Java，使用 goo.gl API 缩短 URL？

Question

我正在尝试在不使用外部库的情况下使用 Java 执行此操作。我不能使用外部库来执行此操作，因为我没有在这个项目中使用 Maven。

我使用的方法是:

public static String shorten(String longUrl) {
    if (longUrl == null) {
        return longUrl;
    }

    StringBuilder sb = null;
    String line = null;
    String urlStr = longUrl;

    try {
        URL url = new URL("https://www.googleapis.com/urlshortener/v1/url");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("POST");
        connection.setRequestProperty("User-Agent", "toolbar");

        OutputStreamWriter writer = new OutputStreamWriter(connection.getOutputStream());
        writer.write("url=" + URLEncoder.encode(urlStr, "UTF-8"));
        writer.close();

        BufferedReader rd = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        sb = new StringBuilder();
        while ((line = rd.readLine()) != null) {
            sb.append(line + '\n');
        }

        String json = sb.toString();
        return json.substring(json.indexOf("http"), json.indexOf("\"", json.indexOf("http")));
    } catch (MalformedURLException e) {
        e.printStackTrace();
        return longUrl;
    } catch (IOException e) {
        e.printStackTrace();
        return longUrl;
    }
}

我得到的错误是:

[23:30:44 WARN]: java.io.IOException: Server returned HTTP response code: 400 for URL: https://www.googleapis.com/urlshortener/v1/url
[23:30:44 WARN]:    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1838)
[23:30:44 WARN]:    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1439)
[23:30:44 WARN]:    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)

如果此方法不起作用，是否有一些不需要外部 jar 的简单 Java URL 缩短替代方案？感谢您的帮助!

编辑

api 的 url 是错误的。也用新错误更新了它。

Answer 1

尝试使用此代码将您的链接重定向到最终目的地。虽然它使用 Apache HTTP 客户端库。这是我可以成功重定向到每个可能的有效链接的唯一方法。其他方法对我来说准确性较低。

private static String linkCorrector(String link) throws ClientProtocolException, IOException{
        HttpClient client = new DefaultHttpClient();
        HttpParams params = client.getParams();
        HttpClientParams.setRedirecting(params, false);
        HttpGet method = new HttpGet(link);
        HttpResponse resp = client.execute(method);
        String location = null;
        Header h = resp.getLastHeader("Location");
        if(h == null || h.getValue() == null){
            location = "";
        }
        else{
            location = resp.getLastHeader("Location").getValue();
        }
        return location;
    }