Android 內存+文件+網絡三級緩存
阿新 • • 發佈：2017-08-04
util andro final map.entry 邏輯 getent factory 文件名 canvas
package com.panpass.main;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
/*
* 圖片管理
* 異步獲取圖片，直接調用loadImage()函數，該函數自己推斷是從緩存還是網絡載入
* 同步獲取圖片，直接調用getBitmap()函數。該函數自己推斷是從緩存還是網絡載入
* 僅從本地獲取圖片，調用getBitmapFromNative()
* 僅從網絡載入圖片，調用getBitmapFromHttp()
*
*/
public class ImageManager {
public static ImageManager im = null;
private final static String TAG = "ImageManager";
private ImageMemoryCache imageMemoryCache; // 內存緩存
private ImageFileCache imageFileCache; // 文件緩存
// 正在下載的image列表
public static HashMap<String, Handler> ongoingTaskMap = new HashMap<String, Handler>();
// 等待下載的image列表
public static HashMap<String, Handler> waitingTaskMap = new HashMap<String, Handler>();
// 同一時候下載圖片的線程個數
final static int MAX_DOWNLOAD_IMAGE_THREAD = 4;
private final Handler downloadStatusHandler = new Handler() {
public void handleMessage(Message msg) {
startDownloadNext();
}
};
public static ImageManager getInstance(Context mContext) {
if (im == null) {
synchronized (ImageManager.class) {
if (im == null) {
im = new ImageManager(mContext);
}
}
}
return im;
}
public ImageManager(Context mContext) {
imageMemoryCache = new ImageMemoryCache();
imageFileCache = new ImageFileCache(mContext);
}
/**
* 獲取圖片。多線程的入口
*/
public void loadBitmap(String urlStr, Handler handler) {
String url = urlStr.hashCode() + "";
// 先從內存緩存中獲取。取到直接載入
Bitmap bitmap = getBitmapFromNative(urlStr);
if (bitmap != null) {
Message msg = Message.obtain();
Bundle bundle = new Bundle();
bundle.putString("url", url);
msg.obj = bitmap;
msg.setData(bundle);
handler.sendMessage(msg);
} else {
downloadBmpOnNewThread(urlStr, handler);
}
}
/**
* 新起線程下載圖片
*/
private void downloadBmpOnNewThread(final String urlStr,
final Handler handler) {
final String url = urlStr.hashCode() + "";
if (ongoingTaskMap.size() >= MAX_DOWNLOAD_IMAGE_THREAD) {
synchronized (waitingTaskMap) {
waitingTaskMap.put(url, handler);
}
} else {
synchronized (ongoingTaskMap) {
ongoingTaskMap.put(url, handler);
}
new Thread() {
public void run() {
Bitmap bmp = getBitmapFromHttp(urlStr);
// 不論下載是否成功，都從下載隊列中移除,再由業務邏輯推斷是否又一次下載
// 下載圖片使用了httpClientRequest，本身已經帶了重連機制
synchronized (ongoingTaskMap) {
ongoingTaskMap.remove(url);
}
if (downloadStatusHandler != null) {
downloadStatusHandler.sendEmptyMessage(0);
}
Message msg = Message.obtain();
msg.obj = bmp;
Bundle bundle = new Bundle();
bundle.putString("url", url);
msg.setData(bundle);
if (handler != null) {
handler.sendMessage(msg);
}
}
}.start();
}
}
/**
* 依次從內存。緩存文件，網絡上載入單個bitmap,不考慮線程的問題
*/
public Bitmap getBitmap(String urlStr) {
String url = urlStr.hashCode() + "";
// 從內存緩存中獲取圖片
Bitmap bitmap = imageMemoryCache.getBitmapFromMemory(url);
if (bitmap == null) {
// 文件緩存中獲取
bitmap = imageFileCache.getImageFromFile(url);
if (bitmap != null) {
// 加入到內存緩存
imageMemoryCache.addBitmapToMemory(url, bitmap);
} else {
// 從網絡獲取
bitmap = getBitmapFromHttp(urlStr);
}
}
return bitmap;
}
/**
* 從內存或者緩存文件裏獲取bitmap
*/
public Bitmap getBitmapFromNative(String urlStr) {
String url = urlStr.hashCode() + "";
Bitmap bitmap = null;
bitmap = imageMemoryCache.getBitmapFromMemory(url);
if (bitmap == null) {
bitmap = imageFileCache.getImageFromFile(url);
if (bitmap != null) {
// 加入到內存緩存
imageMemoryCache.addBitmapToMemory(url, bitmap);
}
}
return bitmap;
}
/**
* 通過網絡下載圖片,與線程無關
*/
public Bitmap getBitmapFromHttp(String urlStr) {
String url = urlStr.hashCode() + "";
Bitmap bmp = null;
try {
byte[] tmpPicByte = getImageBytes(urlStr);
if (tmpPicByte != null) {
bmp = BitmapFactory.decodeByteArray(tmpPicByte, 0,
tmpPicByte.length);
}
tmpPicByte = null;
} catch (Exception e) {
e.printStackTrace();
}
if (bmp != null) {
// 加入到文件緩存
imageFileCache.saveBitmapToFile(bmp, url);
// 加入到內存緩存
imageMemoryCache.addBitmapToMemory(url, bmp);
}
return bmp;
}
/**
* 下載鏈接的圖片資源
*
* @param url
*
* @return 圖片
*/
public byte[] getImageBytes(String urlStr) {
if (urlStr != null && !"".equals(urlStr)) {
HttpGet get = new HttpGet(urlStr);
get.addHeader("Accept-Encoding", "indentity");
HttpClient client = new DefaultHttpClient();
HttpResponse response = null;
try {
