使用Java注解和反射实现JSON字段自动重命名

<dependency>
    <groupId>com.vaadin.external.google</groupId>
    <artifactId>android-json</artifactId>
    <version>0.0.20131108.vaadin1</version>
    <scope>compile</scope>
</dependency>

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.TYPE) // 用于类
@Retention(RetentionPolicy.RUNTIME) // 运行时保留
public @interface AutoRename {
}

import org.json.JSONObject;
import java.lang.reflect.Field;
import java.util.Iterator;

public class JsonAutoRenamer {

    public static <T> T fromJson(String json, Class<T> clazz) throws Exception {
        JSONObject jsonObject = new JSONObject(json);
        T instance = clazz.getDeclaredConstructor().newInstance();

        Field[] fields = clazz.getDeclaredFields();
        for (Field field : fields) {
            field.setAccessible(true);
            String key = field.getName(); // 获取驼峰式命名
            String dataKey = key.replaceAll("([a-z0-9])([A-Z])", "$1_$2").toLowerCase(); // 转换为下划线分隔

            Object value = jsonObject.has(dataKey) ? jsonObject.get(dataKey) : null;
            if (value != null) {
                // 根据字段类型转换值
                Class<?> fieldType = field.getType();
                if (fieldType == String.class) {
                    field.set(instance, value.toString());
                } else if (fieldType == int.class || fieldType == Integer.class) {
                    field.set(instance, (Integer) value);
                } else if (fieldType == boolean.class || fieldType == Boolean.class) {
                    field.set(instance, (Boolean) value);
                } else if (fieldType == double.class || fieldType == Double.class) {
                    field.set(instance, (Double) value);
                } // ...其他类型处理（如果有的话）
            }
        }

        return instance;
    }
}

@AutoRename
public class UserResponse {
    private String userName ;
private Integer age ;

public UserResponse() {
    }

    public UserResponse(String userName , Integer age) {
        this.userName = userName ;
this.age = age ;
}

    public String getUserName() {
        return userName ;
}

    public void setUserName(String userName) {
        this.userName = userName ;
}

    public Integer getAge() {
        return age ;
}

    public void setAge(Integer age) {
        this.age = age ;
}
}

public class Main {
    public static void main(String[] args) {
        String json = "{"user_name":"John Doe","age":30}";

        try {
            UserResponse userResponse = JsonAutoRenamer.fromJson(json, UserResponse.class);
            // 现在 userResponse 中的字段已经被赋值
            System.out.println("User Name: " + userResponse.getUserName());
            System.out.println("Age: " + userResponse.getAge());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}