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Android获取文件的MD5值

package my.bag;import java.io.File;import java.io.FileInputStream;import java.math.BigInteger;import java.security.MessageDigest;import java.util.HashMap;import java.util.Map;import android.app.Activity;import android.os.Bundle;import android.util.Log;public class FileDigest extends Activity { @Override protected void onCreate(Bundle savedInstanceState) {  // TODO Auto-generated method stub  super.onCreate(savedInstanceState);  File file = new File("/mnt/sdcard/123.txt");  Log.e("MD5", getFileMD5(file)); } /**  * 获取单个文件的MD5值!  * @param file  * @return  */ public static String getFileMD5(File file) {  if (!file.isFile()) {   return null;  }  MessageDigest digest = null;  FileInputStream in = null;  byte buffer[] = new byte[1024];  int len;  try {   digest = MessageDigest.getInstance("MD5");   in = new FileInputStream(file);   while ((len = in.read(buffer, 0, 1024)) != -1) {    digest.update(buffer, 0, len);   }   in.close();  } catch (Exception e) {   e.printStackTrace();   return null;  }  BigInteger bigInt = new BigInteger(1, digest.digest());  return bigInt.toString(16); } /**  * 获取文件夹中文件的MD5值  *   * @param file  * @param listChild  *            ;true递归子目录中的文件  * @return  */ public static Map<String, String> getDirMD5(File file, boolean listChild) {  if (!file.isDirectory()) {   return null;  }  Map<String, String> map = new HashMap<String, String>();  String md5;  File files[] = file.listFiles();  for (int i = 0; i < files.length; i++) {   File f = files[i];   if (f.isDirectory() && listChild) {    map.putAll(getDirMD5(f, listChild));   } else {    md5 = getFileMD5(f);    if (md5 != null) {     map.put(f.getPath(), md5);    }   }  }  return map; }}最后不要忘了在manifest中添加权限<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
package my.bag;import java.io.File;import java.io.FileInputStream;import java.math.BigInteger;import java.security.MessageDigest;import java.util.HashMap;import java.util.Map;import android.app.Activity;import android.os.Bundle;import android.util.Log;public class FileDigest extends Activity { @Override protected void onCreate(Bundle savedInstanceState) {  // TODO Auto-generated method stub  super.onCreate(savedInstanceState);  File file = new File("/mnt/sdcard/123.txt");  Log.e("MD5", getFileMD5(file)); } /**  * 获取单个文件的MD5值!  * @param file  * @return  */ public static String getFileMD5(File file) {  if (!file.isFile()) {   return null;  }  MessageDigest digest = null;  FileInputStream in = null;  byte buffer[] = new byte[1024];  int len;  try {   digest = MessageDigest.getInstance("MD5");   in = new FileInputStream(file);   while ((len = in.read(buffer, 0, 1024)) != -1) {    digest.update(buffer, 0, len);   }   in.close();  } catch (Exception e) {   e.printStackTrace();   return null;  }  BigInteger bigInt = new BigInteger(1, digest.digest());  return bigInt.toString(16); } /**  * 获取文件夹中文件的MD5值  *   * @param file  * @param listChild  *            ;true递归子目录中的文件  * @return  */ public static Map<String, String> getDirMD5(File file, boolean listChild) {  if (!file.isDirectory()) {   return null;  }  Map<String, String> map = new HashMap<String, String>();  String md5;  File files[] = file.listFiles();  for (int i = 0; i < files.length; i++) {   File f = files[i];   if (f.isDirectory() && listChild) {    map.putAll(getDirMD5(f, listChild));   } else {    md5 = getFileMD5(f);    if (md5 != null) {     map.put(f.getPath(), md5);    }   }  }  return map; }}最后不要忘了在manifest中添加权限<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>