response = client.execute(get);
if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
InputStream is = response.getEntity().getContent();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buf = new byte[1024];
int len = -1;
while ((len = is.read(buf)) != -1) {
baos.write(buf, 0, len);
}
return baos.toByteArray();
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
/**
* 取出等待隊列第一個任務，開始下載
*/
private void startDownloadNext() {
synchronized (waitingTaskMap) {
Iterator<Entry<String, Handler>> iter = waitingTaskMap.entrySet()
.iterator();
if (iter.hasNext()) {
Map.Entry<String, Handler> entry = (Map.Entry<String, Handler>) iter
.next();
if (entry != null) {
waitingTaskMap.remove(entry.getKey());
downloadBmpOnNewThread((String) entry.getKey(),
(Handler) entry.getValue());
}
}
}
}
/**
* 圖片變為圓角
*
* @param bitmap
* :傳入的bitmap
* @param pixels
* ：圓角的度數，值越大，圓角越大
* @return bitmap:加入圓角的bitmap
*/
public static Bitmap toRoundCorner(Bitmap bitmap, int pixels) {
if (bitmap == null)
return null;
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
final RectF rectF = new RectF(rect);
final float roundPx = pixels;
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
// paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
canvas.drawBitmap(bitmap, rect, rect, paint);
return output;
}
}
package com.panpass.main;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
public class ImageFileCache {
<span style="white-space:pre"> </span>private File cacheDir;
<span style="white-space:pre"> </span>public ImageFileCache(Context context) {
<span style="white-space:pre"> </span>// 假設有SD卡則在SD卡中建一個LazyList的文件夾存放緩存的圖片
<span style="white-space:pre"> </span>// 沒有SD卡就放在系統的緩存文件夾中
<span style="white-space:pre"> </span>if (android.os.Environment.getExternalStorageState().equals(
<span style="white-space:pre"> </span>android.os.Environment.MEDIA_MOUNTED))
<span style="white-space:pre"> </span>cacheDir = new File(
<span style="white-space:pre"> </span>android.os.Environment.getExternalStorageDirectory(),
<span style="white-space:pre"> </span>"LazyList");
<span style="white-space:pre"> </span>else
<span style="white-space:pre"> </span>cacheDir = context.getCacheDir();
<span style="white-space:pre"> </span>if (!cacheDir.exists())
<span style="white-space:pre"> </span>cacheDir.mkdirs();
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public Bitmap getImageFromFile(String url) {
<span style="white-space:pre"> </span>// 將url的hashCode作為緩存的文件名稱
<span style="white-space:pre"> </span>// Another possible solution
<span style="white-space:pre"> </span>// String filename = URLEncoder.encode(url);
<span style="white-space:pre"> </span>File f = new File(cacheDir, url);
<span style="white-space:pre"> </span>if(f.exists()){
<span style="white-space:pre"> </span>return BitmapFactory.decodeFile(f.getAbsolutePath());
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>return null;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void saveBitmapToFile(Bitmap bm ,String url) {
<span style="white-space:pre"> </span>File file=new File(cacheDir,url);//將要保存圖片的路徑
<span style="white-space:pre"> </span>try {
<span style="white-space:pre"> </span>BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
<span style="white-space:pre"> </span>bm.compress(Bitmap.CompressFormat.JPEG, 100, bos);
<span style="white-space:pre"> </span>bos.flush();
<span style="white-space:pre"> </span>bos.close();
<span style="white-space:pre"> </span>} catch (IOException e) {
<span style="white-space:pre"> </span>e.printStackTrace();
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void clear() {
<span style="white-space:pre"> </span>File[] files = cacheDir.listFiles();
<span style="white-space:pre"> </span>if (files == null)
<span style="white-space:pre"> </span>return;
<span style="white-space:pre"> </span>for (File f : files)
<span style="white-space:pre"> </span>f.delete();
<span style="white-space:pre"> </span>}
}
package com.panpass.main;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import android.graphics.Bitmap;
import android.util.Log;
public class ImageMemoryCache {
<span style="white-space:pre"> </span>private static final String TAG = "MemoryCache";
