使用Android应用程序的Java代码（用于AES加密）

我是Android新手。我正在做一个关于AES加密的项目，我想制作一个Android应用程序，我用Java编写了AES加密代码，它工作得非常好：

 //AESAlgorithm Class

package com.example.pr1;

import java.security.Key;
import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

public class AESalgorithm {
public static String encryptedText;
private static String algorithm = "AES";
private static byte[] keyValue =
new byte[] { 'A', 'S', 'e', 'c', 'u', 'r', 'e','S', 'e', 'c', 'r', 'e',   't', 'K', 'e', 'y' };

// Performs Encryption
public static String encrypt(String plainText) throws Exception {
Key key = generateKey();
Cipher chiper = Cipher.getInstance(algorithm);
chiper.init(Cipher.ENCRYPT_MODE, key);
byte[] encVal = chiper.doFinal(plainText.getBytes());
String encryptedValue = encode(encVal);
return encryptedValue;
}

// Performs decryption
 public static String decrypt(String encryptedText) throws Exception {
 // generate key
Key key = generateKey();
Cipher chiper = Cipher.getInstance(algorithm);
chiper.init(Cipher.DECRYPT_MODE, key);
byte[] decordedValue = decode(encryptedText);
byte[] decValue = chiper.doFinal(decordedValue);
String decryptedValue = new String(decValue);
return decryptedValue;
}

// generateKey() is used to generate a secret key for AES algorithm
private static Key generateKey() throws Exception {
Key key = new SecretKeySpec(keyValue, algorithm);
return key;
}

// performs encryption & decryption
public static void main(String[] args) throws Exception {

String  plainText = "This ";

//This is the variable i am passing to MainActivity
encryptedText = AESalgorithm.encrypt(plainText);
String decryptedText = AESalgorithm.decrypt(encryptedText);


 }

 private static String encode(byte[] byteArray) {
 StringBuilder buf = new StringBuilder();
  int intVal = 0;
 String frag = "";

 for (byte b : byteArray) {
  intVal = (int) (0xff & b);
 frag = Integer.toHexString(intVal);
 if (1 == frag.length()) {
 frag = "0" + frag;
  }
 buf.append(frag);
}
 return buf.toString();
}

private static byte[] decode(String textString) {
byte[] byteArray = new byte[(textString.length() / 2)];
int intVal = 0;
String frag = "";
 int c1 = 0;
 for (int i = 0; i < byteArray.length; i++) {
c1 = (i * 2);
frag = textString.substring(c1, (c1 + 2));
 intVal = Integer.parseInt(frag, 16);
byteArray[i] = (byte) (0xff & intVal);
}
return byteArray;
 }
 }

这里的“Show.java”是一个简单的活动，在布局中只有一个文本视图来显示主活动发送的文本。 我想将明文变量传递给aesalgority.java进行加密， 我想从Java文件接收“encryptedtext”变量中的加密文本。 如何修改java代码以在这个android应用程序中工作

这是我的logcat数据：

04-30 21:03:49.968: D/AndroidRuntime(17765): Shutting down VM
04-30 21:03:49.968: W/dalvikvm(17765): threadid=1: thread exiting with uncaught exception (group=0x419d7d40)
04-30 21:03:49.968: W/dalvikvm(17765): threadid=1: uncaught exception occurred
04-30 21:03:49.969: W/System.err(17765): java.lang.RuntimeException: Unable to start activity  ComponentInfo{com.example.pr1/com.example.pr1.Show}: java.lang.NullPointerException
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2469)
 04-30 21:03:49.970: W/System.err(17765):   at android.app.ActivityThread.access$1100(ActivityThread.java:151)
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1362)
04-30 21:03:49.971: W/System.err(17765):    at android.os.Handler.dispatchMessage(Handler.java:110)
04-30 21:03:49.971: W/System.err(17765):    at android.os.Looper.loop(Looper.java:193)
04-30 21:03:49.971: W/System.err(17765):    at android.app.ActivityThread.main(ActivityThread.java:5551)
04-30 21:03:49.971: W/System.err(17765):    at java.lang.reflect.Method.invokeNative(Native Method)
04-30 21:03:49.971: W/System.err(17765):    at java.lang.reflect.Method.invoke(Method.java:515)
04-30 21:03:49.972: W/System.err(17765):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
 04-30 21:03:49.972: W/System.err(17765):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:730)
04-30 21:03:49.972: W/System.err(17765):    at dalvik.system.NativeStart.main(Native Method)
04-30 21:03:49.972: W/System.err(17765): Caused by: java.lang.NullPointerException
04-30 21:03:49.973: W/System.err(17765):    at com.example.pr1.Show.onCreate(Show.java:34)
04-30 21:03:49.973: W/System.err(17765):    at android.app.Activity.performCreate(Activity.java:5310)
04-30 21:03:49.974: W/System.err(17765):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
04-30 21:03:49.974: W/System.err(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)
04-30 21:03:49.974: W/System.err(17765):    ... 11 more
04-30 21:03:49.974: W/dalvikvm(17765): threadid=1: calling UncaughtExceptionHandler
04-30 21:03:49.977: E/AndroidRuntime(17765): FATAL EXCEPTION: main
04-30 21:03:49.977: E/AndroidRuntime(17765): Process: com.example.pr1, PID: 17765
04-30 21:03:49.977: E/AndroidRuntime(17765): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.pr1/com.example.pr1.Show}: java.lang.NullPointerException
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2469)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.access$1100(ActivityThread.java:151)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at   android.app.ActivityThread$H.handleMessage(ActivityThread.java:1362)
 04-30 21:03:49.977: E/AndroidRuntime(17765):   at android.os.Handler.dispatchMessage(Handler.java:110)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.os.Looper.loop(Looper.java:193)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.main(ActivityThread.java:5551)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at java.lang.reflect.Method.invokeNative(Native Method)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at java.lang.reflect.Method.invoke(Method.java:515)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:730)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at dalvik.system.NativeStart.main(Native Method)
04-30 21:03:49.977: E/AndroidRuntime(17765): Caused by: java.lang.NullPointerException
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.example.pr1.Show.onCreate(Show.java:34)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.Activity.performCreate(Activity.java:5310)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at    android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)

