來自json字符串的具體信息

Question

我一直在Eclipse中玩弄推文一段時間，這是作爲一個JSON字符串呈現。

爲此，我創建了一個叫做分享Tweet的對象（原始的，是吧？），這需要從JSON字符串的某些信息，並將其存儲在鳴叫對象。沒有什麼花哨。

我分享Tweet類看起來如下：

public class Tweet implements TwitterMelding { 

public Tweet() { 
} 

String created_at; 
String id; 
String text; 
String user; 

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

public void setText(String text) { 
    this.text = text; 
} 

public void setId(String id) { 
    this.id = id; 
} 

public void setCreated_at(String created_at) { 
    this.created_at = created_at; 
} 
} 

現在，簡單，因爲它可能看起來，還有那些不工作之一。

具體地說字符串用戶。它應該做的是發佈推文的人的商店用戶ID。

以下是作爲鳴叫從Twitter在所有獲得它的可怕長度：

{"created_at":"Sat Feb 08 15:37:37 +0000 2014","id":432176397474623489,"id_str":"432176397474623489","text":"Skal begynne \u00e5 selge vekter.. Eneste m\u00e5ten det konstant kommer penger i lommen","source":"\u003ca href=\"http:\/\/twitter.com\/download\/iphone\" rel=\"nofollow\"\u003eTwitter for iPhone\u003c\/a\u003e","truncated":false,"in_reply_to_status_id":null,"in_reply_to_status_id_str":null,"in_reply_to_user_id":null,"in_reply_to_user_id_str":null,"in_reply_to_screen_name":null,"user":{"id":366301747,"id_str":"366301747","name":"skinny-pete","screen_name":"JFarsund","location":"bj\u00f8rge","url":null,"description":"j\u00f8rgen er en tynn gutt med pack.. Men det teller vel ikke? Det gj\u00f8r vel ikke bio heller","protected":false,"followers_count":427,"friends_count":291,"listed_count":2,"created_at":"Thu Sep 01 23:03:49 +0000 2011","favourites_count":5103,"utc_offset":3600,"time_zone":"Copenhagen","geo_enabled":true,"verified":false,"statuses_count":8827,"lang":"no","contributors_enabled":false,"is_translator":false,"is_translation_enabled":false,"profile_background_color":"C0DEED","profile_background_image_url":"http:\/\/pbs.twimg.com\/profile_background_images\/378800000089578611\/6840970475350d63190eb05d3d7e47ec.png","profile_background_image_url_https":"https:\/\/pbs.twimg.com\/profile_background_images\/378800000089578611\/6840970475350d63190eb05d3d7e47ec.png","profile_background_tile":true,"profile_image_url":"http:\/\/pbs.twimg.com\/profile_images\/431961396528414720\/EwkxQBkW_normal.jpeg","profile_image_url_https":"https:\/\/pbs.twimg.com\/profile_images\/431961396528414720\/EwkxQBkW_normal.jpeg","profile_banner_url":"https:\/\/pbs.twimg.com\/profile_banners\/366301747\/1391822743","profile_link_color":"0084B4","profile_sidebar_border_color":"FFFFFF","profile_sidebar_fill_color":"DDEEF6","profile_text_color":"333333","profile_use_background_image":true,"default_profile":false,"default_profile_image":false,"following":null,"follow_request_sent":null,"notifications":null},"geo":{"type":"Point","coordinates":[60.33700829,5.24626808]},"coordinates":{"type":"Point","coordinates":[5.24626808,60.33700829]},"place":{"id":"2260fcb4a77f2bad","url":"https:\/\/api.twitter.com\/1.1\/geo\/id\/2260fcb4a77f2bad.json","place_type":"city","name":"Bergen","full_name":"Bergen, Hordaland","country_code":"NO","country":"Norge","contained_within":[],"bounding_box":{"type":"Polygon","coordinates":[[[5.1602697,60.1848543],[5.1602697,60.5335445],[5.6866852,60.5335445],[5.6866852,60.1848543]]]},"attributes":{}},"contributors":null,"retweet_count":0,"favorite_count":0,"entities":{"hashtags":[],"symbols":[],"urls":[],"user_mentions":[]},"favorited":false,"retweeted":false,"filter_level":"medium","lang":"no"} 

