反射机制:getDeclaredField和getField的区别说明

import javax.persistence.Column;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass; 
import org.hibernate.annotations.GenericGenerator;
@MappedSuperclass
public abstract class IdEntity {
	private String id; 
	@Id
	@GeneratedValue(generator = "paymentableGenerator")
	@GenericGenerator(name = "paymentableGenerator", strategy = "uuid")
	@Column(name ="ID",nullable=false,length=32)
	public String getId() {
		return id;
	} 
	public void setId(String id) {
		this.id = id;
	} 
}

public class Reflect extends IdEntity { 
 public String publicField;
 private String privateField; 
 public Reflect(String publicField, String privateField) {
  super();
  this.publicField = publicField;
  this.privateField = privateField;
 } 
 public String getPrivateField() {
  return privateField;
 } 
 public void setPrivateField(String privateField) {
  this.privateField = privateField;
 } 
}

import java.lang.reflect.Field; 
public class ReflectDemo { 
 /**
  * @Description: TODO
  * @param @param args
  * @return void
  * @throws SecurityException
  * @throws NoSuchFieldException
  * @throws IllegalAccessException
  * @throws IllegalArgumentException
  * @throws
  * @author ydecai
  * @date 2019-1-23
  */
 public static void main(String[] args) throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
  Reflect re = new Reflect("zhangsan", "lisi");
  re.setId("111");
  //getDeclaredFiled获取本类属性
//  Field publicField = re.getClass().getDeclaredField("publicField");
//  System.out.println(publicField.get(re));
  Field publicField = re.getClass().getField("publicField");
  System.out.println(publicField.get(re));
  //getField获取公有属性，包括父类的，下面语句报错
  //Field privateField = re.getClass().getField("privateField");
  Field privateField = re.getClass().getDeclaredField("privateField");
  privateField.setAccessible(true);
  System.out.println(privateField.get(re));
  //获取父类私有属性并获取值
  Field fileId = re.getClass().getSuperclass().getDeclaredField("id");
  fileId.setAccessible(true);
  System.out.println(fileId.get(re));
 } 
}

Field field;
try {
   field = obj.getClass().getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
   //此处用于解决继承导致的getDeclaredField不能直接获取父类属性的问题
   field = obj.getClass().getSuperclass().getDeclaredField(fieldName);
}