Android 存储网络图片到SD卡，并且无网络状态时显示圆形头像

上一个项目完工有需求是要在无网络状态时能够加载名字和头像，名字好说，在SharedPreferences中存储后，判断无网络链接后就直接读取就行了，但头像需要存储在sd卡，一开始的构思是在onCreate方法中imageview在使用glide显示后再通过imageView的到bitmap然后存储到sd卡中

public static void saveBookpic(ImageView iv, String strLocalFile) {
if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {
//创建一个文件夹对象，赋值为外部存储器的目录
File sdcardDir = Environment.getExternalStorageDirectory();
//得到一个路径，内容是sdcard的文件夹路径和名字
File file = new File(strLocalFile);//图片路径
iv.setDrawingCacheEnabled(true);
if (!file.exists()) {
Bitmap bm = iv.getDrawingCache();
BufferedOutputStream bos;
try {
bos = new BufferedOutputStream(new FileOutputStream(file));
bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
bos.flush();
bos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

但后来发现存储的一直是glide的占位的图片，因为oncreate方法没有执行完，glide的网络图片并没有显示出来，所以只能通过网络直接把网络资源存储在sd卡了，下面就是我的异步任务

class SavePicURLAsync extends AsyncTask<String, String, String> {

@Override
protected String doInBackground(String... params) {
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(图片网址);
try {
HttpResponse response = httpClient.execute(httpGet);
if (response.getStatusLine().getStatusCode() == 200) {
HttpEntity entity = response.getEntity();
InputStream is = entity.getContent();

File f = new File(strLocalFile);//想要存储的本地路径
f.createNewFile();
FileOutputStream fos = null;
try {
fos = new FileOutputStream(f);
byte[] buf = new byte[1024];
int length;
while ((length = is.read(buf)) != -1) {
fos.write(buf, 0, length);
}

is.close();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
try {
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}

注意需要先判断一下有没有网络和sd卡中文件有没有存在哦，

对了，通常情况下头像都是圆形的，在网络情况下使用glide直接加载圆形图片需要使用glide 的bitmapTransform属性，我一直是这么使用

Glide.with(mContext)
.load(Picurl)//图片网址
.error(R.mipmap.bookpic)//加载出错时显示的图片
.placeholder(R.mipmap.bookpic)//加载中显示的图片
.bitmapTransform(new CropCircleTransformation(mContext)).crossFade(1000)//图片转化为圆形
.into(mimglearningBook);

CropCircleTransformation这个类我也忘了是哪个码神大大给的了，

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import com.bumptech.glide.Glide;
import com.bumptech.glide.load.Transformation;
import com.bumptech.glide.load.engine.Resource;
import com.bumptech.glide.load.engine.bitmap_recycle.BitmapPool;
import com.bumptech.glide.load.resource.bitmap.BitmapResource;
/**
* Created by Administrator on 2016/11/24 0024.
*/
public class CropCircleTransformation implements Transformation<Bitmap> {
private BitmapPool mBitmapPool;
public CropCircleTransformation(Context context) {
this(
4000
Glide.get(context).getBitmapPool());
}
public CropCircleTransformation(BitmapPool pool) {
this.mBitmapPool = pool;
}
@Override
public Resource<Bitmap> transform(Resource<Bitmap> resource, int outWidth, int outHeight) {
Bitmap source = resource.get();
int size = Math.min(source.getWidth(), source.getHeight());
int width = (source.getWidth() - size) / 2;
int height = (source.getHeight() - size) / 2;
Bitmap bitmap = mBitmapPool.get(size, size, Bitmap.Config.ARGB_8888);
if (bitmap == null) {
bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
}
Canvas canvas = new Canvas(bitmap);
Paint paint = new Paint();
BitmapShader shader =
new BitmapShader(source, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP);
source.recycle();
if (width != 0 || height != 0) {
// source isn't square, move viewport to center
Matrix matrix = new Matrix();
matrix.setTranslate(-width, -height);
shader.setLocalMatrix(matrix);
}
paint.setShader(shader);
paint.setAntiAlias(true);
float r = size / 2f;
canvas.drawCircle(r, r, r, paint);
return BitmapResource.obtain(bitmap, mBitmapPool);
}
@Override public String getId() {
return "CropCircleTransformation()";
}

}

这样就能加载圆形图片了，一开始脑子抽了一下，忘了glide也可以加载sd卡中的图片了，还想要自定义一个圆形imageView，

if (!Tools.isNetworkConnected(mContext)) {//如果没网
mtextlearingBook.setText(SharedPreferencesUtil.getSaveLearningBookName(mContext));
Glide.with(mContext)
.load( Uri.fromFile( new File(图片网址) ) )
.bitmapTransform(new CropCircleTransformation(mContext)).crossFade(1000)//转化为圆形
.into(mimglearningBook);
} else {
new GetPredictTask().execute();
}

这样就能在无网络状态加载已存在与sd卡的图片文件了