废话不多说了，直接给大家贴代码了，具体代码如下所示；

package com.github.pandafang.tool;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.net.URL;import java.nio.channels.Channels;import java.nio.channels.FileChannel;import java.nio.channels.ReadableByteChannel;import java.nio.file.Files;import java.nio.file.Path;import java.nio.file.Paths;import java.nio.file.StandardCopyOption;import org.apache.commons.io.FileUtils;/** * 文件工具类 * @author panda fang * @date 2017-08-26 * @version 1.0 */public class FileTool { /** * 使用传统io stream 下载文件 * @param url * @param saveDir * @param fileName */ public static void download(String url, String saveDir, String fileName) { BufferedOutputStream bos = null; InputStream is = null; try { byte[] buff = new byte[8192]; is = new URL(url).openStream(); File file = new File(saveDir, fileName); file.getParentFile().mkdirs(); bos = new BufferedOutputStream(new FileOutputStream(file)); int count = 0; while ( (count = is.read(buff)) != -1) { bos.write(buff, 0, count); } } catch (IOException e) { e.printStackTrace(); } finally { if (is != null) { try { is.close(); } catch (IOException e) { e.printStackTrace(); } } if (bos != null) { try { bos.close(); } catch (IOException e) { e.printStackTrace(); } } } } /** * 利用 commonio 库下载文件，依赖Apache Common IO ，官网 https://commons.apache.org/proper/commons-io/ * @param url * @param saveDir * @param fileName */ public static void downloadByApacheCommonIO(String url, String saveDir, String fileName) { try { FileUtils.copyURLToFile(new URL(url), new File(saveDir, fileName)); } catch (IOException e) { e.printStackTrace(); } } /** * 使用NIO下载文件， 需要 jdk 1.4+ * @param url * @param saveDir * @param fileName */ public static void downloadByNIO(String url, String saveDir, String fileName) { ReadableByteChannel rbc = null; FileOutputStream fos = null; FileChannel foutc = null; try { rbc = Channels.newChannel(new URL(url).openStream()); File file = new File(saveDir, fileName); file.getParentFile().mkdirs(); fos = new FileOutputStream(file); foutc = fos.getChannel(); foutc.transferFrom(rbc, 0, Long.MAX_VALUE); } catch (IOException e) { e.printStackTrace(); } finally { if (rbc != null) { try { rbc.close(); } catch (IOException e) { e.printStackTrace(); } } if (foutc != null) { try { foutc.close(); } catch (IOException e) { e.printStackTrace(); } } } } /** * 使用NIO下载文件， 需要 jdk 1.7+ * @param url * @param saveDir * @param fileName */ public static void downloadByNIO2(String url, String saveDir, String fileName) { try (InputStream ins = new URL(url).openStream()) { Path target = Paths.get(saveDir, fileName); Files.createDirectories(target.getParent()); Files.copy(ins, target, StandardCopyOption.REPLACE_EXISTING); } catch (IOException e) { e.printStackTrace(); } }}

下载一个百度logo 测试一下

public static void main(String[] args) { FileTool.downloadByNIO2("http:///img/bd_logo1.png", "/home/panda/picture", "baidu_logo.png"); System.out.println("done..."); }

总结

以上所述是小编给大家介绍的Java 从网上下载文件的几种方式实例代码详解，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！