正则表达式提取嵌套引号内的文本[Java / Json] [重复]

问题描述 投票:-1回答:1

这个问题在这里已有答案:

一个以下文本,我想提取引号内的值,例如“hash”。与哈希关联的值是从引号的开头到结尾,在这种情况下:

00000e96c46d15aeaaf9ef6f88a295a8f17207d4cd9ac074d2314680095befc854d5a00600602af2fe03a24b61566ca2d8a6b858b0af840309ae449316833923

我的模式是

Scanner s = new Scanner(new File(path.toString()));
Pattern pattern = Pattern.compile("\"hash\": \".*\"");
String nextMatch = s.findWithinHorizon(pattern, 0);

模式的解释:我看一下带引号的任何地方的序列,然后是单词hash和另一个引号。然后“:”跟随+ 1空格。之后会出现多个文本,直到出现另一个引号。

可悲的是,这种模式不起作用,我不明白为什么。

{“hash”:“00000e96c46d15aeaaf9ef6f88a295a8f17207d4cd5ac074d231468009500f4856d5a00600602af2fe03a24b61566ca2d8a6b858b0af840309ae449316833923”,“block”:“{\”type \“:\”block \“,\”transactions \“:[],\”timestamp \“:\”2017-09-07T07: 09:52.628676 \“,”奖励“:” 3e16c6d7f08f04f5067dc9a2d0c01015c1af848a1fcd6c64eef039c9c5d8e737c0655a97b6bc876854a34ad94fcd29218524c6c7881bd1ae4a9279edc12f95720d8a010d9a4c7dd19a4415bed2687fb462d95da8436954b5fd82d92b98935650a1fd7fa215ba95e8b20d8594c50cb9a8bc683af32133c007bc0dff3edd36e0c20688385891788de63a5adcbb \ “\ ”难度\“:\ ”0 \“,\ ”随机数\“:\ ”feec6d57f31d8aee18889026e4e484d96de6b874013a1932018e809c60c45019033389671dcc2e3138a555705cec95e365d79d3e68a909efcf15d0d137770131 \“,\ ”亲本\“:\ ”00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 \“}”, “类型”: “block_hash”}

我的整个代码:

public class TryToStream {

    static String url = "SorryICantShowYouThatOne";
    static String charset = "UTF-8";


    public static void main(String[] args) throws IOException, ParseException {
        JSONParser parser = new JSONParser();

        URL getURL = new URL(url + "get?start_at=");
        int counter = 0;
        boolean inputAvail = true;
        //clear textfile
        PrintWriter pw = new PrintWriter("jsonFormatted.txt");


        URL tmpURL = new URL(url + "get?start_at=" + counter);
        URLConnection connection = tmpURL.openConnection();
        InputStream is = connection.getInputStream();
        JSONArray json = (JSONArray) parser.parse(new BufferedReader(new InputStreamReader(is)));
        //   FileOutputStream fos = new FileOutputStream(new File("output2.txt"), true);
        BufferedWriter bw = new BufferedWriter(new FileWriter("jsonFormattedStream.txt"));
        bw.write(json.toJSONString());
        bw.close();

        Iterator iter = json.iterator();
        boolean flagForTesting = true;
        BufferedWriter bw2 = new BufferedWriter(new FileWriter("jsonFormatted.txt"));
        Pattern pattern = Pattern.compile("\"hash\": \"(.*?)\"");

        while (iter.hasNext() && flagForTesting) {

            Matcher matcher = pattern.matcher(iter.next().toString());
            matcher.find();
            System.out.println(matcher.group(1));
            flagForTesting = false;
        }
        bw2.close();


        System.out.println("End");
    }
}

如果我尝试匹配建议的正则表达式,我没有得到匹配。

iter.next()的结果:

{“block”:“{\”type \“:\”block \“,\”transactions \“:[],\”timestamp \“:\”2017-09-07T07:09:52.628676 \“,\”奖励\”: \” dd19a4415bed2687fb462d95da8436954b5fd82d92b98935650a1fd7fa215ba95e8b20d8594c50cb9a8bc683af32133c007bc0dff3edd36e0c20688385891788de63a5adcbb \ “\ ”难度\“:\ ”0 \“,\ ”随机数\“:\ ”feec6d57f31d8aee18889026e4e484d96de6b874013a1932018e809c60c45019033389671dcc2e3138a555705cec95e365d79d3e68a909efcf15d0d137770131 \“,\ ”亲本\“:\ ”00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 \“}”, “类型”: “block_hash”, “哈希”: “00000e96c46d15aeaaf9ef6f88a295a8f17207d4cd9ac074d2314680095befc854d5a00600602af2fe03a24b61566ca2d8a6b858b0af840309ae449316833923”}

java json regex pattern-matching
1个回答
1
投票

你的正则表达几乎就在那里!

你的正则表达式的问题是它试图匹配字符串中的所有内容,直到最后一个引号。因此它将一直匹配到"block_hash"。你只需要告诉它与懒惰匹配,所以它会在遇到第一个引号时停止匹配。

"hash": ".*?" // notice the question mark!

现在这个正则表达式匹配:

"hash": "00000e96c46d15aeaaf9ef6f88a295a8f17207d4cd9ac074d2314680095befc854d5a00600602af2fe03a24b61566ca2d8a6b858b0af840309ae449316833923"

如果你想捕获引号内的东西,我建议你添加一个捕获组:

"hash": "(.*?)"

您可以像这样使用此正则表达式:

Pattern pattern = Pattern.compile("\"hash\": \"(.*?)\"");
Matcher matcher = pattern.matcher(yourString);
matcher.find();
System.out.println(matcher.group(1));
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