!1222 CsvWriter 重载 writeBeans 方法

Merge pull request !1222 from nickname/v5-master

hutool-core/src/main/java/cn/hutool/core/text/csv/CsvWriter.java

@@ -252,6 +252,30 @@ public final class CsvWriter implements Closeable, Flushable, Serializable {
 		return this;
 	}
 
+	/**
+	 * 将一个Bean集合写出到Writer，并自动生成表头
+	 *
+	 * @param beans Bean集合
+	 * @param properties Bean 中指定的可以导出的属性
+	 * @return this
+	 */
+	public CsvWriter writeBeans(Iterable<?> beans, String... properties) {
+		if (CollUtil.isNotEmpty(beans)) {
+			boolean isFirst = true;
+			Map<String, Object> map;
+			for (Object bean : beans) {
+				map = BeanUtil.beanToMap(bean, properties);
+				if (isFirst) {
+					writeHeaderLine(map.keySet().toArray(new String[0]));
+					isFirst = false;
+				}
+				writeLine(Convert.toStrArray(map.values()));
+			}
+			flush();
+		}
+		return this;
+	}
+
 	/**
 	 * 写出一行头部行，支持标题别名
 	 *

hutool-core/src/test/java/cn/hutool/core/text/csv/CsvUtilTest.java

@@ -136,6 +136,41 @@ public class CsvUtilTest {
 		writer.close();
 	}
 
+	@Test
+	@Ignore
+	public void writeBeansWithPropertiesTest() {
+
+		@Data
+		class Student {
+			Integer id;
+			String name;
+			Integer age;
+		}
+
+		String path = FileUtil.isWindows() ? "d:/test/testWriteBeans.csv" : "~/tmp/testWriteBeans.csv";
+		CsvWriter writer = CsvUtil.getWriter(path, CharsetUtil.CHARSET_UTF_8);
+		List<Student> students = new ArrayList<>();
+		Student student1 = new Student();
+		student1.setId(1);
+		student1.setName("张三");
+		student1.setAge(18);
+
+		Student student2 = new Student();
+		student2.setId(2);
+		student2.setName("李四");
+		student2.setAge(22);
+
+		Student student3 = new Student();
+		student3.setId(3);
+		student3.setName("王五");
+		student3.setAge(31);
+
+		students.add(student1);
+		students.add(student2);
+		students.add(student3);
+		writer.writeBeans(students,"name","age");
+		writer.close();
+	}
 	@Test
 	@Ignore
 	public void readLfTest(){