server 端

@RestController
public class Controller1 {
    @RequestMapping(value = "/test1",method = RequestMethod.GET)
    public String test1(HttpServletRequest request){
        String data="'data from server2 which port 8081'";
        String jsonpCallback = request.getParameter("jsonpCallback");//这一步很关键
        String s=jsonpCallback+"("+data+");";
        return s;
    }
}

client端

<script>
$(function () {
$("#test1").click(function () {

    $.getJSON("http://localhost:8081/test1?jsonpCallback=?",function(data){
        console.log(data);
    });

});


});


</script>

result:80端口获取到了81端口的数据(跨域访问)

Paste_Image.png

jsonp原理

<script src="..."></script>可以无视跨域访问