Java小工具：CsvUtils

1 简介

基于hutool，结合自定义注解实现csv文件的生成。

2 引入hutool依赖包

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.7.12</version>
</dependency>

3 定义注解@Csv

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD,ElementType.METHOD})
public @interface Csv {

    /**
     * csv文件字段名称（表头名称）
     */
    String name();
    
    /**
     * 日期格式化（目前仅支持Date）
     */
    String format() default "yyyy-MM-dd HH:mm:ss";

    /**
     * 字段排序
     */
    int orderNum() default 0;

}

4 实现CsvUtils

public final class CsvUtils {

    private static final ConcurrentHashMap<Class<?>, List<CsvFieldEntity>> CSV_FIELD_CACHE = new ConcurrentHashMap<>();

    /**
     * 生成csv文件
     * @param dataSet 需要导出的数据
     * @param pojoClass 数据对象
     * @param filePath 导出文件的目录
     */
    public static void export(List<?> dataSet, Class<?> pojoClass, String filePath) {
        List<CsvFieldEntity> exportFields = getExportFields(pojoClass);
        if (CollectionUtil.isEmpty(exportFields)) {
            throw new RuntimeException(String.format("There is no export field in '%s'", pojoClass));
        }

        try (CsvWriter writer = CsvUtil.getWriter(filePath, CharsetUtil.CHARSET_UTF_8)) {
            writer.setAlwaysDelimitText(true);
            // header
            String[] headers = exportFields.stream().map(f -> f.getCsvAnn().name()).toArray(String[]::new);
            writer.writeLine(headers);
            // data
            String[] line = new String[exportFields.size()];
            for (Object entity : dataSet) {
                addLine(entity, exportFields, line);
                writer.writeLine(line);
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    private static void addLine(Object entity, List<CsvFieldEntity> fields, String[] line) {
        for (int i = 0,length = fields.size(); i < length; i++) {
            try {
                CsvFieldEntity fieldEntity = fields.get(i);
                Object invoke = fieldEntity.getGetter().invoke(entity);
                if (invoke instanceof Date) {
                    line[i] = new SimpleDateFormat(fieldEntity.getCsvAnn().format()).format(invoke);
                } else {
                    line[i] = invoke != null ? invoke.toString() : null;
                }
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }

    private static List<CsvFieldEntity> getExportFields(Class<?> pojoClass) {
        List<CsvFieldEntity> csvFieldEntities = CSV_FIELD_CACHE.get(pojoClass);
        if (csvFieldEntities != null) {
            return csvFieldEntities;
        }
        Field[] fields = ReflectUtil.getFields(pojoClass);
        List<CsvFieldEntity> collect = Arrays.stream(fields).map(field -> {

            Csv annotation = field.getAnnotation(Csv.class);
            if (annotation == null) {
                return null;
            }
            String name = field.getName();
            CsvFieldEntity entity = new CsvFieldEntity();
            entity.setFieldName(name);
            entity.setCsvAnn(annotation);
            entity.setGetter(getGetter(pojoClass, name));
            return entity;
        }).filter(Objects::nonNull)
                .sorted(Comparator.comparingInt(f -> f.getCsvAnn().orderNum()))
                .collect(Collectors.toList());
        CSV_FIELD_CACHE.put(pojoClass, collect);
        return collect;
    }

    private static Method getGetter(Class<?> pojoClass, String name) {
        try {
            char[] chars = name.toCharArray();
            if (chars[0] >= 'a' && chars[0] <= 'z') {
                chars[0] -= 32;
            }
            return pojoClass.getMethod("get" + new String(chars));
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(String.format("There is no getter for property named '%s' in '%s'", name, pojoClass), e);
        }
    }

    private static final class CsvFieldEntity {

        private String fieldName; // 字段名

        private Csv csvAnn;

        private Method getter;

        public String getFieldName() {
            return fieldName;
        }

        public void setFieldName(String fieldName) {
            this.fieldName = fieldName;
        }

        public Csv getCsvAnn() {
            return csvAnn;
        }

        public void setCsvAnn(Csv csvAnn) {
            this.csvAnn = csvAnn;
        }

        public Method getGetter() {
            return getter;
        }

        public void setGetter(Method getter) {
            this.getter = getter;
        }
    }

}

5 使用

step1：定义数据model

public class MsgClient implements java.io.Serializable {
    /** id */
    private String id;
    // 电话号码(主键)
    @Csv(name = "电话号码")
    private String           clientPhone = null;
    // 客户姓名
    @Csv(name = "姓名", orderNum = -1)
    private String           clientName  = null;
    // 所属分组
    // 备注
    @Csv(name = "备注", orderNum = 999)
    private String           remark      = null;
    // 生日
    @Csv(name = "出生日期")
    private Date             birthday    = null;
    // 创建人
    private String           createBy    = null;

    public Date getBirthday() {
        return this.birthday;
    }

    public String getClientName() {
        return this.clientName;
    }

    public String getClientPhone() {
        return this.clientPhone;
    }

    public String getCreateBy() {
        return createBy;
    }

    public String getId() {
        return this.id;
    }

    public String getRemark() {
        return this.remark;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public void setClientName(String clientName) {
        this.clientName = clientName;
    }

    public void setClientPhone(String clientPhone) {
        this.clientPhone = clientPhone;
    }

    public void setCreateBy(String createBy) {
        this.createBy = createBy;
    }

    public void setId(String id) {
        this.id = id;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }
}

step2：创建模拟数据并调用

public static class CsvUtilsTest {
    public static void main(String[] args) throws Exception {
    	// 准备测试数据
    	List<MsgClient> list = getData();
        // 调用工具类
        CsvUtils.export(list, MsgClient.class, "D:/data/test.csv");
    }
    
	private static List<MsgClient> getData() {
        List<MsgClient> list = new ArrayList<MsgClient>();
        for (int i = 0; i < 5; i++) {
            MsgClient client = new MsgClient();
            client.setBirthday(new Date());
            client.setClientName("小明" + i);
            String phone = "18,797" + i;
            client.setClientPhone("1310001000" + i);
            client.setCreateBy("JueYue");
            client.setId("1" + i);
            client.setRemark("测试" + i);
            list.add(client);
        }
        return list;
    }
}

得到文件数据如下

"姓名","电话号码","出生日期","备注"
"小明0","13100010000","2025-05-29 21:28:25","测试0"
"小明1","13100010001","2025-05-29 21:28:25","测试1"
"小明2","13100010002","2025-05-29 21:28:25","测试2"
"小明3","13100010003","2025-05-29 21:28:25","测试3"
"小明4","13100010004","2025-05-29 21:28:25","测试4"