java|java 如何复制非空对象属性值 java如何复制非空对象属性值

java 复制非空对象属性值

然后封装一下得到以下方法
测试方法就不提供了，自行测试即可

java对象属性复制的几种方式

1.使用java反射机制
2.使用spring-beans5.0.8包中的BeanUtils类
3.使用cglib3.2.8包中的net.sf.cglib.beans.BeanCopier类
4.使用spring-core5.0.8包

java 复制非空对象属性值很多时候，我们需要通过对象拷贝，比如说VO类与数据库实体bean类、更新时非空对象不更新，对同一对象不同数据分开存储等
用于对象拷贝，spring 和 Apache都提供了相应的工具类方法，BeanUtils.copyProperties
但是对于非空属性拷贝就需要自己处理了
在这里借用spring中org.springframework.beans.BeanUtils类提供的方法

copyProperties(Object source, Object target, String... ignoreProperties)

/*** Copy the property values of the given source bean into the given target bean,* ignoring the given "ignoreProperties".* Note: The source and target classes do not have to match or even be derived* from each other, as long as the properties match. Any bean properties that the* source bean exposes but the target bean does not will silently be ignored.* This is just a convenience method. For more complex transfer needs,* consider using a full BeanWrapper.* @param source the source bean* @param target the target bean* @param ignoreProperties array of property names to ignore* @throws BeansException if the copying failed* @see BeanWrapper*/public static void copyProperties(Object source, Object target, String... ignoreProperties) throws BeansException {copyProperties(source, target, null, ignoreProperties); /*** Copy the property values of the given source bean into the given target bean.* Note: The source and target classes do not have to match or even be derived* from each other, as long as the properties match. Any bean properties that the* source bean exposes but the target bean does not will silently be ignored.* @param source the source bean* @param target the target bean* @param editable the class (or interface) to restrict property setting to* @param ignoreProperties array of property names to ignore* @throws BeansException if the copying failed* @see BeanWrapper*/private static void copyProperties(Object source, Object target, Class editable, String... ignoreProperties)throws BeansException { Assert.notNull(source, "Source must not be null"); Assert.notNull(target, "Target must not be null"); Class actualEditable = target.getClass(); if (editable != null) {if (!editable.isInstance(target)) {throw new IllegalArgumentException("Target class [" + target.getClass().getName() +"] not assignable to Editable class [" + editable.getName() + "]"); }actualEditable = editable; }PropertyDescriptor[] targetPds = getPropertyDescriptors(actualEditable); List ignoreList = (ignoreProperties != null ? Arrays.asList(ignoreProperties) : null); for (PropertyDescriptor targetPd : targetPds) {Method writeMethod = targetPd.getWriteMethod(); if (writeMethod != null && (ignoreList == null || !ignoreList.contains(targetPd.getName()))) {PropertyDescriptor sourcePd = getPropertyDescriptor(source.getClass(), targetPd.getName()); if (sourcePd != null) {Method readMethod = sourcePd.getReadMethod(); if (readMethod != null &&ClassUtils.isAssignable(writeMethod.getParameterTypes()[0], readMethod.getReturnType())) {try {if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers())) {readMethod.setAccessible(true); }Object value = https://www.it610.com/article/readMethod.invoke(source); if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers())) {writeMethod.setAccessible(true); }writeMethod.invoke(target, value); }catch (Throwable ex) {throw new FatalBeanException("Could not copy property '" + targetPd.getName() + "' from source to target", ex); }}}}}}

然后封装一下得到以下方法

/*** @author zml2015* @Email zhengmingliang911@gmail.com* @Time 2017年2月14日下午5:14:25* @Description 获取到对象中属性为null的属性名
* @param source 要拷贝的对象* @return*/public static String[] getNullPropertyNames(Object source) {final BeanWrapper src = https://www.it610.com/article/new BeanWrapperImpl(source); java.beans.PropertyDescriptor[] pds = src.getPropertyDescriptors(); Set emptyNames = new HashSet(); for (java.beans.PropertyDescriptor pd : pds) {Object srcValue = src.getPropertyValue(pd.getName()); if (srcValue == null)emptyNames.add(pd.getName()); }String[] result = new String[emptyNames.size()]; return emptyNames.toArray(result); } /*** @author zml2015* @Email zhengmingliang911@gmail.com* @Time 2017年2月14日下午5:15:30* @Description 【java|java 如何复制非空对象属性值】 拷贝非空对象属性值
* @param source 源对象* @param target 目标对象*/public static void copyPropertiesIgnoreNull(Object source, Object target) {BeanUtils.copyProperties(source, target, getNullPropertyNames(source)); }

测试方法就不提供了，自行测试即可
如果项目中使用的框架有Hibernate的话，则可以通过在实体类上添加下面两条注解

@DynamicInsert(true)@DynamicUpdate(true)

如果想对该注解进一步了解的话，那么可以去官网看英文文档，文档解释的很清楚，在此不再赘述了

java对象属性复制的几种方式
1.使用java反射机制
获取对象的属性和get、set方法进行复制；

2.使用spring-beans5.0.8包中的BeanUtils类

import org.springframework.beans.BeanUtils; SourceObject sourceObject = new SourceObject(); TargetObject targetObject = new TargetObject(); BeanUtils.copyProperties(sourceObject, targetObject);

3.使用cglib3.2.8包中的net.sf.cglib.beans.BeanCopier类

import net.sf.cglib.beans.BeanCopier; import net.sf.cglib.core.Converter; SourceObject sourceObject = new SourceObject(); TargetObject targetObject = new TargetObject(); BeanCopier beanCopier = BeanCopier.create(SourceObject.class, TargetObject.class, true); --第三个参数表示是否使用转换器，false表示不使用，true表示使用Converter converter = new CopyConverter(); --自定义转换器beanCopier.copy(sourceObject, targetObject, converter);

转换器(当源对象属性类型与目标对象属性类型不一致时，使用转换器)：

import net.sf.cglib.core.Converter; import org.apache.commons.lang3.StringUtils; import java.math.BigDecimal; import java.util.Date; /** * Created by asus on 2019/7/12. */public class CopyConverter implements Converter {@Overridepublic Object convert(Object value, Class target, Object context) {{String s = value.toString(); if (target.equals(int.class) || target.equals(Integer.class)) {return Integer.parseInt(s); }if (target.equals(long.class) || target.equals(Long.class)) {return Long.parseLong(s); }if (target.equals(float.class) || target.equals(Float.class)) {return Float.parseFloat(s); }if (target.equals(double.class) || target.equals(Double.class)) {return Double.parseDouble(s); }if(target.equals(Date.class)){while(s.indexOf("-")>0){s = s.replace("-", "/"); }returnnew Date(s); }if(target.equals(BigDecimal.class)){if(!StringUtils.isEmpty(s)&&!s.equals("NaN")){returnnew BigDecimal(s); }}return value ; }}}

4.使用spring-core5.0.8包
中的org.springframework.cglib.beans.BeanCopier类（用法与第三种一样）

import org.springframework.cglib.beans.BeanCopier; import org.springframework.cglib.core.Converter; SourceObject sourceObject = new SourceObject(); TargetObject targetObject = new TargetObject(); Converter converter = new SpringCopyConverter(); BeanCopier beanCopier = BeanCopier.create(SourceObject.class, TargetObject.class, true); beanCopier.copy(sourceObject, targetObject, converter);

经过循环复制测试(源对象与目标对象各160个属性)：