Vincent Yeh開發筆記: 10月 2018

2018年10月30日星期二

【Linux】建立軟連結

$ls / -la

drwxr-xr-x 23 root root 4096 六 10 22:45 .
drwxr-xr-x 23 root root 4096 六 10 22:45 ..
drwxr-xr-x 2 root root 4096 九 8 22:21 bin
drwxr-xr-x 3 root root 2560 一 1 1970 boot
drwxr-xr-x 16 root root 3580 十 30 21:34 dev
drwxr-xr-x 131 root root 12288 十 30 23:30 etc
drwxr-xr-x 5 root root 4096 十 30 23:23 home
drwxr-xr-x 17 root root 4096 七 1 17:43 lib
drwx------ 2 root root 16384 三 14 2018 lost+found
drwxrwxrwx 5 root root 4096 九 20 00:00 media
drwxr-xr-x 2 root root 4096 三 14 2018 mnt
drwxr-xr-x 16 pi pi 4096 六 10 23:02 mystic
drwxr-xr-x 9 root root 4096 九 4 00:29 opt
dr-xr-xr-x 172 root root 0 一 1 1970 proc
drwx------ 14 root root 4096 十 30 22:45 root
drwxr-xr-x 33 root root 1100 十 30 23:00 run
drwxr-xr-x 2 root root 12288 九 8 22:21 sbin
drwxr-xr-x 3 root root 4096 四 25 2018 srv
drwxr-xr-x 3 ftp-admin ftp 4096 十 30 21:35 storage
dr-xr-xr-x 12 root root 0 十 30 21:25 sys
drwxrwxrwt 14 root root 4096 十 30 23:45 tmp
drwxr-xr-x 11 root root 4096 三 14 2018 usr
drwxr-xr-x 12 root root 4096 四 25 2018 var

$ln -s /storage storage

$ls ~ -la

lrwxrwxrwx 1 pi pi 8 十 30 23:49 storage -> /storage

2018年10月25日星期四

【DOS】如何得知BAT檔目錄位置當以系統管理員開啟時

這幾天再嘗試寫DOS的批次檔，因為要將此目錄的檔案移至Program File，

需要以系統管理員開啟，結果不管呼叫的是%CD%還是pwd，都顯示目前位置在C:\Windows\system32，這樣要copy檔案時還要回來找原本目錄的位置。

test.bat

pwd
echo %CD%
pause

以一般使用者開啟

C:\Users\vincent\Desktop>pwd
C:\Users\vincent\Desktop

C:\Users\vincent\Desktop>echo C:\Users\vincent\Desktop
C:\Users\vincent\Desktop

C:\Users\vincent\Desktop>pause
請按任意鍵繼續 . . .

以系統管理員開啟

C:\Windows\system32>pwd
C:\Windows\system32

C:\Windows\system32>echo C:\Windows\system32
C:\Windows\system32

C:\Windows\system32>pause
請按任意鍵繼續 . . .

解決

test2.bat

SET LOCAL_PATH="%~dp0"

echo %LOCAL_PATH%

以一般使用者開啟

C:\Users\vincent\Desktop>SET LOCAL_PATH="C:\Users\vincent\Desktop\"

C:\Users\vincent\Desktop>echo "C:\Users\vincent\Desktop\"
"C:\Users\vincent\Desktop\"

C:\Users\vincent\Desktop>pause
請按任意鍵繼續 . . .

以系統管理員開啟

C:\Windows\system32>SET LOCAL_PATH="C:\Users\vincent\Desktop\"

C:\Windows\system32>echo "C:\Users\vincent\Desktop\"
"C:\Users\vincent\Desktop\"

C:\Windows\system32>pause
請按任意鍵繼續 . . .

參考資料

Why does 'Run as administrator' change (sometimes) batch file's current directory?

