eclipse里的Random在哪个包

在 Eclipse 中使用 `java.util.Random` 类需要在代码中导入 `java.util` 包，因为 `Random` 类在该包中定义。你可以在代码的开头添加以下语句来导入该包：

import java.util.Random;

这样就可以在代码中使用 `Random` 类了。注意，如果你使用的是其他 Java IDE，也需要导入相应的包才能使用 `Random` 类。

相关问题

如何在eclipse中随机输出20个题目

以下是在Eclipse中使用Java编程语言随机输出20个题目的示例代码：

import java.util.Random;

public class RandomQuestions {
    public static void main(String[] args) {
        String[] questions = {"What is the capital of France?", "What is the square root of 144?", "Who discovered electricity?", "What is the largest planet in our solar system?", "What is the smallest country in the world?", "What is the atomic number of gold?", "What is the highest mountain in the world?", "What is the formula for water?", "What is the name of the first man to walk on the moon?", "What is the boiling point of water at sea level?", "What is the largest ocean on Earth?", "What is the currency of Japan?", "What is the chemical symbol for oxygen?", "What is the highest waterfall in the world?", "What is the name of the longest river in Africa?", "What is the name of the first computer programmer?", "What is the speed of light?", "What is the smallest particle in an element?", "What is the name of the largest desert in the world?", "What is the largest mammal in the world?"};
        
        int count = 1;
        Random rand = new Random();
        
        while(count <= 20) {
            int index = rand.nextInt(questions.length);
            System.out.println(count + ". " + questions[index]);
            count++;
        }
    }
}

该示例代码创建了一个字符串类型的数组，其中包含20个问题。然后，使用Java的Random类生成一个随机数来选择数组中的问题，并将其输出到控制台上。循环20次以输出20个问题。

在eclipse中用Java编写AES和RSA混合加密的交互界面

以下是一个简单的Java Swing界面，用于演示如何使用AES和RSA混合加密。

首先，请确保您已经安装了Java SDK和Eclipse IDE。接下来，按照以下步骤操作：

1. 在Eclipse中创建一个新的Java项目。
2. 在项目中创建一个名为“aesrsa”的包。
3. 在“aesrsa”包中创建一个名为“Main.java”的类，该类将包含主方法和Swing用户界面。

以下是完整的代码：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.crypto.*;
import java.security.*;

public class Main {
    private JFrame frame;
    private JLabel messageLabel;
    private JTextField messageField;
    private JLabel aesLabel;
    private JTextField aesKeyField;
    private JLabel rsaLabel;
    private JTextField rsaKeyField;
    private JButton encryptButton;
    private JButton decryptButton;
    private JTextArea outputArea;
    private Cipher aesCipher;
    private Cipher rsaCipher;

    public Main() {
        initUI();
        initCiphers();
    }

    private void initUI() {
        frame = new JFrame("AES and RSA Hybrid Encryption");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(500, 400);

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(4, 2));

        messageLabel = new JLabel("Message:");
        messageField = new JTextField();
        aesLabel = new JLabel("AES Key:");
        aesKeyField = new JTextField();
        rsaLabel = new JLabel("RSA Key:");
        rsaKeyField = new JTextField();

        panel.add(messageLabel);
        panel.add(messageField);
        panel.add(aesLabel);
        panel.add(aesKeyField);
        panel.add(rsaLabel);
        panel.add(rsaKeyField);

        encryptButton = new JButton("Encrypt");
        encryptButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                encrypt();
            }
        });
        decryptButton = new JButton("Decrypt");
        decryptButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                decrypt();
            }
        });

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout(new FlowLayout());
        buttonPanel.add(encryptButton);
        buttonPanel.add(decryptButton);

        outputArea = new JTextArea();
        outputArea.setEditable(false);

