小米開原始檔管理器MiCodeFileExplorer-原始碼研究(3)-使用最多的工具類Util

Util.java,使用最廣泛~
程式碼中很多地方，都寫了註釋說明~基本不需要怎麼解釋了~

package net.micode.fileexplorer.util;


import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashSet;


import net.micode.fileexplorer.FileViewActivity;
import net.micode.fileexplorer.GlobalConsts;
import net.micode.fileexplorer.R;
import net.micode.fileexplorer.model.FavoriteItem;
import net.micode.fileexplorer.model.FileInfo;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.graphics.drawable.Drawable;
import android.os.Environment;
import android.util.Log;
import android.view.ActionMode;
import android.view.View;
import android.widget.TextView;
/**工具類，包含了很多通用的工具方法，被專案中的很多類呼叫。*/
public class Util {
	//這個資料夾裡面儲存的內容是app2sd產生的資料夾，也就是是你手機上所有安裝到SD卡的應用程式的快取資料夾。
	//androidsecure資料夾可以刪除嗎？
    //如果刪除之後，軟體不能正常使用，和系統沒有關係。
	//刪的話除了會可能導致移動至sd卡的程式損壞，資料丟失，並不會造成什麼嚴重後果。只要把移動到sd卡的損壞程式解除安裝，重灌，手機就完全沒有損傷，資料夾也會在再次app2sd時自動重建的。
	private static String ANDROID_SECURE = "/mnt/sdcard/.android_secure";
    //android.util.Log.log第1個引數，用到“tag”，和log4j中Logger.getLogger(getClass())用法不太一樣
	private static final String LOG_TAG = "Util";


	//獲得SD卡的儲存狀態，“mounted”表示已經就緒
	public static boolean isSDCardReady() {
		return Environment.getExternalStorageState().equals(
				Environment.MEDIA_MOUNTED);
	}


	// if path1 contains path2
	public static boolean containsPath(String path1, String path2) {
		String path = path2;
		while (path != null) {
			if (path.equalsIgnoreCase(path1))
				return true;


			if (path.equals(GlobalConsts.ROOT_PATH))
				break;
			path = new File(path).getParent();
		}


		return false;
	}


	//2個路徑相加的時候，是否需要加上檔案分隔符
	public static String makePath(String path1, String path2) {
		if (path1.endsWith(File.separator))
			return path1 + path2;


		return path1 + File.separator + path2;
	}


	//獲得SD卡的儲存目錄
	public static String getSdDirectory() {
		return Environment.getExternalStorageDirectory().getPath();
	}


	//判斷1個檔案是否為“普通檔案”，ANDROID_SECURE下的檔案都不是普通的
	public static boolean isNormalFile(String fullName) {
		return !fullName.equals(ANDROID_SECURE);
	}


	//根據檔案路徑，獲得Java檔案File，再包裝成FileInfo
	public static FileInfo GetFileInfo(String filePath) {
		File lFile = new File(filePath);
		if (!lFile.exists())
			return null;


		FileInfo lFileInfo = new FileInfo();
		lFileInfo.canRead = lFile.canRead();
		lFileInfo.canWrite = lFile.canWrite();
		lFileInfo.isHidden = lFile.isHidden();
		lFileInfo.fileName = Util.getNameFromFilepath(filePath);
		lFileInfo.ModifiedDate = lFile.lastModified();
		lFileInfo.IsDir = lFile.isDirectory();
		lFileInfo.filePath = filePath;
		lFileInfo.fileSize = lFile.length();
		return lFileInfo;
	}


	//根據File物件，和FilenameFilter等選項，獲得包裝的FileInfo
	//需要注意多少，如果File是個目錄，Count就是當前目錄下的檔案的個數。如果是普通檔案，就計算檔案大小。
	//這個時候，我們知道Count欄位的含義了
	public static FileInfo GetFileInfo(File f, FilenameFilter filter,
			boolean showHidden) {
		FileInfo lFileInfo = new FileInfo();
		String filePath = f.getPath();
		File lFile = new File(filePath);
		lFileInfo.canRead = lFile.canRead();
		lFileInfo.canWrite = lFile.canWrite();
		lFileInfo.isHidden = lFile.isHidden();
		lFileInfo.fileName = f.getName();
		lFileInfo.ModifiedDate = lFile.lastModified();
		lFileInfo.IsDir = lFile.isDirectory();
		lFileInfo.filePath = filePath;
		if (lFileInfo.IsDir) {
			int lCount = 0;
			File[] files = lFile.listFiles(filter);


