!345 CsvWriter添加writeBeans方法，根据Bean自动生成表头，并写入数据

Merge pull request !345 from 马万里/v5-dev

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

@@ -1,5 +1,6 @@
 package cn.hutool.core.text.csv;
 
+import cn.hutool.core.bean.BeanUtil;
 import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.convert.Convert;
 import cn.hutool.core.io.FileUtil;
@@ -18,7 +19,10 @@ import java.io.IOException;
 import java.io.Serializable;
 import java.io.Writer;
 import java.nio.charset.Charset;
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * CSV数据写出器
@@ -205,6 +209,25 @@ 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
+	 * @return this
+	 */
+	public CsvWriter writeBeans(Collection<?> beans) {
+		if (CollUtil.isNotEmpty(beans)) {
+			List<Collection<Object>> res = new ArrayList<>();
+			for (Object bean : beans) {
+				res.add(BeanUtil.beanToMap(bean).keySet().stream().map(k -> (Object) k).collect(Collectors.toList()));
+				break;
+			}
+			res.addAll(beans.stream().map(bean -> BeanUtil.beanToMap(bean).values()).collect(Collectors.toList()));
+			write(res);
+		}
+		return this;
+	}
+
 	/**
 	 * 写出一行
 	 *

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

@@ -61,6 +61,62 @@ public class CsvUtilTest {
 		);
 	}
 
+	@Test
+	@Ignore
+	public void writeBeansTest() {
+		class Student {
+			Integer id;
+			String name;
+			Integer age;
+
+			public Integer getId() {
+				return id;
+			}
+
+			public void setId(Integer id) {
+				this.id = id;
+			}
+
+			public String getName() {
+				return name;
+			}
+
+			public void setName(String name) {
+				this.name = name;
+			}
+
+			public Integer getAge() {
+				return age;
+			}
+
+			public void setAge(Integer age) {
+				this.age = age;
+			}
+		}
+		CsvWriter writer = CsvUtil.getWriter("d:/test/testWriteBeans.csv", CharsetUtil.CHARSET_UTF_8);
+		List<Student> students = new ArrayList<>();
+		Student student1 = new Student();
+		Student student2 = new Student();
+		Student student3 = new Student();
+
+		student1.setId(1);
+		student1.setName("张三");
+		student1.setAge(18);
+
+		student2.setId(2);
+		student2.setName("李四");
+		student2.setAge(22);
+
+		student3.setId(3);
+		student3.setName("王五");
+		student3.setAge(31);
+
+		students.add(student1);
+		students.add(student2);
+		students.add(student3);
+		writer.writeBeans(students);
+	}
+
 	@Test
 	@Ignore
 	public void readLfTest(){