APP開發中常有計算快取大小和清空快取的功能，此功能很常見，幾乎每個應用都能看到，清除快取功能算是個十分雞肋的功能了，但是大多數產品或者客戶都希望有這麼個東西顯得APP功能完善，網上有很多，但是對於新手來說，那些感覺並不詳細，我貼個完整到小白都能懂的。
圖1的介面程式碼我就不帖了，點選清除快取,
findViewById(R.id.text_check).setOnClickListener(this);
case R.id.text_clear:
intent = new Intent(SettingActivity.this , ClearChcheActivity.class) ;
startActivity(intent);
break ;
圖2，圖3的介面程式碼如下：
import java.io.File;
import java.io.IOException;
import org.json.JSONException;
import com.juronggvo.R;
import com.juronggvo.dialog.CustomDialog;
import com.juronggvo.loadimage.ImageFileCache;
import com.juronggvo.ui.BaseActivity;
import com.juronggvo.utils.DataCleanManager;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.widget.TextView;
/**
* @description 清除快取
* @data 2017年9月28日
* @author yang.yang
*/
public class ClearChcheActivity extends BaseActivity implements OnClickListener {
private CustomDialog.Builder ibuilder;
private TextView text_clear ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_clear_chche);
init() ;
}
private void init(){
((TextView)findViewById(R.id.title)).setText("快取管理");
findViewById(R.id.back).setOnClickListener(this);
text_clear = (TextView)this.findViewById(R.id.text_clear) ;
text_clear.setText(DataCleanManager.getFormatSize(ImageFileCache.calculateImageSize())+"");
text_clear.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.text_clear:
show() ;
break;
case R.id.back:
finish();
break;
default:
break;
}
}
private void show(){
ibuilder = new CustomDialog.Builder(ClearChcheActivity.this);
ibuilder.setTitle("清除快取");
ibuilder.setMessage("清除快取會導致下載的內容刪除，是否確定?");
ibuilder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
ibuilder.setPositiveButton("確定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
ImageFileCache.ClearCache() ;
showToast("快取已清除");
text_clear.setText("0.0B");
dialog.dismiss();
}
});
Dialog dialog = ibuilder.create() ;
dialog.show();
WindowManager m = getWindowManager();
Display d = m.getDefaultDisplay(); //為獲取螢幕寬、高
android.view.WindowManager.LayoutParams p = dialog.getWindow().getAttributes(); //獲取對話方塊當前的引數值
p.width = (int) (d.getWidth() * 0.8); //寬度設定為螢幕的0.9
dialog.getWindow().setAttributes(p); //設定生效
}
}
用到的幾個類：首先是ImageFileCache類
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.text.MessageFormat;
import java.util.Arrays;
import java.util.Comparator;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.os.StatFs;
import android.util.Log;
/**
* 檔案快取
*
* @author
*
*/
public class ImageFileCache {
// sd卡上的快取資料夾
private static final String CACHDIR = "eduhighnanjing/imgCache/imgCache";
// 定義快取檔案字尾
private static final String WHOLESALE_CONV = ".cache";
// 快取空間大小
private static final int FREE_SD_SPACE_NEEDED_TO_CACHE = 10;
// 規定的最大快取
private static final int CACHE_SIZE = 10;
// 規定1MB大小
private static final int MB = 1024 * 1024;
// 設定快取檔案過期時間為10天
private static final long MTIMEDIFF = 10 * 24 * 60 * 60 * 1000;
public ImageFileCache() {
// 清理檔案快取
removeCache(getDirectory());
}
/**
* 根據url在圖片快取中得到圖片
*
* @param url
* @return
*/
public Bitmap getImage(final String url) {
final String path = getDirectory() + "/" + convertUrlToFileName(url);
File file = new File(path);
if (file.exists()) {
Bitmap bmp = BitmapFactory.decodeFile(path);
if (bmp == null) {
file.delete();
} else {
// 更新圖片最後修改時間
updateFileTime(path);
return bmp;
}
}
return null;
}
/**
* 將圖片儲存到sd卡
*
* @param bm
* @param url
*/
public void saveBmpToSd(Bitmap bm, String url) {
if (bm == null) {
// 需要儲存的是一個空值
return;
}
// 判斷sdcard上的空間
if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {
// SD空間不足
return;
}
String filename = convertUrlToFileName(url);
String dir = getDirectory();
File file = new File(dir + "/" + filename);
try {
file.getParentFile().mkdirs();
file.createNewFile();
OutputStream outStream = new FileOutputStream(file);
bm.compress(Bitmap.CompressFormat.PNG, 100, outStream);
outStream.flush();
outStream.close();
} catch (FileNotFoundException e) {
Log.w("ImageFileCache", "FileNotFoundException");
} catch (IOException e) {
Log.w("ImageFileCache", "IOException");
}
}
/**
* 計算儲存目錄下的檔案大小，
* 當檔案總大小大於規定的CACHE_SIZE或者sdcard剩餘空間小於FREE_SD_SPACE_NEEDED_TO_CACHE的規定
* 那麼刪除40%最近沒有被使用的檔案
*
* @param dirPath
* @param filename
*/
