javascript - HttpServletRequest无法获取xhr请求参数

Question

我正在使用 Spring 和 javascript。使用 XhrHttpRequest 对象调用 @Controller。

我可以使用 Chrome Inspector 查看我的参数(JSON 字符串)，但是当我调用 request.getParamter("id") 时返回 null。

Calling part with js
function ajax(url, data, callback, method){
    //data is {"id":"system", "password" : "1234"}
    var httpRequest;
    var afterAction = function(){
        if(!httpRequest) {
            console.error('can not find httpRequest variable');
            return;
        }

        if (httpRequest.readyState === XMLHttpRequest.DONE) {
            if (httpRequest.status === 200) {
                var responseData = httpRequest.responseText;
                //alert(JSON.stringify(responseData));
                console.log('Result of API call >>>', responseData);
                if(typeof callback == 'function') {
                    callback(JSON.parse(responseData));
                }
            } else {
                alert('There was a problem with the request.');
            }
        }
    }

    //=========== LOGIC ============
    if (window.XMLHttpRequest) { // Mozilla, Safari, IE7+ ...
        httpRequest = new XMLHttpRequest();
    } else if (window.ActiveXObject) { // IE 6 and older
        httpRequest = new ActiveXObject('Microsoft.XMLHTTP');
    }

    if(!method) method = 'POST';
    data = (!!data) ? JSON.stringify(data) : '';

    httpRequest.onreadystatechange = afterAction;
    httpRequest.open(method.toUpperCase(), url, true);
    httpRequest.setRequestHeader("Content-type", "application/json; charset=utf-8");
    //httpRequest.setRequestHeader("Content-length", data.length);
    //httpRequest.setRequestHeader("Connection", "close");
    httpRequest.send(data);
}

使用Spring接收部分@Controller

@Controller
@RequestMapping(value={"member"}, produces={"application/json"})
@ResponseStatus(value = HttpStatus.OK)
public class MemberController {

    /**
     * @param request
     * @param resp
     * @return
     * @throws Exception
     */
    @RequestMapping(value={"/login"})
    public @ResponseBody String login(HttpServletRequest request, HttpServletResponse resp) throws Exception {
        System.out.println("Login request");
        String id = String.valueOf(request.getParameter("id"));                 //returns null
        String password = String.valueOf(request.getParameter("password"));     //returns null

        Map<String, String> result = new HashMap<String, String>();
        result.put("result", "S");
        result.put("message", "login success");
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(result);
    }
}

我不知道为什么参数变成空。谢谢。

Answer 1

您需要按照以下步骤在 Controller 中接受 Json:

(1)定义UserLogin bean来保存Json

public class UserLogin  {
    private String id;
    private String password;

    //Add getters and setters
}

(2) 更改您的 Controller 以接受 Json 并接收 UserLogin bean

@Controller
@RequestMapping(value={"member"}, produces={"application/json"})
@ResponseStatus(value = HttpStatus.OK)
public class MemberController {

    @RequestMapping(value={"/login"}, method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
    public @ResponseBody String login(UserLogin userLogin) throws Exception {
        System.out.println("Login request");
        String id = userLogin.getId();            
        String password = userLogin.getPassword();

        Map<String, String> result = new HashMap<String, String>();
        result.put("result", "S");
        result.put("message", "login success");
        ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(result);
    }
}