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In order to gain a star in the mark sheet you must complete this exercise. Completing the exercise does not gain you any credit in the examination. In this exercise you will write a client which connects to a server and sends and receive images in JPEG[1] format. An example client is shown in Figure 1, “An example image chat client”.
Your program should have the following features:
Your solution should contain a class called
ImageChatClientwhich extendsJFrameinside a package calleduk.ac.cam.crsid.fjava.tick1star.Your implementation of
ImageChatClientmust contain a constructor which takes two arguments; the first argument should accept the name of the server as aStringand the second argument the port number to connect to, expressed as anint.When an object of type
ImageChatClientis instantiated it should create a Swing GUI with at least two components, an AWTCanvasobject to render images sent by the server, and an AWTButtonwith the text label "Upload". You may add additional GUI components if you wish.Your implementation of
ImageChatClientshould use an additional thread in a similar manner toStringChatyou wrote for Ticklet 1. One thread should listen on aSocketobject connected to the server and draw any new image sent by the server to theCanvasobject; the other thread should listen for user input.If the
Buttonobject is clicked, you should create and show an instance of theJFileChooserclass. In the case where a user selects a suitable JPEG file using the dialog and selects the "Open" button, your program should send the bytes representing the JPEG file to the server over aSocketobject; otherwise your program should do nothing.Clicking on the close button in the top right-hand corner of the Swing window created by the
ImageChatClientclass should close the application.
You may test your implementation by connecting to
java-1b.cl.cam.ac.ukon port number 15002.The data sent by the server is a sequence of JPEG images sent as a stream of bytes. You will need to design a method of working out when you have received all the data representing a single image. One solution is to inspect the stream for the JPEG format End Of Image (EOI) marker, which in hexadecimal is
0xffD9. (In your code you can check whether consecutive bytes have the values-1and-39to detect the end of an image in the stream of bytes; why?)Avoid using the
ImageIO.read(InputStream is)method to directly read data from aSocketobject since the read method (erroneously in this case!) assumes that only a single image exists in a given stream of data. Instead you should read the data from theSocketobject into a small buffer, perform some manual checks to detect whether you have reached the end of the JPEG image or not (e.g. look for the EOI marker), before writing the data out to a second stream which you can feed intoImageIO.read(InputStream is). You will probably find a small array of typebyteand theByteArrayInputStreamandByteArrayOutputStreamclasses useful for this.
Start by joining the Ticklet 1* project then cloning the Ticklet 1* repository from the Chime server: https://www.cl.cam.ac.uk/teaching/current/FJava/ticklet1star. Complete the implementation of ImageChatClient as described above, commit all changes to your local repository and push your changes to the Chime server. On the Chime server, schedule testing for this exercise as you did for Ticklet 1. If, after waiting an hour, you have not received a response, please send an email to ticks1b-admin@cl.cam.ac.uk.