直接下载 和 断点续传(直接下载)

package cn.hp.test;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;


public class Test {
    public static void main(String[] args) {
        String path ="http://softforspeed.51xiazai.cn/down/BaiduNetdisk_6.9.7.4.exe";
        try {
            //创建一个URL对象
            URL url = new URL(path);
            //打开连接 ,获取了url请求的连接对象conn
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            //请求设置
            conn.setConnectTimeout(5000);//setConnectTimeout 请求的超时时间
            conn.setReadTimeout(5000);//setReadTimeout 读取超时时间
            conn.setRequestMethod("GET");//设置请求提交的方法Get Post

            //获取响应码
            int responseCode = conn.getResponseCode();
            System.out.println("responseCode = " + responseCode);

            //如果响应码200 连接成功
            if(responseCode == 200){
                InputStream in = conn.getInputStream(); //获取用于读取网络资源的输入流

                //下载的流
                String fileName = conn.getHeaderField("Content-Disposition"); //获取相应的头部文件(包含由文件名)

                fileName = fileName.split(";")[1];
                fileName = fileName.substring(fileName.indexOf(""")+1,fileName.lastIndexOf("""));

                System.out.println("fileName = " + fileName);//成功获取文件名

                File file = new File("fileName");
                RandomAccessFile raf = new RandomAccessFile(file, "rwd");//"rwd" 赋权限 可读可写

                //读一组,下载一组
                byte[] bytes = new byte[1024];
                int len = 0;
                while ((len=in.read(bytes))!=-1){
                    raf.write(bytes,0,len);
                }

                //关闭流 释放资源
                raf.close();
                in.close();
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}