JavaBean中数据写入文件工具类

import java.beans.PropertyDescriptor;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Writer;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.io.output.FileWriterWithEncoding;

import com.genilex.gRule.ocr.dto.DrivingLicense;

public class FileUtil {
    private FileUtil(){}
    
    /**
     * 实体类数据写入文件中
     * @param <T>
     * @param t 实体类
     * @param fileName 文件名（带后缀）
     * @param fileDir 文件夹路径，不包括文件名及后缀
     * @return
     */
    public static <T> boolean beanToFile(T t,String fileName,String fileDir){
        boolean bl = false;
        try {
            //取得类中所有属性
            Class clazz = t.getClass();
            Field[] fields = clazz.getDeclaredFields();
            
            //判断文件夹是否存在，不存在则创建
            File fileDir2 = new File(fileDir);
            if(!fileDir2.exists()){
                fileDir2.mkdirs();
            }
            //文件
            File file = new File(fileDir,fileName);
            
            //需要封装的list
            List<String> list = new ArrayList<String>();
            //header数组，用来设置数据字符串，使其一一按顺序对应
            String[] titles = null;
            if(!file.exists()){//如果文件不存在，则创建文件并加header
                //header字符串设置
                StringBuilder titleStr = new StringBuilder();
                for (int i = 0; i < fields.length; i++) {
                    if(i > 0){
                        titleStr.append(",");
                    }
                    titleStr.append(fields[i].getName());
                }
                list.add(titleStr.toString());
                
                titles = titleStr.toString().split(",");
            }else{//如果文件存在，则继续追加数据
                //读取文件第一行获得header
                titles = readFirstLine(file).replace(""","").split(",");
            }
            //封装数据字符串，与header按顺序对于设置
            list.add(beanToStr(t,titles,clazz));
            bl = listToFile(list,file);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bl;
    }
    
    /**
     * 根据传入的key数组设置bean中数据，按key的顺序封装成字符串
     * @param obj javaBean
     * @param keys 列名数组
     * @param clazz Class
     * @return
     */
    public static String beanToStr(Object obj,String[] titles,Class<?> clazz){
        try {
            StringBuilder sb = new StringBuilder();
            
            for (int i = 0; i < titles.length; i++) {
                PropertyDescriptor pd = new PropertyDescriptor(titles[i], clazz);
                //得到get方法
                Method method = pd.getReadMethod();
                //执行get方法
                Object value = method.invoke(obj);
                if(i > 0){
                    sb.append(",");
                }
                //封装数据，用","隔开
                sb.append(value != null ? String.valueOf(value) : "");
            }
            return sb.toString();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    
    /**
     * 读取文件第一行
     * @param file
     * @return
     */
    public static String readFirstLine(File file){
        String res = null;
        
        InputStream is = null;
        BufferedReader buffer = null;
        try {
            is = new FileInputStream(file);
            buffer = new BufferedReader(new InputStreamReader(is,"UTF-8"));
            
            res = buffer.readLine();
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(buffer != null){
                try {
                    buffer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    buffer = null;
                }
            }
            if(is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    is = null;
                }
            }
        }
        return res;
    }
    
    /**
     * list 写入文件
     * @param list
     * @param file
     * @return
     */
    public static boolean listToFile(List<String> list,File file){
        boolean bl = true;
        
        Writer writer = null;
        BufferedWriter buffer = null;
        try {
            writer = new FileWriterWithEncoding(file,"UTF-8",true);
            buffer = new BufferedWriter(writer);
            
            if(list != null && !list.isEmpty()){
                for (String str : list) {
                    buffer.write(str);
                    buffer.newLine();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            bl = false;
        }finally{
            if(buffer != null){
                try {
                    buffer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    buffer = null;
                }
            }
            if(writer != null){
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                    writer = null;
                }
            }
        }
        return bl;
    }
    
    public static void main(String[] args) {
        DrivingLicense dl = new DrivingLicense();
        dl.setVin("你");
        dl.setAddress("好");
        dl.setEngineNo("啊");
        
        beanToFile(dl, "xingshizheng.csv", "D:\xingshizeng");
    }
}