Java - 无法从 URL 获取 html 代码

Question

我想获取https://www2.cslb.ca.gov/OnlineServices/CheckLicenseII/LicenseDetail.aspx?LicNum=872423的html源代码 为此，我正在使用此方法，但我没有获得 html 源代码。

public static String getHTML(URL url) {
    HttpURLConnection conn; // The actual connection to the web page
    BufferedReader rd; // Used to read results from the web page
    String line; // An individual line of the web page HTML
    String result = ""; // A long string containing all the HTML
    try {
        conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod("GET");
        rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        while ((line = rd.readLine()) != null) {
            result += line;
        }
        rd.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return result;
}

Answer 1

服务器过滤掉Java的默认User-Agent。这有效:

public static String getHTML(URL url) {
    try {
        final URLConnection urlConnection = url.openConnection();
        urlConnection.addRequestProperty("User-Agent", "Foo?");
        final InputStream inputStream = urlConnection.getInputStream();
        final String html = IOUtils.toString(inputStream);
        inputStream.close();
        return html;
    } catch (Exception e) {
        throw new RuntimeException(e);
    }

看起来用户代理已被列入黑名单。默认情况下，我的 JDK 发送:

User-Agent: Java/1.6.0_26

请注意，我正在使用 IOUtils类来简化示例，但关键是:

urlConnection.addRequestProperty("User-Agent", "Foo?");