用反射实现JavaBean和Map之间的转换
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
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