2022-02-21-解析${}占位符

import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.JSONPath;
import lombok.extern.slf4j.Slf4j;

import java.util.ArrayList;
import java.util.List;

/**
 * 参数转换器
 *
 */
@Slf4j
public class ParamConverter {

    /**
     * 默认前缀占位符
     */
    public static final String DEFAULT_PLACEHOLDER_PREFIX = "${";

    /**
     * 默认后缀占位符
     */
    public static final String DEFAULT_PLACEHOLDER_SUFFIX = "}";

    /**
     * 参数转换
     * 入参：参数模板，数据源
     * 返回：封装好的参数
     * @return
     */
    public static String paramConverter(String paramTemplet,String data ){
        try {
            //找到第一个占位符
            int start = paramTemplet.indexOf(DEFAULT_PLACEHOLDER_PREFIX);
            if(start == -1){
                //没有占位符则返回
                return paramTemplet;
            }

            StringBuilder result = new StringBuilder(paramTemplet);
            while(start != -1){
                //找到占位符的结束位
                int end = result.indexOf(DEFAULT_PLACEHOLDER_SUFFIX);
                //获取占位符属性值，如${mq.id},即取mq.id
                String placeholder = result.substring(start + DEFAULT_PLACEHOLDER_PREFIX.length(),end);
                //解析整个占位符内容，即将mq.id替换为对应的值
                String replaceContent="";
                if(placeholder.trim().isEmpty()){
                    replaceContent="";
                }else{
                    String[] splits = placeholder.split("\\.");
                    String path = "$";
                    for(int i=1; i<splits.length; i++){
                        path = path+"."+splits[i];
                    }
                    replaceContent = (String) JSONPath.read(data,path);
                }
                //替换占位符的内容
                result.replace(start,end + DEFAULT_PLACEHOLDER_SUFFIX.length(),replaceContent);
                //开始查找下一个占位符
                start = result.indexOf(DEFAULT_PLACEHOLDER_PREFIX, start + replaceContent.length());
            }

            return result.toString();


        } catch (Exception e) {
            e.printStackTrace();
            log.error("参数转换器调用报错{},paramTemplet:{},data:{}",e.getMessage(),paramTemplet,data);
            return null;
        }
    }


}