在成功登录Java rest后，如何将成功返回给AngularJS？

@RestController
public class LoginController {
    @PostMapping("/login")
    public ResponseEntity<String> login(@RequestBody LoginRequest loginRequest) {
        // 处理登录逻辑
        if (loginSuccess) {
            return ResponseEntity.ok("Login successful");
        } else {
            return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body("Login failed");
        }
    }
}

app.controller('LoginController', function($scope, $http) {
    $scope.login = function() {
        var loginData = {
            username: $scope.username,
            password: $scope.password
        };

        $http.post('/login', loginData)
            .then(function(response) {
                // 登录成功
                $scope.successMessage = response.data;
            }, function(error) {
                // 登录失败
                $scope.errorMessage = error.data;
            });
    };
});