---

您可以删除Android的psvm方法

但我不明白问题是什么

---

如果您将AES类添加到Android项目中的包中，您可以通过调用静态方法encrypt and decrypt来使用它。

您可以删除Android的psvm方法

但我不明白问题是什么

---

如果您将AES类添加到Android项目中的包中，您可以通过调用静态方法encrypt and decrypt来使用它？

我已经尝试过了，现在我已经更新了代码。我正在将加密的文本变量传递给MainActivity，但应用程序一直崩溃。你能发布错误代码吗？我已经上传了日志中的数据。我通过为java代码创建另一个活动并从main方法调用encrypt and decrypt解决了问题。谢谢。我已经试过了，现在我已经更新了代码。我正在将加密的文本变量传递给MainActivity，但应用程序一直崩溃。你能发布错误代码吗？我已经上传了日志中的数据。我通过为java代码创建另一个活动并从main方法调用encrypt and decrypt解决了问题。谢谢

04-30 21:03:49.968: D/AndroidRuntime(17765): Shutting down VM
04-30 21:03:49.968: W/dalvikvm(17765): threadid=1: thread exiting with uncaught exception (group=0x419d7d40)
04-30 21:03:49.968: W/dalvikvm(17765): threadid=1: uncaught exception occurred
04-30 21:03:49.969: W/System.err(17765): java.lang.RuntimeException: Unable to start activity  ComponentInfo{com.example.pr1/com.example.pr1.Show}: java.lang.NullPointerException
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2469)
 04-30 21:03:49.970: W/System.err(17765):   at android.app.ActivityThread.access$1100(ActivityThread.java:151)
04-30 21:03:49.970: W/System.err(17765):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1362)
04-30 21:03:49.971: W/System.err(17765):    at android.os.Handler.dispatchMessage(Handler.java:110)
04-30 21:03:49.971: W/System.err(17765):    at android.os.Looper.loop(Looper.java:193)
04-30 21:03:49.971: W/System.err(17765):    at android.app.ActivityThread.main(ActivityThread.java:5551)
04-30 21:03:49.971: W/System.err(17765):    at java.lang.reflect.Method.invokeNative(Native Method)
04-30 21:03:49.971: W/System.err(17765):    at java.lang.reflect.Method.invoke(Method.java:515)
04-30 21:03:49.972: W/System.err(17765):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
 04-30 21:03:49.972: W/System.err(17765):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:730)
04-30 21:03:49.972: W/System.err(17765):    at dalvik.system.NativeStart.main(Native Method)
04-30 21:03:49.972: W/System.err(17765): Caused by: java.lang.NullPointerException
04-30 21:03:49.973: W/System.err(17765):    at com.example.pr1.Show.onCreate(Show.java:34)
04-30 21:03:49.973: W/System.err(17765):    at android.app.Activity.performCreate(Activity.java:5310)
04-30 21:03:49.974: W/System.err(17765):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
04-30 21:03:49.974: W/System.err(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)
04-30 21:03:49.974: W/System.err(17765):    ... 11 more
04-30 21:03:49.974: W/dalvikvm(17765): threadid=1: calling UncaughtExceptionHandler
04-30 21:03:49.977: E/AndroidRuntime(17765): FATAL EXCEPTION: main
04-30 21:03:49.977: E/AndroidRuntime(17765): Process: com.example.pr1, PID: 17765
04-30 21:03:49.977: E/AndroidRuntime(17765): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.pr1/com.example.pr1.Show}: java.lang.NullPointerException
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2417)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2469)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.access$1100(ActivityThread.java:151)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at   android.app.ActivityThread$H.handleMessage(ActivityThread.java:1362)
 04-30 21:03:49.977: E/AndroidRuntime(17765):   at android.os.Handler.dispatchMessage(Handler.java:110)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.os.Looper.loop(Looper.java:193)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.ActivityThread.main(ActivityThread.java:5551)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at java.lang.reflect.Method.invokeNative(Native Method)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at java.lang.reflect.Method.invoke(Method.java:515)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:914)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:730)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at dalvik.system.NativeStart.main(Native Method)
04-30 21:03:49.977: E/AndroidRuntime(17765): Caused by: java.lang.NullPointerException
04-30 21:03:49.977: E/AndroidRuntime(17765):    at com.example.pr1.Show.onCreate(Show.java:34)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.Activity.performCreate(Activity.java:5310)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
04-30 21:03:49.977: E/AndroidRuntime(17765):    at    android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2381)