Example usage for javax.swing UIDefaults.LazyValue UIDefaults.LazyValue

Introduction

In this page you can find the example usage for javax.swing UIDefaults.LazyValue UIDefaults.LazyValue.

Prototype

UIDefaults.LazyValue

Source Link

Usage

From source file:Main.java

/**
 * Utility method that creates a <code>UIDefaults.LazyValue</code> that
 * creates an <code>ImageIcon</code> <code>UIResource</code> for the
 * specified image file name. The image is loaded using
 * <code>getResourceAsStream</code>, starting with a call to that method
 * on the base class parameter. If it cannot be found, searching will
 * continue through the base class' inheritance hierarchy, up to and
 * including <code>rootClass</code>.
 *
 * @param baseClass the first class to use in searching for the resource
 * @param rootClass an ancestor of <code>baseClass</code> to finish the
 *                  search at/* w  ww.j  ava2s . co m*/
 * @param imageFile the name of the file to be found
 * @return a lazy value that creates the <code>ImageIcon</code>
 *         <code>UIResource</code> for the image,
 *         or null if it cannot be found
 */
public static Object makeIcon(final Class<?> baseClass, final Class<?> rootClass, final String imageFile) {

    return new UIDefaults.LazyValue() {
        public Object createValue(UIDefaults table) {
            /* Copy resource into a byte array.  This is
             * necessary because several browsers consider
             * Class.getResource a security risk because it
             * can be used to load additional classes.
             * Class.getResourceAsStream just returns raw
             * bytes, which we can convert to an image.
             */
            byte[] buffer = java.security.AccessController
                    .doPrivileged(new java.security.PrivilegedAction<byte[]>() {
                        public byte[] run() {
                            try {
                                InputStream resource = null;
                                Class<?> srchClass = baseClass;

                                while (srchClass != null) {
                                    resource = srchClass.getResourceAsStream(imageFile);

                                    if (resource != null || srchClass == rootClass) {
                                        break;
                                    }

                                    srchClass = srchClass.getSuperclass();
                                }

                                if (resource == null) {
                                    return null;
                                }

                                BufferedInputStream in = new BufferedInputStream(resource);
                                ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
                                byte[] buffer = new byte[1024];
                                int n;
                                while ((n = in.read(buffer)) > 0) {
                                    out.write(buffer, 0, n);
                                }
                                in.close();
                                out.flush();
                                return out.toByteArray();
                            } catch (IOException ioe) {
                                System.err.println(ioe.toString());
                            }
                            return null;
                        }
                    });

            if (buffer == null) {
                return null;
            }
            if (buffer.length == 0) {
                System.err.println("warning: " + imageFile + " is zero-length");
                return null;
            }

            return new ImageIconUIResource(buffer);
        }
    };
}

---