java正则表达式：替换$ {var} [英] java regex: replace ${var}

问题描述

我正在尝试替换类似的字符串：

I'm trying to replace a String like:

Hello, my name is ${name}. I am ${age} years old.

with

Hello, my name is Johannes. I am 22 years old.

变量存储在HashMap中。
到目前为止我的代码：

Variables are stored in a HashMap. My code so far:

private void replace() {
        HashMap<String, String> replacements = new HashMap<String, String>();
        replacements.put("name", "Johannes");
        replacements.put("age", "22");

        String text = "Hello, my name is {name}. I am {age} years old.";
        Pattern pattern = Pattern.compile("\\{(.+?)\\}");
        Matcher matcher = pattern.matcher(text);

        StringBuilder builder = new StringBuilder();
        int i = 0;
        while (matcher.find()) {
            String replacement = replacements.get(matcher.group(1));
            builder.append(text.substring(i, matcher.start()));
            if (replacement == null) {
                builder.append("");
            } else {
                builder.append(replacement);
                i = matcher.end();
            }
        }
        builder.append(text.substring(i, text.length()));
        System.out.println(builder);
    }

这很好，但是我想替换$ {var}而不是{VAR}。
将其更改为Pattern.compile（\ $ {（。+？）\}）;将抛出PatternSyntaxException：Illeagal重复。

It's wokring fine, but I would like to replace ${var} and not {var}. Changing it to Pattern.compile("\${(.+?)\}"); will throw an PatternSyntaxException: "Illeagal repetition".

转义$（Pattern.compile（\\ $ {（。+？）\}）将导致编译错误。

Escaping the $ (Pattern.compile("\\${(.+?)\}") will cause an compiling error.

所以如何更改我的模式以接受$ {var}而不是{var}

推荐答案

在大多数正则表达式库中保留{字符，以便在 {n，m} 的行中重复。尝试正则表达式

The { character is reserved in most regex libraries for repetition along the lines of {n,m}. Try the regex

\\$\\{(.+?)\\}

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