DiskLruCache使用指南

效果图

DiskLruCache下载

使用代码

public class DisLruCacheActivity extends BaseActivity {

private DiskLruCache mDiskLruCache;
private Context context;
private ImageView imageView;
private String imageUrl = "http://img02.sogoucdn.com/app/a/100520024/3083d67034424958852fa8a3c2fcd656";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_retrofit);

context = this;
imageView = (ImageView) findViewById(R.id.iv_new);

try {
File cacheDir = getDiskCacheDir(context, "bitmap");
if (!cacheDir.exists()) {
cacheDir.mkdirs();
}
//获取DiskLruCache对象
mDiskLruCache = DiskLruCache.open(cacheDir, getAppVersion(context), 1, 10 * 1024 * 1024);
} catch (IOException e) {
e.printStackTrace();
}

//获取缓存对象
try {
String key = hashKeyForDisk(imageUrl);
DiskLruCache.Snapshot snapShot = mDiskLruCache.get(key);
if (snapShot != null) {
InputStream is = snapShot.getInputStream(0);
Bitmap bitmap = BitmapFactory.decodeStream(is);
imageView.setImageBitmap(bitmap);
}
} catch (IOException e) {
e.printStackTrace();
}

//写入缓存对象
new Thread(new Runnable() {
@Override
public void run() {
try {
String key = hashKeyForDisk(imageUrl);
DiskLruCache.Editor editor = mDiskLruCache.edit(key);
if (editor != null) {
OutputStream outputStream = editor.newOutputStream(0);
if (downloadUrlToStream(imageUrl, outputStream)) {
editor.commit();
} else {
editor.abort();
}
}
mDiskLruCache.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();

}

//下载图片
private boolean downloadUrlToStream(String urlString, OutputStream outputStream) {
HttpURLConnection urlConnection = null;
BufferedOutputStream out = null;
BufferedInputStream in = null;
try {
final URL url = new URL(urlString);
urlConnection = (HttpURLConnection) url.openConnection();
in = new BufferedInputStream(urlConnection.getInputStream(), 8 * 1024);
out = new BufferedOutputStream(outputStream, 8 * 1024);
int b;
while ((b = in.read()) != -1) {
out.write(b);
}
return true;
} catch (final IOException e) {
e.printStackTrace();
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
try {
if (out != null) {
out.close();
}
if (in != null) {
in.close();
}
} catch (final IOException e) {
e.printStackTrace();
}
}
return false;
}

//生成MD5编码
public String hashKeyForDisk(String key) {
String cacheKey;
try {
final MessageDigest mDigest = MessageDigest.getInstance("MD5");
mDigest.update(key.getBytes());
cacheKey = bytesToHexString(mDigest.digest());
} catch (NoSuchAlgorithmException e) {
cacheKey = String.valueOf(key.hashCode());
}
return cacheKey;
}

private String bytesToHexString(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; i++) {
String hex = Integer.toHexString(0xFF & bytes[i]);
if (hex.length() == 1) {
sb.append('0');
}
sb.append(hex);
}
return sb.toString();
}

//获取缓存路径
public File getDiskCacheDir(Context context, String uniqueName) {
String cachePath;
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())
|| !Environment.isExternalStorageRemovable()) {
cachePath = context.getExternalCacheDir().getPath();
} else {
cachePath = context.getCacheDir().getPath();
}
return new File(cachePath + File.separator + uniqueName);
}

//获取版本号
public int getAppVersion(Context context) {
try {
PackageInfo info = context.getPackageManager().getPackageInfo(context.getPackageName(), 0);
return info.versionCode;
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
return 1;
}

}

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