What is the output of the following code? ( ) public class rtExcept{ public static void throwit0{ System.out.print("throwit "); throw new RuntimeException0; } public static void main(String I aa){ try { System.out print("hello "); throwitO;} catch(Exception re){ System.out.print("caught "); } finally System.out.print("finally "); ' System.out print("after ");}}
时间: 2024-03-23 17:39:36 浏览: 16
The code contains compilation errors. The correct code is:
```
public class rtExcept {
public static void throwit() {
System.out.print("throwit ");
throw new RuntimeException();
}
public static void main(String[] args) {
try {
System.out.print("hello ");
throwit();
} catch (Exception re) {
System.out.print("caught ");
} finally {
System.out.print("finally ");
}
System.out.print("after ");
}
}
```
The output of the corrected code is:
```
hello throwit caught finally
```
相关问题
try{ kp.genKeyPair(); rpk = (RSAPublicKey)kp.getPublic(); // rpvk = (RSAPrivateKey)kp.getPrivate(); RSAPrivateCrtKey priKey = (RSAPrivateCrtKey)kp.getPrivate(); short publicKeySize = (short)(rpk.getSize()/8); short privateKeySize = priKey.getSize(); byte[] publicKey = JCSystem.makeTransientByteArray((short) (publicKeySize), JCSystem.CLEAR_ON_DESELECT); rpk.getModulus(publicKey, (short) 0); priKey.getP(buf, (short) 0); // Util.arrayCopyNonAtomic(publicKey, (short) 0, buf, (short) 0, (short) (publicKeySize )); apdu.setOutgoing(); apdu.setOutgoingLength((short)(publicKeySize)); apdu.sendBytes((short) 0, (short) (publicKeySize)); /* rpk.getExponent(buf, (short)0); rpk.getModulus(buf, (short)3); apdu.setOutgoing(); apdu.setOutgoingLength((short)(rpk.getSize()/8+3)); apdu.sendBytes((short)0, (short)(rpk.getSize()/8+3)); */ }catch(Exception e){ ISOException.throwIt((short) 0x1234); } break;
这段代码看起来像是 Java Card 应用程序中的一部分,用于生成 RSA 密钥对,并将公钥发送回应用程序的主机。代码的主要部分如下:
```
kp.genKeyPair();
rpk = (RSAPublicKey)kp.getPublic();
RSAPrivateCrtKey priKey = (RSAPrivateCrtKey)kp.getPrivate();
short publicKeySize = (short)(rpk.getSize()/8);
short privateKeySize = priKey.getSize();
byte[] publicKey = JCSystem.makeTransientByteArray((short) (publicKeySize), JCSystem.CLEAR_ON_DESELECT);
rpk.getModulus(publicKey, (short) 0);
priKey.getP(buf, (short) 0);
apdu.setOutgoing();
apdu.setOutgoingLength((short)(publicKeySize));
apdu.sendBytes((short) 0, (short) (publicKeySize));
```
首先,它调用 `kp.genKeyPair()` 生成一个 RSA 密钥对。然后,它从生成的密钥对中获取公钥 `rpk` 和私钥 `priKey`。它计算出公钥的长度 `publicKeySize`,并使用 `JCSystem.makeTransientByteArray()` 方法创建一个大小为 `publicKeySize` 的临时数组 `publicKey`,用于存储公钥的模数。接下来,它调用 `rpk.getModulus()` 获取公钥的模数,并将其存储在 `publicKey` 数组中。最后,它将公钥发送回主机。
需要注意的是,这段代码中的一些变量和方法可能是 Java Card API 中的特定部分,因此可能需要更多的上下文才能完全理解其含义。
使用javacard实现动态口令生成功能、身份数据的初始化功能,写出代码
以下是使用JavaCard实现动态口令生成和身份数据初始化的示例代码:
```java
package com.example.javacard;
import javacard.framework.*;
public class DynamicPasswordApplet extends Applet {
private static final byte INS_INIT_IDENTITY = (byte) 0x01;
private static final byte INS_GENERATE_PASSWORD = (byte) 0x02;
private byte[] identity = null;
private byte[] password = null;
private byte[] challenge = null;
public static void install(byte[] bArray, short bOffset, byte bLength) {
new DynamicPasswordApplet().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
}
public void process(APDU apdu) {
if (selectingApplet()) {
return;
}
byte[] buffer = apdu.getBuffer();
switch (buffer[ISO7816.OFFSET_INS]) {
