所以，我正试图从Guardian报纸API中提取JSON。
基本上我可以得到除作者之外的所有内容。
如何或以何种方式提取此内容。
非常感谢提前我对这一切都是新手，并且在过去提出问题并且无济于事。我们将非常感谢任何建议。
QueryUtils.Java
package com.example.android.newsapp;
import android.content.Context;
import android.text.TextUtils;
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
public class QueryUtils {
private static final String TAG = QueryUtils.class.getSimpleName();
public static Context context;
private QueryUtils() {
}
public static List<News> fetchNews(String requestUrl) {
URL url = createUrl(requestUrl);
String json_response = null;
try {
json_response = makeHttpRequest(url);
Log.i(TAG, json_response);
} catch (IOException e) {
e.printStackTrace();
}
List<News> news = extractFromJson(json_response);
return news;
}
private static URL createUrl(String StringUrl) {
URL url = null;
try {
url = new URL(StringUrl);
} catch (MalformedURLException e) {
e.printStackTrace();
}
return url;
}
private static String makeHttpRequest(URL url) throws IOException {
String json_response = "";
if (url == null) {
return json_response;
}
HttpURLConnection httpURLConnection = null;
InputStream inputStream = null;
try {
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setReadTimeout(10000);
httpURLConnection.setConnectTimeout(15000);
httpURLConnection.setRequestMethod("GET");
httpURLConnection.connect();
if (httpURLConnection.getResponseCode() == 200) {
inputStream = httpURLConnection.getInputStream();
json_response = readFromString(inputStream);
} else {
Log.e(TAG, "Error" + httpURLConnection.getResponseCode());
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (httpURLConnection != null) {
httpURLConnection.disconnect();
}
if (inputStream != null) {
inputStream.close();
}
}
return json_response;
}
private static String readFromString(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
} private static String extractString(JSONObject newInfo, String stringName) {
String str = null;
try {
str = newInfo.getString(stringName);
} catch (JSONException e) {
Log.e(TAG, context.getString(R.string.query_util_error_extract_string) + stringName);
}
if (str != null) {
return str;
} else {
return context.getString(R.string.empty_string);
}
}
private static List<News> extractFromJson(String news_json) {
if (TextUtils.isEmpty(news_json)) {
return null;
}
List<News> news = new ArrayList<News>();
try {
JSONObject baseJson = new JSONObject(news_json);
JSONArray news_array = baseJson.getJSONObject("response").getJSONArray("results");
for (int i = 0; i < news_array.length(); i++) {
JSONObject currentNews = news_array.getJSONObject(i);
String name = currentNews.getString("sectionName");
String title = currentNews.getString("webTitle");
String date = currentNews.getString("webPublicationDate");
String url = currentNews.getString("webUrl");
JSONArray tags = baseJson.getJSONArray("tags");
String contributor = null;
if (tags.length() == 1) {
JSONObject contributorTag = (JSONObject) tags.get(0);
contributor = extractString(contributorTag, context.getString(R.string.query_util_json_web_title));
} else {
//no contributor
contributor = context.getString(R.string.empty_string);
}
News mNews = new News(name, title, date, url, contributor);
news.add(mNews);
}
} catch (JSONException e) {
e.printStackTrace();
}
return news;
}
}
这是我正在提取的JSON。 https://content.guardianapis.com/search?q=debate&tag=politics/politics&from-date=2014-01-01&api-key=test
这是数据提供者.. http://open-platform.theguardian.com/documentation/
答案 0 :(得分：2)
我也很难找到作者。我做了两个改变来解决这个问题。
首先，我必须更改添加＆amp; show-tags =贡献者到网址。
其次，我必须在解析阅读时调整你的if语句。我在这里输入代码。而不是：
contributor = extractString(contributorTag, context.getString(R.string.query_util_json_web_title));
我换成了：
contributor = contributorTag.getString("webTitle");
（键＃34; webTitle＆＃34;包含作者姓名）
您遇到的问题是，您使用的网址并不包含包含webTitle密钥的标记数组，即使我使用＆amp; show-tags = contributor调整后也是如此。
完整的QueryUtils.java文件是：
package com.example.android.technewsapps1;
import android.text.TextUtils;
import android.util.Log;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
public final class QueryUtils {
private static final String LOG_TAG = QueryUtils.class.getSimpleName();
private QueryUtils() {
}
/**
* Query the Guardian dataset and return a list of NewsStory objects.
