Java如何获取Object中Value

import java.lang.reflect.Field;  
public class ReflectionExample {  
    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException {  
        class MyClass {  
            private String name = "John Doe";  
            private int age = 30;  
        }  
        MyClass myObject = new MyClass();  
        // 使用反射获取私有字段的值  
        Field nameField = MyClass.class.getDeclaredField("name");  
        nameField.setAccessible(true); // 允许访问私有字段  
        String name = (String) nameField.get(myObject);  
        Field ageField = MyClass.class.getDeclaredField("age");  
        ageField.setAccessible(true);  
        int age = ageField.getInt(myObject);  
        System.out.println("Name: " + name);  
        System.out.println("Age: " + age);  
    }  
}

public class MyClass {  
    private String name = "John Doe";  
    private int age = 30;  
    public String getName() {  
        return name;  
    }  
    public int getAge() {  
        return age;  
    }  
}  
public class GetterExample {  
    public static void main(String[] args) {  
        MyClass myObject = new MyClass();  
        // 使用getter方法获取属性值  
        String name = myObject.getName();  
        int age = myObject.getAge();  
        System.out.println("Name: " + name);  
        System.out.println("Age: " + age);  
    }  
}

import java.util.HashMap;  
import java.util.Map;  
public class MapExample {  
    public static void main(String[] args) {  
        Map<String, Object> attributes = new HashMap<>();  
        attributes.put("name", "John Doe");  
        attributes.put("age", 30);  
        // 直接从Map中获取值  
        String name = (String) attributes.get("name");  
        int age = (int) attributes.get("age");  
        System.out.println("Name: " + name);  
        System.out.println("Age: " + age);  
    }  
}

import com.fasterxml.jackson.databind.ObjectMapper;  
public class SerializationExample {  
    public static void main(String[] args) throws Exception {  
        class MyClass {  
            private String name = "John Doe";  
            private int age = 30;  
            // 需要getter和setter方法或@JsonProperty注解来确保属性被序列化  
            public String getName() {  
                return name;  
            }  
            public void setName(String name) {  
                this.name = name;  
            }  
            public int getAge() {  
                return age;  
            }  
            public void setAge(int age) {  
                this.age = age;  
            }  
        }  
        MyClass myObject = new MyClass();  
        ObjectMapper mapper = new ObjectMapper();  
        String json = mapper.writeValueAsString(myObject); // 序列化  
        // 反序列化（这里不直接展示，因为目的是获取值而不是重新创建对象）  
        // 但你可以通过解析JSON字符串来获取值  
        System.out.println(json); // 输出：{"name":"John Doe","age":30}  
        // 如果你想从JSON字符串中获取值，你可以使用JsonParser或第三方库如Gson、org.json等  
    }  
}  
// 注意：上面的代码示例并没有直接展示如何从JSON字符串中获取值，因为那将涉及JSON解析，  
// 这通常是通过第三方库（如Jackson、Gson、org.json等）来完成的。