Java 为什么服务器要删除我的头

我们正在开发一个带有angularjs前端和JavaEE后端的web应用程序

当我们试图从前端联系后端时，我们收到一个错误，因为服务器位于前端以外的另一个域上。我一直在阅读跨域请求，我认为服务器为响应设置了所需的头。以下是后端代码：

private void fixHeader(HttpServletResponse response) {
    response.addHeader("Access-Control-Allow-Origin", "http://localhost:8383");
    response.addHeader("Access-Control-Allow-Methods", "GET, PUT, POST, OPTIONS, DELETE");
    response.addHeader("Access-Control-Allow-Headers", "Content-type");
    response.addHeader("Access-Control-Max-Age", "86400");
    response.addHeader("Access-Control-Request-Headers", "X-Requested-With, accept, content-type");
    System.out.println(response.getHeaderNames().toString());
}

@Override
protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    fixHeader(resp);
}

这是来自前端的http请求

多洛金函数

 this.doLogin = function(user) {

        var user = {"data": user};
        console.log("test before login http " + JSON.stringify(user));


        return $http({
            method: 'POST',
            url: 'http://localhost:8080/myInnovationBackend/Login',
            headers: {'Content-Type': 'application/json'},
            data: user
        })

    };

和登录控制器：

 loginService.doLogin(user)
            .success(function (data) 
            {
               $scope.loginStatus = data;


                var message = $scope.loginStatus.data.status;
                console.log("test on get: " + message);

                if(message ==='ok'){
                $location.url('/loggedIn');
                console.log("OK")
                }
            })
            .error(function(data)   
            {
            console.log("test after error" + JSON.stringify(data));    
            return data ;
            });

据我在网上看到的，这应该足够了。但是当我们从前端登录时，它会到达错误函数

XMLHttpRequest cannot load http://localhost:8080/myInnovationBackend/Login. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8383' is therefore not allowed access. frontPage.html:1
test after error""

---

以前有人犯过这个错误吗？

刚刚开始工作。我认为我误解了期权法的概念。因此，我将我的FixHeader添加到doPost方法中，然后它就工作了

所以不是

private void fixHeader(HttpServletResponse response) {
response.addHeader("Access-Control-Allow-Origin", "http://localhost:8383");
response.addHeader("Access-Control-Allow-Methods", "GET, PUT, POST, OPTIONS, DELETE");
response.addHeader("Access-Control-Allow-Headers", "Content-type");
response.addHeader("Access-Control-Max-Age", "86400");
response.addHeader("Access-Control-Request-Headers", "X-Requested-With, accept, content-type");
System.out.println(response.getHeaderNames().toString());
}

@Override
protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    fixHeader(resp);
}

我做到了：

private void fixHeader(HttpServletResponse response) {
    response.addHeader("Access-Control-Allow-Origin", "http://localhost:8383");
    response.addHeader("Access-Control-Allow-Methods", "GET, PUT, POST, OPTIONS, DELETE");
    response.addHeader("Access-Control-Allow-Headers", "Content-type");
    response.addHeader("Access-Control-Max-Age", "86400");
    response.addHeader("Access-Control-Request-Headers", "X-Requested-With, accept, content-type");
}

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws     ServletException, IOException {
    fixHeader(response);
}

@Override
protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    fixHeader(resp);
}

---

您是否验证了标题是否确实存在？例如，使用Chrome开发者控制台中的网络选项卡。正在从服务器发送两个响应。第一个响应包含标题，例如访问控制允许来源：访问控制允许方法：GET、PUT、POST、OPTIONS、DELETE访问控制允许标题：内容类型访问控制最大年龄：86400访问控制请求标题：X-Request-With、accept、Content-type和服务器返回OK答案的另一个响应。