我惊奇地发现，今天我找不到任何简单的方法来用Java将InputStream的内容写入OutputStream。显然，编写字节缓冲区代码并不难，但我怀疑我只是缺少了一些可以使我的工作更简单(并且代码更清晰)的东西。
那么，给定一个InputStream in和一个OutputStream out，是否有一种更简单的方法来编写下面的代码?
byte[] buffer = new byte[1024];
int len = in.read(buffer);
while (len != -1) {
out.write(buffer, 0, len);
len = in.read(buffer);
}
当前回答
可读性不是很好，但是很有效，没有依赖关系，可以在任何java版本上运行
byte[] buffer=new byte[1024];
for(int n; (n=inputStream.read(buffer))!=-1; outputStream.write(buffer,0,n));
其他回答
使用Commons Net的Util类:
import org.apache.commons.net.io.Util;
...
Util.copyStream(in, out);
public static boolean copyFile(InputStream inputStream, OutputStream out) {
byte buf[] = new byte[1024];
int len;
long startTime=System.currentTimeMillis();
try {
while ((len = inputStream.read(buf)) != -1) {
out.write(buf, 0, len);
}
long endTime=System.currentTimeMillis()-startTime;
Log.v("","Time taken to transfer all bytes is : "+endTime);
out.close();
inputStream.close();
} catch (IOException e) {
return false;
}
return true;
}
下面是我如何使用最简单的for循环。
private void copy(final InputStream in, final OutputStream out)
throws IOException {
final byte[] b = new byte[8192];
for (int r; (r = in.read(b)) != -1;) {
out.write(b, 0, r);
}
}
试试Cactoos:
new LengthOf(new TeeInput(input, output)).value();
更多详情请访问:http://www.yegor256.com/2017/06/22/object-oriented-input-output-in-cactoos.html
我使用ByteStreamKt。copyTo(src, dst, buffer.length)方法
这是我的代码
public static void replaceCurrentDb(Context context, Uri newDbUri) {
try {
File currentDb = context.getDatabasePath(DATABASE_NAME);
if (currentDb.exists()) {
InputStream src = context.getContentResolver().openInputStream(newDbUri);
FileOutputStream dst = new FileOutputStream(currentDb);
final byte[] buffer = new byte[8 * 1024];
ByteStreamsKt.copyTo(src, dst, buffer.length);
src.close();
dst.close();
Toast.makeText(context, "SUCCESS! Your selected file is set as current menu.", Toast.LENGTH_LONG).show();
}
else
Log.e("DOWNLOAD:::: Database", " fail, database not found");
}
catch (IOException e) {
Toast.makeText(context, "Data Download FAIL.", Toast.LENGTH_LONG).show();
Log.e("DOWNLOAD FAIL!!!", "fail, reason:", e);
}
}