        Container contentPane = frame.getContentPane();
        contentPane.setLayout(new BorderLayout());
        contentPane.add(panel, BorderLayout.NORTH);
        contentPane.add(buttonPanel, BorderLayout.CENTER);
        contentPane.add(outputArea, BorderLayout.SOUTH);

        frame.setVisible(true);
    }

    private void initCiphers() {
        try {
            aesCipher = Cipher.getInstance("AES");
            KeyGenerator aesKeyGen = KeyGenerator.getInstance("AES");
            SecureRandom random = new SecureRandom();
            aesKeyGen.init(random);
            SecretKey aesKey = aesKeyGen.generateKey();
            aesKeyField.setText(bytesToHex(aesKey.getEncoded()));

            rsaCipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            KeyPairGenerator rsaKeyGen = KeyPairGenerator.getInstance("RSA");
            rsaKeyGen.initialize(1024, random);
            KeyPair rsaKeyPair = rsaKeyGen.generateKeyPair();
            rsaKeyField.setText(bytesToHex(rsaKeyPair.getPublic().getEncoded()));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void encrypt() {
        try {
            String message = messageField.getText();
            byte[] aesKeyBytes = hexToBytes(aesKeyField.getText());
            SecretKeySpec aesKeySpec = new SecretKeySpec(aesKeyBytes, "AES");
            aesCipher.init(Cipher.ENCRYPT_MODE, aesKeySpec);
            byte[] encryptedMessage = aesCipher.doFinal(message.getBytes());
            byte[] rsaKeyBytes = hexToBytes(rsaKeyField.getText());
            X509EncodedKeySpec rsaKeySpec = new X509EncodedKeySpec(rsaKeyBytes);
            KeyFactory rsaKeyFactory = KeyFactory.getInstance("RSA");
            PublicKey rsaPublicKey = rsaKeyFactory.generatePublic(rsaKeySpec);
            rsaCipher.init(Cipher.ENCRYPT_MODE, rsaPublicKey);
            byte[] encryptedAesKey = rsaCipher.doFinal(aesKeyBytes);
            outputArea.setText("Encrypted message:\n" + bytesToHex(encryptedMessage) + "\n\nEncrypted AES key:\n" + bytesToHex(encryptedAesKey));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private void decrypt() {
        try {
            byte[] encryptedMessage = hexToBytes(outputArea.getText().split("\n")[1]);
            byte[] encryptedAesKey = hexToBytes(outputArea.getText().split("\n")[4]);
            byte[] rsaKeyBytes = hexToBytes(rsaKeyField.getText());
            PKCS8EncodedKeySpec rsaKeySpec = new PKCS8EncodedKeySpec(rsaKeyBytes);
            KeyFactory rsaKeyFactory = KeyFactory.getInstance("RSA");
            PrivateKey rsaPrivateKey = rsaKeyFactory.generatePrivate(rsaKeySpec);
            rsaCipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey);
            byte[] aesKeyBytes = rsaCipher.doFinal(encryptedAesKey);
            SecretKeySpec aesKeySpec = new SecretKeySpec(aesKeyBytes, "AES");
            aesCipher.init(Cipher.DECRYPT_MODE, aesKeySpec);
            byte[] decryptedMessage = aesCipher.doFinal(encryptedMessage);
            outputArea.append("\n\nDecrypted message:\n" + new String(decryptedMessage));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static String bytesToHex(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            sb.append(String.format("%02X", b));
        }
        return sb.toString();
    }

    private static byte[] hexToBytes(String hex) {
        int len = hex.length();
        byte[] bytes = new byte[len / 2];
        for (int i = 0; i < len; i += 2) {
            bytes[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4) + Character.digit(hex.charAt(i+1), 16));
        }
        return bytes;
    }

    public static void main(String[] args) {
        new Main();
    }
}

在代码中，我们使用了Java的加密API来实现AES和RSA混合加密。我们还使用了Java的Swing库来创建用户界面。

在用户界面中，我们有三个文本字段：消息、AES密钥和RSA密钥。我们还有两个按钮：“加密”和“解密”。当用户单击“加密”按钮时，我们将使用AES加密消息，并使用RSA加密AES密钥。当用户单击“解密”按钮时，我们将解密AES密钥，然后使用AES解密消息。

注意，在代码中，我们使用了一些辅助方法来将字节数组转换为十六进制字符串，以及将十六进制字符串转换回字节数组。

您可以将此代码复制到Eclipse中，并运行它以查看它的工作原理。