今天就跟大家聊聊有关Android中怎么实现文件下载功能，可能很多人都不太了解，为了让大家更加了解，小编给大家总结了以下内容，希望大家根据这篇文章可以有所收获。
普通单线程下载文件：
直接使用URLConnection.openStream()打开网络输入流,然后将流写入到文件中！
public static void downLoad(String path,Context context)throws Exception{ URL url = new URL(path); InputStream is = url.openStream(); //截取最后的文件名 String end = path.substring(path.lastIndexOf(".")); //打开手机对应的输出流,输出到文件中 OutputStream os = context.openFileOutput("Cache_"+System.currentTimeMillis()+end, Context.MODE_PRIVATE); byte[] buffer = new byte[1024]; int len = 0; //从输入六中读取数据,读到缓冲区中 while((len = is.read(buffer)) > 0) { os.write(buffer,0,len); } //关闭输入输出流 is.close(); os.close();}普通多线程下载：
步骤：
获取网络连接
本地磁盘创建相同大小的空文件
计算每条线程需从文件哪个部分开始下载，结束
依次创建，启动多条线程来下载网络资源的指定部分
public class Downloader { //添加@Test标记是表示该方法是Junit测试的方法,就可以直接运行该方法了 @Test public void download() throws Exception { //设置URL的地址和下载后的文件名 String filename = "meitu.exe"; String path = "http://10.13.20.32:8080/Test/XiuXiu_Green.exe"; URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5000); conn.setRequestMethod("GET"); //获得需要下载的文件的长度(大小) int filelength = conn.getContentLength(); System.out.println("要下载的文件长度"+filelength); //生成一个大小相同的本地文件 RandomAccessFile file = new RandomAccessFile(filename, "rwd"); file.setLength(filelength); file.close(); conn.disconnect(); //设置有多少条线程下载 int threadsize = 3; //计算每个线程下载的量 int threadlength = filelength % 3 == 0 ? filelength/3:filelength+1; for(int i = 0;i < threadsize;i++) { //设置每条线程从哪个位置开始下载 int startposition = i * threadlength; //从文件的什么位置开始写入数据 RandomAccessFile threadfile = new RandomAccessFile(filename, "rwd"); threadfile.seek(startposition); //启动三条线程分别从startposition位置开始下载文件 new DownLoadThread(i,startposition,threadfile,threadlength,path).start(); } int quit = System.in.read(); while('q' != quit) { Thread.sleep(2000); } } private class DownLoadThread extends Thread { private int threadid; private int startposition; private RandomAccessFile threadfile; private int threadlength; private String path; public DownLoadThread(int threadid, int startposition, RandomAccessFile threadfile, int threadlength, String path) { this.threadid = threadid; this.startposition = startposition; this.threadfile = threadfile; this.threadlength = threadlength; this.path = path; } public DownLoadThread() {} @Override public void run() { try { URL url = new URL(path); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setConnectTimeout(5000); conn.setRequestMethod("GET"); //指定从什么位置开始下载 conn.setRequestProperty("Range", "bytes="+startposition+"-"); //System.out.println(conn.getResponseCode()); if(conn.getResponseCode() == 206) { InputStream is = conn.getInputStream(); byte[] buffer = new byte[1024]; int len = -1; int length = 0; while(length < threadlength && (len = is.read(buffer)) != -1) { threadfile.write(buffer,0,len); //计算累计下载的长度 length += len; } threadfile.close(); is.close(); System.out.println("线程"+(threadid+1) + "已下载完成"); } }catch(Exception ex){System.out.println("线程"+(threadid+1) + "下载出错"+ ex);} } }}看完上述内容，你们对Android中怎么实现文件下载功能有进一步的了解吗？如果还想了解更多知识或者相关内容，请关注编程网行业资讯频道，感谢大家的支持。
