用反射实现JavaBean和Map之间的转换

曾经终败给现在 2022-11-17 14:55 195阅读 0赞

# 学习内容： #

**需求**  
由于JavaBean结构与Map类似，我们可以把JavaBean与Map进行转换  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3p6dmFy_size_16_color_FFFFFF_t_70]

代码如下：

package com.yy;
    
    import java.beans.BeanInfo;
    import java.beans.IntrospectionException;
    import java.beans.Introspector;
    import java.beans.PropertyDescriptor;
    import java.lang.reflect.Constructor;
    import java.lang.reflect.InvocationTargetException;
    import java.lang.reflect.Method;
    import java.util.HashMap;
    import java.util.Map;
    
    /** * @author YanYang * @description: 采用单例模式实现 * @date 2021/4/10 13:12 */
    public class JavaBeanChangeMap { 
        private static final JavaBeanChangeMap javaBeanChangeMap = new JavaBeanChangeMap();
    
        private JavaBeanChangeMap() { 
        }
        public static JavaBeanChangeMap getInstance() { 
            return javaBeanChangeMap;
        }
    
        /** * JavaBean 转 Map */
        public <T> Map<String, Object> JavaBeanToMap(Class<T> t) throws IntrospectionException, InvocationTargetException, IllegalAccessException, InstantiationException, NoSuchMethodException { 
            // 1、创建 Map 集合
            Map<String, Object> map = new HashMap<>();
            // 2、通过内省机制获取 PropertyDescriptors 属性数组
            // Object.class
            PropertyDescriptor[] propertyDescriptors = Introspector.getBeanInfo(Person.class, Object.class)
                    .getPropertyDescriptors();
    
            Constructor<T> constructor = t.getConstructor(String.class, int.class);
            Object obj = constructor.newInstance("afa", 12);
            System.out.println("obj = " + obj);
            // 3、遍历该数组获取 Get 方法，获取属性名作为 key ，获取对象值作为 value
            for(PropertyDescriptor propertyDescriptor : propertyDescriptors) { 
                String name = propertyDescriptor.getName();
                Method readMethod = propertyDescriptor.getReadMethod();
                Object invoke = readMethod.invoke(obj);
                map.put(name, invoke);
            }
            return map;
        }
    
        /** * Map 转 JavaBean */
        public <T> T mapToJavaBean(Map map, Class<T> c) throws IllegalAccessException, InstantiationException, IntrospectionException, InvocationTargetException { 
            // 1、通过字节码对象创建空的实例
            T o =  c.newInstance();
            // 2、通过 Introspector 类把bean对象信息封装到 beanInfo 中
            BeanInfo beanInfo = Introspector.getBeanInfo(c, Object.class);
            // 3、通过 getPropertyDescriptors() 获取一个属性(get/set)数组
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            // 4、遍历该数组，把获取的名字作为 map 的 key，通过 key 取出对应的 value 值
            for (PropertyDescriptor propertyDescriptor : propertyDescriptors) { 
                String key = propertyDescriptor.getName();
                Object value = map.get(key);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o, value);
            }
            return o;
        }
    }

Junit测试代码：

package com.yy.test;
    
    import com.yy.JavaBeanChangeMap;
    import com.yy.Person;
    import org.junit.Test;
    
    import java.beans.IntrospectionException;
    import java.lang.reflect.InvocationTargetException;
    import java.util.HashMap;
    import java.util.Map;
    
    /** * @author YanYang * @description: 测试 * @date 2021/4/10 13:00 */
    public class JavaBeanChangeMapTest { 
        @Test
        public void testJavaBeanToMap() throws Exception { 
            Map<String, Object> map = JavaBeanChangeMap.getInstance().JavaBeanToMap(Person.class);
            System.out.println("map = " + map);
            System.out.println("================================");
        }
    
        @Test
        public void testMapToJavaBean() throws Exception { 
            Map map = new HashMap();
            map.put("name", "afa");
            map.put("age", 12);
            Person person = JavaBeanChangeMap.getInstance().mapToJavaBean(map, Person.class);
            System.out.println("person = " + person);
        }
    }

运行结果：

"C:\Program Files\Java\jdk-11.0.9\bin\java.exe"
    obj = Person{ name='afa', age=12}
    map = { name=afa, age=12}
    ================================
    person = Person{ name='afa', age=12}
    
    Process finished with exit code 0

# 总结： #

反射基础去请看我的上一篇博客：[上篇博客地址][Link 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3p6dmFy_size_16_color_FFFFFF_t_70]: /images/20221022/908536abed6e4fcab801df756603438b.png
[Link 1]: https://blog.csdn.net/zzvar/article/details/115582555