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groovy优势:自定义动态Bean

2022年07月19日124unruledboy

开发mongodb,json很方便,但有时又需要bean,为了不固定属性,需要动态的生成bean。下面两种方式都可以实现,供参考。

groovy自定义bean

Groovy中Expando类是一种动态Bean。我们可以Expando类的实例增加属性和闭包,当我们对一个简单的bean不想为其创建一个类,是非常有用的。

def user = new Expando(username: 'mrhaki') 
assert 'mrhaki' == user.username 
 
// Add an extra property. 
user.email = 'email@host.com' 
assert 'email@host.com' == user.email 
 
// Assign closure as method. The closure can 
// take parameters. 
user.printInfo = { writer -> 
    writer << "Username: $username" 
    writer << ", email: $email" 
} 
 
def sw = new StringWriter() 
user.printInfo(sw) 
assert 'Username: mrhaki, email: email@host.com' == sw.toString()

java利用cglib实现自定义bean

Java中要实现,利用cglib也可以实现:

public class CglibBean {
      
    /**  
      * 实体Object  
      */   
    public Object object = null;   
 
    /**  
      * 属性map  
      */   
    public BeanMap beanMap = null;   
 
    public CglibBean() {   
      super();   
    }   
 
    @SuppressWarnings("unchecked")   
    public CglibBean(Map propertyMap) {   
      this.object = generateBean(propertyMap);   
      this.beanMap = BeanMap.create(this.object);   
    }   
 
    /**  
      * 给bean属性赋值  
      * @param property 属性名  
      * @param value 值  
      */   
    public void setValue(String property, Object value) {   
      beanMap.put(property, value);   
    }   
 
    /**  
      * 通过属性名得到属性值  
      * @param property 属性名  
      * @return 值  
      */   
    public Object getValue(String property) {   
      return beanMap.get(property);   
    }   
 
    /**  
      * 得到该实体bean对象  
      * @return  
      */   
    public Object getObject() {   
      return this.object;   
    }   
 
    @SuppressWarnings("unchecked")   
    private Object generateBean(Map propertyMap) {   
      BeanGenerator generator = new BeanGenerator();   
      Set keySet = propertyMap.keySet();   
      for (Iterator i = keySet.iterator(); i.hasNext();) {   
       String key = (String) i.next();   
       generator.addProperty(key, (Class) propertyMap.get(key));   
      }   
      return generator.create();   
    }   
    }  

测试CglibBean

import java.lang.reflect.Method;   
import java.util.HashMap;   
 
/**  
 * Cglib测试类  
 * @author cuiran  
 * @version 1.0  
 */   
public class CglibTest {
      
 
 
 
    @SuppressWarnings("unchecked")   
    public static void main(String[] args) throws ClassNotFoundException {   
 
        // 设置类成员属性   
        HashMap propertyMap = new HashMap();   
 
        propertyMap.put("id", Class.forName("java.lang.Integer"));   
 
        propertyMap.put("name", Class.forName("java.lang.String"));   
 
        propertyMap.put("address", Class.forName("java.lang.String"));   
 
        // 生成动态 Bean   
        CglibBean bean = new CglibBean(propertyMap);   
 
        // 给 Bean 设置值   
        bean.setValue("id", new Integer(123));   
 
        bean.setValue("name", "454");   
 
        bean.setValue("address", "789");   
 
        // 从 Bean 中获取值,当然了获得值的类型是 Object   
 
        System.out.println("  >> id      = " + bean.getValue("id"));   
 
        System.out.println("  >> name    = " + bean.getValue("name"));   
 
        System.out.println("  >> address = " + bean.getValue("address"));   
 
        // 获得bean的实体   
        Object object = bean.getObject();   
 
        // 通过反射查看所有方法名   
        Class clazz = object.getClass();   
        Method[] methods = clazz.getDeclaredMethods();   
        for (int i = 0; i < methods.length; i++) {   
            System.out.println(methods[i].getName()); 
        }  

本文参考链接:https://blog.csdn.net/neweastsun/article/details/61414590