Question

我正在使用primfaces 3.5版本来显示数据库中我的数据库中的图像，但不幸的是，实际图像“image”正在写入列，这是我的xhtml文件

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:p="http://primefaces.org/ui">
    <body>

        <ui:composition template="./template.xhtml">    
            <ui:define name="top">    
            </ui:define>    
            <ui:define name="left">
                left
            </ui:define>    
            <ui:define name="content">
                <h:form id="form1">      
                    <p:panel id="panel" header="New Category">      
                        <p:messages id="msgs1"/>      
                        <h:panelGrid columns="3">  
                            <h:outputLabel for="categoryName" value="Category Name: *" />  
                            <p:inputText id="categoryname" value="#{categoryBean.categoryName}" required="true" label="Categoryname">  
                                <f:validateLength minimum="2" />  
                            </p:inputText> 

                            <p:message for="categoryname" display="icon"/>     
                            <h:outputLabel value="Upload Image" />
                            <p:fileUpload fileUploadListener="#{categoryBean.upload}"
                                          allowTypes="/(\.|\/)(gif|jpe?g|png)$/" sizeLimit="100000" description="Select Images"/>        
                        </h:panelGrid>      
                        <p:commandButton id="btn" value="Save"  update=":form:count" />  
                    </p:panel>      
                </h:form>  

                <h:form id="form">    
                    <p:spacer height="20px"></p:spacer>    
                    <p:dataTable id="count" var="category"
                                 value="#{categoryBean.categories}" paginator="true" rows="7">    
                        <f:facet name="header">  
                            Available Categories  
                        </f:facet>

                        <p:column headerText="Category ID" style="width:4%">
                            <h:outputText value="#{category.idCat}" />
                        </p:column>

                        <p:column headerText="Category Name" style="width:24%">
                            <h:outputText value="#{category.categoryName}" />
                        </p:column>

                        <p:column headerText="Category Image" style="width:24%">
                            <p:graphicImage   alt="image"  value="#{category.categoryimg}" cache="false"  >

                            </p:graphicImage>
                    </p:column>

                    <p:column style="width:4%">

                        <p:commandButton value="Delete" action="#{categoryBean.deleteAction(category)}"  update=":form:count"/>

                    </p:column>    
                    </p:dataTable>    
                </h:form>
            </ui:define>

            <ui:define name="bottom">    
            </ui:define>    
        </ui:composition>    
    </body>
</html>

这是我的托管bean：

package com.app.beans;

/**
 *
 * @author 
 */
@ManagedBean
@RequestScoped
public class CategoryBean implements Serializable{
   public  long idCat;
   public  String categoryName;
   public List<Category> categories;
   public ItemController itemController;
   byte[] data;
   private StreamedContent dbImage;

    public StreamedContent getDbImage() {
        return dbImage;
    }

    public void setDbImage(StreamedContent dbImage) {
        this.dbImage = dbImage;
    }

   public StreamedContent getImage(Category cat)throws IOException{
       FacesContext context = FacesContext.getCurrentInstance();
       System.out.println("int get images category id is: "+cat.getCategoryName());
    if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) {
        // So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
        System.out.println("So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.");
        return new DefaultStreamedContent();
    }else{
        System.out.println("in actual image content");
        dbImage= new DefaultStreamedContent(new ByteArrayInputStream(itemController.getImageByName(cat.getCategoryName())), "image/png");
        return dbImage;
    }
   }


    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;

        Category c = new Category();
        c.setCategoryName(categoryName);
        int status = itemController.setCategory(c);
        if(status == 1){
                categories.add(c);
        }
    }

    @PostConstruct
    public void init(){
        categories = new ArrayList<Category>();
        itemController = new ItemController();
        categories = itemController.getAllCategories();
    }

    public long getIdCat() {
        return idCat;
    }

    public void setIdCat(long idCat) {
        this.idCat = idCat;
    }



    public List<Category> getCategories() {
        return categories;
    }

    public void setCategories(List<Category> categories) {
        this.categories = categories;
    }



