文件较验及Google Gson的使用

一，CRC32文件较验

　　文件校验可以确保文件内容不被篡改的方法，刚在工作中用到，记录下来。　　

 1 private void doCheckSum(String fileName){
 2     try {
 3             
 4             Log.d("checksum", fileName);
 5             
 6             CheckedInputStream cis = null;
 7             long fileSize = 0;
 8             try {
 9                 // Computer CRC32 checksum
10                 cis = new CheckedInputStream(
11                         new FileInputStream(fileName), new CRC32());
12  
13                 fileSize = new File(fileName).length();
14                 
15             } catch (FileNotFoundException e) {
16                 System.err.println("File not found.");
17                 System.exit(1);
18             }
19  
20             byte[] buf = new byte[256];
21             while(cis.read(buf) >= 0) {
22                 
23             }
24  
25             //-----------------------------------------------
26                        
27             long checksum = cis.getChecksum().getValue();
28             showText = checksum + " " + fileSize + " " + fileName;
29             
30             System.out.println(showText); 
31             Log.d("checksum", showText);
32             mHanler.sendEmptyMessage(1);
33             
34             
35         } catch (IOException e) {
36             e.printStackTrace();
37             System.exit(1);
38         }
39 }

二，Google Gson

Gson对于使用JSON数据来说是相当方便的，示例

 1 public class WechatConfig {
 2     private int Id;
 3     
 4     public int getId() {
 5         return Id;
 6     }
 7     public void setId(int Id) {
 8         this.Id = Id;
 9     }
10 
11     
12     
13 }

1 WeChat  wc = new WeChat();
2 wc.setId(20);
3 
4 String json = mGson.toJson(wc );
5 
6 {"Id":20}

参考：http://www.oschina.net/code/snippet_12_257

　　　http://www.cnblogs.com/haippy/archive/2012/05/20/2509329.html