package com.nationalelectirc.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.*;


public class MD5Util {


	
	private static String kk = "greenh5";

	public static String encrypt(String data) throws NoSuchAlgorithmException {

		MessageDigest md = messagedigest;
		byte[] array = md.digest((data + kk).getBytes());

		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < array.length; ++i) {
			sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1, 3));
		}
		return sb.toString().toUpperCase();
	}

	
	
    /**
     *  签名加密
     * @param map
     * @return
     */
    public static  String MD5(Map map) {
        //参数按键名升序排序
        List list = new ArrayList();
        Iterator iter = map.entrySet().iterator();
        while(iter.hasNext()) {
            Map.Entry entry = (Map.Entry)iter.next();
            list.add(entry.getKey());
        }
        Collections.sort(list);
        //拼接参数
        StringBuilder param=new StringBuilder();
        for (int i=0;i<list.size();i++){
            if(i==0){
                param.append(list.get(i)+"="+map.get(list.get(i)));
            }else{
                param.append("&"+list.get(i)+"="+map.get(list.get(i)));
            }
        }
        //测试默认密匙，正式上线会约定修改
        param.append("&secretkey=xxxxxxxxx");
        try {
            //MD5加密
            java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
            byte[] array = md.digest(param.toString().getBytes());
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < array.length; ++i) {
                sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1,3));
            }
            return sb.toString().toUpperCase();
        } catch (java.security.NoSuchAlgorithmException e) {
            
        }
        return null;
    }
    
    
    
    public static String getMD5(String param) throws NoSuchAlgorithmException {
    	  //MD5加密
    	        java.security.MessageDigest md = java.security.MessageDigest.getInstance("MD5");
    	        byte[] array = md.digest(param.toString().getBytes());
    	        StringBuffer sb = new StringBuffer();
    	        for (int i = 0; i < array.length; ++i) {
    	            sb.append(Integer.toHexString((array[i] & 0xFF) | 0x100).substring(1,3));
    	        }
    	        return sb.toString();
    	        
    	 }
    
    
//	==========================================
	/** 
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合 
     */  
    protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };  
  
    protected static MessageDigest messagedigest;  
    static {  
        try {  
            messagedigest = MessageDigest.getInstance("MD5");  
        } catch (NoSuchAlgorithmException nsaex) {  
            System.err.println(MD5Util.class.getName() + "初始化失败，MessageDigest不支持MD5Util。");  
            nsaex.printStackTrace();  
        }  
    }  
  
    /** 
     * 生成字符串的md5校验值 
     *  
     * @param s 
     * @return 
     */  
    public static String getMD5String(String s) {  
        return getMD5String(s.getBytes());  
    }  
  
    /** 
     * 判断字符串的md5校验码是否与一个已知的md5码相匹配 
     *  
     * @param 
     *            要校验的字符串 
     * @param  
     *            已知的md5校验码 
     * @return 
     */  
    public static boolean checkPossword(String possword, String md5PwdStr) {  
        String s = getMD5String(possword);  
        return s.equals(md5PwdStr);  
    }  
  
    /** 
     * 生成文件的md5校验值 
     *  
     * @param file 
     * @return 
     * @throws IOException 
     */  
    public static String getFileMD5String(File file) throws IOException {  
        InputStream fis = null;
        try {
        	fis = new FileInputStream(file);
        	byte[] buffer = new byte[1024];  
            int numRead = 0;  
            while ((numRead = fis.read(buffer)) > 0) {  
                messagedigest.update(buffer, 0, numRead);  
            }  
                 
		} catch (Exception e) {

		}finally {
			if (fis != null) {
				fis.close();
			}
		}
        return bufferToHex(messagedigest.digest());
          
    }  
  
    /** 
     * JDK1.4中不支持以MappedByteBuffer类型为参数update方法，并且网上有讨论要慎用MappedByteBuffer， 
     * 原因是当使用 FileChannel.map 方法时，MappedByteBuffer 已经在系统内占用了一个句柄， 而使用 
     * FileChannel.close 方法是无法释放这个句柄的，且FileChannel有没有提供类似 unmap 的方法， 
     * 因此会出现无法删除文件的情况。 
     *  
     * 不推荐使用 
     *  
     * @param file 
     * @return 
     * @throws IOException 
     */  
    public static String getFileMD5String_old(File file) throws IOException {
    	FileInputStream in = null;
    	FileChannel ch = null;
    	try {
    		in = new FileInputStream(file);  
            ch = in.getChannel();  
            MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length());  
            messagedigest.update(byteBuffer);
		} catch (Exception e) {
			//日志
		}finally {
			if (in != null) {
				in.close();
			}
			if (ch != null) {
				ch.close();
			}
		}
         
        return bufferToHex(messagedigest.digest());  
    }  
  
    public static String getMD5String(byte[] bytes) {  
        messagedigest.update(bytes);  
        return bufferToHex(messagedigest.digest());  
    }  
  
    private static String bufferToHex(byte bytes[]) {  
        return bufferToHex(bytes, 0, bytes.length);  
    }  
  
    private static String bufferToHex(byte bytes[], int m, int n) {  
        StringBuffer stringbuffer = new StringBuffer(2 * n);  
        int k = m + n;  
        for (int l = m; l < k; l++) {  
            appendHexPair(bytes[l], stringbuffer);  
        }  
        return stringbuffer.toString();  
    }  
  
    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {  
        char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>>  
                                                // 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同  
        char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换  
        stringbuffer.append(c0);  
        stringbuffer.append(c1);  
    }  
 
}