关于java中byte[]到Image的转换

我把图像存在了Oracle数据库中，Oracle数据库可以以Blob的数据类型进行存取，但是由于有一个演示版本要拿出去演示，不可能时时连着网络，就存到了Access数据库中，结果Access数据库对Blob这个比较无语，它这个数据库，貌似不存在流的概念了，为了使我写的Model层对象更具有兼容性，我把其Blob的属性换成了Image，这样子类就与数据库无关性更少了，所以我就面临着Access中图片到java中如何得到。

首先用getBinaryStream是肯定可以的，但是我比较懒惰，这还要用一个InputStream接受，还要转换，于是我决定用getbytes直接得到一个byte[]数组，byte数组到Image其实蛮简单的，使用Toolkit.getDefaultToolkit().createImage(byte[] bytes)方法就可以得到一个Image了，但是我想知道到底怎么完成的。

于是：Toolkit是一个接口，那么他的getDefaultToolkit()方法肯定就是一个实现了这个接口的对应方法了，找到这个代码

/**     * Gets the default toolkit.     * <p>     * If a system property named <code>"java.awt.headless"</code> is set     * to <code>true</code> then the headless implementation     * of <code>Toolkit</code> is used.     * <p>     * If there is no <code>"java.awt.headless"</code> or it is set to     * <code>false</code> and there is a system property named     * <code>"awt.toolkit"</code>,     * that property is treated as the name of a class that is a subclass     * of <code>Toolkit</code>;     * otherwise the default platform-specific implementation of     * <code>Toolkit</code> is used.     * <p>     * Also loads additional classes into the VM, using the property     * 'assistive_technologies' specified in the Sun reference     * implementation by a line in the 'accessibility.properties'     * file.  The form is "assistive_technologies=..." where     * the "..." is a comma-separated list of assistive technology     * classes to load.  Each class is loaded in the order given     * and a single instance of each is created using     * Class.forName(class).newInstance().  This is done just after     * the AWT toolkit is created.  All errors are handled via an     * AWTError exception.     * @return    the default toolkit.     * @exception  AWTError  if a toolkit could not be found, or     *                 if one could not be accessed or instantiated.     */    public static synchronized Toolkit getDefaultToolkit() {        if (toolkit == null) {            try {                // We disable the JIT during toolkit initialization.  This                // tends to touch lots of classes that aren't needed again                // later and therefore JITing is counter-productiive.                java.lang.Compiler.disable();                java.security.AccessController.doPrivileged(                        new java.security.PrivilegedAction() {                    public Object run() {                        String nm = null;                        Class cls = null;                        try {                            nm = System.getProperty("awt.toolkit");                            try {                                cls = Class.forName(nm);                            } catch (ClassNotFoundException e) {                                ClassLoader cl = ClassLoader.getSystemClassLoader();                                if (cl != null) {                                    try {                                        cls = cl.loadClass(nm);                                    } catch (ClassNotFoundException ee) {                                        throw new AWTError("Toolkit not found: " + nm);                                    }                                }                            }                            if (cls != null) {                                toolkit = (Toolkit)cls.newInstance();                                if (GraphicsEnvironment.isHeadless()) {                                    toolkit = new HeadlessToolkit(toolkit);                                }                            }                        } catch (InstantiationException e) {                            throw new AWTError("Could not instantiate Toolkit: " + nm);                        } catch (IllegalAccessException e) {                            throw new AWTError("Could not access Toolkit: " + nm);                        }                        return null;                    }                });                loadAssistiveTechnologies();            } finally {                // Make sure to always re-enable the JIT.                java.lang.Compiler.enable();            }        }        return toolkit;    }

原来是rt包中sun.awt下的东西，从

System.getProperty("awt.toolkit");   

可以轻松得到他的类名：sun.awt.windows.WToolkit

但是它并没有实现creatImage方法，于是看他父类sun.awt.SunToolkit,果然找到了其方法。

  public Image createImage(byte[] paramArrayOfByte, int paramInt1, int paramInt2)  {    return createImage(new ByteArrayImageSource(paramArrayOfByte, paramInt1, paramInt2));  }  public Image createImage(ImageProducer paramImageProducer)  {    return new ToolkitImage(paramImageProducer);  }

咦，其中是有实现了，但是和我调用的createImage(byte[])这个不相符啊，再看看Toolkit.getDefaultToolkit().createImage(byte[] bytes)中的声明，啊哈，好吧，原来是这样子来完成的，sun公司的人真的都好厉害啊，不看不知道啊，记录下，以备以后学习这种方式。

 /**     * Creates an image which decodes the image stored in the specified     * byte array.     * <p>     * The data must be in some image format, such as GIF or JPEG,     * that is supported by this toolkit.     * @param     imagedata   an array of bytes, representing     *                         image data in a supported image format.     * @return    an image.     * @since     JDK1.1     */    public Image createImage(byte[] imagedata) {        return createImage(imagedata, 0, imagedata.length);    }