How to get image with servlet and display it using GWT Image class?

Question

I\'m using the following code as part of the GWT server-side class (servlet) for GWT-RPC.

private void getImage() {
        HttpServletResponse res = this.ge         


        

Answer 1

Servlets respond to varios HTTP methods: GET, POST, PUT, HEAD. Since you use GWT's new Image(url), and it uses GET, you need to have a servlet that handles GET method.

In order for servlet to handle GET method it must override a doGet(..) method of HttpServlet.

public class ImageServlet extends HttpServlet {

    public void doGet(HttpServletRequest req, HttpServletResponse resp) 
      throws IOException {

        //your image servlet code here
        resp.setContentType("image/jpeg");

        // Set content size
        File file = new File("path/to/image.jpg");
        resp.setContentLength((int)file.length());

        // Open the file and output streams
        FileInputStream in = new FileInputStream(file);
        OutputStream out = resp.getOutputStream();

        // Copy the contents of the file to the output stream
        byte[] buf = new byte[1024];
        int count = 0;
        while ((count = in.read(buf)) >= 0) {
            out.write(buf, 0, count);
        }
        in.close();
        out.close();
    }
}

Then you must configure path to your servlet in your web.xml file:

<servlet>
    <servlet-name>MyImageServlet</servlet-name>
    <servlet-class>com.yourpackage.ImageServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>MyImageServlet</servlet-name>
    <url-pattern>/images</url-pattern>
</servlet-mapping>

Then call it in GWT: new Image("http:yourhost.com/images")