<span style="white-space:pre"> </span>/**
<span style="white-space:pre"> </span> * 放入緩存時是個同步操作 LinkedHashMap構造方法的最後一個參數true代表這個map裏的元素將依照最 近使用次數由少到多排列，
<span style="white-space:pre"> </span> * 即LRU。
<span style="white-space:pre"> </span> * 這種優點是假設要將緩存中的元素替換，則先遍歷出近期最少使用的元素來替換以提高效率
<span style="white-space:pre"> </span> */
<span style="white-space:pre"> </span>private Map<String, Bitmap> cache = Collections
<span style="white-space:pre"> </span>.synchronizedMap(new LinkedHashMap<String, Bitmap>(10, 1.5f, true));
<span style="white-space:pre"> </span>// 緩存中圖片所占用的字節，初始0，將通過此變量嚴格控制緩存所占用的堆內存
<span style="white-space:pre"> </span>private long size = 0;// current allocated size
<span style="white-space:pre"> </span>// 緩存僅僅能占用的最大堆內存
<span style="white-space:pre"> </span>private long limit = 1000000;// max memory in bytes
<span style="white-space:pre"> </span>public ImageMemoryCache() {
<span style="white-space:pre"> </span>// use 25% of available heap size
<span style="white-space:pre"> </span>setLimit(Runtime.getRuntime().maxMemory() / 4);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void setLimit(long new_limit) {
<span style="white-space:pre"> </span>limit = new_limit;
<span style="white-space:pre"> </span>Log.i(TAG, "MemoryCache will use up to " + limit / 1024. / 1024. + "MB");
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public Bitmap getBitmapFromMemory(String id) {
<span style="white-space:pre"> </span>try {
<span style="white-space:pre"> </span>if (!cache.containsKey(id))
<span style="white-space:pre"> </span>return null;
<span style="white-space:pre"> </span>return cache.get(id);
<span style="white-space:pre"> </span>} catch (NullPointerException ex) {
<span style="white-space:pre"> </span>return null;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void addBitmapToMemory(String id, Bitmap bitmap) {
<span style="white-space:pre"> </span>try {
<span style="white-space:pre"> </span>if (cache.containsKey(id))
<span style="white-space:pre"> </span>size -= getSizeInBytes(cache.get(id));
<span style="white-space:pre"> </span>cache.put(id, bitmap);
<span style="white-space:pre"> </span>size += getSizeInBytes(bitmap);
<span style="white-space:pre"> </span>checkSize();
<span style="white-space:pre"> </span>} catch (Throwable th) {
<span style="white-space:pre"> </span>th.printStackTrace();
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>/**
<span style="white-space:pre"> </span> * 嚴格控制堆內存，假設超過將首先替換近期最少使用的那個圖片緩存
<span style="white-space:pre"> </span> *
<span style="white-space:pre"> </span> */
<span style="white-space:pre"> </span>private void checkSize() {
<span style="white-space:pre"> </span>Log.i(TAG, "cache size=" + size + " length=" + cache.size());
<span style="white-space:pre"> </span>if (size > limit) {
<span style="white-space:pre"> </span>// 先遍歷近期最少使用的元素
<span style="white-space:pre"> </span>Iterator<Entry<String, Bitmap>> iter = cache.entrySet().iterator();
<span style="white-space:pre"> </span>while (iter.hasNext()) {
<span style="white-space:pre"> </span>Entry<String, Bitmap> entry = iter.next();
<span style="white-space:pre"> </span>size -= getSizeInBytes(entry.getValue());
<span style="white-space:pre"> </span>iter.remove();
<span style="white-space:pre"> </span>if (size <= limit)
<span style="white-space:pre"> </span>break;
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>Log.i(TAG, "Clean cache. New size " + cache.size());
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void clear() {
<span style="white-space:pre"> </span>cache.clear();
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>/**
<span style="white-space:pre"> </span> * 圖片占用的內存
<span style="white-space:pre"> </span> *
<span style="white-space:pre"> </span> * @param bitmap
<span style="white-space:pre"> </span> * @return
<span style="white-space:pre"> </span> */
<span style="white-space:pre"> </span>long getSizeInBytes(Bitmap bitmap) {
<span style="white-space:pre"> </span>if (bitmap == null)
<span style="white-space:pre"> </span>return 0;
<span style="white-space:pre"> </span>return bitmap.getRowBytes() * bitmap.getHeight();
