实现InputStream的任意拷贝

ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
byte[] buffer = new byte[1024];
int len;
while ((len = input.read(buffer)) > -1 ) {
    baos.write(buffer, 0, len);
}
baos.flush();
 
// 打开一个新的输入流
InputStream is1 = new ByteArrayInputStream(baos.toByteArray()); 
InputStream is2 = new ByteArrayInputStream(baos.toByteArray());

将输入流拷贝成字节数组

public class StreamUtils{ // 在Spring的包下, 可以直接使用
    public static byte[] copyToByteArray(@Nullable InputStream in) throws IOException {
        if (in == null) {
            return new byte[0];
        }

        ByteArrayOutputStream out = new ByteArrayOutputStream(BUFFER_SIZE);
        copy(in, out);
        return out.toByteArray();
    }

    public static int copy(InputStream in, OutputStream out) throws IOException {
        Assert.notNull(in, "No InputStream specified");
        Assert.notNull(out, "No OutputStream specified");

        int byteCount = 0;
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;
        while ((bytesRead = in.read(buffer)) != -1) {
            out.write(buffer, 0, bytesRead);
            byteCount += bytesRead;
        }
        out.flush();
        return byteCount;
    }
}