AngularJS http POST 到 Servlet [英] AngularJS http POST to Servlet

问题描述

我浏览了很多 StackOverflow 的答案并在谷歌上搜索了很多，但仍然找不到我的帖子请求不起作用的原因.

这是我的jsp:

<form class="form-signin" ng-controller="MyController"><h2 class="form-signin-heading">请登录</h2><label for="username" class="sr-only">用户名</label><input type="text" id="username" ng-model="user.name" class="form-control" placeholder="Username" required autofocus><label for="password" class="sr-only">密码</label><input type="password" ng-model="user.password" id="password" class="form-control" placeholder="Password" required><button class="btn btn-lg btn-primary btn-block" ng-click="login()" type="submit">登录</button></表单>

这是我的控制器:

app.controller('MyController', function($scope, $http) {$scope.login = function() {console.log($scope.user);$http({方法:'POST'，网址:'登录'，数据:$scope.user，标题:{'内容类型':'应用程序/json'}}).成功(功能(数据){控制台日志(数据)；}).错误(函数(数据){控制台日志(数据)；});console.log("POST 完成");};});

还有我的 servlet:

protected void doPost(HttpServletRequest request,HttpServletResponse 响应) 抛出 ServletException, IOException {System.out.println("里面做POST");Gson gson = new Gson();JsonParser 解析器 = new JsonParser();JsonObject obj = (JsonObject) 解析器.parse(request.getParameter("data"));Iterator it = (Iterator) obj.entrySet();而 (it.hasNext()) {System.out.println(it.next());}System.out.println("结束");}

我不断收到空指针异常

java.lang.NullPointerException在 java.io.StringReader.(StringReader.java:50)在 com.google.gson.JsonParser.parse(JsonParser.java:45)在 com.zookeeperUI.controller.Login.doPost(Login.java:40)

请告诉我我在这里做错了什么.

解决方案

您的请求不包含名为data"的 URL 参数，因此 request.getParameter("data") 返回 null 并且您得到 NullPointerException.

您尝试通过 URL 参数发送 Javascript 对象，这不适用于非浅层对象.

我建议将数据作为请求负载发送:

JsonObject obj = (JsonObject) parser.parse(request.getReader());

在客户端，您需要确保您的数据以正确的 JSON 格式发送:

$http({方法:'POST'，网址:'登录'，内容类型:'应用程序/json'，数据:JSON.stringify($scope.user),})...

I went through a lot of StackOverflow answers and googled a lot but still could not find why my post request is not working.

This is my jsp:

<div class="container">
      <form class="form-signin" ng-controller="MyController">
        <h2 class="form-signin-heading">Please sign in</h2>
        <label for="username" class="sr-only">Username</label>
        <input type="text" id="username"  ng-model="user.name" class="form-control" placeholder="Username" required autofocus>
        <label for="password" class="sr-only">Password</label>
        <input type="password" ng-model="user.password" id="password" class="form-control" placeholder="Password" required>
        <button class="btn btn-lg btn-primary btn-block" ng-click="login()" type="submit">Sign in</button>
      </form>
    </div> 

This is my controller:

app.controller('MyController', function($scope, $http) {

    $scope.login = function() {
        console.log($scope.user);
        $http({
            method : 'POST',
            url : 'login',
            data : $scope.user,
            headers: {
                'Content-Type': 'application/json'
            }
        }).success(function(data) {
            console.log(data);
        }).error(function(data) {
            console.log(data);
        });
        console.log("POST done");
    };
});

And my servlet:

protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        System.out.println("inside do POST");
        Gson gson = new Gson();
        JsonParser parser = new JsonParser();
        JsonObject obj = (JsonObject) parser
                .parse(request.getParameter("data"));
        Iterator it = (Iterator) obj.entrySet();
        while (it.hasNext()) {
            System.out.println(it.next());
        }
        System.out.println("over");
    }

I keep getting this Null pointer exception

java.lang.NullPointerException
    at java.io.StringReader.<init>(StringReader.java:50)
    at com.google.gson.JsonParser.parse(JsonParser.java:45)
    at com.zookeeperUI.controller.Login.doPost(Login.java:40)

Please tell me what am I doing wrong here .

解决方案

Your request does not contain a URL parameter named "data", therefore request.getParameter("data") returns null and you get the NullPointerException.

You try to send a Javascript object via URL parameters which does not go well with non-shallow objects.

I would recommend to send the data as request payload:

JsonObject obj = (JsonObject) parser.parse(request.getReader());

On the client you need to make sure that your data is sent as proper JSON:

$http({
        method : 'POST',
        url : 'login',
        contentType: 'application/json',
        data : JSON.stringify($scope.user),
    })...

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