			// null means we cannot access this dir
			if (files == null) {
				return null;
			}


			for (File child : files) {
				if ((!child.isHidden() || showHidden)
						&& Util.isNormalFile(child.getAbsolutePath())) {
					lCount++;
				}
			}
			lFileInfo.Count = lCount;


		} else {


			lFileInfo.fileSize = lFile.length();


		}
		return lFileInfo;
	}


	/*
	 * 採用了新的辦法獲取APK圖示，之前的失敗是因為android中存在的一個BUG,通過 appInfo.publicSourceDir =
	 * apkPath;來修正這個問題，詳情參見:
	 * http://code.google.com/p/android/issues/detail?id=9151
	 */
	public static Drawable getApkIcon(Context context, String apkPath) {
		//Android系統為我們提供了很多服務管理類，包括ActivityManager、PowerManager(電源管理)、AudioManager(音訊管理)。
		//PackageManager主要是管理應用程式包，通過它就可以獲取應用程式資訊
		PackageManager pm = context.getPackageManager();
		PackageInfo info = pm.getPackageArchiveInfo(apkPath,
				PackageManager.GET_ACTIVITIES);
		if (info != null) {
			ApplicationInfo appInfo = info.applicationInfo;
			appInfo.sourceDir = apkPath;
			appInfo.publicSourceDir = apkPath;
			try {
				return appInfo.loadIcon(pm);
			} catch (OutOfMemoryError e) {
				Log.e(LOG_TAG, e.toString());
			}
		}
		return null;
	}


	//獲得檔案的副檔名
	public static String getExtFromFilename(String filename) {
		int dotPosition = filename.lastIndexOf('.');
		if (dotPosition != -1) {
			return filename.substring(dotPosition + 1, filename.length());
		}
		return "";
	}


	//獲得去掉“檔案字尾”的檔名字，比如“C:/a/b/c.png”，輸出“C:/a/b/c”
	public static String getNameFromFilename(String filename) {
		int dotPosition = filename.lastIndexOf('.');
		if (dotPosition != -1) {
			return filename.substring(0, dotPosition);
		}
		return "";
	}
	
    //從檔案路徑中，獲得路徑
	public static String getPathFromFilepath(String filepath) {
		int pos = filepath.lastIndexOf('/');
		if (pos != -1) {
			return filepath.substring(0, pos);
		}
		return "";
	}


	//從檔案路徑中，獲得檔名（帶字尾，如果有）
	public static String getNameFromFilepath(String filepath) {
		int pos = filepath.lastIndexOf('/');
		if (pos != -1) {
			return filepath.substring(pos + 1);
		}
		return "";
	}


	// return new file path if successful, or return null
	public static String copyFile(String src, String dest) {
		File file = new File(src);
		if (!file.exists() || file.isDirectory()) {
			Log.v(LOG_TAG, "copyFile: file not exist or is directory, " + src);
			return null;
		}
		FileInputStream fi = null;
		FileOutputStream fo = null;
		try {
			fi = new FileInputStream(file);
			File destPlace = new File(dest);
			if (!destPlace.exists()) {
				if (!destPlace.mkdirs())
					return null;
			}


			String destPath = Util.makePath(dest, file.getName());
			File destFile = new File(destPath);
			int i = 1;
			while (destFile.exists()) {
				String destName = Util.getNameFromFilename(file.getName())
						+ " " + i++ + "."
						+ Util.getExtFromFilename(file.getName());
				destPath = Util.makePath(dest, destName);
				destFile = new File(destPath);
			}


			if (!destFile.createNewFile())
				return null;


			fo = new FileOutputStream(destFile);
			int count = 102400;
			byte[] buffer = new byte[count];
			int read = 0;
			while ((read = fi.read(buffer, 0, count)) != -1) {
				fo.write(buffer, 0, read);
			}


