MD5校验工具
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.HashMap;
import javax.swing.filechooser.FileSystemView;
public class MD5Util {
/**
* 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 = null;
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 password 要校验的字符串
* @param md5PwdStr 已知的md5校验码
* @return
*/
public static boolean checkPassword(String password, String md5PwdStr) {
String s = getMD5String(password);
return s.equals(md5PwdStr);
}
/**
* 生成文件的md5校验值
*
* @param file
* @return
* @throws IOException
*/
public static String getFileMD5String(String path) throws IOException {
File file = new File(path);
InputStream fis;
fis = new FileInputStream(file);
byte[] buffer = new byte[1024];
int numRead = 0;
while ((numRead = fis.read(buffer)) > 0) {
messagedigest.update(buffer, 0, numRead);
}
fis.close();
return bufferToHex(messagedigest.digest());
}
/**
* 不推荐使用
*
* @param file
* @return
* @throws IOException
*/
public static String getFileMD5String_old(File file) throws IOException {
FileInputStream in = new FileInputStream(file);
FileChannel ch = in.getChannel();
MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0,
file.length());
messagedigest.update(byteBuffer);
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);
}
static String PCpath = "C:/Users/ThinkPad/Desktop/新建文件夹/";
static int n=0;
static HashMap<String, String> hashmap = new HashMap<String, String>();
static String[] FilePath = { "NB化学软件介绍.pptx", "NB物理软件介绍.pptx", "公司介绍.docx",
"初中化学/NB化学实验初中完整版v109.exe", "初中化学/序列号.txt",
"初中物理/NB物理实验初中完整版v110.exe", "初中物理/序列号.txt",
"高中化学/NB化学实验高中完整版v106.exe", "高中化学/序列号.txt",
"高中物理/NB物理实验高中完整版v110.exe", "高中物理/序列号.txt" };
public static void main(String[] args) throws IOException {
FileSystemView sys = FileSystemView.getFileSystemView();
File[] f = File.listRoots();
for (int i = 0; i < FilePath.length; i++) {
hashmap.put(FilePath[i], getFileMD5String(PCpath + FilePath[i]));
}
for (int i = 0; i < f.length; i++) {
if (sys.getSystemTypeDescription(f[i]).equals("可移动磁盘")) {
n=0;
for (int j = 0; j < FilePath.length; j++) {
if (!(hashmap.get(FilePath[j]).equals(getFileMD5String(f[i]
+ FilePath[j])) )) {
//System.out.println(FilePath[j] + "--->"
//+ hashmap.get(FilePath[j]));
//System.out.println(f[i] + FilePath[j] + "--->"
//+ getFileMD5String(f[i] + FilePath[j]));
System.out.println(f[i]+FilePath[j]+"有错，请修改！！！");
}else{
n++;
}
}
if(n==FilePath.length){
System.out.println(f[i]+"没有错误！！！！");
}
}
System.out.println("扫描完成");
}
//long begin = System.currentTimeMillis();
//File file = new File("C:/12345.txt");
//String md5 = getFileMD5String(file);
//String md5 = getMD5String("a");
//long end = System.currentTimeMillis();
//System.out.println("md5:" + md5 + " time:" + ((end - begin) / 1000)+ "s");
}
}