fix: SpotBugs扫描分析（七）：更改清除StringBuilder方式(更改getPlaceholderList()方法)

austin-web/src/main/java/com/java3y/austin/web/utils/Convert4Amis.java

@@ -26,7 +26,6 @@ import me.chanjar.weixin.mp.bean.template.WxMpTemplate;
 
 import java.lang.reflect.Field;
 import java.util.*;
-import java.util.stream.Collectors;
 
 /**
  * 【该类的逻辑不用看，没有什么意义】
@@ -231,62 +230,57 @@ public class Convert4Amis {
      * @return
      */
     public static Set<String> getPlaceholderList(String content) {
-        char[] textChars = content.toCharArray();
-        StringBuilder textSofar = new StringBuilder();
+
+        // 内容为空，直接返回
+        if (content == null || content.isEmpty()) {
+            return Collections.emptySet();
+        }
+
         StringBuilder sb = new StringBuilder();
-        // 存储占位符 位置信息集合
-        List<String> placeholderList = new ArrayList<>();
-        // 当前标识
+        Set<String> placeholderSet = new HashSet<>();
         int modeTg = IGNORE_TG;
-        for (int m = 0; m < textChars.length; m++) {
-            char c = textChars[m];
-            textSofar.append(c);
+
+        for (char c : content.toCharArray()) {
             switch (c) {
-                case '{': {
-                    modeTg = START_TG;
-                    sb.append(c);
-                }
-                break;
-                case '$': {
+                case '{':
+                    if (modeTg == IGNORE_TG) {
+                        sb.append(c);
+                        modeTg = START_TG;
+                    }
+                    break;
+                case '$':
                     if (modeTg == START_TG) {
                         sb.append(c);
                         modeTg = READ_TG;
                     } else {
-                        if (modeTg == READ_TG) {
-                            sb = new StringBuilder();
-                            modeTg = IGNORE_TG;
-                        }
+                        sb.setLength(0);
+                        modeTg = IGNORE_TG;
                     }
-                }
-                break;
-                case '}': {
+                    break;
+                case '}':
                     if (modeTg == READ_TG) {
-                        modeTg = IGNORE_TG;
                         sb.append(c);
-                        String str = sb.toString();
-                        if (StrUtil.isNotEmpty(str)) {
-                            placeholderList.add(str);
-                            textSofar = new StringBuilder();
-                        }
-                        sb = new StringBuilder();
+                        String placeholder = sb.toString();
+                        placeholderSet.add(placeholder.replaceAll("[\\{\\$\\}]", ""));
+                        sb.setLength(0);
+                        modeTg = IGNORE_TG;
                     } else if (modeTg == START_TG) {
+                        sb.setLength(0);
                         modeTg = IGNORE_TG;
-                        sb = new StringBuilder();
                     }
                     break;
-                }
-                default: {
+                default:
                     if (modeTg == READ_TG) {
                         sb.append(c);
                     } else if (modeTg == START_TG) {
+                        sb.setLength(0);
                         modeTg = IGNORE_TG;
-                        sb = new StringBuilder();
                     }
-                }
+                    break;
             }
         }
-        Set<String> result = placeholderList.stream().map(s -> s.replaceAll("\\{", "").replaceAll("\\$", "").replaceAll("\\}", "")).collect(Collectors.toSet());
-        return result;
+
+        return placeholderSet;
     }
 
     /**