关于javascript中function eval()执行后变成一个新的funciton对象的发现
Controller部分
@SuppressWarnings("unchecked")
@RequestMapping(value = "/upload", method = RequestMethod.POST)
@ResponseBody
public AjaxResult uploadFile(HttpServletRequest request, HttpServletResponse response) {
AjaxResult result = new AjaxResult();
String fileId = request.getParameter("fileid");
String version = request.getParameter("version");
String keyword = request.getParameter("keyword");
String callback = request.getParameter("callback");
......//文件上传业务处理...
result.setData("查询数据库返回的信息");
request.setAttribute("callback",callback);
request.getRequestDispatcher("/WEB-INF/jsp/file/upload_result_rp.jsp").forward(request, response);
return result;
}
在fileList.jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>File List</title>
<!-- Some contents -->
</head>
<body>
<!-- Some contents -->
<script type="text/javascript">
function callbackparam(data) {
alert(data);
}
</script>
<!-- Some contents -->
</body>
</html>
在upload_result_rp.jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Operate Result Callback</title>
<jsp:include page="/WEB-INF/jsp/file/fileList.jsp"></jsp:include>
</head>
<body>
<script type="text/javascript">
var result = '${result}';
if('${callback' != ""}) {
var op = window.parent?'parent':'opener';
var callback = eval('window.'+op+'.'+'{$callback}');
callback(result);
}
</script>
</body>
</html>
由于@ResponseBody，局部刷新。upload_result_rp.jsp与fileList.jsp实际上还是同一个html，相当于前者是后者的一个局部，所以前者能够调到后者中的function.
以上是一些必要的说明，接下来要表达的是eval()函数在此处的一个亮点，我以前不知道，eval()计算字符串之后可以成为一个函数对象。如果在request中，callback变量的值为callbackparam,然而在跑完var callback = eval('window.'+op+'.${callback}'); 后，实际上在此场景中var callback的callback就变成了 function callbackparam()，转而去调用fileList.jsp中的
function callbackparam(data){
alert(data);
}了，突然发现javascript真的很强大，有木有！！！