JSONP跨域请求原理与SpringMVC实现

$(function(){
  $.ajax(    {url: "http://localhost:8081/rest/itemcat/list?callback=myFunction", 
     success: function(data){
      console.info(data)
   }}); 
 });

XMLHttpRequest cannot load http://localhost:8081/rest/itemcat/list?callback=myFunction. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8082' is therefore not allowed access.

$(function(){
  greateScript("http://localhost:8081/rest/itemcat/list");
  function greateScript(src) {
   $("<script><//script>").attr("src", src).appendTo("body")
  } 
 });

@RequestMapping("/itemcat/list")
 @ResponseBody
 public Object getItemCatList(String callback) {
  CatResult catResult = itemCatService.getItemCatList();
  MappingJacksonValue mappingJacksonValue = new MappingJacksonValue(catResult);
  //设置JSONP回调函数
  mappingJacksonValue.setJsonpFunction(callback);
  return mappingJacksonValue;
 }

$(function(){
  $.ajax(
   { url: "http://localhost:8081/rest/itemcat/list", 
    dataType: "jsonp",
    jsonp: "callback",
    success: function(data){
    console.info(data)
   }}); 
 });