Question

我的gwt-upload有问题：我需要onChange上传来从db获取我的对象;如果存在，Web应用程序可以使用Servlet上传文件，否则将显示警报。

带注释的代码仅在“It works”注释的位置运行。

为什么不在else块中运行？

final MultiUploader upload = new MultiUploader(FileInputType.BUTTON);
upload.addOnChangeUploadHandler(new OnChangeUploaderHandler() {

    @Override
    public void onChange(IUploader uploader) {
        myService.getMyObject(name, new AsyncCallback<List<Object>>() {

            @Override
            public void onFailure(Throwable caught) {
                Window.alert("Something");
            }

            @Override
            public void onSuccess(List<Object> listMyObject) {
                if(listMyObject.size() == 0) {
                    Window.alert("Error.");
                } else {
                    //It doesn't works.
                    String url = GWT.getModuleBaseURL() + "upload?nameObject=" + name;
                    upload.setServletPath(url);
                }
            }
        });
    }
});
//It works.
String url = GWT.getModuleBaseURL() + "upload?nameObject=" + name;
upload.setServletPath(url);

Answer 1

您可以通过添加上传按钮并在服务器调用成功时提交上传表单来解决此问题。这是一个如何做到这一点的大纲。阅读gwtupload documentation以在web.xml中添加servlet映射。

Uploader uploader = new Uploader(FileInputType.BROWSER_INPUT);
uploader.setServletPath("myservletpath");
uploader.setAutoSubmit(false);
uploader.setEnabled(true);

Button uploadButton = new Button("Upload");
uploadButton.addClickHandler(new ClickHandler()){
    myService.getMyObject(name, new AsyncCallback<List<Object>>() {

            @Override
            public void onFailure(Throwable caught) {
                //do something
            }

            @Override
            public void onSuccess(List<Object> listMyObject) {
                //do something if condition satisfies then submit
                if(conditionSatifies){
                    uploader.submit();
                }else{
                    //do something, prompt a message
                }
            }
     });
}

使用gwt上传无法正确上传

1 个答案: