先捡简单的捏一捏
呵呵
工具类一般都具有通用性，以及简单的特点，所以选择工具类作为切入点，好像并不能切入主题，不过可以打扫一下周边的障碍，同时熟悉一下套路。
该类为静态工具类，方法都是静态方法，构造函数为private，类声明为final
这些我们都可以学习的，以后我们自己写工具类的时候也要参考。
源码：
/** * "Less-word" analog of Android {@link android.util.Log logger} * * @author Sergey Tarasevich (nostra13[at]gmail[dot]com) * @since 1.6.4 */ public final class L { private static final String LOG_FORMAT = "%1$s\n%2$s"; private static volatile boolean writeDebugLogs = false;//默认关闭Debug日志 private static volatile boolean writeLogs = true;//默认打开普通日志 private L() { } /** * Enables logger (if {@link #disableLogging()} was called before) * * @deprecated Use {@link #writeLogs(boolean) writeLogs(true)} instead */ @Deprecated public static void enableLogging() { writeLogs(true); } /** * Disables logger, no logs will be passed to LogCat, all log methods will do nothing * * @deprecated Use {@link #writeLogs(boolean) writeLogs(false)} instead */ @Deprecated public static void disableLogging() { writeLogs(false); } /** * Enables/disables detail logging of {@link ImageLoader} work. * Consider {@link com.nostra13.universalimageloader.utils.L#disableLogging()} to disable * ImageLoader logging completely (even error logs)<br /> * Debug logs are disabled by default. */ public static void writeDebugLogs(boolean writeDebugLogs) { L.writeDebugLogs = writeDebugLogs; } /** Enables/disables logging of {@link ImageLoader} completely (even error logs). */ public static void writeLogs(boolean writeLogs) { L.writeLogs = writeLogs; } public static void d(String message, Object... args) { if (writeDebugLogs) { log(Log.DEBUG, null, message, args); } } public static void i(String message, Object... args) { log(Log.INFO, null, message, args); } public static void w(String message, Object... args) { log(Log.WARN, null, message, args); } public static void e(Throwable ex) { log(Log.ERROR, ex, null); } public static void e(String message, Object... args) { log(Log.ERROR, null, message, args); } public static void e(Throwable ex, String message, Object... args) { log(Log.ERROR, ex, message, args); } private static void log(int priority, Throwable ex, String message, Object... args) {//核心方法 if (!writeLogs) return; if (args.length > 0) { message = String.format(message, args); } String log; if (ex == null) {//构造最后的日志信息 log = message; } else { String logMessage = message == null ? ex.getMessage() : message; String logBody = Log.getStackTraceString(ex); log = String.format(LOG_FORMAT, logMessage, logBody); } Log.println(priority, ImageLoader.TAG, log); } } 这个工具类的确太简单了，不过以后我们要用的话，可以之间拷贝过去用就行了。
