src/org/nutz/img/Images.java
public static void write(RenderedImage im, String imFormat, OutputStream out) {
        try {
            ImageIO.write(im, imFormat, out);
        }
        catch (IOException e) {
            throw Lang.wrapThrow(e);
        }
    }
public static void write(RenderedImage im, String imFormat, OutputStream out) {
        try {
            ImageIO.write(im, imFormat, out);
        }
        catch (IOException e) {
            throw Lang.wrapThrow(e);
        }
    }
将内存中的一个写入输出流

@param im
图片对象
@param imFormat
图片格式
@param out
输出流