這真的是一個很長眼痛。

我增加了一些「......」到下一個，讓它稍微更具可讀性，只顯示我感興趣的值：

{…,"user":{"id":366301747,"id_str":"366301747","name":"skinny-pete","screen_name":"JFarsund","location":"bj\u00f8rge","url":null,"description":"j\u00f8rgen er en tynn gutt med pack.. Men det teller vel ikke? Det gj\u00f8r vel ikke bio heller","protected":false,"followers_count":427,"friends_count":291,"listed_count":2,"created_at":"Thu Sep 01 23:03:49 +0000 2011","favourites_count":5103,"utc_offset":3600,"time_zone":"Copenhagen","geo_enabled":true,"verified":false,"statuses_count":8827,"lang":"no","contributors_enabled":false,"is_translator":false,"is_translation_enabled":false,"profile_background_color":"C0DEED","profile_background_image_url":"http:\/\/pbs.twimg.com\/profile_background_images\/378800000089578611\/6840970475350d63190eb05d3d7e47ec.png","profile_background_image_url_https":"https:\/\/pbs.twimg.com\/profile_background_images\/378800000089578611\/6840970475350d63190eb05d3d7e47ec.png","profile_background_tile":true,"profile_image_url":"http:\/\/pbs.twimg.com\/profile_images\/431961396528414720\/EwkxQBkW_normal.jpeg","profile_image_url_https":"https:\/\/pbs.twimg.com\/profile_images\/431961396528414720\/EwkxQBkW_normal.jpeg","profile_banner_url":"https:\/\/pbs.twimg.com\/profile_banners\/366301747\/1391822743","profile_link_color":"0084B4","profile_sidebar_border_color":"FFFFFF","profile_sidebar_fill_color":"DDEEF6","profile_text_color":"333333","profile_use_background_image":true,"default_profile":false,"default_profile_image":false,"following":null,"follow_request_sent":null,"notifications":null}, …} 

權，還是和我在一起？

正如我上面提到的，我想是用戶ID，這是我要分配給在鳴叫對象變量「用戶」。

{…,"user":{"id":366301747,"id_str":"366301747",… }…} 

所有我想要的是指定的號碼，在我分享Tweet對象變量「用戶」。

但對我的生活，我似乎無法。

爲了確保鳴叫對象得到它想要的信息，而不是它不，我使用的是傑克遜對象信息：

ObjectMapper mapper = new ObjectMapper(); 
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); 

所以我的問題。

如何告訴我從我的json字符串中取數字並將其分配給變量「user」？

我寧願它是可行的與傑克遜獨自一人，並沒有超過必要進口更多的JAR文件。

請原諒牆上的文字。

Answer 1

它可以與Gson庫非常簡單。

因爲，你已經通過查看創建完成一個POJO，辛勤工作的json你可以驗證User是一個有效的json對象，而不是String值。

因此，讓我們修改POJO的（Tweet）user屬性稍微有：

User user; 

public User getUser() { 
    return user; 
} 

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

凡User自定義類是：

public class User { 
    private String id; 

    public String getId() { 
     return id; 
    } 

    public void setId(String id) { 
     this.id = id; 
    } 
} 

現在只需撥打你的GSON方法的對象轉換從json（我將json存儲到一個文件並通過BufferedReader讀取）：

public static void main(String[] args) throws FileNotFoundException { 
     Gson gson = new Gson(); 
     BufferedReader br = new BufferedReader(new FileReader(
       "json.txt")); 

     Tweet tweetObj = gson.fromJson(br, Tweet.class); 
     System.out.println(tweetObj.getUser().getId()); 
    } 

輸出：

366301747 

編輯：根據意見，解決方案使用 - 傑克遜2個選項

1. 保持新創建User類中，ObjectMapper代碼保持完全相同， System.out.println(tweet.getUser().getId())讓你的用戶名。
2. 如果不使用User類，改變你的Tweet看起來像這樣：

代碼：

public class Tweet { 

    String created_at; 
    String id; 
    String text; 
    Map<String, String> user; 

    public String getCreated_at() { 
     return created_at; 
    } 

    public void setCreated_at(String created_at) { 
     this.created_at = created_at; 
    } 

    public String getId() { 
     return id; 
    } 

    public void setId(String id) { 
     this.id = id; 
    } 

    public String getText() { 
     return text; 
    } 

    public void setText(String text) { 
     this.text = text; 
    } 

    public Map<String, String> getUser() { 
     return user; 
    } 

    public void setUser(Map<String, String> user) { 
     this.user = user; 
    } 

} 

而在調用方法打印userid爲：

ObjectMapper mapper = new ObjectMapper(); 
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); 

Tweet tweet = mapper.readValue(br, Tweet.class); 

System.out.println(tweet.getUser().get("id")); 

取得：

366301747 

Answer 2

您可以更改setUser方法採取Map和手動設置user.id：

public void setUser(Map<String, Object> props) { 
    user = props.get("id").toString(); 
}