查看网上关于通过InputStream一般是这么写的
public void saveBit(InputStream inStream) throws IOException{
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
//创建一个Buffer字符串
byte[] buffer = new byte[1024];
//每次读取的字符串长度，如果为-1，代表全部读取完毕
int len = 0;
//使用一个输入流从buffer里把数据读取出来
while( (len=inStream.read(buffer)) != -1 ){
//用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度
outStream.write(buffer, 0, len);
}
//关闭输入流
inStream.close();
//把outStream里的数据写入内存
//得到图片的二进制数据，以二进制封装得到数据，具有通用性
byte[] data = outStream.toByteArray();
//new一个文件对象用来保存图片，默认保存当前工程根目录
File imageFile = new File("E:/BeautyGirl.jpg");
//创建输出流
FileOutputStream fileOutStream = new FileOutputStream(imageFile);
//写入数据
fileOutStream .write(data);
}
但是 (len=inStream.read(buffer)) != -1 在kotlin中等式不是一个表达式
因此需要使用also方法 参考https://blog.csdn.net/u011976726/article/details/79125950
inputStream.read(buffer).also { length = it } != -1
Fresco官网有https://www.fresco-cn.org/docs/datasources-datasubscribers.html
关于数据源下载处理方法，一些比较复杂、耗时的操作，并且不涉及UI（如数据库读写、文件IO）我这里用的是Executors.newSingleThreadExecutor()
object FrescoImageLoader {
val SAVE_DIR = File(Environment.getExternalStorageDirectory(), "pic")
fun downImageView(url: String?, onSuccess:(File)-> Unit , onFailure: ((Throwable) -> Unit)? = null) {
if (url.isNullOrEmpty()) {
onFailure?.invoke(IOException("未指定Url"))
}
val dataSource: DataSource<CloseableReference<PooledByteBuffer>> = Fresco.getImagePipeline().fetchEncodedImage(ImageRequest.fromUri(url), null)
dataSource.subscribe(object : BaseDataSubscriber<CloseableReference<PooledByteBuffer>?>() {
override fun onFailureImpl(dataSource: DataSource<CloseableReference<PooledByteBuffer>?>?) {
onFailure?.invoke(IOException("加载失败"))
}
override fun onNewResultImpl(dataSource: DataSource<CloseableReference<PooledByteBuffer>?>?) {
if (dataSource?.isFinished == false) {
return
}
var ref = dataSource?.result
if (ref != null) {
try {
val result = ref.get()
val inputStream: InputStream = PooledByteBufferInputStream(result)
try {
val imageFormat = ImageFormatChecker.getImageFormat(inputStream)
val suffix = when (imageFormat) {
DefaultImageFormats.JPEG -> ".jpg"
DefaultImageFormats.PNG -> ".png"
DefaultImageFormats.GIF -> ".gif"
DefaultImageFormats.BMP -> ".bmp"
else -> ".jpg"
}
val name = "pic_" + System.currentTimeMillis() + suffix
val distFile = FileUtil.generateUniqueFile(SAVE_DIR, name)
val out : FileOutputStream = FileOutputStream(distFile)
val buffer = ByteArray(1024)
var length = 0
/*
val outStream = ByteArrayOutputStream()
inputStream.use { input ->
outStream.use {
while (inputStream.read(buffer).also { length = it } != -1){
it.write(buffer, 0, length)
}
}
}
//得到图片的二进制数据，以二进制封装得到数据，具有通用性
val data = outStream.toByteArray()
out.write(data)*/
inputStream.use {input ->
out.use {
while (input.read(buffer).also { length = it } != -1){
it.write(buffer,0, length)
}
}
}
inputStream.closeSafe()
out.closeSafe()
if (distFile != null){
onSuccess(distFile)
} else {
onFailure?.invoke(IOException("下载失败"))
}
} catch (e: Exception) {
onFailure?.invoke(IOException("下载失败"))
} finally {
Closeables.closeQuietly(inputStream)
}
} catch (e: Exception) {
onFailure?.invoke(IOException("下载失败"))
} finally {
CloseableReference.closeSafely(ref)
ref = null
}
}
}
}, Executors.newSingleThreadExecutor())
}
}
