fix pinyin

hutool-extra/src/main/java/cn/hutool/extra/pinyin/PinyinEngine.java

@@ -48,6 +48,6 @@ public interface PinyinEngine {
 	default String getFirstLetter(String str, String separator) {
 		final String splitSeparator = StrUtil.isEmpty(separator) ? "#" : separator;
 		final String[] split = StrUtil.split(getPinyin(str, splitSeparator), splitSeparator);
-		return ArrayUtil.join(split, separator, (s)->String.valueOf(s.charAt(0)));
+		return ArrayUtil.join(split, separator, (s)->String.valueOf(s.length() > 0 ? s.charAt(0) : ""));
 	}
 }

hutool-extra/src/main/java/cn/hutool/extra/pinyin/engine/pinyin4j/Pinyin4jEngine.java

@@ -1,5 +1,6 @@
 package cn.hutool.extra.pinyin.engine.pinyin4j;
 
+import cn.hutool.core.text.StrBuilder;
 import cn.hutool.core.util.ArrayUtil;
 import cn.hutool.core.util.StrUtil;
 import cn.hutool.extra.pinyin.PinyinEngine;
@@ -83,16 +84,27 @@ public class Pinyin4jEngine implements PinyinEngine {
 
 	@Override
 	public String getPinyin(String str, String separator) {
-		// 添加一个后缀是为了解决Pinyin4j的bug，在指定分隔符后，最后两个词的分隔符失效
-		str += StrUtil.SPACE;
-		String result;
+		final StrBuilder result = StrUtil.strBuilder();
+		boolean isFirst = true;
+		final int strLen = str.length();
 		try {
-			result = PinyinHelper.toHanYuPinyinString(str, format, separator, true);
+			for(int i = 0; i < strLen; i++){
+				if(isFirst){
+					isFirst = false;
+				} else{
+					result.append(separator);
+				}
+				final String[] pinyinStringArray = PinyinHelper.toHanyuPinyinStringArray(str.charAt(i), format);
+				if(ArrayUtil.isEmpty(pinyinStringArray)){
+					result.append(str.charAt(i));
+				} else{
+					result.append(pinyinStringArray[0]);
+				}
+			}
 		} catch (BadHanyuPinyinOutputFormatCombination e) {
 			throw new PinyinException(e);
 		}
 
-		return StrUtil.removeSuffix(result, StrUtil.SPACE);
+		return result.toString();
 	}
-
 }

hutool-extra/src/test/java/cn/hutool/extra/pinyin/PinyinUtilTest.java

@@ -13,10 +13,10 @@ public class PinyinUtilTest {
 	}
 
 	@Test
-	public void getPinyinByPinyin4jTest(){
+	public void getPinyinByPinyin4jTest() {
 		final Pinyin4jEngine engine = new Pinyin4jEngine();
-		final String pinyin = engine.getPinyin("你好", " ");
-		Assert.assertEquals("ni hao", pinyin);
+		final String pinyin = engine.getPinyin("你好h", " ");
+		Assert.assertEquals("ni hao h", pinyin);
 	}
 
 	@Test