Java - 读取UTF-8-BOM文件，第一个字段值为Null

问题复现

Phone.java

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Phone {
    private String brand;
    private String type;
}      

PhoneTest.java

import cn.hutool.core.io.IORuntimeException;
import cn.hutool.core.io.file.FileReader;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

import java.util.*;

public class PhoneTest {
    public static void main(String[] args) {
        String filePath = "C:\\Projects\\aap\\phone.txt";

        try {
            FileReader fr = new FileReader(filePath);
            List<String> lines = fr.readLines();

            List<Phone> phoneList = new ArrayList<>();

            String[] columnNames = lines.get(0).split("\t");

            for (int i = 1; i < lines.size(); i++) {
                List<String> list = Arrays.asList(lines.get(i).split("\t"));

                Map<String, Object> map = new HashMap<>();
                for (int j = 0; j < list.size(); j++) {
                    map.put(columnNames[j], list.get(j));
                }

                JSONObject jsonObject = new JSONObject(map);
                phoneList.add(JSON.toJavaObject(jsonObject, Phone.class));
            }

            System.out.println(phoneList);
        } catch (IORuntimeException e) {
            e.printStackTrace();
        }
    }
}      

复现步骤：

1. 本地新建文本phone.txt

2. 从xls中copy数据到phone.txt中，此时phone.txt默认格式为UTF-8-BOM。

3. 查看文本编码格式，用nodepad打开文件，Encoding 即可查看文本编码格式。

运行结果

UTF-8-DOM

如果格式为UTF-8-DOM，则首列数据为null（类的第一个字段）。

[Phone(brand=null, type=12), Phone(brand=null, type=n96), Phone(brand=null, type=5), Phone(brand=null, type=Nova)]

UTF-8

如果格式为UTF-8，正常打印结果。

[Phone(brand=apple, type=12), Phone(brand=nokia, type=n96), Phone(brand=小米, type=5), Phone(brand=华为, type=Nova)]

解决方案

方案1：更改文本编码格式

方案2：读取文件时设置编码格式

import cn.hutool.core.io.IORuntimeException;
import cn.hutool.core.io.file.FileReader;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;

import java.util.*;

public class PhoneTest {
    public static void main(String[] args) {
        String filePath = "C:\\Projects\\aap\\phone.txt";

        try {
            FileReader fr = new FileReader(filePath, "UTF-8");
            List<String> lines = fr.readLines();

            List<Phone> phoneList = new ArrayList<>();

            String[] columnNames = lines.get(0).split("\t");

            for (int i = 1; i < lines.size(); i++) {
                List<String> list = Arrays.asList(lines.get(i).split("\t"));

                Map<String, Object> map = new HashMap<>();
                for (int j = 0; j < list.size(); j++) {
                    map.put(columnNames[j], list.get(j));
                }

                JSONObject jsonObject = new JSONObject(map);
                phoneList.add(JSON.toJavaObject(jsonObject, Phone.class));
            }

            System.out.println(phoneList);
        } catch (IORuntimeException e) {
            e.printStackTrace();
        }
    }
}