Java为实体类动态添加属性的方法详解-Java开发

这篇文章主要介绍了Java如何给已有实体类动态的添加字段并返回新的实体对象且不影响原来的实体对象结构。文中的方法讲解详细，需要的可以参考一下

添加依赖

        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>2.2.2</version>
        </dependency>

        <dependency>
            <groupId>commons-beanutils</groupId>
            <artifactId>commons-beanutils</artifactId>
            <version>1.9.4</version>
        </dependency>

代码

import com.google.common.collect.Maps;
import net.sf.cglib.beans.BeanGenerator;
import net.sf.cglib.beans.BeanMap;
import org.apache.commons.beanutils.PropertyUtilsBean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.beans.PropertyDescriptor;
import java.util.Map;

/**
 * 动态为bean添加字段
 * @Author gongl
 * @Create 2022-01-11
 */
public class DynamicBeanUtils {

    private static final Logger logger = LoggerFactory.getLogger(DynamicBeanUtils.class);

    public static Object getTarget(Object dest, Map<String, Object> addProperties) {
        PropertyUtilsBean propertyUtilsBean = new PropertyUtilsBean();
        //得到原对象的属性
        PropertyDescriptor[] descriptors = propertyUtilsBean.getPropertyDescriptors(dest);
        Map<String, Class<?>> propertyMap = Maps.newHashMap();
        for (PropertyDescriptor d : descriptors) {
            if (!"class".equalsIgnoreCase(d.getName())) {
                propertyMap.put(d.getName(), d.getPropertyType());
            }
        }
        addProperties.forEach((k, v) -> propertyMap.put(k, v.getClass()));
        //构建新的对象
        DynamicBean dynamicBean = new DynamicBean(dest.getClass(), propertyMap);
        for (Map.Entry<String, Class<?>> entry : propertyMap.entrySet()) {
            try {
                if (!addProperties.containsKey(entry.getKey())) {//原来的值
                    dynamicBean.setValue(entry.getKey(), propertyUtilsBean.getNestedProperty(dest, entry.getKey()));
                }else {//新增的值
                    dynamicBean.setValue(entry.getKey(), addProperties.get(entry.getKey()));
                }
            } catch (Exception e) {
                logger.error(e.getMessage(), e);
            }
        }
        return dynamicBean.getTarget();
    }

    private static class DynamicBean {
        /**
         * 目标对象
         */
        private Object target;

        /**
         * 属性集合
         */
        private BeanMap beanMap;

        public DynamicBean(Class<?> superclass, Map<String, Class<?>> propertyMap) {
            this.target = generateBean(superclass, propertyMap);
            this.beanMap = BeanMap.create(this.target);
        }


        /**
         * bean 添加属性和值
         *
         * @param property
         * @param value
         */
        public void setValue(String property, Object value) {
            beanMap.put(property, value);
        }

        /**
         * 获取属性值
         *
         * @param property
         * @return
         */
        public Object getValue(String property) {
            return beanMap.get(property);
        }

        /**
         * 获取对象
         *
         * @return
         */
        public Object getTarget() {
            return this.target;
        }


        /**
         * 根据属性生成对象
         *
         * @param superclass
         * @param propertyMap
         * @return
         */
        private Object generateBean(Class<?> superclass, Map<String, Class<?>> propertyMap) {
            BeanGenerator generator = new BeanGenerator();
            if (null != superclass) {
                generator.setSuperclass(superclass);
            }
            BeanGenerator.addProperties(generator, propertyMap);
            return generator.create();
        }
    }
}

测试

public static class TestBean{
        private String name;

        public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }
    }
    public static void main(String[] args) throws InvocationTargetException, IllegalAccessException {
        TestBean bean = new TestBean();
        bean.setName("张三");
        Map<String, Object> map = new HashMap<>();
        map.put("age", 29);
        //添加参数age--->29
        Object obj = DynamicBeanUtils.getTarget(bean, map);
        //打印结果
        Method[] declaredMethods = obj.getClass().getDeclaredMethods();
        for(Method method:declaredMethods){
            if(method.getName().startsWith("get")){
                Object o=method.invoke(obj);
                System.out.println("属性值get方法->"+o);
            }
        }
    }

结果打印出name和age的值