Java 正则表达式注释和 HTTP 正文 POST 的要求

Question

我刚刚完成了一个从 POST 方法返回字符串的项目。返回的字符串是“答案”，POST BODY 接受字符串“问题”。我的对象属性如下:

@NotNull(message = "Question can't be null.")
@NotEmpty(message = "Question must contain text.")
@Pattern(regexp = "\\?$",
        message = "Invalid question. Requires a question mark at the end.")
private String question;
private String answer;

POSTMapping如下:

@PostMapping(value = "/answer")
@ResponseStatus(HttpStatus.OK)
public String getOneAnswer(@RequestBody @Valid String question) throws Exception {

    if(question.equals("")) {
        String missingInputErrorMessage = "question input is an empty or does not exist.";
        throw new IllegalArgumentException(missingInputErrorMessage);
    }

    int random = random.nextInt((10) + 1);
    for(Answers answer: seriesOfAnswers) {
        if(random == answer.getAnswerId()) {
            return answer.getAnswer().toString();
        }
    }

    return "Return this string if all else fails";
}

我所做的帖子正文如下:

{
"question": "This is a question"
}

和

{
"question": "This is a question?"
}

目前正则表达式不验证 POST BODY 末尾是否有 ?。不管怎样，它只是运行答案。如果我将输入更改为对象类型，则正则表达式会验证并显示消息，无论是否存在 ? 。我的问题是这样的:如果可以使用这种格式的正则表达式，我如何让正则表达式正确验证帖子正文中的“问题”值以 ? 结尾？

编辑:下面，艾玛提到我的实现可能不正确。她是对的。目前，可能有更好的方法来处理这个问题，但在听取她的建议时，我决定不使用 @Pattern 注释，而是在 @PostMapping 部分中进行正则表达式调用。

@PostMapping(value = "/answer")
@ResponseStatus(HttpStatus.OK)
public String getOneAnswer(@RequestBody @Valid String question) throws Exception {

    // The string with the regex we'll need to use. "q" for question.
    String qMarkEndingRegex = "\\?$";
    // The pattern we're going to check.
    Pattern checkForQMark = Pattern.compile(qMarkEndingregex, Pattern.MULTILINE);
    // The matcher to actually check the question
    Matcher qMarkMatcher = checkForQMark.matcher(question);

    // if the matcher does NOT detect a question mark as the regex states, run this code.
    if (!qMarkMatcher.find()) {
        String needsQ = "You need to add a question mark at the end of your question.";
        return needsQ;
    }

Answer 1

你的表达很好，应该可以正常工作，也许你没有正确实现它:

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class RegularExpression{

    public static void main(String[] args){

        final String regex = "\\?\\s*$";
        final String string = "This is a question?\n"
             + "This is a question? ";

        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(string);

        while (matcher.find()) {
            System.out.println("Full match: " + matcher.group(0));
            for (int i = 1; i <= matcher.groupCount(); i++) {
                System.out.println("Group " + i + ": " + matcher.group(i));
            }
        }
    }
}

Demo

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如果您想简化/修改/探索表达式，regex101.com 的右上角面板已对此进行了解释。 。如果您愿意，也可以在 this link 观看，它如何与一些示例输入相匹配。

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