使用Java进行带有授权令牌的API请求

Question

我是一个新手软件开发者，目前正在处理一个涉及到与带有Bearer Token的事务服务器进行API调用的项目。

我已经通过命令行了解了如何通过curl调用API。它看起来像这样（由于我使用的是测试服务器，该测试服务器仅支持http请求，因此使用http而不是https）

curl http://api.testwebsite.com/transactions/ \
-H "Authorization: Bearer <TOKEN ID>" \
-d amount=500 \
-d currency="USD" \
-d card_number="<card number>" \
-d card_exp_month=<exp month> \
-d card_exp_year=<exp year> \
-d card_cvv="<card's ccv>"

现在我正在使用Java编写一个程序（必须是Java），只能使用本地的Java库（不能使用Spring或Apache等第三方包），并尝试通过HttpUrlConnection调用API。

import java.io.BufferedReader; 
import java.io.InputStreamReader;
import java.io.DataOutputStream; 
import java.net.URL;             
import javax.net.ssl.HttpsURLConnection;
import java.net.HttpURLConnection;

public class TestHttpsPost {

public static void main(String[] args) throws Exception {

    // Uncomment one of these next two lines:
    URL url = new URL("http://api.testwebsite.com/transactions");
    //URL url = new URL("https://httpbin.org/post"); // good for testing

    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
    connection.setRequestMethod("POST");
    connection.setDoInput(true);
    connection.setDoOutput(true);

    // Change this to a valid token:
    connection.setRequestProperty("Authorization", "Bearer <TOKEN ID>");
    /*

    connection.setRequestProperty("amount", "500");
    connection.setRequestProperty("currency", "USD");
    connection.setRequestProperty("card_number", "<CARD_NUMBER>");
    connection.setRequestProperty("card_exp_month", "<EXP_MONTH>");
    connection.setRequestProperty("card_exp_year", "<EXP_YEAR");
    connection.setRequestProperty("card_cvv", "<CCV>");
    */




    String jsonData1 = "amount=500";
    String jsonData2 = "currency=\"USD\"";
    String jsonData3 = "card_number=\"11111111111111111\"";
    String jsonData4 = "card_exp_month=11";
    String jsonData5 = "card_exp_year=2011";
    String jsonData6 = "card_cvv=\"123\"";




    try {
        // Post the data:
        DataOutputStream output = new DataOutputStream(connection.getOutputStream());
        output.writeBytes(jsonData1);
        output.writeBytes(jsonData2);
        output.writeBytes(jsonData3);
        output.writeBytes(jsonData4);
        output.writeBytes(jsonData5);
        output.writeBytes(jsonData6);

        output.close();

        // Read the response:
        BufferedReader reader = new BufferedReader(new InputStreamReader(
          connection.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            System.out.println(line);
        }
        reader.close();
    } catch (Exception e) {
        System.out.println(e.getMessage());
    }

    System.out.println("Response code:" + connection.getResponseCode());
    System.out.println("Response message:" + connection.getResponseMessage());
}
}

但我一直收到以下错误信息：

Server returned HTTP response code: 400 for URL: http://api.testwebsite.com/transactions
Response code:400
Response message:Bad Request

我遵循了在Java中将PayPal curl请求转换为http请求，但是PayPal API 的字段相当不同，我不确定是否有任何问题。

提前致谢！

- Zekun Wang

Answer 1

非常不错的选择是使用 Retrofit（一种适用于 Java 和 Android 的类型安全的 HTTP 客户端）

http://square.github.io/retrofit/

这是一个使用身份验证令牌的服务示例：

public class ServiceGenerator {
    public static final String BASE_URL = "https://your.api.url";
    // returns an API client of type serviceClass
    public static <S> S createService(
            Class<S> serviceClass, final String token) {
        RestAdapter.Builder builder = new RestAdapter.Builder() .setEndpoint(BASE_URL)
                .setClient(new OkClient(new OkHttpClient()));
        if (token != null) {
            builder.setRequestInterceptor(new RequestInterceptor() {
                @Override
                public void intercept(RequestFacade request) { request.addHeader("Accept", "application/json"); request.addHeader("Authorization", token);
                } });
        }
        RestAdapter adapter = builder.build();
        return adapter.create(serviceClass); }
}

- Bogdan Ustyak