一、前言：
我们在视频直播时，展示背景图片，经常由于网络较差，展示背景图片失败，所以提前把图片缓存到本地。
最后需要注意的下载保存需要读写权限，6.0以上需手动申请权限
android.permission.WRITE_EXTERNAL_STORAGE
android.permission.READ_EXTERNAL_STORAGE
二、下载过程：
1. 调用
Observable.create(new ObservableOnSubscribe<File>() {
@Override
public void subscribe(ObservableEmitter<File> e) throws Exception {
//通过gilde下载得到file文件,这里需要注意android.permission.INTERNET权限
e.onNext(Glide.with(mContext)
.load(imagePathList.get(currentViewPosition).getPath())
.downloadOnly(Target.SIZE_ORIGINAL, Target.SIZE_ORIGINAL)
.get());
e.onComplete();
}
}).subscribeOn(Schedulers.io())
.observeOn(Schedulers.newThread())
.subscribe(new Consumer<File>() {
@Override
public void accept(File file) throws Exception {
//获取到下载得到的图片，进行本地保存
File pictureFolder = Environment.getExternalStorageDirectory();
//第二个参数为你想要保存的目录名称
File appDir = new File(pictureFolder, "your_picture_save_path");
if (!appDir.exists()) {
appDir.mkdirs();
}
String fileName = System.currentTimeMillis() + ".jpg";
File destFile = new File(appDir, fileName);
//把gilde下载得到图片复制到定义好的目录中去
copy(file, destFile);
// 最后通知图库更新
sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
Uri.fromFile(new File(destFile.getPath()))));
}
});
2. 带上复制文件的方法：
/**
* 复制文件
*
* @param source 输入文件
* @param target 输出文件
*/
public void copy(File source, File target) {
FileInputStream fileInputStream = null;
FileOutputStream fileOutputStream = null;
try {
fileInputStream = new FileInputStream(source);
fileOutputStream = new FileOutputStream(target);
byte[] buffer = new byte[1024];
while (fileInputStream.read(buffer) > 0) {
fileOutputStream.write(buffer);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
fileInputStream.close();
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
原文链接：https://blog.csdn.net/asswc2004/article/details/80537255
