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亿速云。
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