java中的HTTPS和HTTP连接答案

【问题标题】：HTTPS and HTTP connection in javajava中的HTTPS和HTTP连接
【发布时间】：2017-11-09 13:25:33
【问题描述】：

我知道 HTTPS 扩展了 http。那么这是否意味着我可以做到这一点？

HttpUrlConnection connect = passmyurl.openconnection(url);

和

HttpsUrlConnection connect = passmyurl.openconnection(url);



public static HttpsURLConnection passmyurl(URL url) throws IOException {
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
        return connection;
    }

这是否意味着两者都会起作用？由于 HTTps 扩展了 HTTP，这意味着我也可以将 HTTP url 传递给这个函数吗？

【问题讨论】：

标签： java http url httpurlconnection

【解决方案1】：

在您的代码中：

public static HttpsURLConnection passmyurl(URL url) throws IOException {
    HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
    return connection;
}

你应该将返回类型HttpsURLConnection更改为URLConnection。因为url.openConnection()结果的类型是URLConnection的子类型，具体类型取决于参数url的协议。 openConnection() 在URL 类中：

If for the URL's protocol (such as HTTP or JAR), there exists a public, specialized URLConnection subclass belonging to one of the following packages or one of their subpackages: java.lang, java.io, java.util, java.net, the connection returned will be of that subclass. For example, for HTTP an HttpURLConnection will be returned, and for JAR a JarURLConnection will be returned.

因此您可以将Http url 或Https url 传递给您的方法。

见以下代码：

    URLConnection httpConnection = new URL("http://test").openConnection();
    System.out.println(httpConnection.getClass());
    URLConnection httpsConnection = new URL("https://test").openConnection();
    System.out.println(httpsConnection.getClass());
    URLConnection ftpConnection = new URL("ftp://test").openConnection();
    System.out.println(ftpConnection.getClass());`

打印的是：

class sun.net.www.protocol.http.HttpURLConnection
class sun.net.www.protocol.https.HttpsURLConnectionImpl
class sun.net.www.protocol.ftp.FtpURLConnection

【讨论】：