將變量從腳本傳遞到 jsp - null 指針

Question

努力將一個 jsp 中的腳本中的變量傳遞給“調用 jsp”

assetedit.jsp 將二進制 stream 發布到 upload.jsp。 upload.jsp proceses that stream and determines a filepath which I want to make available in assedit.jsp but the returned value always produces null pointer.

我顯然在做一些根本性的錯誤，我什至在帖子中嘗試異步“停止”jsp，以防事情發生得太快。

想法贊賞。

資產編輯.jsp -

//post binary to upload.jsp
$.ajax({
url: '/wz/upload.jsp',
data: decodedstring,
type: 'POST',
contentType: false,
processData: false,
}).done(function(data) {
console.log(data);
});     

upload.jsp （刪除了一些行以便於理解 -

<%
try {
String root = getServletContext().getRealPath("/uploads/"); 
BufferedInputStream bis = new BufferedInputStream(request.getInputStream());
String nm = System.currentTimeMillis() + ".jpg";
String filepath = root + "/" + nm;
String realpath = (filepath.substring(filepath.lastIndexOf("/") - 7));
System.out.println("realpath is   "  + realpath);
pageContext.setAttribute("pathtogo", realpath);

}
fos.close();
bis.close();
);
} catch (Exception ex) {
ex.printStackTrace();
}
%>

資產編輯.jsp -

<%
String str = request.getAttribute("pathtogo").toString();
System.out.println("pathtogo is   "  + str);
%>  

也嘗試過（在assetedit.jsp中） -

<%
        String name=(pageContext.getAttribute("pathtogo").toString()); 
        System.out.println("pathtogo is "+name); 
%>

導致 - Uncaught TypeError: getElemRefs(...) is null

想法表示贊賞，我是否需要在upload.jsp 中再發一篇帖子以將pathtogo 發送回assetedit.jsp？

拉爾夫

Answer 1

您能否嘗試使用 Session Scope，以便在不同的 JSP 頁面之間傳遞適當的變量。

pageContext.setAttribute("pathtogo",realPath,PageContext.SESSION_SCOPE);  
    
pageContext.getAttribute("pathtogo",PageContext.SESSION_SCOPE);  

https://docs.oracle.com/javaee/6/api/javax/servlet/jsp/PageContext.html

----已編輯----

好的，讓我們試試別的：

上傳.jsp

session.setAttribute("pathtogo",realPath);

資產編輯.jsp -

<%
String str = (String)session.getAttribute("pathtogo");

System.out.println("pathtogo is   "  + str);
%>  

或String.valueOf(session.getAttribute("pathtogo"));