add toOutputStream(InputStream is, OutputStream os, long start, long end)

src/main/java/com/imyeyu/io/IO.java

@@ -643,6 +643,24 @@ public class IO implements OS.FileSystem {
 		return !interrupt;
 	}
 
+	public static void toOutputStream(InputStream is, OutputStream os, long start, long end) throws IOException {
+		long skip = is.skip(start);
+		if (skip != start) {
+			throw new TimiException(TimiCode.ERROR, "skip fail");
+		}
+		byte[] buffer = new byte[8192];
+		long remaining = end - start + 1;
+		while (0 < remaining) {
+			int toRead = (int) Math.min(buffer.length, remaining);
+			int read = is.read(buffer, 0, toRead);
+			if (read == -1) {
+				break;
+			}
+			os.write(buffer, 0, read);
+			remaining -= read;
+		}
+	}
+
 	/**
 	 * 写入字节到文件随机访问对象，此操作不会关闭流
 	 *