我正在尝试从我的虚拟设备（Genymotion）加密/解密文件。我将向您展示我所拥有的代码和例外情况。我想nullPointerException来自我在View v = null方法中声明onActivityResult的行，但我不知道如何修复它。
例外
07-22 13:34:10.241 10419-10419/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: application.nikola.com.encryptdecrypt, PID: 10419
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=file:///storage/emulated/0/nikola.txt }} to activity {application.nikola.com.encryptdecrypt/application.nikola.com.encryptdecrypt.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getId()' on a null object reference
at android.app.ActivityThread.deliverResults(ActivityThread.java:3539)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3582)
at android.app.ActivityThread.access$1300(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1327)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getId()' on a null object reference
at application.nikola.com.encryptdecrypt.MainActivity.onActivityResult(MainActivity.java:70)
at android.app.Activity.dispatchActivityResult(Activity.java:6135)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3535)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3582)
at android.app.ActivityThread.access$1300(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1327)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
07-22 13:34:10.263 765-1598/? W/ActivityManager﹕ Force finishing activity application.nikola.com.encryptdecrypt/.MainActivity
07-22 13:34:10.350 765-1598/? E/ActivityManager﹕ Invalid thumbnail dimensions: 576x576
07-22 13:34:10.400 765-2035/? I/OpenGLRenderer﹕ Initialized EGL, version 1.4
07-22 13:34:10.466 765-2035/? W/EGL_emulation﹕ eglSurfaceAttrib not implemented
07-22 13:34:10.466 765-2035/? W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0x9ea263c0, error=EGL_SUCCESS
07-22 13:34:10.903 765-786/? W/ActivityManager﹕ Activity pause timeout for ActivityRecord{2ef175ff u0 application.nikola.com.encryptdecrypt/.MainActivity t26 f}
07-22 13:34:11.032 1006-1265/? W/EGL_emulation﹕ eglSurfaceAttrib not implemented
07-22 13:34:11.033 1006-1265/? W/OpenGLRenderer﹕ Failed to set EGL_SWAP_BEHAVIOR on surface 0xa095a020, error=EGL_SUCCESS
07-22 13:34:11.786 2640-2640/? I/art﹕ Explicit concurrent mark sweep GC freed 3007(201KB) AllocSpace objects, 0(0B) LOS objects, 24% free, 16MB/21MB, paused 301us total 21.960ms
07-22 13:34:11.808 2640-2640/? I/art﹕ Explicit concurrent mark sweep GC freed 3080(224KB) AllocSpace objects, 4(252KB) LOS objects, 24% free, 15MB/21MB, paused 173us total 7.668ms
07-22 13:34:11.822 2640-2640/? I/art﹕ Explicit concurrent mark sweep GC freed 3(96B) AllocSpace objects, 0(0B) LOS objects, 24% free, 15MB/21MB, paused 237us total 13.937ms
07-22 13:34:12.735 10419-10419/? I/Process﹕ Sending signal. PID: 10419 SIG: 9
07-22 13:34:12.738 765-823/? W/AudioTrack﹕ AUDIO_OUTPUT_FLAG_FAST denied by client
07-22 13:34:12.764 765-805/? W/InputDispatcher﹕ channel '25d12a93 application.nikola.com.encryptdecrypt/application.nikola.com.encryptdecrypt.MainActivity (server)' ~ Consumer closed input channel or an error occurred. events=0x9
07-22 13:34:12.764 765-805/? E/InputDispatcher﹕ channel '25d12a93 application.nikola.com.encryptdecrypt/application.nikola.com.encryptdecrypt.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!
