import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CsvUtil {
    /**
     * 读取CSV格式的文档数据
     * @param filePath CSV格式的文件路劲
     * @return dataList csv数据读取放入二维list中。
     */
    public static List<List<String>> readCSVFileData(String filePath){
        BufferedReader reader=null;
        List<List<String>> dataList=new ArrayList<>();
        try {
            reader = new BufferedReader(new InputStreamReader(new FileInputStream(filePath), "UTF-8"));
        }catch(FileNotFoundException | UnsupportedEncodingException e){
            e.printStackTrace();
        }
        try{
            String line=null;
            int lineNum =0;
            while ((line=reader.readLine())!=null){
                if (lineNum != 0) {
                    //(1)内容不存在逗号
//                  String aa[]=line.split(",");
//                  List<String> cellList= Arrays.asList(aa);
//                  //System.out.println(cellList);
//                  dataList.add(cellList);

                    //(1)内容可能存在逗号，且存在“”英文双引号
                    String str;
                    line += ",";
                    Pattern pCells = Pattern.compile("(\"[^\"]*(\"{2})*[^\"]*\")*[^,]*,");
                    Matcher mCells = pCells.matcher(line);
                    List<String> cells = new LinkedList();//每行记录一个list
                    //读取每个单元格
                    while (mCells.find()) {
                        str = mCells.group();
                        str = str.replaceAll("(?sm)\"?([^\"]*(\"{2})*[^\"]*)\"?.*,", "$1");
                        str = str.replaceAll("(?sm)(\"(\"))", "$2");
                        cells.add(str);
                    }
                    dataList.add(cells);
                }
                lineNum++;

            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            try {
                if (reader != null) {
                    //释放资源
                    reader.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return dataList;
    }
    /**
     * 写入数据到csv格式的文档
     * @param filePath CSV格式的文件路劲
     * @param dataList 需要写入的数据
     * @return dataList csv数据读取放入二维list中。
     */
    public static void writeCSVFileData(String filePath,List<List<String>> dataList){
        BufferedWriter bw=null;
        try {
            bw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filePath, true), "GBK"));
            for(int i = 0; i<dataList.size(); i++) {
                bw.write(dataList.get(i).get(0)+","+dataList.get(i).get(1));
                bw.newLine();
            }
        } catch (FileNotFoundException e) {
            //e.printStackTrace();
            System.out.println(e);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        finally {
            try {
                if (bw != null) {
                    bw.flush();
                    //释放资源
                    bw.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}