学步园

public class TestHttpResume {

    public static void main(String[] args) throws Exception {
        BufferedOutputStream output = null;
        BufferedInputStream br = null;
        URL url = new URL("http://IP/test.war");
        HttpURLConnection httpConnection = (HttpURLConnection) url.openConnection(Proxy.NO_PROXY); // 设置 User-Agent
        httpConnection.setRequestProperty("User-Agent", "NetFox"); // 设置断点续传的开始位置
        httpConnection.setRequestProperty("RANGE", "bytes=0-100"); // 获得输入流
        InputStream input = httpConnection.getInputStream();

        RandomAccessFile file = new RandomAccessFile(new File("D://lms3.war"), "rw");
        long nPos = 0;
        // 定位文件指针到 nPos 位置
        file.seek(0);
        byte[] b = new byte[1024];
        int nRead; // 从输入流中读入字节流，然后写到文件中
        while ((nRead = input.read(b)) > 0) {
            file.write(b, 0, nRead);
        }

    }
}

实现前100 的 下载

之后修改httpConnection.setRequestProperty("RANGE", "bytes=0-100"); // 获得输入流
 为100-

文件定位到   file.seek(100);

至此文件完结 

实际可动态修改 参数 实现http文件流的 断点下载