			// TODO: set access privilege


			return destPath;
		} catch (FileNotFoundException e) {
			Log.e(LOG_TAG, "copyFile: file not found, " + src);
			e.printStackTrace();
		} catch (IOException e) {
			Log.e(LOG_TAG, "copyFile: " + e.toString());
		} finally {
			try {
				if (fi != null)
					fi.close();
				if (fo != null)
					fo.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}


		return null;
	}


	// does not include sd card folder
	private static String[] SysFileDirs = new String[] { "miren_browser/imagecaches" };


	//判斷一個檔案是否需要顯示，根據Setting中的設定。特別說明：某個系統檔案目錄，不顯示。
	public static boolean shouldShowFile(String path) {
		return shouldShowFile(new File(path));
	}


	//判斷一個檔案是否需要顯示，根據Setting中的設定。特別說明：某個系統檔案目錄，不顯示。
	public static boolean shouldShowFile(File file) {
		boolean show = Settings.instance().getShowDotAndHiddenFiles();
		if (show)
			return true;


		if (file.isHidden())
			return false;


		if (file.getName().startsWith("."))
			return false;


		String sdFolder = getSdDirectory();
		for (String s : SysFileDirs) {
			if (file.getPath().startsWith(makePath(sdFolder, s)))
				return false;
		}


		return true;
	}


	//根據上下文物件Context，獲得預設的收藏集合
	public static ArrayList<FavoriteItem> getDefaultFavorites(Context context) {
		ArrayList<FavoriteItem> list = new ArrayList<FavoriteItem>();
		list.add(new FavoriteItem(context.getString(R.string.favorite_photo),
				makePath(getSdDirectory(), "DCIM/Camera")));
		list.add(new FavoriteItem(context.getString(R.string.favorite_sdcard),
				getSdDirectory()));
		// list.add(new FavoriteItem(context.getString(R.string.favorite_root),
		// getSdDirectory()));
		list.add(new FavoriteItem(context
				.getString(R.string.favorite_screen_cap), makePath(
				getSdDirectory(), "MIUI/screen_cap")));
		list.add(new FavoriteItem(
				context.getString(R.string.favorite_ringtone), makePath(
						getSdDirectory(), "MIUI/ringtone")));
		return list;
	}


	//向View中的某個TextView設定文字
	public static boolean setText(View view, int id, String text) {
		TextView textView = (TextView) view.findViewById(id);
		if (textView == null)
			return false;


		textView.setText(text);
		return true;
	}


	//向View中的某個TextView設定文字
	public static boolean setText(View view, int id, int text) {
		TextView textView = (TextView) view.findViewById(id);
		if (textView == null)
			return false;


		textView.setText(text);
		return true;
	}


	// comma separated number
	public static String convertNumber(long number) {
		return String.format("%,d", number);
	}


	// storage, G M K B
	public static String convertStorage(long size) {
		long kb = 1024;
		long mb = kb * 1024;
		long gb = mb * 1024;


		if (size >= gb) {
			return String.format("%.1f GB", (float) size / gb);
		} else if (size >= mb) {
			float f = (float) size / mb;
			return String.format(f > 100 ? "%.0f MB" : "%.1f MB", f);
		} else if (size >= kb) {
			float f = (float) size / kb;
			return String.format(f > 100 ? "%.0f KB" : "%.1f KB", f);
		} else
			return String.format("%d B", size);
	}


	public static class SDCardInfo {
		public long total;


		public long free;
	}


	//獲得SD卡的各種資訊，總容量大小和剩餘容量大小等
	public static SDCardInfo getSDCardInfo() {
		String sDcString = android.os.Environment.getExternalStorageState();


		if (sDcString.equals(android.os.Environment.MEDIA_MOUNTED)) {
			File pathFile = android.os.Environment
					.getExternalStorageDirectory();


			try {
				android.os.StatFs statfs = new android.os.StatFs(
						pathFile.getPath());


