背景

這是好久之前在網上找的一個常用類，已經忘記原文鏈接了，但是覺得很好用一直都在用，可以將日志寫到file里面也可以定位你是在哪個類哪一行打印的日志，保存到文件的路徑就是android/data/你的包名/files/目錄下，然后我們就可以愉快的找問題了

import android.text.TextUtils;import android.util.Log;import com.smartlink.suixing.App;import com.smartlink.suixing.BuildConfig;import java.io.BufferedWriter;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;import java.text.SimpleDateFormat;import java.util.Date;import java.util.Formatter;import java.util.Locale;public class LogUtils {public static StringcustomTagPrefix= 'log';// 自定義Tag的前綴，可以是作者名private static final booleanisSaveLog= true;// 是否把保存日志到SD卡中private static StringcacheDirPath;private LogUtils() {}// 容許打印日志的類型，默認是true，設置為false則不打印public static booleanallowD= BuildConfig.DEBUG;public static booleanallowE= BuildConfig.DEBUG;public static booleanallowI= BuildConfig.DEBUG;public static booleanallowV= BuildConfig.DEBUG;public static booleanallowW= BuildConfig.DEBUG;public static booleanallowWtf= BuildConfig.DEBUG;// public static boolean allowD = true;// public static boolean allowE = true;// public static boolean allowI = true;// public static boolean allowV = true;// public static boolean allowW = true;// public static boolean allowWtf = true;private static String generateTag(StackTraceElement caller) {String tag = '%s.%s(Line:%d)'; // 占位符String callerClazzName = caller.getClassName(); // 獲取到類名callerClazzName = callerClazzName.substring(callerClazzName.lastIndexOf('.') + 1);tag = String.format(tag, callerClazzName, caller.getMethodName(), caller.getLineNumber()); // 替換tag = TextUtils.isEmpty(customTagPrefix) ? tag : customTagPrefix + ':' + tag;return tag;}/*** * 打印控制臺顯示不了那么長的日志問題 * * @param msg */public static void logE(String msg) { // 信息太長,分段打印if (!allowE) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);// 因為String的length是字符數量不是字節數量所以為了防止中文字符過多，// 把4*1024的MAX字節打印長度改為2001字符數int max_str_length = 2001 - tag.length();// 大于4000時while (msg.length() > max_str_length) {// Log.e(tag, msg.substring(0, max_str_length));LogUtils.e(msg.substring(0, max_str_length));msg = msg.substring(max_str_length);}// 剩余部分// Log.e(tag, msg);LogUtils.e(msg);}/** * 自定義的logger */public static CustomLogger customLogger;public interface CustomLogger {void d(String tag, String content);void d(String tag, String content, Throwable tr);void e(String tag, String content);void e(String tag, String content, Throwable tr);void i(String tag, String content);void i(String tag, String content, Throwable tr);void v(String tag, String content);void v(String tag, String content, Throwable tr);void w(String tag, String content);void w(String tag, String content, Throwable tr);void w(String tag, Throwable tr);void wtf(String tag, String content);void wtf(String tag, String content, Throwable tr);void wtf(String tag, Throwable tr);}public static void d(String content) {if (!allowD) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.d(tag, content);} else {Log.d(tag, content);}}public static void d(String content, Throwable tr) {if (!allowD) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.d(tag, content, tr);} else {Log.d(tag, content, tr);}}public static void e(String content) {if (!allowE) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.e(tag, content);} else {Log.e(tag, content);}if (isSaveLog) {point(cacheDirPath, tag, content);}}public static void e(String content, Throwable tr) {if (!allowE) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.e(tag, content, tr);} else {Log.e(tag, content, tr);}if (isSaveLog) {point(cacheDirPath, tag, tr.getMessage());}}public static void e(Throwable tr) {if (!allowE) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.e(tag, '', tr);} else {Log.e(tag, '', tr);}if (isSaveLog) {point(cacheDirPath, tag, tr.getMessage());}}public static void i(String content) {if (!allowI) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.i(tag, content);} else {Log.i(tag, content);}}public static void i(String content, Throwable tr) {if (!allowI) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.i(tag, content, tr);} else {Log.i(tag, content, tr);}}public static void v(String content) {if (!allowV) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.v(tag, content);} else {Log.v(tag, content);}}public static void v(String content, Throwable tr) {if (!allowV) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.v(tag, content, tr);} else {Log.v(tag, content, tr);}}public static void w(String content) {if (!allowW) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.w(tag, content);} else {Log.w(tag, content);}}public static void w(String content, Throwable tr) {if (!allowW) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.w(tag, content, tr);} else {Log.w(tag, content, tr);}}public static void w(Throwable tr) {if (!allowW) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.w(tag, tr);} else {Log.w(tag, tr);}}public static void wtf(String content) {if (!allowWtf) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.wtf(tag, content);} else {Log.wtf(tag, content);}}public static void wtf(String content, Throwable tr) {if (!allowWtf) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.wtf(tag, content, tr);} else {Log.wtf(tag, content, tr);}}public static void wtf(Throwable tr) {if (!allowWtf) return;StackTraceElement caller = getCallerStackTraceElement();String tag = generateTag(caller);if (customLogger != null) {customLogger.wtf(tag, tr);} else {Log.wtf(tag, tr);}}private static StackTraceElement getCallerStackTraceElement() {return Thread.currentThread().getStackTrace()[4];}public static void point(String path, String tag, String msg) {if (isSDAva()) {path = cacheDirPath;Date date = new Date();SimpleDateFormat dateFormat = new SimpleDateFormat('', Locale.SIMPLIFIED_CHINESE);dateFormat.applyPattern('yyyy');path = path + dateFormat.format(date) + '/';dateFormat.applyPattern('MM');path += dateFormat.format(date) + '/';dateFormat.applyPattern('dd');path += dateFormat.format(date) + '.log';dateFormat.applyPattern('[yyyy-MM-dd HH:mm:ss]');String time = dateFormat.format(date);File file = new File(path);if (!file.exists()) createDipPath(path);BufferedWriter out = null;try {out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file, true)));out.write(time + ' ' + tag + ' ' + msg + 'rn');} catch (Exception e) {e.printStackTrace();} finally {try {if (out != null) {out.close();}} catch (IOException e) {e.printStackTrace();}}}}/** * 根據文件路徑 遞歸創建文件 * * @param file */public static void createDipPath(String file) {String parentFile = file.substring(0, file.lastIndexOf('/'));File file1 = new File(file);File parent = new File(parentFile);if (!file1.exists()) {parent.mkdirs();try {file1.createNewFile();LogUtils.e('日志文件的路徑是' + file1.getAbsolutePath());} catch (IOException e) {e.printStackTrace();}}}/** * A little trick to reuse a formatter in the same thread */private static class ReusableFormatter {private Formatterformatter;private StringBuilderbuilder;public ReusableFormatter() {builder = new StringBuilder();formatter = new Formatter(builder);}public String format(String msg, Object... args) {formatter.format(msg, args);String s = builder.toString();builder.setLength(0);return s;}}private static final ThreadLocal<ReusableFormatter> thread_local_formatter = new ThreadLocal<ReusableFormatter>() {protected ReusableFormatter initialValue() {return new ReusableFormatter();}};public static String format(String msg, Object... args) {ReusableFormatter formatter = thread_local_formatter.get();return formatter.format(msg, args);}public static boolean isSDAva() {if (cacheDirPath == null) cacheDirPath = App.getAppContext().getExternalFilesDir('log').getAbsolutePath();if (!TextUtils.isEmpty(cacheDirPath)) {return true;} else {return false;}}}