private boolean removeCache(String dirPath) {
File dir = new File(dirPath);
File[] files = dir.listFiles();
if (files == null) {
return true;
}
// 判斷是否可操作sd卡
if (!android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED)) {
return false;
}
// 計算出快取檔案總大小
int dirSize = 0;
for (int i = 0; i < files.length; i++) {
if (files[i].getName().contains(WHOLESALE_CONV)) {
// 刪除三天過期檔案
removeExpiredCache(files[i]);
dirSize += files[i].length();
}
}
if (dirSize > CACHE_SIZE * MB
|| FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {
// 刪除百分之40
int removeFactor = (int) ((0.4 * files.length) + 1);
// 根據最後修改時間排序
Arrays.sort(files, new FileLastModifSort());
try {
Log.i("ImageFileCache", "清理快取檔案");
for (int i = 0; i < removeFactor; i++) {
if (files[i].getName().contains(WHOLESALE_CONV)) {
files[i].delete();
}
}
} catch (IndexOutOfBoundsException e) {
e.printStackTrace();
}
}
if (freeSpaceOnSd() <= CACHE_SIZE) {
return false;
}
return true;
}
/** * 根據檔案的最後修改時間進行排序 */private class FileLastModifSort implements Comparator{
public int compare(File arg0, File arg1) {
if (arg0.lastModified() > arg1.lastModified()) {
return 1;
} else if (arg0.lastModified() == arg1.lastModified()) {
return 0;
} else {
return -1;
}
}
}
/**
* 刪除超過三天的過期檔案
*
* @param dirPath
* @param filename
*/
public void removeExpiredCache(File file) {
if (System.currentTimeMillis() - file.lastModified() > MTIMEDIFF) {
Log.i("ImageFileCache", "清除三天過期快取檔案");
file.delete();
}
}
/**
* 修改檔案的最後修改時間 這裡需要考慮,是否將使用的圖片日期改為當前日期
*
* @param path
*/
public void updateFileTime(String path) {
File file = new File(path);
long newModifiedTime = System.currentTimeMillis();
file.setLastModified(newModifiedTime);
}
/**
* 計算sdcard上的剩餘空間
*
* @return
*/
private int freeSpaceOnSd() {
StatFs stat = new StatFs(Environment.getExternalStorageDirectory()
.getPath());
double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat
.getBlockSize()) / MB;
return (int) sdFreeMB;
}
/**
* 將url轉成檔名
*
* @param url
* @return
*/
private String convertUrlToFileName(String url) {
String[] strs = url.split("/");
return strs[strs.length - 1] + WHOLESALE_CONV;
}
/**
* 獲得快取目錄
*
* @return
*/
private static String getDirectory() {
String dir = getSDPath() + "/" + CACHDIR;
String substr = dir.substring(0, 4);
if (substr.equals("/mnt")) {
dir = dir.replace("/mnt", "");
}
return dir;
}
/**
* 取SD卡路徑
*
* @return
*/
public static String getSDPath() {
File sdDir = null;
boolean sdCardExist = Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED); // 判斷sd卡是否存在
if (sdCardExist) {
sdDir = Environment.getExternalStorageDirectory();// 獲取跟目錄
}
if (sdDir != null) {
return sdDir.toString();
} else {
return "";
}
}
public static String ClearCache() {
ImageMemoryCache.clear();
String clearResult1 = ClearFiles(getDirectory());
String clearResult2 = ClearFiles(ImageGetForHttp.getDirectory());
String result = "";
if (!clearResult1.equals("快取清除成功") || !clearResult2.equals("快取清除成功")) {
if (!clearResult1.equals("快取清除成功")) {
result += clearResult1;
}
if (!clearResult2.equals("快取清除成功") && !result.equals(clearResult1)) {
result += clearResult2;
}
} else {
result = "快取清除成功";
}
return result;
}
private static String ClearFiles(String dirPath) {
File dir = new File(dirPath);
File[] files = dir.listFiles();
if (files == null) {
return "快取清除成功";
}
// 判斷是否可操作sd卡
if (!android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED)) {
return "沒有許可權操作sd card";
}
for (int i = 0; i < files.length; i++) {
if (files[i].getName().contains(WHOLESALE_CONV)) {
files[i].delete();
}
}
return "快取清除成功";
}
public static long calculateImageSize() {
String dirPath = getDirectory();
File dir = new File(dirPath);
File[] files = dir.listFiles();
if (files == null) {
return 0;
}
// 判斷是否可操作sd卡
if (!android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED)) {
return 0;
}
// 計算出快取檔案總大小
int dirSize = 0;
for (int i = 0; i < files.length; i++) {
if (files[i].getName().contains(WHOLESALE_CONV)) {
dirSize += files[i].length();
}
}
return dirSize;
}
}
然後就是DataCleanManager類
import java.io.File;
import java.math.BigDecimal;
import android.content.Context;
import android.os.Environment;
import android.text.TextUtils;
public class DataCleanManager {
/**
