如何在Android上获取重定向的URL？

Question

我可以使用以下代码在java中执行此操作：

  String url = "http://t.co/i5dE1K4vSs";

  URLConnection conn = new URL( url ).openConnection();
  System.out.println( "orignal url: " + conn.getURL() );
  conn.connect();
  System.out.println( "connected url: " + conn.getURL() );
  InputStream inputS = conn.getInputStream();
  System.out.println( "redirected url: " + conn.getURL() );
  inputS.close();

现在在Android中，当点击一个按钮时，它会调用：

public void followRedirects(View v) throws ClientProtocolException, IOException, URISyntaxException
{
  String url = "http://t.co/i5dE1K4vSs";

  URLConnection conn = new URL( url ).openConnection();
  System.out.println( "orignal url: " + conn.getURL() );
  conn.connect();
  System.out.println( "connected url: " + conn.getURL() );
  InputStream inputS = conn.getInputStream();
  System.out.println( "redirected url: " + conn.getURL() );
  inputS.close();
}

这是我在android中的错误日志

Answer 1

就像你看到最底层的例外是NetworkOnMainThreadException。为了确保性能，Android SDK可以防止开发人员（及其应用程序）在主（UI）线程上进行非本地连接及其操作。您可以使用您发布的相同代码段，只需要确保它在非UI线程上运行。

E.g。

new Thread(new Runnable() {
    @Override
    public void run() {
        followRedirects(null);
    }
}).start();

或者如果您希望它在点击时执行：

 public void followRedirects(View v) throws ClientProtocolException, IOException, URISyntaxException
{
  new Thread(new Runnable() {
    @Override
    public void run() {
        String url = "http://t.co/i5dE1K4vSs";

        URLConnection conn = new URL( url ).openConnection();
        System.out.println( "orignal url: " + conn.getURL() );
        conn.connect();
        System.out.println( "connected url: " + conn.getURL() );
        InputStream inputS = conn.getInputStream();
        System.out.println( "redirected url: " + conn.getURL() );
        inputS.close();
    }
  }).start();
}