android 日志文件LogUtils实例

背景

这是好久之前在网上找的一个常用类，已经忘记原文链接了，但是觉得很好用一直都在用，可以将日志写到file里面也可以定位你是在哪个类哪一行打印的日志，保存到文件的路径就是android/data/你的包名/files/目录下，然后我们就可以愉快的找问题了

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 String			customTagPrefix	= "log";	// 自定义Tag的前缀，可以是作者名

	private static final boolean	isSaveLog		= true;		// 是否把保存日志到SD卡中

	private static String			cacheDirPath;

	private LogUtils() {

	}

	// 容许打印日志的类型，默认是true，设置为false则不打印
	public static boolean	allowD		= BuildConfig.DEBUG;
	public static boolean	allowE		= BuildConfig.DEBUG;
	public static boolean	allowI		= BuildConfig.DEBUG;
	public static boolean	allowV		= BuildConfig.DEBUG;
	public static boolean	allowW		= BuildConfig.DEBUG;
	public static boolean	allowWtf	= 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(); // 获取到类名
		callerClazzName = callerClazzName.substring(callerClazzName.lastIndexOf(".") + 1);
		tag = String.format(tag, callerClazzName, caller.getMethodName(), caller.getLineNumber()); // 替换
		tag = TextUtils.isEmpty(customTagPrefix) ? tag : customTagPrefix + ":" + tag;
		return tag;
	}

	/***
	 * 打印控制台显示不了那么长的日志问题
	 * 
	 * @param msg
	 */
	public static void logE(String msg) { // 信息太长,分段打印
		if (!allowE) return;
		StackTraceElement caller = getCallerStackTraceElement();
		String tag = generateTag(caller);
		// 因为String的length是字符数量不是字节数量所以为了防止中文字符过多，
		// 把4*1024的MAX字节打印长度改为2001字符数
		int max_str_length = 2001 - tag.length();
		// 大于4000时
		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);
	}

	/**
	 * 自定义的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 + "\r\n");
			} catch (Exception e) {
				e.printStackTrace();
			} finally {
				try {
					if (out != null) {
						out.close();
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	/**
	 * 根据文件路径 递归创建文件
	 * 
	 * @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("日志文件的路径是" + file1.getAbsolutePath());
			} 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 (cacheDirPath == null) cacheDirPath = App.getAppContext().getExternalFilesDir("log").getAbsolutePath();

		if (!TextUtils.isEmpty(cacheDirPath)) {
			return true;
		} else {
			return false;
		}
	}
}

补充知识：Android日志打印类LogUtils，能够定位到类名，方法名以及出现错误的行数并保存日志文件

在开发中，我们常常用打印log的方式来调试我们的应用。在Java中我们常常使用方法System.out.println()来在控制台打印日志，以便我们的调试。Android中有一个专门的类Log来实现在Android系统下日志的打印，更加方便我们定位程序出现问题的地方。　　

但是Android官方提供的Log类在实际项目使用中，也不是非常方便。当程序出现错误时，我们最希望的就是这个Log类能帮我们定位到是哪个类的哪个方法，甚至于是那一行出现了错误。这样就能给我们的调试带来很大的便利。　　

同时我们也应该想到为了应用程序的安全起见，在app正式上线之前，我们应该要把打印日志的功能关闭掉，以防别人通过Log来破解你的应用。生产模式的下打印Log，正式模式就把打印日志的功能关闭掉，要做到Log的灵活关闭与打开，也需要在原生的Log类上进行一些封装。　　

还有一种时候，当我们的程序出现问题崩溃了，我们希望能够收集到出现异常的原因进行分析，所以可以把Log日志保存到一个文件中，放在SD卡程序创建的目录下。也可以在用户联网的情况下，在程序的后台把出异常的Log日志文件上传到服务端，方便程序员进行分析，解决bug。　　

今天就给大家分享一个做项目中很实用的一个Log类LogUtils,这个类是从xUtils中提取出来，稍作修改的，有注释。　　

示例：

我们在MainActivity中调用一些LogUtils中的方法，注意看行数。　　 1

接着看看控制台打印的日志是不是像MainActivity调用的那样，Log中有这个类的名字和oncreate方法名，已及当前行数；　 2

看到上图中的Log日志是不是很方便定位程序中的问题了，出现异常也能快速的定位到。然后把下面的Log类型在程序的任何地方设置为false则不会打印日志，使用起来相当的方便。　

　// 容许打印日志的类型，默认是true，设置为false则不打印
 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;

代码贴在下面：

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，类似android.util.Log。 tag自动产生，格式:
 * customTagPrefix:className.methodName(Line:lineNumber),
 * customTagPrefix为空时只输出：className.methodName(Line:lineNumber)。
 */
public class LogUtils {

 public static String customTagPrefix = "finddreams"; // 自定义Tag的前缀，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卡中的根目录
 private static final String PATH_LOG_INFO = ROOT + "info/";

 private LogUtils() {
 }

 // 容许打印日志的类型，默认是true，设置为false则不打印
 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(); // 获取到类名
  callerClazzName = callerClazzName.substring(callerClazzName
    .lastIndexOf(".") + 1);
  tag = String.format(tag, callerClazzName, caller.getMethodName(),
    caller.getLineNumber()); // 替换
  tag = TextUtils.isEmpty(customTagPrefix) ? tag : customTagPrefix + ":"
    + tag;
  return tag;
 }

 /**
  * 自定义的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 + "\r\n");
   } catch (Exception e) {
    e.printStackTrace();
   } finally {
    try {
     if (out != null) {
      out.close();
     }
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
  }
 }

 /**
  * 根据文件路径 递归创建文件
  * 
  * @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;
  }
 }
}

以上这篇android 日志文件LogUtils实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持自学编程网。

编程技巧