反射工具箱 - ObjectWrapper

ObjectWrapper

ObjectWrapper 是对对象的包装的接口，抽象了对象的字段信息、 getter| setter 方法、和上面三个成员的数据类型,它定义了一系列查询对象属性信息的方法,以及更新属性的方法 。

UML

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BaseWrapper

BaseWrapper 抽象类 定义了集合的相关操作。
BeanWrapper 是原始对象的封装，MapWrapper 是 Map 集合对象的封装。

public abstract class BaseWrapper implements ObjectWrapper {

  protected static final Object[] NO_ARGUMENTS = new Object[0];
  protected final MetaObject metaObject;

  protected BaseWrapper(MetaObject metaObject) {
    this.metaObject = metaObject;
  }

  protected Object resolveCollection(PropertyTokenizer prop, Object object) {
    if ("".equals(prop.getName())) {
      return object;
    } else {
      return metaObject.getValue(prop.getName());
    }
  }

  /**
   * 获取对象的集合属性值
   * @param prop
   * @param collection
   * @return
   */
  protected Object getCollectionValue(PropertyTokenizer prop, Object collection) {
    // 如果是 Map 类型，则 index 为 key
    if (collection instanceof Map) {
      return ((Map) collection).get(prop.getIndex());
    } else {
      // 如果是其他类型，则 index 为下标
      int i = Integer.parseInt(prop.getIndex());
      if (collection instanceof List) {
        return ((List) collection).get(i);
      } else if (collection instanceof Object[]) {
        return ((Object[]) collection)[i];
      } else if (collection instanceof char[]) {
        return ((char[]) collection)[i];
      } else if (collection instanceof boolean[]) {
        return ((boolean[]) collection)[i];
      } else if (collection instanceof byte[]) {
        return ((byte[]) collection)[i];
      } else if (collection instanceof double[]) {
        return ((double[]) collection)[i];
      } else if (collection instanceof float[]) {
        return ((float[]) collection)[i];
      } else if (collection instanceof int[]) {
        return ((int[]) collection)[i];
      } else if (collection instanceof long[]) {
        return ((long[]) collection)[i];
      } else if (collection instanceof short[]) {
        return ((short[]) collection)[i];
      } else {
        throw new ReflectionException("The '" + prop.getName() + "' property of " + collection + " is not a List or Array.");
      }
    }
  }

  /**
   * 设置对象的集合值
   * @param prop
   * @param collection
   * @param value
   */
  protected void setCollectionValue(PropertyTokenizer prop, Object collection, Object value) {
    if (collection instanceof Map) {
      ((Map) collection).put(prop.getIndex(), value);
    } else {
      int i = Integer.parseInt(prop.getIndex());
      if (collection instanceof List) {
        ((List) collection).set(i, value);
      } else if (collection instanceof Object[]) {
        ((Object[]) collection)[i] = value;
      } else if (collection instanceof char[]) {
        ((char[]) collection)[i] = (Character) value;
      } else if (collection instanceof boolean[]) {
        ((boolean[]) collection)[i] = (Boolean) value;
      } else if (collection instanceof byte[]) {
        ((byte[]) collection)[i] = (Byte) value;
      } else if (collection instanceof double[]) {
        ((double[]) collection)[i] = (Double) value;
      } else if (collection instanceof float[]) {
        ((float[]) collection)[i] = (Float) value;
      } else if (collection instanceof int[]) {
        ((int[]) collection)[i] = (Integer) value;
      } else if (collection instanceof long[]) {
        ((long[]) collection)[i] = (Long) value;
      } else if (collection instanceof short[]) {
        ((short[]) collection)[i] = (Short) value;
      } else {
        throw new ReflectionException("The '" + prop.getName() + "' property of " + collection + " is not a List or Array.");
      }
    }
  }

}

BeanWrapper

BeanWrapper 是对象的信息封装，包括 getter、setter 方法、字段、及(getter、setter 方法、字段)的返回数据类型。

包装了一个 object 对象，还有这个对象所属类的 MetaClass 对象，然后包装了 MetaClass 对象的方法，对外提供方法调用。

public class BeanWrapper extends BaseWrapper {

  private final Object object;
  private final MetaClass metaClass;

  public BeanWrapper(MetaObject metaObject, Object object) {
    super(metaObject);
    this.object = object;
    this.metaClass = MetaClass.forClass(object.getClass(), metaObject.getReflectorFactory());
  }

