Android MVVM 和 Retrofit api 响应为空

Question

此函数用于登录用户。我正在使用数据绑定和 RxJava

public void loginUser(String idNumber, String password) {
    RetrofitService.getApiService()
            .agentLogin(new LoginRequest(idNumber, password))
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Action1<Response<LoginResponse>>() {
                @Override
                public void call(Response<LoginResponse> userResponse) {
                    if (userResponse.isSuccessful() ) {
                        executor.execute(new Runnable() {
                            @Override
                            public void run() {

                                Log.i("AUTHKEY",userResponse.body().getUser().getAuthKey());
                                userDao.insert(userResponse.body().getUser());
                            }
                        });
                    }
                }
            });

}

当我登录时应用程序失败 Log.i("AUTHKEY",userResponse.body().getUser().getAuthKey());

错误java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Integer com.vuna.agent.model.LoginResponse$User.getId()' on a null object reference

From the Okhttp logger, the server returns the right response

2019-04-12 12:33:36.707 28896-29064/com.vuna.agent D/OkHttp: <-- 200 OK http://example.com/login (923ms)

2019-04-12 12:33:36.709 28896-29064/com.vuna.agent D/OkHttp: {"code":201,"message":"You are now logged in!","id":2,"firstname":"Victor","lastname":"Amwollo","authkey":"22sA1JvVo4hmzhps1NVIO7_B6f4yCp_e"}
2019-04-12 12:33:36.709 28896-29064/com.vuna.agent D/OkHttp: <-- END HTTP (141-byte body)

Here is the LoginResponse class with an inner Entity class

public class LoginResponse {

    private Boolean success;

    private User user;


    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }


    @Entity(tableName = "user")
    public static class User {

        @PrimaryKey(autoGenerate = true)
        @SerializedName("id")
        private Integer id;

        private String firstName;
        private String lastName;

        private String authKey;

        //getters and setters

    }
}

为什么我会收到错误消息？

Answer 1

response 上的 response.body() 方法将读取输入 (network) 流并将其转换为字符串。所以它动态地构建字符串并 returns 给你。第二次调用时，网络流已经被消耗，不再可用

所以，解决办法就是将响应的结果保存到一个变量中，然后根据需要多次访问它。

查看以下代码：

@Override
public void call(Response<LoginResponse> userResponse) {
    if (userResponse.isSuccessful() ) {
        LoginResponse data = userResponse.body(); // Consume response body once and then use it in this method further
        executor.execute(new Runnable() {
            @Override
            public void run() {
                Log.i("AUTHKEY", data.getUser().getAuthKey()); // access data variable here
                userDao.insert(data.getUser()); // access data variable here
            }
        });
    }
}

Answer 2

您得到空指针是因为您的 json 没有映射到 LoginResponse。

尝试

public class LoginResponse {

    private Boolean success;
    private Integer id;
    private String firstName;
    private String lastName;
    private String authKey;

}

我清理了你的 RX。注意：由于我习惯了kotlin，括号可能是错误的。

public void loginUser(String idNumber, String password) {
    RetrofitService.getApiService()
        .agentLogin(new LoginRequest(idNumber, password))
        .filter { it.isSuccessful(); }
        .map { it.body(); }
        .map { new User(it.getId()...) /* covert LoginResponse to User here */ } 
        .flatMapCompletable { Completable.fromAction { userDao.insert(it); } }
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe();                                 
}

Android MVVM 和 Retrofit api 响应为空

Android MVVM and Retrofit api response is null

android

mvvm

retrofit

android-room

android-databinding