* 格式化單位
*
* @param size
* @return
*/
public static String getFormatSize(double size) {
double kiloByte = size / 1024;
if (kiloByte < 1) {
return size + "B";
}
double megaByte = kiloByte / 1024;
if (megaByte < 1) {
BigDecimal result1 = new BigDecimal(Double.toString(kiloByte));
return result1.setScale(2, BigDecimal.ROUND_HALF_UP)
.toPlainString() + "K";
}
double gigaByte = megaByte / 1024;
if (gigaByte < 1) {
BigDecimal result2 = new BigDecimal(Double.toString(megaByte));
return result2.setScale(2, BigDecimal.ROUND_HALF_UP)
.toPlainString() + "M";
}
double teraBytes = gigaByte / 1024;
if (teraBytes < 1) {
BigDecimal result3 = new BigDecimal(Double.toString(gigaByte));
return result3.setScale(2, BigDecimal.ROUND_HALF_UP)
.toPlainString() + "G";
}
BigDecimal result4 = new BigDecimal(teraBytes);
return result4.setScale(2, BigDecimal.ROUND_HALF_UP).toPlainString()
+ "T";
}
/**
* * 清除本應用內部快取(/data/data/com.xxx.xxx/cache) * *
*
* @param context
*/
public static void cleanInternalCache(Context context) {
deleteFilesByDirectory(context.getCacheDir());
}
/**
* * 清除本應用所有資料庫(/data/data/com.xxx.xxx/databases) * *
*
* @param context
*/
public static void cleanDatabases(Context context) {
deleteFilesByDirectory(new File("/data/data/"
+ context.getPackageName() + "/databases"));
}
/**
* * 清除本應用SharedPreference(/data/data/com.xxx.xxx/shared_prefs) *
*
* @param context
*/
public static void cleanSharedPreference(Context context) {
deleteFilesByDirectory(new File("/data/data/"
+ context.getPackageName() + "/shared_prefs"));
}
/**
* * 按名字清除本應用資料庫 * *
*
* @param context
* @param dbName
*/
public static void cleanDatabaseByName(Context context, String dbName) {
context.deleteDatabase(dbName);
}
/**
* * 清除/data/data/com.xxx.xxx/files下的內容 * *
*
* @param context
*/
public static void cleanFiles(Context context) {
deleteFilesByDirectory(context.getFilesDir());
}
/**
* * 清除外部cache下的內容(/mnt/sdcard/android/data/com.xxx.xxx/cache)
*
* @param context
*/
public static void cleanExternalCache(Context context) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
deleteFilesByDirectory(context.getExternalCacheDir());
}
}
/**
* * 清除自定義路徑下的檔案，使用需小心，請不要誤刪。而且只支援目錄下的檔案刪除 * *
*
* @param filePath
* */
public static void cleanCustomCache(String filePath) {
deleteFilesByDirectory(new File(filePath));
}
/**
* * 清除本應用所有的資料 * *
*
* @param context
* @param filepath
*/
public static void cleanApplicationData(Context context, String... filepath) {
cleanInternalCache(context);
cleanExternalCache(context);
cleanDatabases(context);
cleanSharedPreference(context);
cleanFiles(context);
if (filepath == null) {
return;
}
for (String filePath : filepath) {
cleanCustomCache(filePath);
}
}
/**
* * 刪除方法 這裡只會刪除某個資料夾下的檔案，如果傳入的directory是個檔案，將不做處理 * *
*
* @param directory
*/
private static void deleteFilesByDirectory(File directory) {
if (directory != null && directory.exists() && directory.isDirectory()) {
for (File item : directory.listFiles()) {
item.delete();
}
}
}
// 獲取檔案
//Context.getExternalFilesDir() --> SDCard/Android/data/你的應用的包名/files/ 目錄，一般放一些長時間儲存的資料
//Context.getExternalCacheDir() --> SDCard/Android/data/你的應用包名/cache/目錄，一般存放臨時快取資料
public static long getFolderSize(File file) throws Exception {
long size = 0;
try {
File[] fileList = file.listFiles();
for (int i = 0; i < fileList.length; i++) {
// 如果下面還有檔案
if (fileList[i].isDirectory()) {
size = size + getFolderSize(fileList[i]);
} else {
size = size + fileList[i].length();
}
}
} catch (Exception e) {
e.printStackTrace();
}
return size;
}
/**
* 刪除指定目錄下檔案及目錄
*
* @param deleteThisPath
* @param filepath
* @return
*/
public static void deleteFolderFile(String filePath, boolean deleteThisPath) {
if (!TextUtils.isEmpty(filePath)) {
try {
File file = new File(filePath);
if (file.isDirectory()) {// 如果下面還有檔案
File files[] = file.listFiles();
for (int i = 0; i < files.length; i++) {
deleteFolderFile(files[i].getAbsolutePath(), true);
}
}
if (deleteThisPath) {
if (!file.isDirectory()) {// 如果是檔案，刪除
file.delete();
} else {// 目錄
if (file.listFiles().length == 0) {// 目錄下沒有檔案或者目錄，刪除
file.delete();
}
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
好了，基本就這樣吧！
偉大的哲學家我自己曾經說過，有夢想就要大聲說出來 ，萬丈高樓平地起，能不能行靠自己！