Android進階：一、日誌列印和儲存策略

安卓開發 · 發表 2019-03-19 16:27:31

摘要：前言：專案開始沒有做好日誌統計工作，每次有問題後端都得找前端對接，嚴重影響工作效率。最近特地在專案中加上日誌儲存策略，在此分享，供需要的人學習。更詳細的日誌資訊既然決定自定義一個log，那我們就可以讓它顯示更多的資訊，如執行緒資訊：threadId，threa...

前言：

專案開始沒有做好日誌統計工作，每次有問題後端都得找前端對接，嚴重影響工作效率。最近特地在專案中加上日誌儲存策略，在此分享，供需要的人學習。

更詳細的日誌資訊

既然決定自定義一個log，那我們就可以讓它顯示更多的資訊，如執行緒資訊：threadId，threadName等：

private String getFunctionName() {
StackTraceElement[] sts = Thread.currentThread().getStackTrace();
if (sts == null) {
return null;
}

for (StackTraceElement st : sts) {
if (st.isNativeMethod()) {
continue;
}
if (st.getClassName().equals(Thread.class.getName())) {
continue;
}
if (st.getClassName().equals(this.getClass().getName())) {
continue;
}

Thread t = Thread.currentThread();
return "[T(id:" + t.getId() +
", name:" + t.getName() +
", priority:" + t.getPriority() +
", groupName:" + t.getThreadGroup().getName() +
"): " + st.getFileName() + ":"
+ st.getLineNumber() + " " + st.getMethodName() + " ]";
}
return "";
}

StackTrace(堆疊軌跡)存放的就是方法呼叫棧的資訊，我們從中獲取方法執行的執行緒相關的資訊，以及執行的方法名稱等。這些資訊能幫助我們更好的查詢問題之所在。

private void logPrint(int logLevel, Object msg) {
if (isDebug) {
String name = getFunctionName();
customTag = TextUtils.isEmpty(customTag) ? defaultTag : customTag;
Log.println(logLevel, customTag, name + " - " + msg);
}
}

使用Log.println方法列印相關資訊即可。

日誌儲存策略

後端的人在測試的時候會遇到BUG，有時候不知道到底是前端出了問題還是後端的問題，為了更好更快速的定位，後端應該知道前端的日誌儲存在哪裡。這就需要我們制定一個日誌儲存策略。（即使要上傳日誌，也應該先儲存成檔案再上傳檔案，不然每一條日誌呼叫一次介面，介面的壓力會很大，很不合理）

由於儲存日誌的過程是個耗時過程，我們需要開啟執行緒去儲存。但是日誌產生的頻率可能很高，又不能採用一般的執行緒去處理，太多的執行緒也會損耗效能。所以我們應該考慮佇列的形式儲存日誌，然後一條一條的去儲存。

public void initSaveStrategy(Context context) {
if (saveLogStrategy != null || !isDebug) {
return;
}
final int MAX_BYTES = 1024 * 1024;
String diskPath = Environment.getExternalStorageDirectory().getAbsolutePath();
File cacheFile = context.getCacheDir();
if (cacheFile != null) {
diskPath = cacheFile.getAbsolutePath();
}
String folder = diskPath + File.separatorChar + "log";
HandlerThread ht = new HandlerThread("SohuLiveLogger." + folder);
ht.start();
Handler handler = new SaveLogStrategy.WriteHandler(ht.getLooper(), folder, MAX_BYTES);
saveLogStrategy = new SaveLogStrategy(handler);
}

public static class WriteHandler extends Handler {

private final String folder;
private final int maxFileSize;

WriteHandler(@NonNull Looper looper, @NonNull String folder, int maxFileSize) {
super(checkNotNull(looper));
this.folder = checkNotNull(folder);
this.maxFileSize = maxFileSize;
}

@Override
public void handleMessage(@NonNull Message msg) {
String content = (String) msg.obj;
FileWriter fileWriter = null;
File logFile = getLogFile(folder, "logs");
try {
fileWriter = new FileWriter(logFile, true);
writeLog(fileWriter, content);
fileWriter.flush();
fileWriter.close();
} catch (IOException e) {
if (fileWriter != null) {
try {
fileWriter.flush();
fileWriter.close();
} catch (IOException e1) {

}
}
}
}

我們使用HandlerThread來處理這個任務。HandlerThread是一個可以使用handler的Thread。當我們把訊息儲存到訊息佇列中去之後會線上程中去處理，又能保證不會產生很多執行緒。其實這裡也可以使用instentservice實現，這個服務適合量大而不太耗時的任務。

最後在一個方法中統一列印和儲存即可：

private void logPrint(int logLevel, Object msg) {
if (isDebug) {
String name = getFunctionName();
if (saveLogStrategy != null) {
saveLogStrategy.log(Log.ERROR, customTag, name + " - " + msg);
}
Log.println(logLevel, customTag, name + " - " + msg);
}
}

