Java中的字符串模式匹配

Question

I want to search for a given string pattern in an input sting.

For Eg.

String URL = "https://localhost:8080/sbs/01.00/sip/dreamworks/v/01.00/cui/print/$fwVer/{$fwVer}/$lang/en/$model/{$model}/$region/us/$imageBg/{$imageBg}/$imageH/{$imageH}/$imageSz/{$imageSz}/$imageW/{$imageW}/movie/Kung_Fu_Panda_two/categories/3D_Pix/item/{item}/_back/2?$uniqueID={$uniqueID}"

Now I need to search whether the string URL contains " /{item}/ ". Please help me.

This is an example. Actually I need is check whether the URL contains a string matching "/{a-zA-Z0-9}/"

Answer 1

You can use the Pattern class for this. If you want to match only word characters inside the {} then you can use the following regex. \\w is a shorthand for [a-zA-Z0-9_] . If you are ok with _ then use \\w or else use [a-zA-Z0-9] .

String URL = "https://localhost:8080/sbs/01.00/sip/dreamworks/v/01.00/cui/print/$fwVer/{$fwVer}/$lang/en/$model/{$model}/$region/us/$imageBg/{$imageBg}/$imageH/{$imageH}/$imageSz/{$imageSz}/$imageW/{$imageW}/movie/Kung_Fu_Panda_two/categories/3D_Pix/item/{item}/_back/2?$uniqueID={$uniqueID}";
Pattern pattern = Pattern.compile("/\\{\\w+\\}/");
Matcher matcher = pattern.matcher(URL);
if (matcher.find()) {
    System.out.println(matcher.group(0)); //prints /{item}/
} else {
    System.out.println("Match not found");
}

Answer 2

That's just a matter of String.contains :

if (input.contains("{item}"))

If you need to know where it occurs, you can use indexOf :

int index = input.indexOf("{item}");
if (index != -1) // -1 means "not found"
{
    ...
}

That's fine for matching exact strings - if you need real patterns (eg "three digits followed by at most 2 letters AC") then you should look into regular expressions .

EDIT: Okay, it sounds like you do want regular expressions. You might want something like this:

private static final Pattern URL_PATTERN =
    Pattern.compile("/\\{[a-zA-Z0-9]+\\}/");

...

if (URL_PATTERN.matches(input).find())

Answer 3

If you want to check if some string is present in another string, use something like String.contains

If you want to check if some pattern is present in a string, append and prepend the pattern with '.*'. The result will accept strings that contain the pattern.

Example: Suppose you have some regex a(b|c) that checks if a string matches ab or ac
.*(a(b|c)).* will check if a string contains a ab or ac .

A disadvantage of this method is that it will not give you the location of the match.

Answer 4

You can do it using string.indexOf("{item}") . If the result is greater than -1 {item} is in the string