*/
public static List<NewsStory> fetchNewsStoryData(String requestUrl) {
// Create URL object
URL url = createUrl(requestUrl);
// Perform HTTP request to the URL and receive a JSON response back
String jsonResponse = null;
try {
jsonResponse = makeHttpRequest(url);
} catch (IOException e) {
Log.e(LOG_TAG, "Problem making the HTTP request.", e);
}
// Extract relevant fields from the JSON response and create a list of NewsStories
List<NewsStory> newsStories = extractFeatureFromJson(jsonResponse);
// Return the list of NewsStories
return newsStories;
}
/**
* Returns new URL object from the given String URL.
*/
private static URL createUrl(String stringUrl) {
URL url = null;
try {
url = new URL(stringUrl);
} catch (MalformedURLException e) {
Log.e(LOG_TAG, "Problem building the URL ", e);
}
return url;
}
/**
* Make an HTTP request to the given URL and return a String as the response.
*/
private static String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
// If the URL is null, then return early.
if (url == null) {
return jsonResponse;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// If the request was successful (response code 200),
// then read the input stream and parse the response.
if (urlConnection.getResponseCode() == 200) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
} else {
Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG, "Problem retrieving the newsStory JSON results.", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
// Closing the input stream could throw an IOException, which is why
// the makeHttpRequest(URL url) method signature specifies than an IOException
// could be thrown.
inputStream.close();
}
}
return jsonResponse;
}
/**
* Convert the {@link InputStream} into a String which contains the
* whole JSON response from the server.
*/
private static String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
/**
* Return a list of NewsStory objects that has been built up from
* parsing the given JSON response.
*/
private static List<NewsStory> extractFeatureFromJson(String newsStoryJSON) {
// If the JSON string is empty or null, then return early.
if (TextUtils.isEmpty(newsStoryJSON)) {
return null;
}
// Create an empty ArrayList that we can start adding news stories to
List<NewsStory> newsStories = new ArrayList<>();
// Try to parse the JSON response string. If there's a problem with the way the JSON
// is formatted, a JSONException exception object will be thrown.
// Catch the exception so the app doesn't crash, and print the error message to the logs.
try {
// Create a JSONObject from the JSON response string
JSONObject baseJsonResponse = new JSONObject(newsStoryJSON);
//Create the JSONObject with the key "response"
JSONObject responseJSONObject = baseJsonResponse.getJSONObject("response");
//JSONObject responseJSONObject = baseJsonResponse.getJSONObject("response");
// Extract the JSONArray associated with the key called "results",
// which represents a list of news stories.
JSONArray newsStoryArray = responseJSONObject.getJSONArray("results");
// For each newsStory in the newsStoryArray, create an NewsStory object
for (int i = 0; i < newsStoryArray.length(); i++) {
// Get a single newsStory at position i within the list of news stories
JSONObject currentStory = newsStoryArray.getJSONObject(i);
// Extract the value for the key called "webTitle"
String title = currentStory.getString("webTitle");
// Extract the value for the key called "sectionName"
String sectionName = currentStory.getString("sectionName");
// Extract the value for the key called "webPublicationDate"
String date = currentStory.getString("webPublicationDate");
// Extract the value for the key called "url"
String url = currentStory.getString("webUrl");
//Extract the JSONArray with the key "tag"
JSONArray tagsArray = currentStory.getJSONArray("tags");
//Declare String variable to hold author name
String authorName = null;
if (tagsArray.length() == 1) {
JSONObject contributorTag = (JSONObject) tagsArray.get(0);
authorName = contributorTag.getString("webTitle");
}
// Create a new NewsStory object with the title, section name, date,
// and url from the JSON response.
NewsStory newsStory = new NewsStory(title, sectionName, date, url, authorName);
// Add the new NewsStory to the list of newsStories.
newsStories.add(newsStory);
}
} catch (JSONException e) {
// If an error is thrown when executing any of the above statements in the "try" block,
// catch the exception here, so the app doesn't crash. Print a log message
// with the message from the exception.
Log.e("QueryUtils", "Problem parsing the newsStory JSON results", e);
}
// Return the list of earthquakes
return newsStories;
}
}