java如何实现txt下载 就是从远程FTP服务器上直接把TXT文本下载下来！

strUrl为文件地址，fileName为文件在本地的保存路径，试试吧~

public static void writeFile(String strUrl, String fileName) {

URL url = null

try {

url = new URL(strUrl)

} catch (MalformedURLException e2) {

e2.printStackTrace()

}

InputStream is = null

try {

is = url.openStream()

} catch (IOException e1) {

e1.printStackTrace()

}

OutputStream os = null

try {

os = new FileOutputStream( fileName)

int bytesRead = 0

byte[] buffer = new byte[8192]

while ((bytesRead = is.read(buffer, 0, 8192)) != -1) {

os.write(buffer, 0, bytesRead)

}

System.out.println("下载成功："+strUrl)

} catch (FileNotFoundException e) {

e.printStackTrace()

} catch (IOException e) {

e.printStackTrace()

}

}

import java.io.File

import java.io.FileNotFoundException

import java.io.IOException

import java.io.RandomAccessFile

public class Io{

public static void main(String [] s){

File filename = new File("F:\\suncity.txt")

String filein="你好！"

RandomAccessFile mm = null

try {

mm = new RandomAccessFile(filename,"rw")

mm.writeBytes(filein)

} catch (IOException e1) {

// TODO 自动生成 catch 块

e1.printStackTrace()

} finally{

if(mm!=null){

try {

mm.close()

} catch (IOException e2) {

// TODO 自动生成 catch 块

e2.printStackTrace()

}

}

}

}

}

在jsp/servlet中断点/多线程下载文件

<%@ page import="java.io.File" %>

<%@ page import="java.io.IOException" %>

<%@ page import="java.io.OutputStream" %>

<%@ page import="java.io.RandomAccessFile" %>

<%!

    public void downloadFile(HttpServletRequest request, HttpServletResponse response, File file) throws IOException {

        RandomAccessFile raf = new RandomAccessFile(file, "r")

        java.io.FileInputStream fis = new java.io.FileInputStream(raf.getFD())

        response.setHeader("Server", "www.trydone.com")

        response.setHeader("Accept-Ranges", "bytes")

        long pos = 0

        long len

        len = raf.length()

        if (request.getHeader("Range") != null) {

            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT)

            pos = Long.parseLong(request.getHeader("Range")

                    .replaceAll("bytes=", "")

                    .replaceAll("-", "")

            )

        }

        response.setHeader("Content-Length", Long.toString(len - pos))

        if (pos != 0) {

            response.setHeader("Content-Range", new StringBuffer()

                    .append("bytes ")

                    .append(pos)

                    .append("-")

                    .append(Long.toString(len - 1))

                    .append("/")

                    .append(len)

                    .toString()

            )

        }

        response.setContentType("application/octet-stream")

        response.setHeader("Content-Disposition", new StringBuffer()

                .append("attachmentfilename=\"")

                .append(file.getName())

                .append("\"").toString())

        raf.seek(pos)

        byte[] b = new byte[2048]

        int i

        OutputStream outs = response.getOutputStream()

        while ((i = raf.read(b)) != -1) {

            outs.write(b, 0, i)

        }

        raf.close()

        fis.close()

    }

%>

<%

    String filePath = request.getParameter("file")

    filePath = application.getRealPath(filePath)

    File file = new File(filePath)

    downloadFile(request, response, file)

%>

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