使用indexOf將占位符替換為Map值

Question

我正在嘗試使用indexOf在字符串（“ $ {...}”）中查找占位符。 到目前為止，我下面的小示例效果很好，但顯然僅適用於首次出現。 我如何更改此代碼以能夠遍歷所有占位符並最終重建String。 輸入的String可以是隨機的，並且其中沒有固定數量的占位符。 不太確定從這里去哪里。

// example Hashmap
HashMap <String, String> placeHolderMap = new HashMap<String, String>();
placeHolderMap.put("name", "device");
placeHolderMap.put("status", "broken");
placeHolderMap.put("title", "smartphone");

// input String
String content = "This ${name} is ${status} and categorized as ${title} in the system";
int left = content.indexOf("${");
int right = content.indexOf("}");

// getting the name of the placeholder, if the placeholdermap contains the placeholder as a key it sets the placeholder to the corresponding value
String contentPlaceHolder = content.substring(left+2, right);
if (placeHolderMap.containsKey(contentPlaceHolder)){
    contentPlaceHolder = placeHolderMap.get(contentPlaceHolder);
}
content = content.substring(0, left) + contentPlaceHolder + content.substring(right+1);

當前，輸出為“此設備為$ {status}，在系統中歸類為$ {title}”。

Answer 1

為什么不使用String.replaceAll（）方法？

    Map<String, String> placeHolderMap = new HashMap<>();
    placeHolderMap.put("\\$\\{name}", "device");
    placeHolderMap.put("\\$\\{status}", "broken");
    placeHolderMap.put("\\$\\{title}", "smartphone");


    // input String
    String content = "This ${name} is ${status} and categorized as ${title} in the system";

    for (Map.Entry<String, String> entry : placeHolderMap.entrySet()) {
          content = content.replaceAll(entry.getKey(), entry.getValue());
    }

更新 Stefan，Neil和Kennet，謝謝。

更新17/07/17您還可以使用不使用正則表達式的String.replace（）方法，或者使用Pattern.quote（）方法：

    Map<String, String> placeHolderMap = new HashMap<>();
    placeHolderMap.put("${name}", "device");
    placeHolderMap.put("${status}", "broken");
    placeHolderMap.put("${title}", "smartphone");


    // input String
    String content = "This ${name} is ${status} and categorized as ${title} in the system";

    for (Map.Entry<String, String> entry : placeHolderMap.entrySet()) {
          content = content.replace(entry.getKey(), entry.getValue());
          // content = content.replaceAll(Pattern.quote(entry.getKey()), entry.getValue());
    }

Answer 2

您需要回溯地調用方法：

private String replace(String content) {
    int left = content.indexOf("${");
    if (left < 0) {
        // breaking the recursion
        return content;
    }
    int right = content.indexOf("}");

    // getting the name of the placeholder, if the placeholdermap contains the placeholder as a key it sets the placeholder to the corresponding value
    String contentPlaceHolder = content.substring(left + 2, right);
    if (placeHolderMap.containsKey(contentPlaceHolder)) {
        contentPlaceHolder = placeHolderMap.get(contentPlaceHolder);
    }
    content = content.substring(0, left) + contentPlaceHolder + content.substring(right + 1);
    return replace(content);
}