Question

我正在研究表达式值阅读器。在寻找像这样的API而没有找到任何东西后，我决定创建自己的。我创建了一个名为ExpressionMatcher的类。这是它应该如何工作：

    private static final String TEMPLATE = "my name is {username} and i am {userage} years old";
private ExpressionMatcher expressionMatcher = new ExpressionMatcher(TEMPLATE);
  ...
  String matias = "my name is Matias and i am 25 years old";
  String fede = "my name is Federico and i am 23 years old";

    Map<String, String> variables = expressionMatcher.getValuesFromString(matias);

    assertEquals("Matias", variables.get("username"));

表达式匹配器的代码是：

public class ExpressionMatcher {

List<String> variableNames = new ArrayList<String>();
private final Pattern expressionPattern;

public ExpressionMatcher(String template) {
    // Look for variable names in the string
    Pattern pattern = Pattern.compile("\\{(.*?)\\}");
    Matcher matcher = pattern.matcher(template);
    while(matcher.find()) {
        // Add variable names into a list
        variableNames.add(matcher.group(1));
    }
    // replace the variable names with a new regex that will match all incoming expressions and compile a pattern
    this.expressionPattern = Pattern.compile(matcher.replaceAll("(.*?)"));

}

public Map<String, String> getValuesFromString(String expression) {
    Matcher matcher = this.expressionPattern.matcher(expression);
    Map<String, String> variables = new HashMap<String, String>();
    if(!matcher.matches()) {
        return Collections.emptyMap();
    } else {
        int i = 0;
        while(matcher.find()) {

            variables.put(variables.get(i), matcher.group(1));
            i++;
        }
    }
    return variables;
}

到目前为止，我已经能够成功获取变量名称，但我无法获得的是纯文本表达式的值。我怎样才能做到这一点？谢谢，

Answer 1

没关系，

经过测试后，我解决了这个问题。在getValueFromString方法中，我添加了以下代码：

    public Map<String, String> getValuesFromExpression(String expression) {
    Matcher matcher = this.expressionPattern.matcher(expression);
    Map<String, String> variables = new HashMap<String, String>();
    if(!matcher.matches()) {
        return Collections.emptyMap();
    } else {
        // Iterate over the groups
        for(int i = 0; i < matcher.groupCount(); i++) {
            variables.put(variableNames.get(i), matcher.group(i + 1));
        }
    }
    return variables;
}

我希望至少这对某人有帮助。

Answer 2

请使用以下代码执行

public static void main(String[] args) {
    String template = "Hello {user} request id is {id}. {name} ";
    String testString = "Hello ABC , your  request id is 1234.  Ihab ";
    getPlaceholderValues(template, testString);
}

public static Map<String , String> getPlaceholderValues(String template , String testString){
    List<String> list = getPatternKeys(template);

    String  patternFromTemplate = template.replaceAll("\\.", "\\\\."); 

    for (String item : list){
        patternFromTemplate = patternFromTemplate.replace("{"+item+"}", "(.*)");
    };

    Map<String , String> map = new HashMap<String , String>();

    Pattern p = Pattern.compile(patternFromTemplate);
    Matcher m = p.matcher(testString);
    if (m.matches()) {
        for (String item : list){
            System.out.println(item +" = "+m.group(list.indexOf(item)+1));
            map.put(item, m.group(list.indexOf(item)+1));
        }
    }
    return map;
}

public static List<String> getPatternKeys(String template){
    List<String> list = new ArrayList<String>();
    Pattern pattern = Pattern.compile("\\{(.*?)\\}");
    Matcher matcher = pattern.matcher(template);

    while(matcher.find()) {
         list.add(matcher.group(1));
    }
    return list;
}

Answer 3

String inputStr1 = "Welcome to dataqlo. This is John Doe.";

String template1 = "Welcome to $company. This is $host.";

System.out.println(tpObj.parse(inputStr1,template1));

//Result {host=John Doe, company=dataqlo}

https://github.com/AbhishekSolanki/StringTemplate/blob/master/README.md

如何从与Java中的某个表达式匹配的字符串中获取值？

3 个答案: