Android 清除缓存功能实现

** APP开发中常有计算缓存大小和清空缓存的功能，此功能很常见，几乎每个应用都能看到，清除缓存功能算是个十分鸡肋的功能了，但是大多数产品或者客户都希望有这么个东西显得APP功能完善，网上有很多，但是对于新手来说，那些感觉并不详细，我贴个完整到小白都能懂的。**

image

图1的界面代码我就不帖了，点击清除缓存,

findViewById(R.id.text_check).setOnClickListener(this);
case R.id.text_clear:
                    intent = new Intent(SettingActivity.this , ClearChcheActivity.class) ;
                    startActivity(intent);
                     break ;

image

图2，图3的界面代码如下：

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 清除缓存

 * @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("缓存管理");

        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("清除缓存");
        ibuilder.setMessage("清除缓存会导致下载的内容删除，是否确定?");
        ibuilder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        });
        ibuilder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                ImageFileCache.ClearCache() ;
                showToast("缓存已清除");
                text_clear.setText("0.0B");
                dialog.dismiss();
            }
        });

        Dialog dialog = ibuilder.create() ;
        dialog.show();
        WindowManager m = getWindowManager();
        Display d = m.getDefaultDisplay();  //为获取屏幕宽、高
        android.view.WindowManager.LayoutParams p =
                dialog.getWindow().getAttributes();  //获取对话框当前的参数值
        p.width = (int) (d.getWidth() * 0.8);    //宽度设置为屏幕的0.9
        dialog.getWindow().setAttributes(p);    //设置生效
    }

}

image

用到的几个类：首先是ImageFileCache类

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;

/**

 * 文件缓存

 *

 * @author

 *

 */

public class ImageFileCache {

// sd卡上的缓存文件夹

    private static final String CACHDIR = "eduhighnanjing/imgCache/imgCache";

// 定义缓存文件后缀

    private static final String WHOLESALE_CONV = ".cache";

// 缓存空间大小

    private static final int FREE_SD_SPACE_NEEDED_TO_CACHE = 10;

// 规定的最大缓存

    private static final int CACHE_SIZE = 10;

// 规定1MB大小

    private static final int MB = 1024 * 1024;

// 设置缓存文件过期时间为10天

    private static final long MTIMEDIFF = 10 * 24 * 60 * 60 * 1000;

    public ImageFileCache() {

// 清理文件缓存

        removeCache(getDirectory());

    }

    /**

     * 根据url在图片缓存中得到图片

     *

     * @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 {

// 更新图片最后修改时间

                updateFileTime(path);

                return bmp;

            }

        }

        return null;

    }

    /**

     * 将图片保存到sd卡

     *

     * @param bm

     * @param url

     */

    public void saveBmpToSd(Bitmap bm, String url) {

        if (bm == null) {

// 需要保存的是一个空值

            return;

        }

// 判断sdcard上的空间

        if (FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {

// SD空间不足

            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");

        }

    }

    /**

     * 计算存储目录下的文件大小，

     * 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

     * 那么删除40%最近没有被使用的文件

     *

     * @param dirPath

     * @param filename

     */

    private boolean removeCache(String dirPath) {

        File dir = new File(dirPath);

        File[] files = dir.listFiles();

        if (files == null) {

            return true;

        }

// 判断是否可操作sd卡

        if (!android.os.Environment.getExternalStorageState().equals(

                android.os.Environment.MEDIA_MOUNTED)) {

            return false;

        }

// 计算出缓存文件总大小

        int dirSize = 0;

        for (int i = 0; i < files.length; i++) {

            if (files[i].getName().contains(WHOLESALE_CONV)) {

// 删除三天过期文件

                removeExpiredCache(files[i]);

                dirSize += files[i].length();

            }

        }

        if (dirSize > CACHE_SIZE * MB

                || FREE_SD_SPACE_NEEDED_TO_CACHE > freeSpaceOnSd()) {

// 删除百分之40

            int removeFactor = (int) ((0.4 * files.length) + 1);

// 根据最后修改时间排序

            Arrays.sort(files, new FileLastModifSort());

            try {

                Log.i("ImageFileCache", "清理缓存文件");

                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;

    }

    /** * 根据文件的最后修改时间进行排序 */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;

            }

        }

    }

    /**

     * 删除超过三天的过期文件

     *

     * @param dirPath

     * @param filename

     */

    public void removeExpiredCache(File file) {

        if (System.currentTimeMillis() - file.lastModified() > MTIMEDIFF) {

            Log.i("ImageFileCache", "清除三天过期缓存文件");

            file.delete();

        }

    }

    /**

     * 修改文件的最后修改时间 这里需要考虑,是否将使用的图片日期改为当前日期

     *

     * @param path

     */

    public void updateFileTime(String path) {

        File file = new File(path);

        long newModifiedTime = System.currentTimeMillis();

        file.setLastModified(newModifiedTime);

    }

    /**

     * 计算sdcard上的剩余空间

     *

     * @return

     */

    private int freeSpaceOnSd() {

        StatFs stat = new StatFs(Environment.getExternalStorageDirectory()

                .getPath());

        double sdFreeMB = ((double) stat.getAvailableBlocks() * (double) stat

                .getBlockSize()) / MB;

        return (int) sdFreeMB;

    }

    /**

     * 将url转成文件名

     *

     * @param url

     * @return

     */

    private String convertUrlToFileName(String url) {

        String[] strs = url.split("/");

        return strs[strs.length - 1] + WHOLESALE_CONV;