<span style="white-space:pre"> </span>}
}
package com.panpass.main;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Window;
import android.widget.ImageView;
import com.example.imgdemo.R;
public class MainActivity extends Activity {
<span style="white-space:pre"> </span>private Context mContext = this;
<span style="white-space:pre"> </span>private ImageView img1,img2,img3,img4,img5;
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>protected void onCreate(Bundle savedInstanceState) {
<span style="white-space:pre"> </span>super.onCreate(savedInstanceState);
<span style="white-space:pre"> </span>getWindow().requestFeature(Window.FEATURE_NO_TITLE);
<span style="white-space:pre"> </span>setContentView(R.layout.main_acticity);
<span style="white-space:pre"> </span>img1 = (ImageView) findViewById(R.id.img1);
<span style="white-space:pre"> </span>img2 = (ImageView) findViewById(R.id.img2);
<span style="white-space:pre"> </span>img3 = (ImageView) findViewById(R.id.img3);
<span style="white-space:pre"> </span>img4 = (ImageView) findViewById(R.id.img4);
<span style="white-space:pre"> </span>img5 = (ImageView) findViewById(R.id.img5);
<span style="white-space:pre"> </span>ImageManager.getInstance(mContext).loadBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif", new Handler(){
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void handleMessage(Message msg) {
<span style="white-space:pre"> </span>super.handleMessage(msg);
<span style="white-space:pre"> </span>img1.setImageBitmap((Bitmap)msg.obj);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>ImageManager.getInstance(mContext).loadBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif", new Handler(){
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void handleMessage(Message msg) {
<span style="white-space:pre"> </span>super.handleMessage(msg);
<span style="white-space:pre"> </span>img2.setImageBitmap((Bitmap)msg.obj);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>ImageManager.getInstance(mContext).loadBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif", new Handler(){
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void handleMessage(Message msg) {
<span style="white-space:pre"> </span>super.handleMessage(msg);
<span style="white-space:pre"> </span>img3.setImageBitmap((Bitmap)msg.obj);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>ImageManager.getInstance(mContext).loadBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif", new Handler(){
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void handleMessage(Message msg) {
<span style="white-space:pre"> </span>super.handleMessage(msg);
<span style="white-space:pre"> </span>img4.setImageBitmap((Bitmap)msg.obj);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>ImageManager.getInstance(mContext).loadBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?
v=26599715.gif", new Handler(){
<span style="white-space:pre"> </span>@Override
<span style="white-space:pre"> </span>public void handleMessage(Message msg) {
<span style="white-space:pre"> </span>super.handleMessage(msg);
<span style="white-space:pre"> </span>img5.setImageBitmap((Bitmap)msg.obj);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>});
<span style="white-space:pre"> </span>//<span style="white-space:pre"> </span>img2.setImageBitmap(ImageManager.getInstance(mContext).getBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?
v=26599715.gif"));
<span style="white-space:pre"> </span>//
<span style="white-space:pre"> </span>//<span style="white-space:pre"> </span>img3.setImageBitmap(ImageManager.getInstance(mContext).getBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif"));
<span style="white-space:pre"> </span>//<span style="white-space:pre"> </span>img4.setImageBitmap(ImageManager.getInstance(mContext).getBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif"));
<span style="white-space:pre"> </span>//<span style="white-space:pre"> </span>img5.setImageBitmap(ImageManager.getInstance(mContext).getBitmap("https://www.baidu.com/img/baidu_jgylogo3.gif?v=26599715.gif"));
<span style="white-space:pre"> </span>}
}
Android 內存+文件+網絡三級緩存