JSF 输入文件：要上传的文件数组（语法）

Question

Does my syntax is wrong to manage an array of files to upload?

In my java bean:

private List<Part> files = new ArrayList<Part>();

public void setFiles(List<Part> files) {
    this.files = files;
}
public List<Part> getFiles() {
    return files;
}

In my xhtml:

<div class="form-group">
    <h:inputFile id="file1" value="#{theBean.files[0]}">
    </h:inputFile>
    <p:message for="file1"/>
    <ui:fragment rendered="#{fn:length(theBean.files) > 1}">
        <h:inputFile id="file2" value="#{theBean.files[1]}">
        </h:inputFile>
    </ui:fragment>
    <ui:fragment rendered="#{fn:length(theBean.files) > 2}">
        <h:inputFile id="file3" value="#{theBean.files[2]}">
        </h:inputFile>
    </ui:fragment>
</div>

I have an array of files to upload defined in my java code and I want to use the index of the array in the xhtml. The java code is not called. What is the better solution and keeping the list.

Answer 1

Your list is empty.

System.out.println(files.size()); // 0

As Part is immutable, you'd better use a list of mutable beans instead.

public class UploadedFile {
    private Part value;
    // Getter+setter.
}

private List<UploadedFile> files = new ArrayList<>();

@PostConstruct
public void init() {
    files.add(new UploadedFile());
    files.add(new UploadedFile());
    System.out.println(files.size()); // 2
}

<h:inputFile value="#{bean.files[0].value}" />

Or alternatively use a plain vanilla array instead which you can preinitialize with a fixed size.

private Part[] files = new Part[2]; // 2 items.