【Java Web开发学习】跨域请求

时间：2021-05-24 23:26:02

【Java Web开发学习】跨域请求

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1、使用jsonp

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代码很简单不做解释
json和jsonp的区别阅读   https://kb.cnblogs.com/page/139725/

package ycx.crossdomain.controller;

import com.fasterxml.jackson.databind.ObjectMapper;

import org.springframework.util.StringUtils;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.PrintWriter;

import java.util.HashMap;

import java.util.Map;

@RestController

public class IndexController {

    @RequestMapping("/")

    public void index(HttpServletRequest request, HttpServletResponse response) throws Exception {

        Map<String, Object> dataMap = new HashMap<>();

        dataMap.put("status", 200);

        dataMap.put("message", "OK");

        dataMap.put("data", "hello world");

        ObjectMapper mapper = new ObjectMapper();

        String data = mapper.writeValueAsString(dataMap);

        PrintWriter out = response.getWriter();

        String callback = request.getParameter("callback");

        if (StringUtils.isEmpty(callback)) {

            out.print(data);

        } else {

            out.print(callback + "(" + data + ")");

        }

        out.flush();

        out.close();

    }

}
<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>jsonp</title>

    <script type="text/javascript" src="js/jquery-3.4.1.js"></script>

</head>

<body>

<script>

    // has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

    // $.ajax({

    //     type: "GET",

    //     async: false,

    //     url: "http://localhost:9902",

    //     success: function (result) {

    //         console.dir(result);

    //     },

    //     error: function (e) {

    //         console.dir(e);

    //     }

    // });

    $.ajax({

        type: "GET",

        async: false,

        url: "http://localhost:9902",

        dataType: "jsonp",

        jsonp: "callback",

        jsonpCallback:"handler",

        success: function (result) {

            console.dir(result);

        },

        error: function (e) {

            console.dir(e);

        }

    });

</script>

</body>

</html>

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