Java比較兩個對象中全部屬性值是否相等的方法

例如下述Java類:

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 "當前拓撲的PK為:" + topology_pk + ",ID為:" + topology_id;
 }
}

如下想判斷下面兩個對象中全部屬性值是否一致時,有哪些辦法呢?

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:重寫Bean_Topology的equals方法和hashcode方法,代碼如下:

@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();
    }

測試代碼如下:

if(topology1.equals(topology2)) {
 System.out.println("對象1與對象2的屬性值無差異。");
}else {
 System.out.println("對象1與對象2的屬性值有差異。"); 
}

輸出結果為:

對象1與對象2的屬性值有差異。

方法二:調用文章末尾的工具類,代碼如下:

Map<String, Map<String,Object>> resultMap=compareFields(topology1,topology2);
int size=resultMap.size();
if(size>0) {
    System.out.println("對象1與對象2的屬性值有差異,差異結果如下:");
  
    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("對象1與對象2的屬性值無差異!");
}

輸出結果為:

對象1與對象2的屬性值有差異,差異結果如下:
  topology_pk(oldValue:null,newValue:1)

工具類如下:

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 {
 /**
  * 比較兩個實體屬性值,返回一個boolean,true則表時兩個對象中的屬性值無差異
  * @param oldObject 進行屬性比較的對象1
  * @param newObject 進行屬性比較的對象2
  * @return 屬性差異比較結果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;
  }
 }
 
 /**
  * 比較兩個實體屬性值,返回一個map以有差異的屬性名為key,value為一個Map分別存oldObject,newObject此屬性名的值
  * @param oldObject 進行屬性比較的對象1
  * @param newObject 進行屬性比較的對象2
  * @return 屬性差異比較結果map
  */
 @SuppressWarnings("rawtypes")
 public static Map<String, Map<String,Object>> compareFields(Object oldObject, Object newObject) {
  Map<String, Map<String, Object>> map = null;
  
  try{ 
   /**
    * 隻有兩個對象都是同一類型的才有可比性
    */
   if (oldObject.getClass() == newObject.getClass()) {
    map = new HashMap<String, Map<String,Object>>();
    
    Class clazz = oldObject.getClass();
    //獲取object的所有屬性
    PropertyDescriptor[] pds = Introspector.getBeanInfo(clazz,Object.class).getPropertyDescriptors();
    
    for (PropertyDescriptor pd : pds) {
     //遍歷獲取屬性名
     String name = pd.getName();
     
     //獲取屬性的get方法
     Method readMethod = pd.getReadMethod();
     
     // 在oldObject上調用get方法等同於獲得oldObject的屬性值
     Object oldValue = readMethod.invoke(oldObject);
     // 在newObject上調用get方法等同於獲得newObject的屬性值
     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)) {// 比較這兩個值是否相等,不等就可以放入map瞭
      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;
 }
}

註意:本工具類不適用於比較包含List,Map等類的Class。

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