通过s:graphicImageDynamic组件显示保存到数据库中的图片

使用s:graphicImageDynamic组件，要有tomahawk-sandbox的jar包，我使用的是tomahawk-sandbox-1.1.6-SNAPSHOT.jar 。

 

JSF代码：

<%@ taglib uri="http://myfaces.apache.org/sandbox" prefix="s"%>

...

<s:graphicImageDynamic height="32" width="32" imageRendererClass="#{gmShowImageBean.imageRendererClass}" >
<f:param value="#{info.imageId}" name="imageId"/>
</s:graphicImageDynamic>

 

<s:graphicImageDynamic/>组件允许使用<f:param进行传值，#{info.imageId}是循环对象的主键，通过"imageId"名称传到request中，接在ImageRenderer类中获取，然后查询数据库得到image对象，从而进行渲染图片内容。

 

#{gmShowImageBean.imageRendererClass}这是返回渲染图片的Render类，gmShowImageBean类中代码如下：

public Class getImageRendererClass(){
    return ImageRendererImpl.class;
}

 

 

Java代码：

 

public class ImageRendererImpl implements ImageRenderer {//必须实现ImageRenderer接口

    private static final Log logger = LogFactory.getLog(ImageRendererImpl.class);

    private byte[] image=null;
    private int imageLength=0;
    private String imageType="image/jpeg";

    public void setContext(FacesContext facesContext, ResourceContext imageContext) throws Exception
    {

        //1.获取showImageBean,进而得到showImaeBean中注入的uploadservice，此service是用于根据imageId主键查询返回image对象

        ShowImageBean imageBean =    (ShowImageBean)facesContext.getApplication().getVariableResolver().resolveVariable(facesContext, "gmShowImageBean");

 

        if(imageBean!=null){
            //得到uploadService
            UploadService uploadService = imageBean.getUploadService();
            if(uploadService!=null){

                //从request中获取<f:param传进来的"imageId"变量
                HttpServletRequest request = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
                Long imageId=Long.valueOf(request.getParameter("imageId") );

 

                //根据ImageId主键查询数据库，返回uploadImage,这是图片的bo类，对图片的属性进行一个简单的封装
                UploadImage uploadImage=uploadService.getUploadImage(imageId);

                if(uploadImage!=null){
                   
                    if(uploadImage.getFile()!=null && uploadImage.getFileType()!=null){
                        imageLength=uploadImage.getFile().length;//返回字节数组的长度
                        imageType=uploadImage.getFileType();//返回图片的类型
                        image=uploadImage.getFile(); //返回图片的字节数组
                    }
                }else{
                    logger.error(LogUtil.msg("uploadImage is null!"));  
                }
            }//if
        }

    }

    /**
     * @see org.apache.myfaces.custom.graphicimagedynamic.ImageRenderer#getContentLength()
     */
    public int getContentLength() {
        return imageLength;
    }

    /**
     * @see org.apache.myfaces.custom.graphicimagedynamic.ImageRenderer#getContentType()
     */
    public String getContentType()
    {
        return imageType;
    }

    /**
     * @see org.apache.myfaces.custom.graphicimagedynamic.ImageRenderer # renderImage()
     */
    public void renderResource(ResponseStream out)
            throws IOException{
        InputStream is = new ByteArrayInputStream(image);
        try
        {
            byte[] buffer = new byte[1024];
            int len = is.read(buffer);
            while (len != -1)
            {
                out.write(buffer, 0, len);
                len = is.read(buffer);
            }
        }finally{
            is.close();
        }
    }

}

 

UploadImage类代码如下：

public class UploadImage implements Serializable {

    private Long id;//主键ID
    private byte[] file;//图片字节数组
    private String fileType;//图片类型
    private String fileName;//图片名称
    private Long fileSize;//图片大小(单位K)
    private Date uploadTime;//上传时间

 

    ....//省略get/set方法

 

}