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java - 为什么我所有解码的字符串都有'？在最后？Java字符串解码

问题描述

我正在使用 Tweepy 库 (Python) 和 Kafka 从 Twitter 检索推文。文本以 UTF-8 编码，如下行所示：

self.producer.send('my-topic', data.encode('UTF-8'))

其中“数据”是一个字符串。然后，这些数据以键值格式存储到 Oracle NoSQL 数据库中。出于这个原因，推文本身是经过编码的。我用Java做到这一点：

Value myValue = Value.createValue(msg.value().getBytes("UTF-8"));

最后，推文由用 Java 开发的 Formatter 检索。为了将其存储在关系模式中，我必须解析推文，以便将其作为字符串检索。

String data = new String(value.toByteArray(),StandardCharsets.UTF_8);

如您所见，我在执行的所有步骤中都保持 UTF-8 编码。然而，当我在我的数据库中看到推文的文本时，它总是被剪掉。例如：

RT @briIIohead：今年我不得不吞下的最艰难的药丸是学习，无论你对某人有多好，无论多么多？

注意它是如何以 '?' 结尾的。符号，并且已经被清晰地切割了。好吧，每条长推文都会发生这种情况。我的意思是，如果文本长 30 个字符，那么它显示得很好，但是任何超过 100 个字符的东西都会被剪掉。

起初我以为这可能是我的表格定义，但“文本”字段被声明为VARCHAR2(400 CHAR)推文在社交网络中可以包含的最大字符数。

关于如何发现剪切文本并放置“？”的任何想法 最后的符号？

“数据”的样子：

{"created_at":"Tue May 28 09:23:36 +0000 2019","id":1133302792129351681,"id_str":"1133302792129351681","text":"RT @AppleEDU: Learn, create, and do more with iPad in your classroom. Get the free Everyone Can Create curriculum and bring projects to lif\u2026","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":1060510851889750022,"id_str":"1060510851889750022","name":"Rem.0112","screen_name":"0112Rem","location":"Mawson Lakes, Adelaide","url":null,"description":null,"translator_type":"none","protected":false,"verified":false,"followers_count":739,"friends_count":1853,"listed_count":10,"favourites_count":33406,"statuses_count":36936,"created_at":"Thu Nov 08 12:34:25 +0000 2018","utc_offset":null,"time_zone":null,"geo_enabled":true,"lang":null,"contributors_enabled":false,"is_translator":false,"profile_background_color":"F5F8FA","profile_background_image_url":"","profile_background_image_url_https":"","profile_background_tile":false,"profile_link_color":"1DA1F2","profile_sidebar_border_color":"C0DEED","profile_sidebar_fill_color":"DDEEF6","profile_text_color":"333333","profile_use_background_image":true,"profile_image_url":"http:\/\/pbs.twimg.com\/profile_images\/1093157842163355649\/6oAdJTCs_normal.jpg","profile_image_url_https":"https:\/\/pbs.twimg.com\/profile_images\/1093157842163355649\/6oAdJTCs_normal.jpg","profile_banner_url":"https:\/\/pbs.twimg.com\/profile_banners\/1060510851889750022\/1546155144","default_profile":true,"default_profile_image":false,"following":null,"follow_request_sent":null,"notifications":null},"geo":null,"coordinates":null,"place":null,"contributors":null,"retweeted_status":{"created_at":"Thu May 23 15:15:16 +0000 2019","id":1131579354964725760,"id_str":"1131579354964725760","text":"Learn, create, and do more with iPad in your classroom. 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Get the free Everyone Can Create curriculum and bring projects to life through music, drawing, video and photography.","display_text_range":[0,173],"entities":{"hashtags":[],"urls":[],"user_mentions":[],"symbols":[]}},"quote_count":0,"reply_count":3,"retweet_count":3,"favorite_count":58,"entities":{"hashtags":[],"urls":[{"url":"https:\/\/t.co\/aeeSPTXtFx","expanded_url":"https:\/\/twitter.com\/i\/web\/status\/1131579354964725760","display_url":"twitter.com\/i\/web\/status\/1\u2026","indices":[117,140]}],"user_mentions":[],"symbols":[]},"favorited":false,"retweeted":false,"scopes":{"followers":false},"filter_level":"low","lang":"en"},"is_quote_status":false,"quote_count":0,"reply_count":0,"retweet_count":0,"favorite_count":0,"entities":{"hashtags":[],"urls":[],"user_mentions":[{"screen_name":"AppleEDU","name":"Apple Education","id":468741166,"id_str":"468741166","indices":[3,12]}],"symbols":[]},"favorited":false,"retweeted":false,"filter_level":"low","lang":"en","timestamp_ms":"1559035416048"}

我还必须提到，这整个块是编码的。然后解码，最后解析到数据库中引入。所有字段都被正确解码和解析，除了被剪切的“文本”

标签： javapythonstringtweepydecoding

解决方案

根据官方文档，一条推文不超过“140”个字符（这是一个广义的定义）；但最近他们将其更改为280.

同一份文件说：

Twitter 使用文本的规范化表格 C (NFC) 版本计算推文的长度。

所以他们首先对文本进行规范化（我会让你弄清楚这是如何完成的是java）。后来他们说：

Twitter 还计算文本中的代码点数，而不是 UTF-8 字节数。

因此：

String test = "RT @briIIohead: the hardest pill i had to swallow this year was learning that no matter how good you could be to somebody, no matter how mu";
System.out.println(test.codePoints().count()); // 139

最初的推文似乎是 280 个“字符”，而您使用的库不知道这一点，因此它只使用之前的 140 个。由于这会进行一些分块，因此分块似乎也是错误的，它在最后删除了一些“部分”字节。当您尝试打印这些时 - java 不知道那些（最后）字节的实际含义（因为一些错误的分块）并且只是说?（这是当它根本不理解某些东西时显示什么的默认策略）。

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