如何使用改造和 gson 异步解析 json

Question

我有 1 个请求，可以得到 2 个不同的响应：

登录名和密码正确时：

{
    "token": "token..",
    "expires": "2016-04-28T10:46:36+0000"
}

错误时：

{
    "error": {
        "id": "0123456789",
        "code": 401,
        "message": "invalid credentials"
    }
}

虽然更正它解析成功，但是当我得到错误的响应（错误的登录名或密码）时，它返回 null（未解析）。

Error.java

public class Error {
    @SerializedName("id")
    @Expose
    public String id;
    @SerializedName("code")
    @Expose
    public int code;
    @SerializedName("message")
    @Expose
    public String message;

    public Error() {}

    public Error(String id, int code, String message) {
        this.id = id;
        this.code = code;
        this.message = message;
    }
}

Auth.java

public class Auth {
    @SerializedName("token")
    @Expose
    public String token;

    @SerializedName("expires")
    @Expose
    public String expires;

    @SerializedName("error")
    @Expose
    public Error error;

    public Auth(String token, String expires, Error error) {
        this.token = token;
        this.expires = expires;
        this.error = error;
    }

    public Auth() {
        error = new Error();
    }
}

ApiRequests.java

public interface ApiRequests {
    @FormUrlEncoded
    @POST("auth/token")
    Call<Auth> auth(@Field("login") String login, @Field("password") String password);

}

Api.java

Gson gson = new GsonBuilder()
        .setDateFormat(DATE_FORMAT)
        .create();

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(URL_MAIN)
        .addConverterFactory(GsonConverterFactory.create(gson))
        .build();

ApiRequests service = retrofit.create(ApiRequests.class);
Call<Auth> call = service.auth("login", "password");

call.enqueue(new Callback<Auth>() {
    @Override
    public void onResponse(Call<Auth> call, Response<Auth> response) {
        Auth responseBody = response.body(); // null when login/password are wrong
    }

    @Override
    public void onFailure(Call<Auth> call, Throwable t) {

    }
});

build.gradle

dependencies {
    compile 'com.squareup.retrofit2:retrofit:2.0.2'
    compile 'com.squareup.retrofit2:converter-gson:2.0.2'
    compile 'com.google.code.gson:gson:2.6.2'
}

Answer 1

Auth.java

public class Auth implements Serializable {

    private String token;
    private String expires;
    private Error error;

    //Implements getters and setters
}

错误.java

public class Error implements Serializable {

    private String id;
    private int code;
    private String message;

    //Implements getters and setters
}

API.java

call.enqueue(new Callback<Auth>() {
    @Override
    public void onResponse(Call<Auth> call, Response<Auth> response) {
        if(response.code() == 401){
            //failure
            Log.e("Error", response.body().getError().getMessage());
        } else{
            //success
            Log.e("Success", response.body().getToken());
        }
    }

    @Override
    public void onFailure(Call<Auth> call, Throwable t) {

    }
});