case INS_INIT_IDENTITY:
initIdentity(apdu);
break;
case INS_GENERATE_PASSWORD:
generatePassword(apdu);
break;
default:
ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
break;
}
}
private void initIdentity(APDU apdu) {
byte[] buffer = apdu.getBuffer();
short length = apdu.setIncomingAndReceive();
identity = new byte[length];
Util.arrayCopy(buffer, ISO7816.OFFSET_CDATA, identity, (short) 0, length);
}
private void generatePassword(APDU apdu) {
byte[] buffer = apdu.getBuffer();
short length = apdu.setIncomingAndReceive();
challenge = new byte[length];
Util.arrayCopy(buffer, ISO7816.OFFSET_CDATA, challenge, (short) 0, length);
if (identity == null || password == null) {
ISOException.throwIt(ISO7816.SW_CONDITIONS_NOT_SATISFIED);
}
byte[] secret = new byte[identity.length + password.length + challenge.length];
short offset = 0;
Util.arrayCopy(identity, (short) 0, secret, offset, (short) identity.length);
offset += identity.length;
Util.arrayCopy(password, (short) 0, secret, offset, (short) password.length);
offset += password.length;
Util.arrayCopy(challenge, (short) 0, secret, offset, (short) challenge.length);
byte[] hash = MessageDigest.getInstance(MessageDigest.ALG_SHA_256, false).doFinal(secret, (short) 0, (short) secret.length);
byte[] dynamicPassword = new byte[8];
Util.arrayCopy(hash, (short) 0, dynamicPassword, (short) 0, (short) 8);
apdu.setOutgoing();
apdu.setOutgoingLength((short) dynamicPassword.length);
Util.arrayCopy(dynamicPassword, (short) 0, buffer, (short) 0, (short) dynamicPassword.length);
apdu.sendBytes((short) 0, (short) dynamicPassword.length);
}
public static byte[] getPassword() {
return new byte[]{0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
}
}
```
上述代码中,我们定义了两个指令,`INS_INIT_IDENTITY`用于初始化身份数据,`INS_GENERATE_PASSWORD`用于生成动态口令。在实现中,我们使用了JavaCard API提供的`Util`类和`MessageDigest`类来进行数据复制和哈希计算。
在身份数据初始化指令中,我们将APDU中的数据复制到`identity`数组中。在动态口令生成指令中,我们将APDU中的数据复制到`challenge`数组中,并将身份数据、密码数据和挑战数据合并成一个字节数组`secret`,然后使用SHA-256哈希算法计算出哈希值,并取前8个字节作为动态口令的值。
为了演示示例代码的使用,我们还需要编写一个JavaCard应用程序,该应用程序将在JavaCard上安装动态口令应用程序,并提供`getPassword`方法返回预设的密码数据。
```java
package com.example.javacard;
import javacard.framework.*;
public class DynamicPasswordInstaller extends Applet {
private static final byte[] AID = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09 };
private static final byte[] PASSWORD = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08 };
private byte[] password = null;
public static void install(byte[] bArray, short bOffset, byte bLength) {
new DynamicPasswordInstaller().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
}
public void process(APDU apdu) {
if (selectingApplet()) {
return;
}
byte[] buffer = apdu.getBuffer();
switch (buffer[ISO7816.OFFSET_INS]) {
case ISO7816.INS_SELECT:
select(apdu);
break;
default:
ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
break;
}
}
private void select(APDU apdu) {
byte[] buffer = apdu.getBuffer();
short length = apdu.setIncomingAndReceive();
if (Util.arrayCompare(buffer, ISO7816.OFFSET_CDATA, AID, (short) 0, (short) AID.length) != 0) {
ISOException.throwIt(ISO7816.SW_APPLET_SELECT_FAILED);
}
password = DynamicPasswordApplet.getPassword();
}
public static byte[] getPassword() {
return PASSWORD;
}
}
```
在此应用程序中,我们定义了一个AID和一个密码数据,并在`select`指令中检查APDU中的选择数据是否与预定AID相同。如果相同,则返回预设的密码数据。
为了将这两个应用程序安装到JavaCard上,我们需要编写一个Java程序来与JavaCard进行通信,并发送APDU指令以安装和使用这两个应用程序。