【OAuth】

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONObject;

public class OAuthExample {

    public static void main(String[] args) {
        // 客户端ID和密钥，根据实际情况进行替换
        String clientId = "YOUR_CLIENT_ID";
        String clientSecret = "YOUR_CLIENT_SECRET";

        // 请求授权码
        String authorizationCode = requestAuthorizationCode(clientId);

        // 通过授权码获取访问令牌
        String accessToken = requestAccessToken(clientId, clientSecret, authorizationCode);

        // 使用访问令牌访问受保护资源
        String protectedResource = accessProtectedResource(accessToken);
        System.out.println("Protected Resource: " + protectedResource);
    }

    public static String requestAuthorizationCode(String clientId) {
        // 构建授权码请求URL，根据实际情况进行替换
        String authorizationUrl = "https://example.com/oauth/authorize?client_id=" + clientId + "&response_type=code&redirect_uri=http://localhost";

        // 使用浏览器打开授权码请求URL，用户登录并授权后，将重定向到指定的重定向URI，并返回授权码
        // 在这个例子中，用户将手动复制并粘贴授权码
        String authorizationCode = "AUTHORIZATION_CODE";
        return authorizationCode;
    }

    public static String requestAccessToken(String clientId, String clientSecret, String authorizationCode) {
        // 构建请求获取访问令牌的URL，根据实际情况进行替换
        String tokenUrl = "https://example.com/oauth/token";

        // 使用HttpClient发送POST请求，发送授权码和其他必要参数，返回包含访问令牌的JSON响应
        HttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(tokenUrl);
        httpPost.setHeader("Content-Type", "application/x-www-form-urlencoded");

        // 构建请求体，包含授权码、客户端ID、客户端密钥等参数
        String requestBody = "grant_type=authorization_code&code=" + authorizationCode + "&client_id=" + clientId + "&client_secret=" + clientSecret;

        try {
            httpPost.setEntity(new StringEntity(requestBody));
            HttpResponse response = httpClient.execute(httpPost);
            HttpEntity entity = response.getEntity();
            String responseString = EntityUtils.toString(entity);
            JSONObject jsonResponse = new JSONObject(responseString);
            String accessToken = jsonResponse.getString("access_token");
            return accessToken;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String accessProtectedResource(String accessToken) {
        // 构建请求访问受保护资源的URL，根据实际情况进行替换
        String protectedResourceUrl = "https://example.com/api/resource";

        // 使用HttpClient发送GET请求，添加访问令牌到请求头，返回受保护资源的响应
        HttpClient httpClient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(protectedResourceUrl);
        httpGet.setHeader("Authorization", "Bearer " + accessToken);

        try {
            HttpResponse response = httpClient.execute(httpGet);
            HttpEntity entity = response.getEntity();
            String responseString = EntityUtils.toString(entity);
            return responseString;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}