java 网络编程-爬虫+模拟浏览器

public class http {

public static void main(String[]args) throws  Exception
{
    //http+s更安全
    //URL.openStream()打开于URL的连接，并返回一个InputStream用于从连接中读取数据
    //获取URL
    URL url=new URL("https://www.jd.com");
    //下载资源
    InputStream is = url.openStream();
    BufferedReader br=new BufferedReader(new InputStreamReader(is,"UTF-8"));;
    String msg=null;
    while((msg=br.readLine())!=null)
    {

        System.out.println(msg);
    }
    br.close();
}
}

获取有权限网络资源:

public class http {

public static void main(String[]args) throws  Exception
{
    //.openConnectio，,返回一个URLConnection实例表示由所引用的远程对象的连接URL
    //URLConnection的子类有HttpURLConnection和JarURLConnection
    URL url=new URL("https://www.jd.com");
    //下载资源
    HttpURLConnection conn=(HttpURLConnection)url.openConnection();
    conn.setRequestMethod("GET");//模拟浏览器得get请求
    conn.setRequestProperty( "User-Agent","Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML,like Gecko) Chrome/64.0.3282.140 Safari/537.36 Edge/18.17763");
    BufferedReader br=new BufferedReader(new InputStreamReader(conn.getInputStream(),"UTF-8"));
    String msg=null;
    while((msg=br.readLine())!=null)
    {

        System.out.println(msg);
    }
    br.close();
}
}