Start by verifying that uploadedInputStream is a valid image, prehaps by writing it out using ImageIO.write. You can always use ImageIO.read to read the image back in and write it back out to a ByteArrayInputStream 😉 I did a quick test using H2 database. A few things I noted. Blob#length returns a long, while Blob#getBytes … Read more
You should use Java’s built in serialization mechanism. To use it, you need to do the following: Declare the Club class as implementing Serializable: public class Club implements Serializable { … } This tells the JVM that the class can be serialized to a stream. You don’t have to implement any method, since this is … Read more
An InputStream is the raw method of getting information from a resource. It grabs the data byte by byte without performing any kind of translation. If you are reading image data, or any binary file, this is the stream to use. A Reader is designed for character streams. If the information you are reading is … Read more
String message = URLEncoder.encode(“my message”, “UTF-8”); try { // instantiate the URL object with the target URL of the resource to // request URL url = new URL(“http://www.example.com/comment”); // instantiate the HttpURLConnection with the URL object – A new // connection is opened every time by calling the openConnection // method of the protocol handler … Read more
The problem you have is related to TCP streaming nature. The fact that you sent 100 Bytes (for example) from the server doesn’t mean you will read 100 Bytes in the client the first time you read. Maybe the bytes sent from the server arrive in several TCP segments to the client. You need to … Read more
In InputStreams, read() calls are said to be “blocking” method calls. That means that if no data is available at the time of the method call, the method will wait for data to be made available. The available() method tells you how many bytes can be read until the read() call will block the execution … Read more
Because a byte can only hold -128 until 127, while it should return 0 until 255 (and -1 when there’s no byte left (i.e. EOF)). Even if it returned byte, there would be no room to represent EOF. A more interesting question is why it doesn’t return short.
It’s looking for more data because nothing’s told it that there won’t be more data. The other end of the network could send more data at any time. It’s not clear whether you’re designing the client/server protocol or just trying to implement it, but typically there are three common ways of detecting the end of … Read more
The underlying data source for some implementations of InputStream can signal that the end of the stream has been reached, and no more data will be sent. Until this signal is received, read operations on such a stream can block. For example, an InputStream from a Socket socket will block, rather than returning EOF, until … Read more
What am I doing wrong? Using multiple scanners on the same stream is the underlying problem. Scanners can (and will) consume the stream – this may (will) lead to unexpected side-effects. Best not to do it. If the input is closed, then the input (but Strings have no close method) is closed for everyone – … Read more