Links to the original text: https://www.cnblogs.com/shuilangyizu/p/9750428.html

Explain

Because in general, the browser (front-end) sends requests and the server (back-end) responds to json data, this paper describes it with js.

1. The server returns json data

Way 1: Return JSON format data (JSON object)

/**
     * Return to json
     * @param request
     * @param response
     * @param session
     */
    @RequestMapping("/returnjson")
    public void returnjson(HttpServletRequest request,HttpServletResponse response, HttpSession session) {
        response.setCharacterEncoding("UTF-8"); 
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter wirte = null;
        JSONObject json = new JSONObject();
        try {
            wirte = response.getWriter();
            if(1==1){
                json.put("Equality is established", "yes");
            }else{
                json.put("Equation does not hold", "no");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            wirte.print(json);
            wirte.flush();
            wirte.close();
        }response.getWriter().print(jo);
    }

Mode 2: Return JSON format string (JSON string)

// Set return character set
response.setContentType("charset=utf-8");
String result = "{\"name\":\"Marydon\"}";
// Return data
response.getWriter().print(result);

2. Client receives and processes json data

For the first return format

Get (), $. Ajax (), $. post (), $. getJSON () these four ways can get the value directly without any extra processing.

$.post(baseUrl + "/test.do",function(result){
    alert(result.name);// Marydon
});　　

For the second return format

Get (), $. Ajax (), $. post (); these three ways require data processing to get values;

$.get(baseUrl + "/test.do",function(result){
    // json string - > json object
    result = eval('(' + result + ')');
    alert(result.name);// Marydon
});

getJSON(); this way the value can be obtained directly without further processing.

$.getJSON(baseUrl + "/test.do",function(result){
    alert(result.name);// Marydon
});