java动态给实体类添加属性

 

需要的jar包有两个： cglib-3.1.jar 和 google-collections-1.0.jar 
如果是maven项目，就不需要cglib-3.1.jar，直接用spring自带的 org.springframework.cglib即可。 
1、创建一个实体：DynamicBean

 

public class DynamicBean { private Object target; private BeanMap beanMap; public DynamicBean(Class superclass, Map<String, Class> propertyMap) { this.target = generateBean(superclass, propertyMap); this.beanMap = BeanMap.create(this.target); } public void setValue(String property, Object value) { beanMap.put(property, value); } public Object getValue(String property) { return beanMap.get(property); } public Object getTarget() { return this.target; } /** * 根据属性生成对象 * */ 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(); } } 

 

2、创建映射类，用来生成动态bean

public class ReflectUtil { private static Logger logger = LoggerFactory.getLogger(ReflectUtil.class); public static Object getObject(Object dest, Map<String, Object> addProperties) { PropertyUtilsBean propertyUtilsBean = new PropertyUtilsBean(); 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) -> { String sclass = v.getClass().toString(); if(sclass.equals("class java.util.Date")) {//对日期进行处理 propertyMap.put(k, Long.class); }else { propertyMap.put(k, v.getClass()); } }); DynamicBean dynamicBean = new DynamicBean(dest.getClass(), propertyMap); propertyMap.forEach((k, v) -> { try { if (!addProperties.containsKey(k)) { dynamicBean.setValue(k, propertyUtilsBean.getNestedProperty(dest, k)); } } catch (Exception e) { logger.error("动态添加字段出错", e); } }); addProperties.forEach((k, v) -> { try { String sclass = v.getClass().toString(); if(sclass.equals("class java.util.Date")) {//动态添加的字段为date类型需要进行处理 Date date = (Date) v; dynamicBean.setValue(k, date.getTime()); }else { dynamicBean.setValue(k, v); } } catch (Exception e) { logger.error("动态添加字段值出错", e); } }); Object obj = dynamicBean.getTarget(); return obj; } } 

 

3、使用方法
现有一个用户实体User：

public class User { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } } 

 

User只有一个name属性，现在要动态的为User添加年龄属性，代码如下：

public static void main(String[] args) { User user = new User(); user.setName("Daisy"); System.out.println("User："+JSON.toJSONString(user)); Map<String,Object> propertiesMap = new HashMap<String,Object>(); propertiesMap.put("age", 18); Object obj = ReflectUtil.getTarget(user, propertiesMap); System.out.println("动态为User添加age之后，User："+JSON.toJSONString(obj)); }

 

打印结果如下：

User：{"name":"Daisy"} 动态为User添加age之后，User：{"age":18,"name":"Daisy"}