package com.lcjian.library.util.cache;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.Arrays;
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import java.util.Comparator;
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import android.graphics.Bitmap;
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import android.graphics.BitmapFactory;
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import android.os.Environment;
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import android.os.StatFs;
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import android.util.Log;
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public class ImageFileCache {
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private static final String CACHDIR = "ImgCach";
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private static final String WHOLESALE_CONV = ".cach";
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private static final int MB = 1024 * 1024;
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private static final int CACHE_SIZE = 10;
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private static final int FREE_SD_SPACE_NEEDED_TO_CACHE = 10;
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public ImageFileCache() {
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// 清理文件缓存
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removeCache(getDirectory());
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}
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/** 从缓存中获取图片 **/
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public Bitmap getImage(final String url) {
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final String path = getDirectory() + "/" + convertUrlToFileName(url);
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File file = new File(path);
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if (file.exists()) {
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Bitmap bmp = BitmapFactory.decodeFile(path);
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if (bmp == null) {
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file.delete();
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} else {
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updateFileTime(path);
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return bmp;
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}
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}
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return null;
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}
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/** 将图片存入文件缓存 **/
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public void saveBitmap(Bitmap bm, String url) {
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if (bm == null) {
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return;
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}
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// 判断sdcard上的空间
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if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {
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// SD空间不足
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return;
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}
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String filename = convertUrlToFileName(url);
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String dir = getDirectory();
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File dirFile = new File(dir);
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if (!dirFile.exists()) {
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dirFile.mkdirs();
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}
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File file = new File(dir, filename);
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try {
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file.createNewFile();
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OutputStream outStream = new FileOutputStream(file);
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bm.compress(Bitmap.CompressFormat.JPEG, 100, outStream);
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outStream.flush();
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outStream.close();
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} catch (FileNotFoundException e) {
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Log.w("ImageFileCache", "FileNotFoundException");
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} catch (IOException e) {
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e.printStackTrace();
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Log.w("ImageFileCache", "IOException");
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}
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}
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/**
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* 计算存储目录下的文件大小，
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* 当文件总大小大于规定的CACHE_SIZE或者sdcard剩余空间小于FREE_SD_SPACE_NEEDED_TO_CACHE的规定
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* 那么删除40%最近没有被使用的文件
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*/
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private boolean removeCache(String dirPath) {
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File dir = new File(dirPath);
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File[] files = dir.listFiles();
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if (files == null) {
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return true;
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}
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if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
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return false;
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}
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int dirSize = 0;
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for (int i = 0; i < files.length; i++) {
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if (files[i].getName().contains(WHOLESALE_CONV)) {
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dirSize += files[i].length();
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}
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}
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if (dirSize > CACHE_SIZE * MB
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|| FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {
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int removeFactor = (int) ((0.4 * files.length) + 1);
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Arrays.sort(files, new FileLastModifSort());
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for (int i = 0; i < removeFactor; i++) {
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if (files[i].getName().contains(WHOLESALE_CONV)) {
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files[i].delete();
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}
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}
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}
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if (freeSpaceOnSd() <= CACHE_SIZE) {
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return false;
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}
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return true;
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}
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/** 修改文件的最后修改时间 **/
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public void updateFileTime(String path) {
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File file = new File(path);
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long newModifiedTime = System.currentTimeMillis();
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file.setLastModified(newModifiedTime);
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}
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/** 计算sdcard上的剩余空间 **/
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private int freeSpaceOnSd() {
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StatFs stat = new StatFs(Environment.getExternalStorageDirectory().getPath());
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double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat.getBlockSize()) / MB;
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return (int) sdFreeMB;
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}
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/** 将url转成文件名 **/
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private String convertUrlToFileName(String url) {
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String filename = url;
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filename = filename.replace("http://", "");
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filename = filename.replace("/", ".");
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filename = filename.replace(":", ".");
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return filename + WHOLESALE_CONV;
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}
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/** 获得缓存目录 **/
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private String getDirectory() {
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String dir = getSDPath() + "/" + CACHDIR;
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return dir;
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}
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/** 取SD卡路径 **/
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private String getSDPath() {
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File sdDir = null;
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boolean sdCardExist = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED); // 判断sd卡是否存在
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if (sdCardExist) {
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sdDir = Environment.getExternalStorageDirectory(); // 获取根目录
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}
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if (sdDir != null) {
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return sdDir.toString();
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} else {
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return "";
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}
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}
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/**
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* 根据文件的最后修改时间进行排序
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*/
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private class FileLastModifSort implements Comparator<File> {
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public int compare(File arg0, File arg1) {
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if (arg0.lastModified() > arg1.lastModified()) {
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return 1;
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} else if (arg0.lastModified() == arg1.lastModified()) {
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return 0;
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} else {
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return -1;
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}
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}
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}
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}
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