用于解析id的正则表达式

Question

I'm looking for a regular expression to parse the id of a record in MongoDB:

{"$oid":"5527b117d3d511091e1735e2"}

I'm trying with the following one but it fails:

 private static final Pattern p = Pattern.compile("\\{\"([a-zA-Z\\d]+)\"\\}");

 Matcher m = p.matcher("{\"$oid\":\"5527b117d3d511091e1735e2\"}");
 if(!m.find()) {
            throw new IllegalArgumentException("The id should be within parenthesis and quotes.");
 }

Any help ?

Answer 1

You need to include the key part also in the regex or just "\\\\{\\"([a-zA-Z\\\\d$]+)\\":" because [a-zA-Z\\\\d]+ won't match the inbetween : and there isn't a closing curly brace immediately following the key part.

final Pattern p = Pattern.compile("\\{\"([a-zA-Z\\d$]+)\":\"([^\"]*)\"\\}");
Matcher m = p.matcher("{\"$oid\":\"5527b117d3d511091e1735e2\"}");
if(m.find())
{
    System.out.println("Key : " + m.group(1));
    System.out.println("Value : " + m.group(2));
}

Output:

Key : $oid
Value : 5527b117d3d511091e1735e2

Answer 2

这对我有用

    String id = str.replaceAll(".*\"(\\w+)\"}", "$1");

Answer 3

Use a JSON parser:

String j = "{\"$oid\":\"5527b117d3d511091e1735e2\"}";

JSONParser p = new JSONParser();
JSONObject o = (JSONObject) p.parse(j);
System.out.println(o.get("$oid"));

Output:

5527b117d3d511091e1735e2

JSON library used:

    <dependency>
        <groupId>org.simpleframework</groupId>
        <artifactId>simple-xml</artifactId>
        <version>2.7.1</version>
    </dependency>