使用Servlet和H:GraphIcimage显示在PostgressQL中存储的图像列表

Question

我可以从我的数据库中显示图像，它们被存储为 bytea ，我是这样映射的：

@Entity
@Table(name = "photograph", schema = "public")
public class Photograph{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "photograph_id", unique = true, nullable = false)
    private Long id;
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "diagnostic_id", nullable = false, insertable = false, updatable = false)
    private Diagnostic diagnostic;
    @Column(name = "photo", nullable = false)
    private byte[] photo;
    @Column(name = "photograph_description", nullable = false, length = 100)
    private String photographDescription;
    @Column(name = "photograph_content_type")
    private String photographContentType;
//Getters and Setters...
}

我可以毫无问题地将所有图像存储在数据库中。问题是当我想在 p：datatable 中显示它们时：

<p:dataTable id="dataTableLoadedPhotos"
                value="#{imageController.photographListUpdate}" var="image">
                <p:column headerText="Fotografías cargadas" width="110">
                    <h:graphicImage value="images?id=#{image.photographId}" style="width:100px;"
                        alt="#{msgs['label.diagnostic.photograph.notFound']}" />
                </p:column>
            </p:dataTable>

我正在使用基于balusc代码的servlet：imagservlet和我尝试使用o：graphicimage而没有成功，mi代码中缺少某些东西：

@WebServlet("/images/*")   //<<<<<<<I am not sure if this is ok
public class ImageServlet extends HttpServlet {
/**
 * 
 */
private static final long serialVersionUID = 1L;
@EJB
private PhotographService photographService;
@Override
protected void doGet(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
    // Get ID from request.
    String imageId = request.getParameter("id");
    // Check if ID is supplied to the request.
    if (imageId == null) {
        // Do your thing if the ID is not supplied to the request.
        // Throw an exception, or send 404, or show default/warning image,
        // or just ignore it.
        response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
        return;
    }
    // Lookup Image by ImageId in database.
    // Do your "SELECT * FROM Image WHERE ImageID" thing.
    Photograph image = null;
    try {
        image = photographService.findPhotoById(Long.valueOf(imageId));
    } catch (ServiceException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    // Check if image is actually retrieved from database.
    if (image == null) {
        // Do your thing if the image does not exist in database.
        // Throw an exception, or send 404, or show default/warning image,
        // or just ignore it.
        response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
        return;
    }
    // Init servlet response.
    response.reset();
    response.setContentType(image.getPhotographContentType());
    response.setContentLength(image.getPhoto().length);
    // Write image content to response.
    response.getOutputStream().write(image.getPhoto());
}
}

当我使用Maven时，我的应用程序目录是这样的：

src
|----main
     |----webapp
          |----images

我的server.log中没有错误，但是我看不到页面中的图像，代码中缺少什么？

我还尝试了一些类似的内容，类似于＆lt; p：graphicimage＆gt; gt;内部＆lt; ui：重复＆gt;

Answer 1

这不是真正且真正的答案，但可能会有所帮助，如果数据库不需要您，则根据您的不同，您可以将图片直接存储在源代码文件中，并直接使用：

getClass().getResoure(name of image.fileType); 
//fileType example png jpg gif so image.png`

示例：

ImageIcon icon = new ImageIcon(getClass().getResource("Icon.png"));
BufferedImage bf = ImageIO.read(getClass().getResource("image.png"));

绘画缓冲图像

ga.drawimage（图像，int distfromleft，int distfromtop，horrizontalsize，verticlesize，null）