利用动态代理实现类中属性的动态生成。

使用场景：当不确定返回类中字段个数时，可使用动态生成属性个数实现需求。

 注意：由于CGLib由于是采用动态创建子类的方法，对于final方法，无法进行代理。

1. 引入依赖

<dependency>    <groupId>cglibgroupId>    <artifactId>cglib-nodepartifactId>    <version>3.2.5version>dependency> <dependency>    <groupId>commons-beanutilsgroupId>    <artifactId>commons-beanutilsartifactId>    <version>1.9.3version>dependency><dependency>    <groupId>com.google.guavagroupId>    <artifactId>guavaartifactId>    <version>14.0version>dependency>

2、动态Bean

public class DynamicBean {    private Object target;    private BeanMap beanMap;    public DynamicBean(Class superclass, Map 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 propertyMap) {        BeanGenerator generator = new BeanGenerator();        if (null != superclass) {            generator.setSuperclass(superclass);        }        BeanGenerator.addProperties(generator, propertyMap);        return generator.create();    }}

3、动态工具类 ReflectUtil

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;    }}

4、测试 TEST

//测试类public class User {     String userName;     Integer userAge;}

@GetMapping("cglib")public ResultData cglib (){    User user = new User();    Map<String,Object> propertiesMap = new HashMap<String,Object>();    Map<String,Object> hashMap = new HashMap<String,Object>();    for (int i = 0; i < 5; i++) {        propertiesMap.put("activity"+i, "活动"+i);    }    Object obj = ReflectUtil.getObject(user, propertiesMap);    return new ResultData().setData(obj);}

返回结果

遇到情况：利用 System.out.println(); 打印结果不会显示，只能在调用返回结果时，才会显示动态添加了类属性。