07-22 13:34:12.777 765-782/? I/ActivityManager﹕ Process application.nikola.com.encryptdecrypt (pid 10419) has died
07-22 13:34:12.778 765-981/? I/WindowState﹕ WIN DEATH: Window{25d12a93 u0 application.nikola.com.encryptdecrypt/application.nikola.com.encryptdecrypt.MainActivity}
07-22 13:34:12.778 765-981/? W/InputDispatcher﹕ Attempted to unregister already unregistered input channel '25d12a93 application.nikola.com.encryptdecrypt/application.nikola.com.encryptdecrypt.MainActivity (server)'
MainActivity
public class MainActivity extends Activity implements View.OnClickListener {
Button btnEncrypt;
Button btnDecrypt;
final int ACTIVITY_CHOOSE_FILE = 1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnEncrypt = (Button) this.findViewById(R.id.btnActivity1);
btnEncrypt.setOnClickListener(this);
btnDecrypt = (Button) this.findViewById(R.id.btnActivity2);
btnDecrypt.setOnClickListener(this);
}
@Override
public void onClick(View v) {
Intent chooseFile;
Intent intent;
chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.setType("file*//*");
intent = Intent.createChooser(chooseFile, "Choose a file");
startActivityForResult(intent, ACTIVITY_CHOOSE_FILE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
EncryptDecrypt crypto = new EncryptDecrypt();
View v = null;
String filePath = null;
switch(requestCode) {
case ACTIVITY_CHOOSE_FILE: {
if (resultCode == RESULT_OK){
Uri uri = data.getData();
filePath = uri.getPath();
switch(v.getId()) {
case R.id.btnActivity1:
crypto.encryptor(filePath);
break;
case R.id.btnActivity2:
crypto.decryptor(filePath);
break;
}
}
}
}
}
}
这是我使用的加密/解密算法。
public class EncryptDecrypt {
public void encryptor(String inputFilePath) {
FileOutputStream fos = null;
File file = new File(inputFilePath);
String keyString = "140405PX_0.$88";
String algorithm = "DESede";
try {
FileInputStream fileInputStream = new FileInputStream(file);
byte[] fileByteArray = new byte[fileInputStream.available()];
fileInputStream.read(fileByteArray);
for (byte b : fileByteArray) {
System.out.println(b);
}
SecretKey secretKey = getKey(keyString);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new CipherOutputStream(new FileOutputStream("encrypt.file"), cipher));
objectOutputStream.writeObject(fileByteArray);
objectOutputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public void decryptor(String inputFilePath) {
String outputFilePath = "decrypt.txt";
String keyString = "140405PX_0.$88";
String algorithm = "DESede";
try {
File inputFileNAme = new File(inputFilePath);
FileInputStream fileInputStream = new FileInputStream(inputFileNAme);
FileOutputStream fileOutputStream = new FileOutputStream(outputFilePath);
SecretKey secretKey = getKey(keyString);
Cipher cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, secretKey);
ObjectInputStream objectInputStream = new ObjectInputStream(new CipherInputStream(fileInputStream, cipher));
System.out.println(objectInputStream.available());
fileOutputStream.write((byte[]) objectInputStream.readObject());
fileOutputStream.flush();
fileOutputStream.close();
fileInputStream.close();
objectInputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public static SecretKey getKey(String message) throws Exception {
String messageToUpperCase = message.toUpperCase();
byte[] digestOfPassword = messageToUpperCase.getBytes();
byte[] keyBytes = Arrays.copyOf(digestOfPassword, 24);
SecretKey key = new SecretKeySpec(keyBytes, "DESede");
return key;
}
}
答案 0 :(得分：1)
View v = null; // v is null
String filePath = null;
switch(requestCode) {
case ACTIVITY_CHOOSE_FILE: {
if (resultCode == RESULT_OK){
Uri uri = data.getData();
filePath = uri.getPath();
switch(v.getId()) { // v is still null
case R.id.btnActivity1:
crypto.encryptor(filePath);
break;
case R.id.btnActivity2:
crypto.decryptor(filePath);
break;
}
}
}
}
您的v为空，您正在尝试v.getId()。这就是你得到NullPointerException的原因。
要解决此问题，您可能需要向btnActivity1和btnActivity2添加OnClickListener。
btnActivity1.setOnCLickListerner(new OnClickListener() {
@Override
public void onClick(View arg0) {
crypto.encryptor(filePath);
}
});
}
btnActivity2.setOnCLickListerner(new OnClickListener() {
@Override
public void onClick(View arg0) {
crypto.decryptor(filePath);
}
});
}
答案 1 :(得分：1)
在switch-case的{{1}}中，您使用的是MainActivity，但v.getId()已初始化为v，因此您将获得null
猜测您要做的是，您正在尝试根据是否单击布局中的两个按钮来决定是解密还是加密文件。但是你没有以适当的方式做到这一点。对每个按钮使用NullPointerException并设置布尔标志以检查是否在这些按钮的OnClickListener事件处解密或加密。然后显示您的onClick。
您可以通过这种方式修改MainActivity
FILE CHOOSER}