    /**
     * Creates a new instance of CategoryBean
     */
    public CategoryBean() {

    }

        public String deleteAction(Category c) {

        System.out.println("from deleteAction"+c.getCategoryName());
        int status = itemController.deleteCategory(c.getCategoryName());
        if(status == 1){
            categories.remove(c);
        }
        return null;
    }

        public void upload(FileUploadEvent event) {
        FacesMessage msg = new FacesMessage("Success! ", event.getFile().getFileName() + " is uploaded.");
        FacesContext.getCurrentInstance().addMessage(null, msg);
        // Do what you want with the file        
        System.out.println("From Upload" + event.getFile().getFileName());

        int nRead;
        data = new byte[16384];
        InputStream is = null;
        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
        try {
            is = event.getFile().getInputstream();
             while ((nRead = is.read(data, 0, data.length)) != -1) {
                buffer.write(data, 0, nRead);
             }
              buffer.flush();
        } catch (IOException ex) {
            Logger.getLogger(UpdateItem.class.getName()).log(Level.SEVERE, null, ex);
        }



    }
}

我正在获取对应于类别名称的图像，即在日志中出现，我试图理解为什么我的getImage函数的一部分未被调用这是生成的日志：

WARNING: JSF1091: No mime type could be found for file dynamiccontent.  To resolve this, add a mime-type mapping to the applications web.xml.
Jun 07, 2013 11:14:41 PM com.sun.faces.context.ExternalContextImpl getMimeType
WARNING: JSF1091: No mime type could be found for file dynamiccontent.  To resolve this, add a mime-type mapping to the applications web.xml.
int get images category id is: xyz
So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
int get images category id is: x1
So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
int get images category id is: x2
So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
int get images category id is: Main Course
So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
int get images category id is: Drinks
So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.
Jun 07, 2013 11:14:41 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. java.lang.NullPointerException
Jun 07, 2013 11:14:41 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. java.lang.NullPointerException
Jun 07, 2013 11:14:41 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. java.lang.NullPointerException
Jun 07, 2013 11:14:41 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. java.lang.NullPointerException
Jun 07, 2013 11:14:41 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. java.lang.NullPointerException
Jun 07, 2013 11:14:42 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. Expression cannot be null
Jun 07, 2013 11:14:42 PM org.primefaces.application.PrimeResourceHandler handleResourceRequest
SEVERE: Error in streaming dynamic resource. Expression cannot be null

当评论if else子句时，它会抛出以下错误：

    SEVERE: Error Rendering View[/categoryUpdate.xhtml]
java.lang.NullPointerException
    at org.primefaces.component.graphicimage.GraphicImageRenderer.getImageSrc(GraphicImageRenderer.java:110)
    at org.primefaces.component.graphicimage.GraphicImageRenderer.encodeEnd(GraphicImageRenderer.java:46)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1763)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1759)
    at org.primefaces.component.datatable.DataTableRenderer.encodeRegularCell(DataTableRenderer.java:741)
    at org.primefaces.component.datatable.DataTableRenderer.encodeRow(DataTableRenderer.java:693)

Answer 1

到目前为止，您的方法存在两个错误：

您必须使用<f:param>内的<p:graphicImage>来传递图片ID。您不能在<p:graphicImage value>中使用传递的EL 2.2方法参数。图像由完全独立的HTTP请求请求。 EL 2.2方法参数传递仅在生成HTML输出时使用，此时需要为<img src>生成URL。但是，该URL又必须唯一地标识图像，并且只能通过<f:param>来完成。
不是技术问题，而是更多的设计问题：你应该将图片流媒体放在一个完全独立的应用程序范围的bean中，而不是将它与＆＃34;常规＆＃34;托管bean代码。通过这种方式，图像流可以重复使用，您可以清楚地分离使代码更易于理解和维护的问题。

使用primefaces的数据表中的动态图像，图像未显示在数据表中

1 个答案:

另见：