補充知識：Android日志打印類LogUtils，能夠定位到類名，方法名以及出現錯誤的行數并保存日志文件

在開發中，我們常常用打印log的方式來調試我們的應用。在Java中我們常常使用方法System.out.println()來在控制臺打印日志，以便我們的調試。Android中有一個專門的類Log來實現在Android系統下日志的打印，更加方便我們定位程序出現問題的地方。

但是Android官方提供的Log類在實際項目使用中，也不是非常方便。當程序出現錯誤時，我們最希望的就是這個Log類能幫我們定位到是哪個類的哪個方法，甚至于是那一行出現了錯誤。這樣就能給我們的調試帶來很大的便利。

同時我們也應該想到為了應用程序的安全起見，在app正式上線之前，我們應該要把打印日志的功能關閉掉，以防別人通過Log來破解你的應用。生產模式的下打印Log，正式模式就把打印日志的功能關閉掉，要做到Log的靈活關閉與打開，也需要在原生的Log類上進行一些封裝。

還有一種時候，當我們的程序出現問題崩潰了，我們希望能夠收集到出現異常的原因進行分析，所以可以把Log日志保存到一個文件中，放在SD卡程序創建的目錄下。也可以在用戶聯網的情況下，在程序的后臺把出異常的Log日志文件上傳到服務端，方便程序員進行分析，解決bug。

今天就給大家分享一個做項目中很實用的一個Log類LogUtils,這個類是從xUtils中提取出來，稍作修改的，有注釋。

示例：

我們在MainActivity中調用一些LogUtils中的方法，注意看行數。 1

接著看看控制臺打印的日志是不是像MainActivity調用的那樣，Log中有這個類的名字和oncreate方法名，已及當前行數；　 2

看到上圖中的Log日志是不是很方便定位程序中的問題了，出現異常也能快速的定位到。然后把下面的Log類型在程序的任何地方設置為false則不會打印日志，使用起來相當的方便。　

　// 容許打印日志的類型，默認是true，設置為false則不打印 public static boolean allowD = true; public static boolean allowE = true; public static boolean allowI = true; public static boolean allowV = true; public static boolean allowW = true; public static boolean allowWtf = true;