2018年10月20日星期六

【Android】Android Studio拋錯llvm-rs-cc is missing

Android Studio拋錯

java.lang.IllegalStateException: llvm-rs-cc is missing

Caused by: java.lang.IllegalStateException: llvm-rs-cc is missing
at com.android.builder.core.AndroidBuilder.compileAllRenderscriptFiles(AndroidBuilder.java:1194)
at com.android.build.gradle.tasks.RenderscriptCompile.taskAction(RenderscriptCompile.java:206)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.doExecute(StandardTaskAction.java:46)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:26)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:788)
at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:755)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:124)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:113)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:95)
... 108 more

解決

刪除SDK目錄下的build-tools
開啟SDK Manager，重新下載Android SDK build-tools

參考

llvm-rs-cc is missing flutter

2018年10月14日星期日

【Java】使用Cipher實現字串加密/解密

程式碼：CipherAdaptor.java

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Provider;
import java.util.Base64;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherSpi;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class CipherAdaptor{
private Base64.Decoder decoder=Base64.getDecoder();
private Base64.Encoder encoder=Base64.getEncoder();
private final SecretKey secretKey;
private final String algorithm,charset;
private Cipher cipher;
CipherAdaptor(String algorithm,SecretKey secretKey,String charset) throws NoSuchPaddingException, NoSuchAlgorithmException {
encoder=encoder.withoutPadding();//設定Base64的解碼規則：編碼器省略末段的'='字符（如果有的話）。
this.secretKey=secretKey;
this.algorithm=algorithm;
this.charset=charset;
cipher=Cipher.getInstance(algorithm);//定義Cipher所使用的演算法

}
/*
* 明文：訊息
* 密文：明文經過加密所產生的信息被稱為密文
*
*/
String encrypt(String str) throws Exception {
// 將明文轉換成位元組陣列
byte[] executed=encrypt(str.getBytes(charset));

// 將已加密的位元組陣列使用Base64表示，因為輸出的位元組值不一定在字碼表內，
// Base64可以將原始資料轉換為字串，提供後續使用的方便性。
return encoder.encodeToString(executed);
}

byte[] encrypt(byte[] raw) throws Exception {
// 將位元組陣列編碼成Base64格式
return execute(raw,Cipher.ENCRYPT_MODE,secretKey);
}

String decrypt(String str) throws Exception {
// 將密文解碼成位元組陣列
byte[] CryptedBytes=decoder.decode(str);

return new String(decrypt(CryptedBytes),charset);
}

byte[] decrypt(byte[] raw) throws Exception {
// 將已加密的位元組解密成位元組
return execute(raw,Cipher.DECRYPT_MODE,secretKey);
}

String getAlgorithm(){
return cipher.getAlgorithm();
}

private byte[] execute(byte[] raw,int mode,SecretKey secretKey) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException{
cipher.init(mode,secretKey);//初始化Cipher
return cipher.doFinal(raw);//加密(Cipher.ENCRYPT_MODE)/解密(DECRYPT_MODE)
}

static SecretKey Str2Key(String str,String algorithm) throws UnsupportedEncodingException {
// 將字串轉換成位元組陣列
byte[] byte_key=str.getBytes("UTF-8");

// 將位元組轉成SecretKey
return new SecretKeySpec(byte_key,0,byte_key.length,algorithm);
}

}

2018年10月10日星期三

【Java】Base64編碼與解碼

程式碼：

package ciphertest;

import com.sun.org.apache.xml.internal.security.exceptions.Base64DecodingException;
import com.sun.org.apache.xml.internal.security.utils.Base64;
import java.util.Scanner;

public class Base64_Test {

public static void main(String[] args) {
Scanner src = new Scanner(System.in);
while (true) {
System.out.print("mode:");
String mode = src.nextLine();
if (mode.equals("x")) {
System.exit(0);
}

System.out.print("input:");
String contain = src.nextLine();

if (mode.equals("e")) {
System.out.println(encode(contain));
} else if (mode.equals("d")) {
try {
System.out.println(decode(contain));
} catch (Base64DecodingException e) {
System.err.println(e.getMessage());
}
}

}
}

static String encode(String msg) {
byte[] bytes_str = msg.getBytes();
return Base64.encode(bytes_str);
}

static String decode(String msg) throws Base64DecodingException {
return new String(Base64.decode(msg));
}
}

執行

Console

mode:e
input:Hello!! I am Vincent Yeh.
SGVsbG8hISBJIGFtIFZpbmNlbnQgWWVoLg==
mode:d
input:SGVsbG8hISBJIGFtIFZpbmNlbnQgWWVoLg==
Hello!! I am Vincent Yeh. mode:x