Java List Object[]转换成List T的实例

package com.oysept.utils; 
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.List;
 
/**
 * List<Object[]>转换成一个List<T>
 * @author ouyangjun
 */
public class ObjectToBeanUtils {
 
 /**
  * 把List<Object[]>转换成List<T>
  */
 public static <T> List<T> objectToBean(List<Object[]> objList, Class<T> clz) throws Exception{
  if (objList==null || objList.size()==0) {
   return null;
  }
 
  Class<?>[] cz = null;
  Constructor<?>[] cons = clz.getConstructors();
  for (Constructor<?> ct : cons) {
   Class<?>[] clazz = ct.getParameterTypes();
   if (objList.get(0).length == clazz.length) {
    cz = clazz;
    break;
   }
  }
 
  List<T> list = new ArrayList<T>();
  for (Object[] obj : objList) {
   Constructor<T> cr = clz.getConstructor(cz);
   list.add(cr.newInstance(obj));
  }
  return list;
 }
}

package com.oysept.bean;
 
import java.io.Serializable;
import java.math.BigDecimal; 
public class PhoneEntity implements Serializable { 
 private static final long serialVersionUID = 1L; 
 public PhoneEntity() {}
 
 /**
  * 构造器
  * 注意: 实体类中必须有无参数构造器，有参数构造器，且构造器参数的顺序和数据的顺序必须一致。如果数据格式有变化，需要重新编写一个实体类的构造器
  */
 public PhoneEntity(String plate, BigDecimal number, double memory, double size) {
  super();
  this.plate = plate;
  this.number = String.valueOf(number);
  this.memory = String.valueOf(memory);
  this.size = String.valueOf(size);
 }
 
 private String plate;
 private String number;
 private String memory;
 private String size;
 
 public String getPlate() { return plate; }
 public void setPlate(String plate) { this.plate = plate; }
 
 public String getNumber() { return number; }
 public void setNumber(String number) { this.number = number; }
 
 public String getMemory() { return memory; }
 public void setMemory(String memory) { this.memory = memory; }
 
 public String getSize() { return size; }
 public void setSize(String size) { this.size = size;}
}
 

package com.oysept.test;
 
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List; 
import com.oysept.bean.PhoneEntity;
import com.oysept.utils.ObjectToBeanUtils;
 
/**
 * 测试类
 * @author ouyangjun
 */
public class ObjectToBeanTest {
 
 public static void main(String[] args) throws Exception {
  // 初始化数据
  Object[] obj = new Object[4];
  obj[0] = "hw";
  obj[1] = BigDecimal.valueOf(13699999999L);
  obj[2] = 4.7;
  obj[3] = 5.0;
 
  Object[] obj1 = new Object[4];
  obj1[0] = "vivo";
  obj1[1] = BigDecimal.valueOf(13611111111L);
  obj1[2] = 4.8;
  obj1[3] = 5.7;
 
  List<Object[]> objList = new ArrayList<Object[]>();
  objList.add(obj);
  objList.add(obj1);
 
  // 工具类
  List<PhoneEntity> list = ObjectToBeanUtils.objectToBean(objList, PhoneEntity.class);
  for (PhoneEntity phone : list) {
   System.out.println(phone.getPlate() + "\t" + phone.getNumber()
    + "\t" + phone.getMemory() + "\t" + phone.getSize());
  }
 }
}

public class ListWithoutGeneric {
 public static void main(String[] args) {
  // 第一段：不使用泛型的方式
  List a1 = new ArrayList();
  a1.add(new Object());
  a1.add(new Integer(1));
  a1.add(new String("a1"));
 
  // 第二段：把a1赋值给List<Object>类型的a2，看似a2与a1没有区别
  List<Object> a2 = a1;
  a2.add(new Object());
  a2.add(new Integer(2));
  a2.add(new String("a2"));
  // 但是如果尝试把一个带有其它类型泛型的b2赋值给a2，则会编译报错
  List<String> b2 = new ArrayList<>();
  // 编译报错，这也是List与List<Object>的区别
  a2 = b2;
 
  // 第三段：把a1赋值给List<Integer>类型的a3，赋值过程没有编译报错，主要为了向前兼容（泛型jdk1.5之后才出现）
  List<Integer> a3 = a1;
  a3.add(new Integer(3));
  // java.lang.ClassCastException: java.lang.Object cannot be cast to java.lang.Integer
  Integer integer = a3.get(0);
  // 编译报错，不允许add非Integer类型
  a3.add(new Object());
  a3.add(new String("a3"));
 
  // 第四段：把a1赋值给List<?>类型的a4
  List<?> a4 = a1;
  a4.remove(0);
  a4.clear();
  a4.add(null);
  // 编译出错，不允许add非null的数据
  a4.add(new Object());
 }
}