如何正确使用a4j:mediaOutput显示图像？

Question

使用下面的代码我无法在网页中获取图像.我不确定我是否以正确的方式理解文档,并且我无法找到此代码的任何问题.

BEAN

@ManagedBean(name = "imageBean")
@RequestScoped
public class ImageBean {
    public void paint(OutputStream os, Object data) throws IOException {
        BinaryContent content = (BinaryContent) data;
        BufferedImage image = ImageIO.read(new ByteArrayInputStream(content.getContent()));
        ImageIO.write(image, "jpg", os);
    }
}

PAGE

<rich:dataTable value="#{dataProviderBean.aoRequests}" var="item">
    <f:facet name="noData">No messages are available.</f:facet>
    ...
    <rich:column>
        <f:facet name="header">Image data</f:facet>
        <rich:list value="#{item.imageContents}" var="content">
            <a4j:mediaOutput element="img" cacheable="false" session="false"
                createContent="#{imageBean.paint}" value="#{content}" />
        </rich:list>
    </rich:column>
</rich:dataTable>

Answer 1

如果将来有人会遇到同样的问题,这是解决方案:

的content投入我value属性是保持一个图像的二进制数据的对象.因为它是在URL中序列化的,所以长度太大而且不起作用.你必须传递一些id并在paint方法中获取对象.

Example

<rich:dataTable value="#{dataProviderBean.aoRequests}" var="item">
    <f:facet name="noData">No messages are available.</f:facet>
    ...
    <rich:column>
        <f:facet name="header">Image data</f:facet>
        <rich:list value="#{item.imageContents}" var="content">
            <a4j:mediaOutput element="img" cacheable="false" session="false"
                createContent="#{imageBean.paint}" value="#{content.id}" />
        </rich:list>
    </rich:column>
</rich:dataTable>

BEAN

public void paint(OutputStream os, Object data) throws IOException {
    String id = (String) data;
    BinaryContent content = (BinaryContent) getContentById(id);
    os.write(content.getContent());
}