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。　　

private void doCheckSum(String fileName){
    try {
            
            Log.d("checksum", fileName);
            
            CheckedInputStream cis = null;
            long fileSize = 0;
            try {
                // Computer CRC32 checksum
                cis = new CheckedInputStream(
                        new FileInputStream(fileName), new CRC32());
 
                fileSize = new File(fileName).length();
                
            } catch (FileNotFoundException e) {
                System.err.println("File not found.");
                System.exit(1);
            }
 
            byte[] buf = new byte[256];
            while(cis.read(buf) >= 0) {
                
            }
 
            //-----------------------------------------------
                       
            long checksum = cis.getChecksum().getValue();
            showText = checksum + " " + fileSize + " " + fileName;
            
            System.out.println(showText); 
            Log.d("checksum", showText);
            mHanler.sendEmptyMessage(1);
            
            
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(1);
        }
}

二，Google Gson

Gson对于使用JSON数据来说是相当方便的，示例

public class WechatConfig {
    private int Id;
    
    public int getId() {
        return Id;
    }
    public void setId(int Id) {
        this.Id = Id;
    }

    
    
}

WeChat  wc = new WeChat();
wc.setId(20);

String json = mGson.toJson(wc );

{"Id":20}

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

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