代碼貼在下面：

package com.finddreams.log;import java.io.BufferedWriter;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;import java.text.SimpleDateFormat;import java.util.Date;import java.util.Formatter;import java.util.Locale;import android.os.Environment;import android.text.TextUtils;import android.util.Log;/** * Log工具，類似android.util.Log。 tag自動產生，格式: * customTagPrefix:className.methodName(Line:lineNumber), * customTagPrefix為空時只輸出：className.methodName(Line:lineNumber)。 */public class LogUtils { public static String customTagPrefix = 'finddreams'; // 自定義Tag的前綴，可以是作者名 private static final boolean isSaveLog = false; // 是否把保存日志到SD卡中 public static final String ROOT = Environment.getExternalStorageDirectory() .getPath() + '/finddreams/'; // SD卡中的根目錄 private static final String PATH_LOG_INFO = ROOT + 'info/'; private LogUtils() { } // 容許打印日志的類型，默認是true，設置為false則不打印 public static boolean allowD = true; public static boolean allowE = true; public static boolean allowI = true; public static boolean allowV = true; public static boolean allowW = true; public static boolean allowWtf = true; private static String generateTag(StackTraceElement caller) { String tag = '%s.%s(Line:%d)'; // 占位符 String callerClazzName = caller.getClassName(); // 獲取到類名 callerClazzName = callerClazzName.substring(callerClazzName .lastIndexOf('.') + 1); tag = String.format(tag, callerClazzName, caller.getMethodName(), caller.getLineNumber()); // 替換 tag = TextUtils.isEmpty(customTagPrefix) ? tag : customTagPrefix + ':' + tag; return tag; } /** * 自定義的logger */ public static CustomLogger customLogger; public interface CustomLogger { void d(String tag, String content); void d(String tag, String content, Throwable tr); void e(String tag, String content); void e(String tag, String content, Throwable tr); void i(String tag, String content); void i(String tag, String content, Throwable tr); void v(String tag, String content); void v(String tag, String content, Throwable tr); void w(String tag, String content); void w(String tag, String content, Throwable tr); void w(String tag, Throwable tr); void wtf(String tag, String content); void wtf(String tag, String content, Throwable tr); void wtf(String tag, Throwable tr); } public static void d(String content) { if (!allowD) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.d(tag, content); } else { Log.d(tag, content); } } public static void d(String content, Throwable tr) { if (!allowD) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.d(tag, content, tr); } else { Log.d(tag, content, tr); } } public static void e(String content) { if (!allowE) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.e(tag, content); } else { Log.e(tag, content); } if (isSaveLog) { point(PATH_LOG_INFO, tag, content); } } public static void e(String content, Throwable tr) { if (!allowE) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.e(tag, content, tr); } else { Log.e(tag, content, tr); } if (isSaveLog) { point(PATH_LOG_INFO, tag, tr.getMessage()); } } public static void i(String content) { if (!allowI) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.i(tag, content); } else { Log.i(tag, content); } } public static void i(String content, Throwable tr) { if (!allowI) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.i(tag, content, tr); } else { Log.i(tag, content, tr); } } public static void v(String content) { if (!allowV) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.v(tag, content); } else { Log.v(tag, content); } } public static void v(String content, Throwable tr) { if (!allowV) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.v(tag, content, tr); } else { Log.v(tag, content, tr); } } public static void w(String content) { if (!allowW) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.w(tag, content); } else { Log.w(tag, content); } } public static void w(String content, Throwable tr) { if (!allowW) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.w(tag, content, tr); } else { Log.w(tag, content, tr); } } public static void w(Throwable tr) { if (!allowW) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.w(tag, tr); } else { Log.w(tag, tr); } } public static void wtf(String content) { if (!allowWtf) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.wtf(tag, content); } else { Log.wtf(tag, content); } } public static void wtf(String content, Throwable tr) { if (!allowWtf) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.wtf(tag, content, tr); } else { Log.wtf(tag, content, tr); } } public static void wtf(Throwable tr) { if (!allowWtf) return; StackTraceElement caller = getCallerStackTraceElement(); String tag = generateTag(caller); if (customLogger != null) { customLogger.wtf(tag, tr); } else { Log.wtf(tag, tr); } } private static StackTraceElement getCallerStackTraceElement() { return Thread.currentThread().getStackTrace()[4]; } public static void point(String path, String tag, String msg) { if (isSDAva()) { Date date = new Date(); SimpleDateFormat dateFormat = new SimpleDateFormat('', Locale.SIMPLIFIED_CHINESE); dateFormat.applyPattern('yyyy'); path = path + dateFormat.format(date) + '/'; dateFormat.applyPattern('MM'); path += dateFormat.format(date) + '/'; dateFormat.applyPattern('dd'); path += dateFormat.format(date) + '.log'; dateFormat.applyPattern('[yyyy-MM-dd HH:mm:ss]'); String time = dateFormat.format(date); File file = new File(path); if (!file.exists()) createDipPath(path); BufferedWriter out = null; try { out = new BufferedWriter(new OutputStreamWriter( new FileOutputStream(file, true))); out.write(time + ' ' + tag + ' ' + msg + 'rn'); } catch (Exception e) { e.printStackTrace(); } finally { try { if (out != null) { out.close(); } } catch (IOException e) { e.printStackTrace(); } } } } /** * 根據文件路徑 遞歸創建文件 * * @param file */ public static void createDipPath(String file) { String parentFile = file.substring(0, file.lastIndexOf('/')); File file1 = new File(file); File parent = new File(parentFile); if (!file1.exists()) { parent.mkdirs(); try { file1.createNewFile(); } catch (IOException e) { e.printStackTrace(); } } } /** * A little trick to reuse a formatter in the same thread */ private static class ReusableFormatter { private Formatter formatter; private StringBuilder builder; public ReusableFormatter() { builder = new StringBuilder(); formatter = new Formatter(builder); } public String format(String msg, Object... args) { formatter.format(msg, args); String s = builder.toString(); builder.setLength(0); return s; } } private static final ThreadLocal<ReusableFormatter> thread_local_formatter = new ThreadLocal<ReusableFormatter>() { protected ReusableFormatter initialValue() { return new ReusableFormatter(); } }; public static String format(String msg, Object... args) { ReusableFormatter formatter = thread_local_formatter.get(); return formatter.format(msg, args); } public static boolean isSDAva() { if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED) || Environment.getExternalStorageDirectory().exists()) { return true; } else { return false; } }}

以上這篇android 日志文件LogUtils實例就是小編分享給大家的全部內容了，希望能給大家一個參考，也希望大家多多支持好吧啦網。