我在Eclipse中使用推文已有一段时间了，这些推文以json字符串形式呈现。
为此，我创建了一个名为Tweet的对象（原始的，是吧？），该对象从json字符串中获取某些信息，并将其存储在Tweet对象中。没有什么花哨。
我的Tweet类如下所示：
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;
}
}
现在，看起来很简单，但是其中一种无效。
特别是String用户。假设要做的是存储发布推文的用户的用户ID。
以下是从Twitter获得的全部可怕的推文：
{"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"}
这真是一个漫长的痛苦。
我在下一个添加了一些“ ...”，以使其更具可读性，仅显示我感兴趣的值：
{…,"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}, …}
是的，还有我吗？
如上所述，我想要的是用户ID，我希望将其分配给Tweet对象中的变量“ user”。
{…,"user":{"id":366301747,"id_str":"366301747",… }…}
我想要的是将数字366301747分配给我的Tweet对象中的变量“ user”。
但是对于我的一生，我似乎无法。
为了确保Tweet对象获取所需的信息，而不获取不需要的信息，我使用了Jackson对象：
ObjectMapper mapper = new ObjectMapper();
mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
所以我的问题。
如何告诉Tweet从json字符串中获取366301747号并将其分配给变量“ user”？
我更希望它仅与Jackson一起使用，而不需要导入过多的JAR。
请原谅墙。
使用Gson库可以很简单。
从那以后，您已经完成了创建pojo的艰苦工作，通过查看json您可以确认这User是一个有效的json对象而不是一个String值。
因此，让我们用以下命令稍微修改pojo的（Tweet）user属性：
User user;
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
当User自定义类是：
public class User {
private String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}
现在，只需调用您的Gson方法即可将您的对象从转换json（我将json转换为文件并通过读取BufferedReader）：
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());
}
输出：
366301747
编辑：基于评论，使用杰克逊的解决方案-2个选项
User类，ObjectMapper代码保持不变，并System.out.println(tweet.getUser().getId())获得用户ID。User不使用类，则将您更改Tweet为以下形式：码：
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;
}
}
并将userid调用方法中的打印为：
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"));
让您：
366301747
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我来说两句