Java 按名称替换花括号中的单词

Question

我有一个像这样的字符串：

String message = "This is a message for {ID_PW}. Your result is {exam_result}. Please quote {ID_PW} if replying";

我正在从 CSV 导入数据，我想用它来替换花括号之间的项目。

// Using OpenCSV to read in CSV...code omitted for brevity
values = (Map<String, String>) reader.readMap();
// values has 'ID_PW', 'exam_result', etc keys

如何将message中花括号中的项目替换为 values 中键的等效values ？

Answer 1

可能您正在寻找：

String s = "I bought {0,number,integer} mangos. From {1}, the fruit seller. Out of them {2,number,percent} were bad.";
MessageFormat formatter = new MessageFormat(s);
Object[] argz = {22, "John", 0.3};
System.out.println(formatter.format(argz));

这输出：

I bought 22 mangos. From John, the fruit seller. Out of them 30% were bad.

有关详细信息，请参阅https://docs.oracle.com/javase/8/docs/api/java/text/MessageFormat.html 。

Answer 2

String message = "This is a message for {ID_PW}. Your result is {exam_result}. Please quote {ID_PW} if replying"; LinkedHashSet<String> fields = new LinkedHashSet<>(); // 'Automatically' handle duplicates Pattern p = Pattern.compile("\\{([^}]*)\\}"); Matcher m = p.matcher(message); // Find 'fields' in the message that are wrapped in curly braces and add to hash set while (m.find()) { fields.add((m.group(1))); } // Go through CSV and parse the message with the associated fields while (((values = (Map<String, String>) reader.readMap())) != null) { Iterator itr = fields.iterator(); String newMsg = message; while (itr.hasNext()) { String field = (String) itr.next(); String value = values.get(field); if(value != null) { newMsg = newMsg.replaceAll("\\{" + field + "\\}", value); } } }

Answer 3

使用StringBuilder 。 StringBuilder被明确设计为String的可变类型。 接下来，不要在循环中使用正则表达式。 正则表达式可能很强大，但是由于您将使用循环来搜索多个模式，因此不涉及任何正则（多个模式意味着多个表达式）。

我只需从左到右搜索{然后}提取key并在values map 中搜索它。 就像是，

Map<String, String> values = new HashMap<>();
values.put("ID_PW", "SimpleOne");
values.put("exam_result", "84");
String message = "This is a message for {ID_PW}. Your result "
        + "is {exam_result}. Please quote {ID_PW} if replying";

StringBuilder sb = new StringBuilder(message);
int p = -1;
while ((p = sb.indexOf("{", p + 1)) > -1) {
    int e = sb.indexOf("}", p + 1);
    if (e > -1) {
        String key = sb.substring(p + 1, e);
        if (values.containsKey(key)) {
            sb.replace(p, p + key.length() + 2, values.get(key));
        }
    }
}
System.out.println(sb);

输出

This is a message for SimpleOne. Your result is 84. Please quote SimpleOne if replying