JavaBeans比较 [英] JavaBeans Comparison

问题描述

有没有人知道一个免费的开源库（实用程序类），它允许你比较一个Java bean的两个实例，并返回一个属性的列表/数组，这些值在这两个实例中是不同的？

解决方案

干杯

Tomas

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ApacheComponator 是您正在寻找的。

更新。一个简单的例子，比较JavaBeans和一个属性（比较只是一个属性，你应该创建尽可能多的BeanComparators作为属性你想匹配）。

  import org.apache.commons.beanutils.BeanComparator; 
 
 public class TestBeanComparator 
 {
 public TestBeanComparator（）
 {
} 
 
 public class TestBean 
 { 
 int value; 
 
 public TestBean（）
 {
} 
 
 public int getValue（）
 {
 return value; 
} 
 
 public void setValue（int value）
 {
 this.value = value; 
} 
} 
 
 public static void main（String [] args）
 {
 TestBeanComparator tbc = new TestBeanComparator（）; 
 
 tbc.go（）; 
} 
 
 public void go（）
 {
 TestBean tbs [] = new TestBean [10]; 
 
 for（int i = 0; i  {
 tbs [i] = new TestBeanComparator.TestBean（）; 
 tbs [i] .setValue（（int）（Math.random（）* 10））; 
 
 System.out.println（TestBean [+ i +] =+ tbs [i] .getValue（））; 
} 
 
 BeanComparator bc = new BeanComparator（value）; 
 
 System.out.println（）; 
 System.out.println（Value to match：+ tbs [0] .getValue（））; 
 for（int i = 1; i  {
 if（bc.compare（tbs [i]，tbs [0]）== 0）
 {
 System.out.println（Match found in bean+ i）; 
} 
} 
} 
} 
  

一些测试一个结果是成功的。这是输出：

  TestBean [0] = 0 
 TestBean [1] = 4 
 TestBean [2] = 0 
 TestBean [3] = 2 
 TestBean [4] = 7 
 TestBean [5] = 3 
 TestBean [ [7] = 3 
 TestBean [8] = 7 
 TestBean [9] = 3 
 
匹配值：0 
在bean中找到匹配2 
在bean中找到的匹配6 
  

显然增加TestBean数组大小将增加匹配的机会。 p>

您需要将以下jars文件导入到您的项目：commons-logging- version .jar，commons-beanutils- > .jar，commons-beanutils-core- version .jar，commons-beanutils-bean-collections- version .jar，commons-collections- em> .jar。

这些文件包含在 commons-logging ， commons-beanutils 和 commons-collections API。

Does anyone know about a free open source library (utility class) which allows you to compare two instances of one Java bean and return a list/array of properties which values are different in those two instances? Please post a small sample.

Cheers
Tomas

解决方案

BeanComparator of Apache commons is what you are looking for.

Update. A simple example that compares JavaBeans with one property (comparation is made agains only one property, you should create as many BeanComparators as properties you want to match).

import org.apache.commons.beanutils.BeanComparator;

public class TestBeanComparator
{
    public TestBeanComparator()
    {
    }

    public class TestBean
    {
        int value;

        public TestBean()
        {
        }

        public int getValue()
        {
            return value;
        }

        public void setValue(int value)
        {
            this.value = value;
        }
    }

    public static void main(String[] args)
    {
        TestBeanComparator tbc = new TestBeanComparator();

        tbc.go();
    }

    public void go()
    {
        TestBean tbs [] = new TestBean[10];

        for (int i = 0; i < tbs.length; i++)
        {
            tbs[i] = new TestBeanComparator.TestBean();
            tbs[i].setValue((int) (Math.random() * 10));

            System.out.println("TestBean["+i+"] = " + tbs[i].getValue());
        }

        BeanComparator bc = new BeanComparator("value");

        System.out.println("");
        System.out.println("Value to match: " + tbs[0].getValue());
        for (int i = 1; i < tbs.length; i++)
        {
            if(bc.compare(tbs[i], tbs[0]) == 0)
            {
               System.out.println("Match found in bean "+ i); 
            }
        }
    }
}

After some tests one result is successful. This is the output:

TestBean[0] = 0
TestBean[1] = 4
TestBean[2] = 0
TestBean[3] = 2
TestBean[4] = 7
TestBean[5] = 3
TestBean[6] = 0
TestBean[7] = 3
TestBean[8] = 7
TestBean[9] = 3

Value to match: 0
Match found in bean 2
Match found in bean 6

Obviously increasing TestBean array size will increase the chances to get matches.

You need to import to your project the following jars: commons-logging-version.jar, commons-beanutils-version.jar, commons-beanutils-core-version.jar, commons-beanutils-bean-collections-version.jar, commons-collections-version.jar.

The files are included inside commons-logging, commons-beanutils and commons-collections APIs.

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