  /**
   * 获取属性表达式的值
   * @param prop
   * @return
   */
  @Override
  public Object get(PropertyTokenizer prop) {
    // 存在索引信息，则表示属性表达式中的 name 部分为集合属性
    if (prop.getIndex() != null) {
      // 通过 MetaObject.getValue() 方法获取 Object 对象中的指定集合属性
      Object collection = resolveCollection(prop, object);
      return getCollectionValue(prop, collection);
    } else {
      // name 属性为普通对象，查找并调用 Invoker 相关方法获取属性
      return getBeanProperty(prop, object);
    }
  }

  /**
   * 设置属性表达式的值
   * @param prop
   * @param value
   */
  @Override
  public void set(PropertyTokenizer prop, Object value) {
    if (prop.getIndex() != null) {
      Object collection = resolveCollection(prop, object);
      setCollectionValue(prop, collection, value);
    } else {
      setBeanProperty(prop, object, value);
    }
  }

  /**
   * 是否包含这个属性表达式
   * @param name
   * @param useCamelCaseMapping
   * @return
   */
  @Override
  public String findProperty(String name, boolean useCamelCaseMapping) {
    return metaClass.findProperty(name, useCamelCaseMapping);
  }

  /**
   * 获取对象的可读属性们
   * @return
   */
  @Override
  public String[] getGetterNames() {
    return metaClass.getGetterNames();
  }

  /**
   * 获取对象的可写属性们
   * @return
   */
  @Override
  public String[] getSetterNames() {
    return metaClass.getSetterNames();
  }

  /**
   * 属性表达式 set 方法参数类型
   * @param name
   * @return
   */
  @Override
  public Class<?> getSetterType(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
      if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
        return metaClass.getSetterType(name);
      } else {
        return metaValue.getSetterType(prop.getChildren());
      }
    } else {
      return metaClass.getSetterType(name);
    }
  }

  /**
   * 属性表达式的 get 方法的返回值类型
   * @param name
   * @return
   */
  @Override
  public Class<?> getGetterType(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
      if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
        return metaClass.getGetterType(name);
      } else {
        return metaValue.getGetterType(prop.getChildren());
      }
    } else {
      return metaClass.getGetterType(name);
    }
  }

  /**
   * 是否包含属性表达式的 setter 方法
   * @param name
   * @return
   */
  @Override
  public boolean hasSetter(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      if (metaClass.hasSetter(prop.getIndexedName())) {
        MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
        if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
          return metaClass.hasSetter(name);
        } else {
          return metaValue.hasSetter(prop.getChildren());
        }
      } else {
        return false;
      }
    } else {
      return metaClass.hasSetter(name);
    }
  }

  /**
   * 是否包含表达式的 getter 方法
   * @param name
   * @return
   */
  @Override
  public boolean hasGetter(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      if (metaClass.hasGetter(prop.getIndexedName())) {
        MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
        if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
          return metaClass.hasGetter(name);
        } else {
          return metaValue.hasGetter(prop.getChildren());
        }
      } else {
        return false;
      }
    } else {
      return metaClass.hasGetter(name);
    }
  }

  /**
   * 为属性表达式指定的属性创建相应的 MetaObject 对象
   * @param name
   * @param prop
   * @param objectFactory
   * @return
   */
  @Override
  public MetaObject instantiatePropertyValue(String name, PropertyTokenizer prop, ObjectFactory objectFactory) {
    MetaObject metaValue;
    Class<?> type = getSetterType(prop.getName());
    try {
      Object newObject = objectFactory.create(type);
      metaValue = MetaObject.forObject(newObject, metaObject.getObjectFactory(), metaObject.getObjectWrapperFactory(), metaObject.getReflectorFactory());
      set(prop, newObject);
    } catch (Exception e) {
      throw new ReflectionException("Cannot set value of property '" + name + "' because '" + name + "' is null and cannot be instantiated on instance of " + type.getName() + ". Cause:" + e.toString(), e);
    }
    return metaValue;
  }

  /**
   * 调用对象的 getter 方法，获取对象属性值
   * @param prop
   * @param object
   * @return
   */
  private Object getBeanProperty(PropertyTokenizer prop, Object object) {
    try {
      Invoker method = metaClass.getGetInvoker(prop.getName());
      try {
        return method.invoke(object, NO_ARGUMENTS);
      } catch (Throwable t) {
        throw ExceptionUtil.unwrapThrowable(t);
      }
    } catch (RuntimeException e) {
      throw e;
    } catch (Throwable t) {
      throw new ReflectionException("Could not get property '" + prop.getName() + "' from " + object.getClass() + ".  Cause: " + t.toString(), t);
    }
  }

