空安全编程的典范：Java 8中的安全应用指南

public static void main(String[] args) {
        // 原始字符串
        String originalInput = "Hello World!";

        // 编码为Base64
        String encodedString = Base64.getEncoder().encodeToString(originalInput.getBytes());
        System.out.println("Encoded string: " + encodedString);

        // 解码Base64
        byte[] decodedBytes = Base64.getDecoder().decode(encodedString);
        String decodedString = new String(decodedBytes);
        System.out.println("Decoded string: " + decodedString);
    }

// 输出
Encoded string: SGVsbG8gV29ybGQh
Decoded string: Hello World!

public static void main(String[] args) throws UnsupportedEncodingException {
        // 原始字符串
        String originalInput = "Hello World!";

        // URL 和文件名安全的 Base64 编码
        String encodedString = Base64.getUrlEncoder().encodeToString(originalInput.getBytes("utf-8"));
        System.out.println("Encoded string (URL safe): " + encodedString);

        // 解码 URL 和文件名安全的 Base64
        byte[] decodedBytes = Base64.getUrlDecoder().decode(encodedString);
        String decodedString = new String(decodedBytes, "utf-8");
        System.out.println("Decoded string: " + decodedString);
    }

// 输出
Encoded string (URL safe): SGVsbG8gV29ybGQh
Decoded string: Hello World!

public static void main(String[] args) throws UnsupportedEncodingException {
        // 原始字符串
        String originalInput = "Hello World!";

        // MIME Base64 编码
        String encodedString = Base64.getMimeEncoder().encodeToString(originalInput.getBytes("utf-8"));
        System.out.println("Encoded string (MIME):" + encodedString);

        // 解码 MIME Base64
        byte[] decodedBytes = Base64.getMimeDecoder().decode(encodedString);
        String decodedString = new String(decodedBytes, "utf-8");
        System.out.println("Decoded string: " + decodedString);
    }

// 输出
Encoded string (MIME):SGVsbG8gV29ybGQh
Decoded string: Hello World!

public static void main(String[] args) {
        // 创建一个包含非空值的 Optional 对象
        Optional<String> optional1 = Optional.of("Hello");
        System.out.println("Optional 1 value: " + optional1.get());

        // 创建一个可能为 null 的 Optional 对象
        String nullableValue = null;
        Optional<String> optional2 = Optional.ofNullable(nullableValue);
        System.out.println("Optional 2 is present? " + optional2.isPresent());

        // 获取 Optional 对象中的值
        String value = optional1.get();
        System.out.println("Value: " + value);

        // 检查 Optional 对象中是否有值
        if (optional1.isPresent()) {
            System.out.println("Optional contains value.");
        } else {
            System.out.println("Optional is empty.");
        }

        // 使用 orElse 提供默认值
        String result1 = optional2.orElse("Default Value");
        System.out.println("Result 1: " + result1);

        // 使用 orElseGet 提供默认值
        String result2 = optional2.orElseGet(() -> {
            // 处理逻辑，返回默认值
            return "Default Value from Supplier";
        });
        System.out.println("Result 2: " + result2);

        // 如果 Optional 对象中有值，则执行操作
        optional1.ifPresent(val -> System.out.println("Value is present: " + val));

        // 过滤值
        Optional<String> filteredOptional = optional1.filter(val -> val.startsWith("H"));
        System.out.println("Filtered Optional value: " + filteredOptional.orElse("Not found"));

        // 映射值
        Optional<String> transformedOptional = optional1.map(val -> val.toUpperCase());
        System.out.println("Transformed Optional value: " + transformedOptional.orElse("No value"));

        // 抛出异常
        try {
            value = optional2.orElseThrow(() -> new IllegalArgumentException("Value is required."));
            System.out.println("Value: " + value);
        } catch (IllegalArgumentException e) {
            System.out.println("Exception: " + e.getMessage());
        }
    }

// 输出
Optional 1 value: Hello
Optional 2 is present? false
Value: Hello
Optional contains value.
Result 1: Default Value
Result 2: Default Value from Supplier
Value is present: Hello
Filtered Optional value: Hello
Transformed Optional value: HELLO
Exception: Value is required.

public static void main(String[] args) throws Exception {
    // 创建 Nashorn 脚本引擎
    ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");

   // 执行 JavaScript 代码
    engine.eval("print('Hello Nashorn!')");
}

public static void main(String[] args) throws Exception {
   ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");

   // 将 Java 变量传递给 JavaScript
   engine.put("name", "Alice");
   engine.eval("print('Hello, ' + name + '!')");
}

// Java 类
public class Person {
    public String getName() {
        return "Alice";
    }
}

// JavaScript 代码
engine.eval("var person = new Person(); print(person.getName());");

$ jjs script.js