fix bugs

hutool-json/src/main/java/cn/hutool/json/JSONUtil.java

@@ -543,7 +543,7 @@ public class JSONUtil {
 	 * @see JSON#getByPath(String)
 	 */
 	public static Object getByPath(JSON json, String expression) {
-		return (null == json || StrUtil.isBlank(expression)) ? null : json.getByPath(expression);
+		return getByPath(json, expression, null);
 	}
 
 	/**
@@ -572,7 +572,15 @@ public class JSONUtil {
 	 */
 	@SuppressWarnings("unchecked")
 	public static <T> T getByPath(JSON json, String expression, T defaultValue) {
-		return (T) ObjectUtil.defaultIfNull(getByPath(json, expression), defaultValue);
+		if((null == json || StrUtil.isBlank(expression))){
+			return defaultValue;
+		}
+
+		if(null != defaultValue){
+			final Class<T> type = (Class<T>) defaultValue.getClass();
+			return ObjectUtil.defaultIfNull(json.getByPath(expression, type), defaultValue);
+		}
+		return (T) json.getByPath(expression);
 	}
 
 	/**

hutool-json/src/test/java/cn/hutool/json/IssueI3BS4S.java

@@ -0,0 +1,27 @@
+package cn.hutool.json;
+
+import cn.hutool.core.bean.BeanUtil;
+import lombok.Data;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.time.LocalDateTime;
+
+/**
+ * 测试带毫秒的日期转换
+ */
+public class IssueI3BS4S {
+
+	@Test
+	public void toBeanTest(){
+		String jsonStr = "{date: '2021-03-17T06:31:33.99'}";
+		final Bean1 bean1 = new Bean1();
+		BeanUtil.copyProperties(JSONUtil.parseObj(jsonStr), bean1);
+		Assert.assertEquals("2021-03-17T06:31:33.099", bean1.getDate().toString());
+	}
+
+	@Data
+	public static class Bean1{
+		private LocalDateTime date;
+	}
+}

hutool-json/src/test/java/cn/hutool/json/JSONPathTest.java

@@ -5,7 +5,7 @@ import org.junit.Test;
 
 /**
  * JSON路径单元测试
- * 
+ *
  * @author looly
  *
  */
@@ -19,4 +19,12 @@ public class JSONPathTest {
 		value = JSONUtil.parseArray(json).getByPath("[1].name");
 		Assert.assertEquals("mingzi", value);
 	}
+
+	@Test
+	public void getByPathTest2(){
+		String str = "{'accountId':111}";
+		JSON json = JSONUtil.parse(str);
+		Long accountId = JSONUtil.getByPath(json, "$.accountId", 0L);
+		Assert.assertEquals(111L, accountId.longValue());
+	}
 }