一般进行文件下载需求时，都会附带有文件完整性和正确性校验，避免下载的文件不完整或者被第三方劫持注入，貌似很多都是采用MD5校验，但也有采用sha1或者sha256校验，最近做的两个项目中刚好先后遇到了md5和sha256校验，跟了一下MessageDigest源码，提取出工具类供以后使用，同时在此贡献出来，如有不正确的地方欢迎指正。
1、采用枚举定义需要校验的类型，屏蔽直接传入不支持的校验方式，增加容错率：
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| public enum TypeEnum {
MD5, SHA1, SHA256
}
|
2、获取指定文件的md5/sha1/sha256
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| private static String getFileSignature(File file, TypeEnum typeEnum) {
MessageDigest digest;
String type = "";
switch (typeEnum) {
case MD5:
type = "MD5";
break;
case SHA1:
type = "SHA-1";
break;
case SHA256:
type = "SHA-256";
break;
}
if (TextUtils.isEmpty(type)) {
LogUtil.e(Constants.LOG_TAG, "type undefined");
return null;
}
try {
digest = MessageDigest.getInstance(type);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
}
InputStream is;
try {
is = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
LogUtil.e(TAG, "Exception while getting FileInputStream");
return null;
}
byte[] buffer = new byte[8192];
int read;
try {
while ((read = is.read(buffer)) > 0) {
digest.update(buffer, 0, read);
}
byte[] md5sum = digest.digest();
BigInteger bigInt = new BigInteger(1, md5sum);
String output = bigInt.toString(16);
output = String.format("%32s", output).replace(' ', '0');
return output;
} catch (IOException e) {
e.printStackTrace();
LogUtil.e(TAG,"Unable to process file for ");
return null;
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
LogUtil.e(TAG, "Exception on closing inputstream:" );
}
}
}
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3、与服务器给的文件md5/sha1/sha256对比
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| public static boolean validateFile(TypeEnum typeEnum, String standardStr, File fileToCheck) {
if (TextUtils.isEmpty(standardStr) || fileToCheck == null) {
LogUtil.e(TAG, "MD5 string empty or updateFile null");
return false;
}
String calculatedDigest = getFileSignature(fileToCheck, typeEnum);
if (TextUtils.isEmpty(calculatedDigest)) {
LogUtil.d(TAG, "calculatedDigest null");
return false;
}
return calculatedDigest.equalsIgnoreCase(standardStr);
}
|
全部代码如下：
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| public class FileValidateUtil {
private static final String TAG = Constants.LOG_TAG;
public enum TypeEnum {
MD5, SHA1, SHA256
}
public static boolean validateFile(TypeEnum typeEnum, String standardStr, File fileToCheck) {
if (TextUtils.isEmpty(standardStr) || fileToCheck == null) {
LogUtil.e(TAG, "MD5 string empty or updateFile null");
return false;
}
String calculatedDigest = getFileSignature(fileToCheck, typeEnum);
if (TextUtils.isEmpty(calculatedDigest)) {
LogUtil.d(TAG, "calculatedDigest null");
return false;
}
return calculatedDigest.equalsIgnoreCase(standardStr);
}
private static String getFileSignature(File file, TypeEnum typeEnum) {
MessageDigest digest;
String type = "";
switch (typeEnum) {
case MD5:
type = "MD5";
break;
case SHA1:
type = "SHA-1";
break;
case SHA256:
type = "SHA-256";
break;
}
if (TextUtils.isEmpty(type)) {
LogUtil.e(Constants.LOG_TAG, "type undefined");
return null;
}
try {
digest = MessageDigest.getInstance(type);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
return null;
}
InputStream is;
try {
is = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
LogUtil.e(TAG, "Exception while getting FileInputStream");
return null;
}
byte[] buffer = new byte[8192];
int read;
try {
while ((read = is.read(buffer)) > 0) {
digest.update(buffer, 0, read);
}
byte[] md5sum = digest.digest();
BigInteger bigInt = new BigInteger(1, md5sum);
String output = bigInt.toString(16);
output = String.format("%32s", output).replace(' ', '0');
return output;
} catch (IOException e) {
e.printStackTrace();
LogUtil.e(TAG,"Unable to process file for ");
return null;
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
LogUtil.e(TAG, "Exception on closing inputstream:" );
}
}
}
}
|
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版权声明：本文为CSDN博主「校长_494344756」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/qq_35168368/article/details/80064472
