java - 我正在尝试使用 java 下载 facebook 个人资料图片。但是出现错误

Question

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Authenticator;
import java.net.PasswordAuthentication;
import java.net.URL;

public class SaveImageFromUrl {

    public static void main(String[] args) throws Exception {

        // proxy settings
        System.setProperty("http.proxyHost", "porxyHost");
        System.setProperty("http.proxyPort", "8080");
        Authenticator authenticator = new Authenticator() {
             public PasswordAuthentication getPasswordAuthentication() {
            return (new PasswordAuthentication("userxyz","password".toCharArray()));
            }
        };
        Authenticator.setDefault(authenticator);

        String imageUrl = "https://graph.facebook.com/10000012233xxxx/picture";
        String destinationFile = "D://image4.jpg";

        saveImage(imageUrl, destinationFile);
    }

    public static void saveImage(String imageUrl, String destinationFile) throws IOException {
        URL url = new URL(imageUrl);
        InputStream is = url.openStream();
        OutputStream os = new FileOutputStream(destinationFile);

        byte[] b = new byte[2048];
        int length;

        while ((length = is.read(b)) != -1) {
            os.write(b, 0, length);
        }

        is.close();
        os.close();
    }

}

我的代码工作正常并下载其他 imageurl 路径的图像。但是当我使用 String imageUrl = "https://graph.facebook.com/10000012233xxxx/picture "; 时它不起作用

我收到以下错误:

Exception in thread "main" java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.connect(Unknown Source)
    at sun.security.ssl.BaseSSLSocketImpl.connect(Unknown Source)
    at sun.net.NetworkClient.doConnect(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.http.HttpClient.openServer(Unknown Source)
    at sun.net.www.protocol.https.HttpsClient.<init>(Unknown Source)
    at sun.net.www.protocol.https.HttpsClient.New(Unknown Source)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
    at java.net.URL.openStream(Unknown Source)
    at SaveImageFromUrl.saveImage(SaveImageFromUrl.java:33)
    at SaveImageFromUrl.main(SaveImageFromUrl.java:28)

Answer 1

您需要确保您的应用程序可以遵循重定向，因为如果您请求，Facebook 就会发送重定向

/{user_id}/picture

要实现这一点，请查看 http://www.mkyong.com/java/java-httpurlconnection-follow-redirect-example/

另外，尝试像这样设置代理身份验证:

System.setProperty( "http.proxyUserName", "username" );
System.setProperty( "http.proxyPassword", "password" );

我怀疑您的代理连接超时，但您应该能够自己测试这一点。