mBuffWriter.close();
mBuffWriter = null;
} catch (IOException e) {
e.printStackTrace();
}
}
}
}// end of inner class
}// end of outer class
这个方法有三个参数，命令，能力和processName(ActivityName)。
此方法只是执行command parameter到Runtime.getRuntime().exec方法调用，并将其保存到SD卡上的.txt文件。我的问题是，命令
adb logcat AndroidRuntime:E *:E
工作在Windows中，但不是在Android手机上。
我想实现的是将此类AndroidRuntime错误注销到SD卡上的日志文件。我只对导致我的应用程序执行ANR的AndroidRuntime错误感兴趣。
有些人可能认为我只是创建自己的Log.d, Log.e, Log.v并将它们写入一个文件，但我不希望出现这种情况..
有人可以帮我吗？
+0
那么解释你为什么不直接使用自定义标记输出logcat的错误？似乎不是试图重新创建轮子，而应该使用现有的功能。 –
2013-04-26 13:20:33
+0
在Android手机上，您只需使用'logcat'命令。 –
2013-04-26 13:22:59
+0
@Booger我不确定是否有任何其他方式注销AndroidRuntime异常，而不在'Try/Catch'中执行。在我的例子中，我应该如何记录我忘记'super.onPause'？ –
2013-04-26 13:23:57
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