找出两个java bean之间的差异，用于版本跟踪

java entity javabeans

2022-09-02 00:32:02

假设我有一个具有100个字段的java bean /一个实体（在这种情况下继承与否都不相关）。更新操作后 - 在事务中，我想确定修改了哪些字段以跟踪CVS之类的更新。最简单的方法是什么？任何框架建议？我应该创建此对象的两个实例并循环访问所有字段并匹配字段的值吗？在这种情况下，最佳等式方法看起来如何？以下 equals（）似乎很尴尬：

return (field1.equals(o.field1)) && 
(field2.equals(o.field2)) &&  
(field3.equals(o.field3)) &&  
...
(field100.equals(o.field100));

答案 1

你可以使用Apache Commons Beanutils。下面是一个简单的示例：

package at.percom.temp.zztests;

import java.lang.reflect.InvocationTargetException;
import org.apache.commons.beanutils.BeanMap;
import org.apache.commons.beanutils.PropertyUtilsBean;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Objects;
import java.util.Set;

public class Main {

    public static void main(String[] args) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
        Main main = new Main();
        main.start();
    }

    public void start() throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
        SampleBean oldSample = new SampleBean("John", "Doe", 1971);
        SampleBean newSample = new SampleBean("John X.", "Doe", 1971);

        SampleBean diffSample = (SampleBean) compareObjects(oldSample, newSample, new HashSet<>(Arrays.asList("lastName")), 10L);
    }

public Object compareObjects(Object oldObject, Object newObject, Set<String> propertyNamesToAvoid, Long deep) {
    return compareObjects(oldObject, newObject, propertyNamesToAvoid, deep, null);
}

private Object compareObjects(Object oldObject, Object newObject, Set<String> propertyNamesToAvoid, Long deep,
        String parentPropertyPath) {
    propertyNamesToAvoid = propertyNamesToAvoid != null ? propertyNamesToAvoid : new HashSet<>();
    parentPropertyPath = parentPropertyPath != null ? parentPropertyPath : "";

    Object diffObject = null;
    try {
        diffObject = oldObject.getClass().newInstance();
    } catch (Exception e) {
        return diffObject;
    }

    BeanMap map = new BeanMap(oldObject);

    PropertyUtilsBean propUtils = new PropertyUtilsBean();

    for (Object propNameObject : map.keySet()) {
        String propertyName = (String) propNameObject;
        String propertyPath = parentPropertyPath + propertyName;

        if (!propUtils.isWriteable(diffObject, propertyName) || !propUtils.isReadable(newObject, propertyName)
                || propertyNamesToAvoid.contains(propertyPath)) {
            continue;
        }

        Object property1 = null;
        try {
            property1 = propUtils.getProperty(oldObject, propertyName);
        } catch (Exception e) {
        }
        Object property2 = null;
        try {
            property2 = propUtils.getProperty(newObject, propertyName);
        } catch (Exception e) {
        }
        try {
            if (property1 != null && property2 != null && property1.getClass().getName().startsWith("com.racing.company")
                    && (deep == null || deep > 0)) {
                Object diffProperty = compareObjects(property1, property2, propertyNamesToAvoid,
                        deep != null ? deep - 1 : null, propertyPath + ".");
                propUtils.setProperty(diffObject, propertyName, diffProperty);
            } else {
                if (!Objects.deepEquals(property1, property2)) {
                    propUtils.setProperty(diffObject, propertyName, property2);
                    System.out.println("> " + propertyPath + " is different (oldValue=\"" + property1 + "\", newValue=\""
                            + property2 + "\")");
                } else {
                    System.out.println("  " + propertyPath + " is equal");
                }
            }
        } catch (Exception e) {
        }
    }

    return diffObject;
}

    public class SampleBean {

        public String firstName;
        public String lastName;
        public int yearOfBirth;

        public SampleBean(String firstName, String lastName, int yearOfBirth) {
            this.firstName = firstName;
            this.lastName = lastName;
            this.yearOfBirth = yearOfBirth;
        }

        public String getFirstName() {
            return firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public int getYearOfBirth() {
            return yearOfBirth;
        }
    }
}

答案 2

嘿，看看Javers，这正是你所需要的 - 对象审计和差异框架。使用Javers，您可以在每次更新后通过一次调用来保留对域对象所做的更改。当您保留某些更改时，您可以轻松地通过以下方式读取它们，例如javers.commit()javers.getChangeHistory

public static void main(String... args) {
    //get Javers instance
    Javers javers = JaversBuilder.javers().build();

    //create java bean
    User user = new User(1, "John");

    //commit current state
    javers.commit("author", user);

    //update operation
    user.setUserName("David");

    //commit change
    javers.commit("author", user);

    //read 100 last changes
    List<Change> changes = javers.getChangeHistory(instanceId(1, User.class), 100);

    //print change log
    System.out.printf(javers.processChangeList(changes, new SimpleTextChangeLog()));
}

输出为：

commit 2.0, author:author, 2015-01-07 23:00:10
  changed object: org.javers.demo.User/1
    value changed on 'userName' property: 'John' -> 'David'
commit 1.0, author:author, 2015-01-07 23:00:10
    new object: 'org.javers.demo.User/1