Security Considerations for URLConnections

URLConnection objects are subject to all the usual security restrictions about making network connections, reading or writing files, and so forth. For instance, a URLConnection can be created by an untrusted applet only if the URLConnection is pointing to the host that the applet came from. However, the details can be a little tricky because different URL schemes and their corresponding connections can have different security implications. For example, a jar URL that points into the applet’s own jar file should be fine. However, a file URL that points to a local hard drive should not be.

Before attempting to connect a URL, you may want to know whether the connection will be allowed. For this purpose, the URLConnection class has a getPermission() method: