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Java比较两个对象中全部属性值是否相等的方法

时间:2023-03-11 10:59:58 | 栏目:JAVA代码 | 点击:

例如下述Java类:

import java.io.Serializable;
import java.util.List;

public class Bean_Topology implements Serializable {
 private static final long serialVersionUID = 1L;
 public static long getSerialversionuid() {
  return serialVersionUID;
 }

 private Long topology_pk;

 private String topology_id;

 public String getTopology_id() {
  return topology_id;
 }

 public void setTopology_id(String topology_id) {
  this.topology_id = topology_id;
 }

 public Long getTopology_pk() {
  return topology_pk;
 }

 public void setTopology_pk(Long topology_pk) {
  this.topology_pk = topology_pk;
 }

 @Override
 public String toString() {
  return "当前拓扑的PK为:" + topology_pk + ",ID为:" + topology_id;
 }
}

如下想判断下面两个对象中全部属性值是否一致时,有哪些办法呢?

Bean_Topology topology1 = new Bean_Topology();
 topology1.setTopology_id("1");

Bean_Topology topology2 = new Bean_Topology();
 topology2.setTopology_pk(1L);
 topology2.setTopology_id("1");

方法一:重写Bean_Topology的equals方法和hashcode方法,代码如下:

@Override
public boolean equals(Object obj) {
    if (this == obj) {
        return true;
    }
  
    if (obj == null || getClass() != obj.getClass()) {
        return false;
     }

    Bean_Topology topology = (Bean_Topology) obj;
    if (topology_pk == null) {
        if (topology.topology_pk != null) {
            return false;
        } 
    }else if (!topology_pk.equals(topology.topology_pk)) {
        return false; 
    }
        
    if (topology_id == null) {
        if (topology.topology_id != null) {
            return false;
        } 
    }else if (!topology_id.equals(topology.topology_id)) {
        return false; 
    }
        
        return true;
    }
 
    @Override
    public int hashCode() {
        return  topology_pk.hashCode()+topology_id.hashCode();
    }

测试代码如下:

if(topology1.equals(topology2)) {
 System.out.println("对象1与对象2的属性值无差异。");
}else {
 System.out.println("对象1与对象2的属性值有差异。"); 
}

输出结果为:

对象1与对象2的属性值有差异。

方法二:调用文章末尾的工具类,代码如下:

Map<String, Map<String,Object>> resultMap=compareFields(topology1,topology2);
int size=resultMap.size();
if(size>0) {
    System.out.println("对象1与对象2的属性值有差异,差异结果如下:");
  
    Iterator<String> it = resultMap.keySet().iterator();
    while(it.hasNext()) {
        String key=it.next();
        System.out.println("  "+key+"(oldValue:"+resultMap.get(key).get("oldValue")+",newValue:"+resultMap.get(key).get("newValue")+")");
        } 
}else {
 System.out.println("对象1与对象2的属性值无差异!");
}

输出结果为:

对象1与对象2的属性值有差异,差异结果如下:
  topology_pk(oldValue:null,newValue:1)

工具类如下:

package com.sitech.modual.util.compare;

import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import com.sitech.modual.bean.Bean_Link;
import com.sitech.modual.bean.Bean_Topology;

public class ClassCompareUtil {
 /**
  * 比较两个实体属性值,返回一个boolean,true则表时两个对象中的属性值无差异
  * @param oldObject 进行属性比较的对象1
  * @param newObject 进行属性比较的对象2
  * @return 属性差异比较结果boolean
  */
 public static boolean compareObject(Object oldObject, Object newObject) {
  Map<String, Map<String,Object>> resultMap=compareFields(oldObject,newObject);
  
  if(resultMap.size()>0) {
   return false;
  }else {
   return true;
  }
 }
 
 /**
  * 比较两个实体属性值,返回一个map以有差异的属性名为key,value为一个Map分别存oldObject,newObject此属性名的值
  * @param oldObject 进行属性比较的对象1
  * @param newObject 进行属性比较的对象2
  * @return 属性差异比较结果map
  */
 @SuppressWarnings("rawtypes")
 public static Map<String, Map<String,Object>> compareFields(Object oldObject, Object newObject) {
  Map<String, Map<String, Object>> map = null;
  
  try{ 
   /**
    * 只有两个对象都是同一类型的才有可比性
    */
   if (oldObject.getClass() == newObject.getClass()) {
    map = new HashMap<String, Map<String,Object>>();
    
    Class clazz = oldObject.getClass();
    //获取object的所有属性
    PropertyDescriptor[] pds = Introspector.getBeanInfo(clazz,Object.class).getPropertyDescriptors();
    
    for (PropertyDescriptor pd : pds) {
     //遍历获取属性名
     String name = pd.getName();
     
     //获取属性的get方法
     Method readMethod = pd.getReadMethod();
     
     // 在oldObject上调用get方法等同于获得oldObject的属性值
     Object oldValue = readMethod.invoke(oldObject);
     // 在newObject上调用get方法等同于获得newObject的属性值
     Object newValue = readMethod.invoke(newObject);
     
     if(oldValue instanceof List){
      continue;
     }
     
     if(newValue instanceof List){
      continue;
     }
     
     if(oldValue instanceof Timestamp){
      oldValue = new Date(((Timestamp) oldValue).getTime());
     }
     
     if(newValue instanceof Timestamp){
      newValue = new Date(((Timestamp) newValue).getTime());
     }
     
     if(oldValue == null && newValue == null){
      continue;
     }else if(oldValue == null && newValue != null){
      Map<String,Object> valueMap = new HashMap<String,Object>();
       valueMap.put("oldValue",oldValue);
       valueMap.put("newValue",newValue);
      
      map.put(name, valueMap);
      
      continue;
     }
     
     if (!oldValue.equals(newValue)) {// 比较这两个值是否相等,不等就可以放入map了
      Map<String,Object> valueMap = new HashMap<String,Object>();
       valueMap.put("oldValue",oldValue);
       valueMap.put("newValue",newValue);
      
      map.put(name, valueMap);
     }
    }
   }
  }catch(Exception e){
   e.printStackTrace();
  }
  
  return map;
 }
}

注意:本工具类不适用于比较包含List,Map等类的Class。

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