使用java原生API模拟请求下载文件

 1     /**
 2      * 
 3      * @param urlPath
 4      *            下载路径
 5      * @param saveDir
 6      *            下载存放目录
 7      * @return 返回下载文件
 8      * @throws Exception
 9      */
10     public static void downloadFile(String urlPath, String saveDir) throws Exception {
11         URL url = new URL(urlPath);
12         // 连接类的父类，抽象类
13         URLConnection urlConnection = url.openConnection();
14         // http的连接类
15         HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
16         // 设定请求的方法，默认是GET
17         httpURLConnection.setRequestMethod("GET");
18         // 设置字符编码
19         httpURLConnection.setRequestProperty("Charset", "UTF-8");
20         //状态码 200：成功连接
21         int code = httpURLConnection.getResponseCode();    
22         if (code == 200) {
23             System.out.println("链接地址成功！");
24         }
25         InputStream inputStream = httpURLConnection.getInputStream();
26         File file = new File(saveDir);
27         OutputStream out = new FileOutputStream(file);
28         int size = 0;
29         byte[] buf = new byte[1024];
30         while ((size = inputStream.read(buf)) != -1) {
31             out.write(buf, 0, size);
32         }
33         inputStream.close();
34         out.close();
35     }