用java实现一个多线程的ftp解析文件工具

这是一个比较复杂的工具，需要考虑很多细节，以下是一个简单的示例代码，仅供参考：

import java.io.*;
import java.net.*;

public class FtpParser {
    private String ftpUrl;
    private String ftpUser;
    private String ftpPass;
    private String localPath;
    private int threadNum;
    private int bufferSize;
    private String[] fileList;
    private int fileNum;

    public FtpParser(String ftpUrl, String ftpUser, String ftpPass, String localPath, int threadNum, int bufferSize) {
        this.ftpUrl = ftpUrl;
        this.ftpUser = ftpUser;
        this.ftpPass = ftpPass;
        this.localPath = localPath;
        this.threadNum = threadNum;
        this.bufferSize = bufferSize;
    }

    public void parse() {
        getFileList();

        if (fileList == null || fileList.length == 0) {
            System.out.println("No files to parse.");
            return;
        }

        fileNum = fileList.length;

        int blockSize = fileNum / threadNum + 1;

        for (int i = 0; i < threadNum; i++) {
            int start = i * blockSize;
            int end = Math.min((i + 1) * blockSize, fileNum);
            new Thread(new ParserThread(start, end)).start();
        }
    }

    private void getFileList() {
        try {
            URL url = new URL(ftpUrl);
            URLConnection conn = url.openConnection();
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
            String line;
            StringBuilder fileListBuilder = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                if (line.startsWith("drwx")) {
                    continue;
                }
                fileListBuilder.append(line).append("\n");
            }
            reader.close();
            fileList = fileListBuilder.toString().split("\n");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private class ParserThread implements Runnable {
        private int startIdx;
        private int endIdx;

        public ParserThread(int startIdx, int endIdx) {
            this.startIdx = startIdx;
            this.endIdx = endIdx;
        }

        @Override
        public void run() {
            for (int i = startIdx; i < endIdx; i++) {
                String fileName = fileList[i];
                if (fileName.isEmpty()) {
                    continue;
                }
                parseFile(fileName);
            }
        }

        private void parseFile(String fileName) {
            try {
                URL url = new URL(ftpUrl + fileName);
                URLConnection conn = url.openConnection();
                BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                String line;
                StringBuilder contentBuilder = new StringBuilder();
                while ((line = reader.readLine()) != null) {
                    contentBuilder.append(line).append("\n");
                }
                reader.close();

                File file = new File(localPath + fileName);
                if (!file.getParentFile().exists()) {
                    file.getParentFile().mkdirs();
                }
                BufferedWriter writer = new BufferedWriter(new FileWriter(file));
                writer.write(contentBuilder.toString());
                writer.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

使用示例：

FtpParser parser = new FtpParser("ftp://example.com/", "username", "password", "/path/to/local/folder/", 4, 1024 * 1024);
parser.parse();

其中，`ftpUrl`为FTP服务器的地址，`ftpUser`和`ftpPass`为登录FTP服务器的用户名和密码，`localPath`为要保存文件的本地文件夹路径，`threadNum`为线程数，`bufferSize`为缓冲区大小。在`parse()`方法中，首先获取FTP服务器上的文件列表，然后根据线程数启动多个线程来解析文件。每个线程处理一部分文件，对于每个文件，首先下载到本地，然后保存到指定的本地文件夹中。