				// 獲取SDCard上BLOCK總數
				long nTotalBlocks = statfs.getBlockCount();


				// 獲取SDCard上每個block的SIZE
				long nBlocSize = statfs.getBlockSize();


				// 獲取可供程式使用的Block的數量
				long nAvailaBlock = statfs.getAvailableBlocks();


				// 獲取剩下的所有Block的數量(包括預留的一般程式無法使用的塊)
				long nFreeBlock = statfs.getFreeBlocks();


				SDCardInfo info = new SDCardInfo();
				// 計算SDCard 總容量大小MB
				info.total = nTotalBlocks * nBlocSize;


				// 計算 SDCard 剩餘大小MB
				info.free = nAvailaBlock * nBlocSize;


				return info;
			} catch (IllegalArgumentException e) {
				Log.e(LOG_TAG, e.toString());
			}
		}


		return null;
	}


	//顯示一條系統通知
	public static void showNotification(Context context, Intent intent,
			String title, String body, int drawableId) {
		NotificationManager manager = (NotificationManager) context
				.getSystemService(Context.NOTIFICATION_SERVICE);
		Notification notification = new Notification(drawableId, body,
				System.currentTimeMillis());
		notification.flags = Notification.FLAG_AUTO_CANCEL;
		notification.defaults = Notification.DEFAULT_SOUND;
		if (intent == null) {
			// FIXEME: category tab is disabled
			intent = new Intent(context, FileViewActivity.class);
		}
		PendingIntent contentIntent = PendingIntent.getActivity(context, 0,
				intent, PendingIntent.FLAG_ONE_SHOT);
		notification.setLatestEventInfo(context, title, body, contentIntent);
		manager.notify(drawableId, notification);
	}


	//格式化毫秒格式的時間
	public static String formatDateString(Context context, long time) {
		DateFormat dateFormat = android.text.format.DateFormat
				.getDateFormat(context);
		DateFormat timeFormat = android.text.format.DateFormat
				.getTimeFormat(context);
		Date date = new Date(time);
		return dateFormat.format(date) + " " + timeFormat.format(date);
	}


	public static void updateActionModeTitle(ActionMode mode, Context context,
			int selectedNum) {
		if (mode != null) {
			mode.setTitle(context.getString(R.string.multi_select_title,
					selectedNum));
			if (selectedNum == 0) {
				mode.finish();
			}
		}
	}


	//MimeType
	public static HashSet<String> sDocMimeTypesSet = new HashSet<String>() {
		{
			add("text/plain");
			add("text/plain");
			add("application/pdf");
			add("application/msword");
			add("application/vnd.ms-excel");
			add("application/vnd.ms-excel");
		}
	};


	public static String sZipFileMimeType = "application/zip";


	public static int CATEGORY_TAB_INDEX = 0;
	public static int SDCARD_TAB_INDEX = 1;
}

遇到一個奇怪的問題，為了驗證某個函式，寫了個main函式執行，結果發生了奇葩事項~


在Java環境下的工程中執行以下程式碼，正常輸出。

public class Test {
	public static void main(String[] args) {
			System.out.println(getNameFromFilename("C:/a/b/c.png"));
		}
	public static String getNameFromFilename(String filename) {
		int dotPosition = filename.lastIndexOf('.');
		if (dotPosition != -1) {
			return filename.substring(0, dotPosition);
		}
		return "";
	}
}

列印“C:/a/b/c”


在Android環境下的工程中，竟然直接把JVM搞崩潰了，不明所以啊~
Invalid layout of java.lang.String at value
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (javaClasses.cpp:129), pid=8236, tid=3188
#  fatal error: Invalid layout of preloaded class
#
# JRE version: 7.0_17-b02
# Java VM: Java HotSpot(TM) 64-Bit Server VM (23.7-b01 mixed mode windows-amd64 compressed oops)
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
# J:\AndroidCenter\MiCodeFileExplorer\hs_err_pid8236.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp
#