import java.io.*;
import java.util.Arrays;
import java.util.List;

// CSV文件转 json文件
// 使用csvToJSon对象的.ConvertToJson方法 带入 csv文件路径及导出路径。
public class CSVToJSon {
    //cvs文件
    private static String startFile = "E:\\xiangshu\\积水点位置及经纬度.csv";
    //目标文件
    private static String endFile = "E:\\xiangshu\\987654.json";

    private List<String> stringToList(String s, String sep) {
        if (s == null) {
            return null;
        }
        String[] parts = s.split(sep);
        return Arrays.asList(parts);
    }

    //将分割的第一行的表头list和后面的值list进行拼接
    //拼接完后以string返回
    //示例如{"name" : "kevin","sex" : "man"}
    private String stringToJson(List<String> header, List<String> lineData) throws Exception {

        if (header == null || lineData == null) {
            throw new Exception("输入不能为null。");
        } else if (header.size() != lineData.size()) {
            throw new Exception("表头个数和数据列个数不等。");
        }
        StringBuilder sBuilder = new StringBuilder();
        sBuilder.append("{ ");
        for (int i = 0; i < header.size(); i++) {

            String mString = String.format("\"%s\": \"%s\"", header.get(i), lineData.get(i));
            sBuilder.append(mString);
            if (i != header.size() - 1) {
                sBuilder.append(", ");
            }
        }
        sBuilder.append(" },");
        return sBuilder.toString();
    }

    //获取行数
    public int getTotalLines(File file) throws IOException {
        long startTime = System.currentTimeMillis();
        FileReader in = new FileReader(file);
       /*LineNumberReader这个类多了跟踪行号的功能，它定义了setLineNumber(int)和getLineNumber()方法，
       分别起到设置行号和获取行号的作用。默认情况下，行编号从0开始，所以一开始获取行号，就是0了，
       每当换行一次，就会+1，这样来记录行号的。比如，我们调用了setLineNumber(int)方法，
       那么文件指针会跳转到指定的行吗？答案是:不会！因为，它只是起到了设置LineNumber的值的作用，
*/
        LineNumberReader reader = new LineNumberReader(in);
        reader.skip(Long.MAX_VALUE);
        int lines = reader.getLineNumber();
        reader.close();
        long endTime = System.currentTimeMillis();

        System.out.println("统计文件行数运行时间： " + (endTime - startTime) + "ms");
        return lines;
    }

    public void ConvertToJson(InputStream filePath, OutputStream outPutPath, int count) throws Exception {
        //创建BufferedReader 来读文件
        //创建使用BufferedWriter 来写文件
        InputStreamReader isr = new InputStreamReader(filePath, "utf-8");
        BufferedReader reader = new BufferedReader(isr);
        OutputStreamWriter osw = new OutputStreamWriter(outPutPath, "utf-8");
        BufferedWriter writer = new BufferedWriter(osw);
        int counts = --count;
        try {

            String sep = ",";
            //将csv表格第一行构建成string
            String headerStr = reader.readLine();
            if (headerStr.trim().isEmpty()) {
                System.out.println("表格头不能为空");
                return;
            }
            //将String字符串通过split（","）csv是以，作分隔符
            // 进行切割输出成List
            List<String> header = stringToList(headerStr, sep);
            String line;
            int lineCnt = 0;
            writer.write("[\n");
            while ((line = reader.readLine()) != null) {
                lineCnt++;
                System.out.println("行数" + line);
                if (line.trim().isEmpty()) {
                    System.out.println("第" + lineCnt + "行为空，已跳过");
                    continue;
                }

                List<String> lineData = stringToList(line, sep);

                if (lineData.size() != header.size()) {
                    String mString = String.format("第%d行数据列和表头列个数不一致\r\n%s", lineCnt, line);
                    System.err.println(mString);
                    break;
                }

                String jsonStr = stringToJson(header, lineData);
                //将最后一行的逗号去掉
                if (counts == lineCnt) {
                    jsonStr = jsonStr.replaceAll(".$", "");
                }

                writer.write(jsonStr);
                writer.write("\r\n");
                // lineCnt++;
                System.out.println(lineCnt);

            }

            writer.write("]");
        } finally {
            if (reader != null) {
                reader.close();
            }
            if (writer != null) {
                writer.close();
            }
        }
    }

    public static void main(String[] args) throws Exception {
        //使用Java IO流操作打开/导出文件

        InputStream filePath = new FileInputStream(startFile);
        OutputStream outPutPath = new FileOutputStream(endFile);
        File file = new File(startFile);
        CSVToJSon csvToJSon = new CSVToJSon();
        int count = csvToJSon.getTotalLines(file);
        csvToJSon.ConvertToJson(filePath, outPutPath, count);
        System.out.println("转换完成");
    }

}