java - 通过 Java 反射重新创建(通用)成员并填充/分配字段成员

Question

我有一组包含任意数量的非自定义成员的类——只是原语、包装器等；其中一些可以用 @Encrypted 注释，以便进行不同的处理。所有类型都实现了 Envelope。

我正在创建两个 Map(基于给定类型)，存储“字段名称”(作为键)和“字段值”(作为值)。

问题是当我尝试根据 Map 重新创建类型时。这是我目前所拥有的:

import io.shido.domain.Envelope;
import org.apache.commons.lang3.reflect.FieldUtils;

import java.util.Map;

public final class Factory<T extends Envelope> {
  private final Map<String, Object> regularMembers;

  private final Map<String, Object> secureMembers;

  public Factory(final Map<String, Object> regularMembers, final Map<String, Object> secureMembers) {
    this.regularMembers = regularMembers;
    this.secureMembers = secureMembers;
  }

  public T build() {
    try {
      final ParameterizedType superClass = (ParameterizedType) getClass().getGenericSuperclass(); // This doesn't work >:(
      final Class<T> type = (Class<T>) superClass.getActualTypeArguments()[0];
      final T result = type.newInstance();
      regularMembers.forEach((fieldName, fieldValue) -> assign(result, fieldName, fieldValue));
      secureMembers.forEach((fieldName, fieldValue) -> assign(result, fieldName, fieldValue));
      return result;
    } catch (final Exception e) {
      logger.error("Cannot build type based on input parameters due to:", e);
      throw new IllegalStateException(e.toString());
    }
  }

  private void assign(final T type, final String fieldName, final Object fieldValue) {
    try {
      FieldUtils.getField(type.getClass(), fieldName).set(type, fieldValue);
    } catch (final IllegalAccessException e) {
      e.printStackTrace();
    }
  }
}

任何线索如何处理这个？我可以使用任何库。

---

我唯一的限制是当前类型没有 setter — 我无法添加它们，而且我使用的是 Java 8。

例如，这是一个例子:

public final class ExampleType implements Envelope {
  @Encrypted
  private String first;

  private String second;

  @Encrypted
  private String third;

  public ExampleType() { }

  public ExampleType(final String first, final String second, final String third) {
    this.first = first;
    this.second = second;
    this.third = third;
  }

  public String getFirst() { return first; }

  public String getSecond() { return second; }

  public String getThird() { return third; }
}

Answer 1

要扩展我的评论，请尝试这样的事情(未经测试):

import io.shido.domain.Envelope;
import org.apache.commons.lang3.reflect.FieldUtils;

import java.util.Map;

public final class Factory<T extends Envelope> {
  private final Class<T> clazz;

  private final Map<String, Object> regularMembers;

  private final Map<String, Object> secureMembers;

  public Factory(final Class<T> clazz, final Map<String, Object> regularMembers, final Map<String, Object> secureMembers) {
    this.clazz = clazz;
    this.regularMembers = regularMembers;
    this.secureMembers = secureMembers;
  }

  public T build() {
    try {
      final T result = clazz.newInstance();
      regularMembers.forEach((fieldName, fieldValue) -> assign(result, fieldName, fieldValue));
      secureMembers.forEach((fieldName, fieldValue) -> assign(result, fieldName, fieldValue));
      return result;
    } catch (final Exception e) {
      logger.error("Cannot build type based on input parameters due to:", e);
      throw new IllegalStateException(e.toString());
    }
  }

  private void assign(final T type, final String fieldName, final Object fieldValue) {
    try {
      FieldUtils.getField(type.getClass(), fieldName).set(type, fieldValue);
    } catch (final IllegalAccessException e) {
      e.printStackTrace();
    }
  }
}