str = str.replace(/(\w)\1+/g,function(a){return "#".repeat(a.length)})
package examplespublic class javaRegu {
public static void main(String[] args) {
String str = "{username: zhangsan, password: abc}"
String pattern = "(\\w+)\\:\\s*(\\w+)"
System.out.println(str.replaceAll(pattern, "$1:\"$2\""))
//{username:"zhangsan", password:"abc"}
}
}