  /**
   * 调用对象的 setter 方法，设置对象属性值
   * @param prop
   * @param object
   * @param value
   */
  private void setBeanProperty(PropertyTokenizer prop, Object object, Object value) {
    try {
      Invoker method = metaClass.getSetInvoker(prop.getName());
      Object[] params = {value};
      try {
        method.invoke(object, params);
      } catch (Throwable t) {
        throw ExceptionUtil.unwrapThrowable(t);
      }
    } catch (Throwable t) {
      throw new ReflectionException("Could not set property '" + prop.getName() + "' of '" + object.getClass() + "' with value '" + value + "' Cause: " + t.toString(), t);
    }
  }

  /**
   * 对象不是 Collection ，返回 False
   * @return
   */
  @Override
  public boolean isCollection() {
    return false;
  }

  /**
   * 对象不支持 add，集合支持
   * @param element
   */
  @Override
  public void add(Object element) {
    throw new UnsupportedOperationException();
  }
  /**
   * 对象不支持 addAll，集合支持
   * @param list
   */
  @Override
  public <E> void addAll(List<E> list) {
    throw new UnsupportedOperationException();
  }

}

MapWrapper

Map 对象包装器

public class MapWrapper extends BaseWrapper {

  private final Map<String, Object> map;

  public MapWrapper(MetaObject metaObject, Map<String, Object> map) {
    super(metaObject);
    this.map = map;
  }

  @Override
  public Object get(PropertyTokenizer prop) {
    if (prop.getIndex() != null) {
      Object collection = resolveCollection(prop, map);
      return getCollectionValue(prop, collection);
    } else {
      return map.get(prop.getName());
    }
  }

  @Override
  public void set(PropertyTokenizer prop, Object value) {
    if (prop.getIndex() != null) {
      Object collection = resolveCollection(prop, map);
      setCollectionValue(prop, collection, value);
    } else {
      map.put(prop.getName(), value);
    }
  }

  @Override
  public String findProperty(String name, boolean useCamelCaseMapping) {
    return name;
  }

  @Override
  public String[] getGetterNames() {
    return map.keySet().toArray(new String[map.keySet().size()]);
  }

  @Override
  public String[] getSetterNames() {
    return map.keySet().toArray(new String[map.keySet().size()]);
  }

  @Override
  public Class<?> getSetterType(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
      if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
        return Object.class;
      } else {
        return metaValue.getSetterType(prop.getChildren());
      }
    } else {
      if (map.get(name) != null) {
        return map.get(name).getClass();
      } else {
        return Object.class;
      }
    }
  }

  @Override
  public Class<?> getGetterType(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
      if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
        return Object.class;
      } else {
        return metaValue.getGetterType(prop.getChildren());
      }
    } else {
      if (map.get(name) != null) {
        return map.get(name).getClass();
      } else {
        return Object.class;
      }
    }
  }

  @Override
  public boolean hasSetter(String name) {
    return true;
  }

  @Override
  public boolean hasGetter(String name) {
    PropertyTokenizer prop = new PropertyTokenizer(name);
    if (prop.hasNext()) {
      if (map.containsKey(prop.getIndexedName())) {
        MetaObject metaValue = metaObject.metaObjectForProperty(prop.getIndexedName());
        if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
          return true;
        } else {
          return metaValue.hasGetter(prop.getChildren());
        }
      } else {
        return false;
      }
    } else {
      return map.containsKey(prop.getName());
    }
  }

  @Override
  public MetaObject instantiatePropertyValue(String name, PropertyTokenizer prop, ObjectFactory objectFactory) {
    HashMap<String, Object> map = new HashMap<>();
    set(prop, map);
    return MetaObject.forObject(map, metaObject.getObjectFactory(), metaObject.getObjectWrapperFactory(), metaObject.getReflectorFactory());
  }

  @Override
  public boolean isCollection() {
    return false;
  }

  @Override
  public void add(Object element) {
    throw new UnsupportedOperationException();
  }

  @Override
  public <E> void addAll(List<E> element) {
    throw new UnsupportedOperationException();
  }

}