HttpURLConnection根据URL下载图片

冷不防 2022-08-02 06:24 281阅读 0赞

来看下最简单的根据URL下载图片，此方法在实际开发中，不建议使用，因为有些图片是下载不了的，比如百度上的一些图片，返回http的响应码是405

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1.  **package** cn.ztz.test;  
2.    
3.  **import** java.io.BufferedOutputStream;  
4.  **import** java.io.File;  
5.  **import** java.io.FileOutputStream;  
6.  **import** java.io.InputStream;  
7.  **import** java.io.OutputStream;  
8.  **import** java.net.HttpURLConnection;  
9.  **import** java.net.InetAddress;  
10. **import** java.net.URL;  
11.   
12. **public** **class** HttpDownLoad \{  
13.     **public** **static** **void** download(String url, String dir,String fileName) \{  
14.         HttpURLConnection httpURLConnection = **null**;  
15.         OutputStream out = **null**;  
16.         InputStream in = **null**;  
17.         **try** \{  
18.             URL sendUrl = **new** URL(url);  
19.             httpURLConnection = (HttpURLConnection) sendUrl.openConnection();  
20.             httpURLConnection.setRequestMethod("POST");  
21.             httpURLConnection.setRequestProperty("contentType", "utf-8");  
22.             httpURLConnection.setDoOutput(**true**);   
23.             httpURLConnection.setUseCaches(**false**);  
24.             httpURLConnection.setConnectTimeout(3000);  
25.             httpURLConnection.setReadTimeout(3000);  
26.             httpURLConnection.setRequestProperty(  
27.                     "User-agent",InetAddress.getLocalHost().getHostAddress() + ":"  
28.                             + System.getProperty("catalina.home"));  
29.             out = httpURLConnection.getOutputStream();  
30.             // 清空缓冲区数据  
31.             out.flush();  
32.             // 获取HTTP状态码  
33.             **int** httpStatusCode = httpURLConnection.getResponseCode();  
34.             **if**(httpStatusCode!=200)\{  
35.                 **throw** **new** RuntimeException("异常");  
36.             \}  
37.             in = httpURLConnection.getInputStream();  
38.             // 获取文件长度  
39.             **int** len = httpURLConnection.getContentLength();  
40.             // 路径+文件名  
41.             String pathAndName = dir + File.separator + fileName;  
42.             // 保存文件  
43.             saveFileByByte(in, pathAndName, len);  
44.         \} **catch** (Exception e) \{  
45.             e.printStackTrace();  
46.         \} **finally** \{  
47.             **if** (out != **null**) \{  
48.                 **try** \{  
49.                     out.close();  
50.                 \} **catch** (Exception e) \{  
51.                     e.printStackTrace();  
52.                     **throw** **new** RuntimeException(e.getMessage());  
53.                 \}  
54.             \}  
55.             **if** (in != **null**) \{  
56.                 **try** \{  
57.                     in.close();  
58.                 \} **catch** (Exception e) \{  
59.                     e.printStackTrace();  
60.                 \}  
61.             \}  
62.             **if** (httpURLConnection != **null**) \{  
63.                 httpURLConnection.disconnect();  
64.                 httpURLConnection = **null**;  
65.             \}  
66.         \}  
67.     \}  
68.   
69.     //写文件  
70.     **private** **static** **void** saveFileByByte(InputStream in, String path, **int** len)  
71.             **throws** Exception \{  
72.         **byte**\[\] byteDatas = **new** **byte**\[len\];  
73.         BufferedOutputStream bw = **null**;  
74.         **try** \{  
75.             // 创建文件对象  
76.             File f = **new** File(path);  
77.             // 创建文件路径  
78.             **if** (!f.getParentFile().exists())  
79.                 f.getParentFile().mkdirs();  
80.             // 写入文件  
81.             bw = **new** BufferedOutputStream(**new** FileOutputStream(path));  
82.             **int** bytesRead = 0;  
83.             **while** ((bytesRead = in.read(byteDatas, 0, byteDatas.length)) != -1) \{  
84.                 bw.write(byteDatas, 0, bytesRead);  
85.             \}  
86.         \} **catch** (Exception e) \{  
87.             e.printStackTrace();  
88.             **throw** e;  
89.         \} **finally** \{  
90.             **try** \{  
91.                 **if** (bw != **null**)  
92.                     bw.close();  
93.             \} **catch** (Exception e) \{  
94.                 **throw** e;  
95.             \}  
96.         \}  
97.     \}  
98. \}  
99.

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