自定義的log策略還是比較簡單，主要就是這個思想：列印日誌資訊詳細，儲存要採用佇列的形式。一下是全部程式碼：

public class Logger {
public final static String tag = "";
private static SaveLogStrategy saveLogStrategy;
private final static boolean logFlag = true;
private static Logger logger;
private int logLevel = Log.VERBOSE;
private static boolean isDebug = BuildConfig.DEBUG;
private String customTag = null;

private Logger(String customTag) {
this.customTag = customTag;
}

public void initSaveStrategy(Context context) {
if (saveLogStrategy != null || !isDebug) {
return;
}
final int MAX_BYTES = 1024 * 1024;
String diskPath = Environment.getExternalStorageDirectory().getAbsolutePath();
File cacheFile = context.getCacheDir();
if (cacheFile != null) {
diskPath = cacheFile.getAbsolutePath();
}
String folder = diskPath + File.separatorChar + "log";
HandlerThread ht = new HandlerThread("Logger." + folder);
ht.start();
Handler handler = new SaveLogStrategy.WriteHandler(ht.getLooper(), folder, MAX_BYTES);
saveLogStrategy = new SaveLogStrategy(handler);
}

public static Logger getLogger(String tag) {
if (logger == null) {
logger = new Logger(tag);
}
return logger;
}

public static Logger getLogger() {
if (logger == null) {
logger = new Logger(tag);
}
return logger;
}

/**
* Verbose(2) 級別日誌
*
* @param str String
*/
public void v(Object str) {
logLevel = Log.VERBOSE;
logPrint(logLevel, str);
}

/**
* Debug(3) 級別日誌
*
* @param str String
*/
public void d(Object str) {
logLevel = Log.DEBUG;
logPrint(logLevel, str);
}

/**
* Info(4) 級別日誌
*
* @param str String
*/
public void i(Object str) {
logLevel = Log.INFO;
logPrint(logLevel, str);
}

/**
* Warn(5) 級別日誌
*
* @param str String
*/
public void w(Object str) {
logLevel = Log.WARN;
logPrint(logLevel, str);
}

/**
* Error(6) 級別日誌
*
* @param str String
*/
public void e(Object str) {
logLevel = Log.ERROR;
logPrint(logLevel, str);
}

private void logPrint(int logLevel, Object msg) {
if (isDebug) {
String name = getFunctionName();
if (saveLogStrategy != null) {
saveLogStrategy.log(Log.ERROR, customTag, name + " - " + msg);
}
Log.println(logLevel, customTag, name + " - " + msg);
}
}

/**
* 獲取當前方法名
*
* @return 方法名
*/
private String getFunctionName() {
StackTraceElement[] sts = Thread.currentThread().getStackTrace();
if (sts == null) {
return null;
}

for (StackTraceElement st : sts) {
if (st.isNativeMethod()) {
continue;
}
if (st.getClassName().equals(Thread.class.getName())) {
continue;
}
if (st.getClassName().equals(this.getClass().getName())) {
continue;
}

Thread t = Thread.currentThread();
return "[Thread(id:" + t.getId() +
", name:" + t.getName() +
", priority:" + t.getPriority() +
", groupName:" + t.getThreadGroup().getName() +
"): " + st.getFileName() + ":"
+ st.getLineNumber() + " " + st.getMethodName() + " ]";
}
return "";
}
}

public class SaveLogStrategy {

@NonNull
private final Handler handler;

public SaveLogStrategy(@NonNull Handler handler) {
this.handler = checkNotNull(handler);
}

public void log(int level, @Nullable String tag, @NonNull String message) {
checkNotNull(message);
handler.sendMessage(handler.obtainMessage(level, message));
}

static class WriteHandler extends Handler {

private final String folder;
private final int maxFileSize;

WriteHandler(@NonNull Looper looper, @NonNull String folder, int maxFileSize) {
super(checkNotNull(looper));
this.folder = checkNotNull(folder);
this.maxFileSize = maxFileSize;
}

@SuppressWarnings("checkstyle:emptyblock")
@Override
public void handleMessage(@NonNull Message msg) {
String content = (String) msg.obj;
FileWriter fileWriter = null;
File logFile = getLogFile(folder, "logs");

try {
fileWriter = new FileWriter(logFile, true);

writeLog(fileWriter, content);

fileWriter.flush();
fileWriter.close();
} catch (IOException e) {
if (fileWriter != null) {
try {
fileWriter.flush();
fileWriter.close();
} catch (IOException e1) {

}
}
}
}

private void writeLog(@NonNull FileWriter fileWriter, @NonNull String content) throws IOException {
checkNotNull(fileWriter);
checkNotNull(content);
fileWriter.append("\n").append(content);
}

private File getLogFile(@NonNull String folderName, @NonNull String fileName) {
checkNotNull(folderName);
checkNotNull(fileName);

File folder = new File(folderName);
if (!folder.exists()) {
if (!folder.mkdirs()) {
Log.println(Log.ERROR, "saveLog", "檔案未建立成功，可能是讀寫許可權沒給");
}
}

int newFileCount = 0;
File newFile;
File existingFile = null;

newFile = new File(folder, String.format("%s_%s.txt", fileName, newFileCount));
while (newFile.exists()) {
existingFile = newFile;
newFileCount++;
newFile = new File(folder, String.format("%s_%s.txt", fileName, newFileCount));
}

if (existingFile != null) {
if (existingFile.length() >= maxFileSize) {
return newFile;
}
return existingFile;
}

return newFile;
}
}
}

以上就是全部內容，希望對大家有所幫助

Android進階：一、日誌列印和儲存策略

前言：

更詳細的日誌資訊

日誌儲存策略

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