    }

    /**

     * 获得缓存目录

     *

     * @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卡路径

     *

     * @return

     */

    public static String getSDPath() {

        File sdDir = null;

        boolean sdCardExist = Environment.getExternalStorageState().equals(

                android.os.Environment.MEDIA_MOUNTED); // 判断sd卡是否存在

        if (sdCardExist) {

            sdDir = Environment.getExternalStorageDirectory();// 获取跟目录

        }

        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("缓存清除成功") || !clearResult2.equals("缓存清除成功")) {

            if (!clearResult1.equals("缓存清除成功")) {

                result += clearResult1;

            }

            if (!clearResult2.equals("缓存清除成功") && !result.equals(clearResult1)) {

                result += clearResult2;

            }

        } else {

            result = "缓存清除成功";

        }

        return result;

    }

    private static String ClearFiles(String dirPath) {

        File dir = new File(dirPath);

        File[] files = dir.listFiles();

        if (files == null) {

            return "缓存清除成功";

        }

// 判断是否可操作sd卡

        if (!android.os.Environment.getExternalStorageState().equals(

                android.os.Environment.MEDIA_MOUNTED)) {

            return "没有权限操作sd card";

        }

        for (int i = 0; i < files.length; i++) {

            if (files[i].getName().contains(WHOLESALE_CONV)) {

                files[i].delete();

            }

        }

        return "缓存清除成功";

    }

    public static long calculateImageSize() {

        String dirPath = getDirectory();

        File dir = new File(dirPath);

        File[] files = dir.listFiles();

        if (files == null) {

            return 0;

        }

// 判断是否可操作sd卡

        if (!android.os.Environment.getExternalStorageState().equals(

                android.os.Environment.MEDIA_MOUNTED)) {

            return 0;

        }

// 计算出缓存文件总大小

        int dirSize = 0;

        for (int i = 0; i < files.length; i++) {

            if (files[i].getName().contains(WHOLESALE_CONV)) {

                dirSize += files[i].length();

            }

        }

        return dirSize;

    }

}

然后就是DataCleanManager类

import java.io.File;

import java.math.BigDecimal;

import android.content.Context;

import android.os.Environment;

import android.text.TextUtils;

public class DataCleanManager {

    /**

     * 格式化单位

     *

     * @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";

    }

    /**

     * * 清除本应用内部缓存(/data/data/com.xxx.xxx/cache) * *

     *

     * @param context

     */

    public static void cleanInternalCache(Context context) {

        deleteFilesByDirectory(context.getCacheDir());

    }

    /**

     * * 清除本应用所有数据库(/data/data/com.xxx.xxx/databases) * *

     *

     * @param context

     */

    public static void cleanDatabases(Context context) {

        deleteFilesByDirectory(new File("/data/data/"

                + context.getPackageName() + "/databases"));

    }

    /**

     * * 清除本应用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"));

    }

    /**

     * * 按名字清除本应用数据库 * *

     *

     * @param context

     * @param dbName

     */

    public static void cleanDatabaseByName(Context context, String dbName) {

        context.deleteDatabase(dbName);

    }

    /**

     * * 清除/data/data/com.xxx.xxx/files下的内容 * *

     *

     * @param context

     */

    public static void cleanFiles(Context context) {

        deleteFilesByDirectory(context.getFilesDir());

    }

    /**

     * * 清除外部cache下的内容(/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());

        }

    }

    /**

     * * 清除自定义路径下的文件，使用需小心，请不要误删。而且只支持目录下的文件删除 * *

     *

     * @param filePath

     * */

    public static void cleanCustomCache(String filePath) {

        deleteFilesByDirectory(new File(filePath));

    }

    /**

     * * 清除本应用所有的数据 * *

     *

     * @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);

        }

    }

    /**

     * * 删除方法 这里只会删除某个文件夹下的文件，如果传入的directory是个文件，将不做处理 * *

     *

     * @param directory

     */

    private static void deleteFilesByDirectory(File directory) {

        if (directory != null && directory.exists() && directory.isDirectory()) {

            for (File item : directory.listFiles()) {

                item.delete();

            }

        }

    }

// 获取文件

//Context.getExternalFilesDir() --> SDCard/Android/data/你的应用的包名/files/ 目录，一般放一些长时间保存的数据

//Context.getExternalCacheDir() --> SDCard/Android/data/你的应用包名/cache/目录，一般存放临时缓存数据

    public static long getFolderSize(File file) throws Exception {

        long size = 0;

        try {

            File[] fileList = file.listFiles();

            for (int i = 0; i < fileList.length; i++) {

// 如果下面还有文件

                if (fileList[i].isDirectory()) {

                    size = size + getFolderSize(fileList[i]);

                } else {

                    size = size + fileList[i].length();

                }

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

        return size;

    }

    /**

     * 删除指定目录下文件及目录

     *

     * @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()) {// 如果下面还有文件

                    File files[] = file.listFiles();

                    for (int i = 0; i < files.length; i++) {

                        deleteFolderFile(files[i].getAbsolutePath(), true);

                    }

                }

                if (deleteThisPath) {

                    if (!file.isDirectory()) {// 如果是文件，删除

                        file.delete();

                    } else {// 目录

                        if (file.listFiles().length == 0) {// 目录下没有文件或者目录，删除

                            file.delete();

                        }

                    }

                }

            } catch (Exception e) {

// TODO Auto-generated catch block

                e.printStackTrace();

            }

        }

    }

}

好了，基本就这样吧！

伟大的哲学家我自己曾经说过，有梦想就要大声说出来 ，万丈高楼平地起，能不能行靠自己！