Java 内省

package cn.itcast.introspector;

import java.util.Date;

public class Student {
	private String name;  //字段
	private int age;
	private Date birthday;
	
	
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	public String getName() {//属性  name
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {  //age
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	
	public int getAbc(){  //abc
		return 10;
	}
}

package cn.itcast.introspector;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;

import org.junit.Test;

public class Demo1 {
	
	/*
	 * Introspector构建一个BeanInfo对象。
	 * BeanInfo将一个类的所有属性进行了封装
	 * //属性描述器
		PropertyDescriptor[] pds = bf.getPropertyDescriptors();
		
		PropertyDescriptor对象：
			 Method getReadMethod() 
          		获得应该用于读取属性值的方法。 
 			 Method getWriteMethod() 
          		获得应该用于写入属性值的方法。 

	 * */
	@Test
	public void test1() throws Exception{
		//将Student中的所有属性封装到BeanInfo对象中
		BeanInfo bf = Introspector.getBeanInfo(Student.class);
		//属性描述器
		PropertyDescriptor[] pds = bf.getPropertyDescriptors();
		
	//	System.out.println(pds.length);
		
		for (PropertyDescriptor pd : pds) {
			System.out.println(pd.getName());
		}
	}
	
	@Test
	public void test2() throws Exception{
		Student stu = new Student();
		//得到指定的属性对象
		PropertyDescriptor pd = new PropertyDescriptor("name", Student.class);
		Method setter = pd.getWriteMethod();//得到setter方法：setName()
		setter.invoke(stu, "tom");
		
		Method getter = pd.getReadMethod(); //得到getter方法：getName()
		System.out.println(getter.invoke(stu, null));
	}
	
	@Test
	public void test3() throws Exception{
		Student stu = new Student();
		//得到指定的属性对象
		PropertyDescriptor pd = new PropertyDescriptor("age", Student.class);
		Method setter = pd.getWriteMethod();//得到setter方法：setName()
		setter.invoke(stu, 18);
		
		Method getter = pd.getReadMethod(); //得到getter方法：getName()
		System.out.println(getter.invoke(stu, null));
	}
}

package cn.itcast.introspector;

import java.lang.reflect.InvocationTargetException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;
import org.apache.commons.beanutils.ConvertUtils;
import org.apache.commons.beanutils.Converter;
import org.apache.commons.beanutils.locale.converters.DateLocaleConverter;
import org.junit.Test;

public class Demo2 {
	@Test
	public void test1() throws Exception{
		Student stu = new Student();
		
		BeanUtils.setProperty(stu, "name", "张三"); //给属性赋值
		String s = BeanUtils.getProperty(stu, "name");
		
		System.out.println(s);
	}
	
	@Test
	public void test2() throws Exception{
		Student stu = new Student();
		//BeanUtils默认支持8种基本数据类型，自动转换
		BeanUtils.setProperty(stu, "age", "18"); //给属性赋值
		String s = BeanUtils.getProperty(stu, "age");
		
		System.out.println(s);
	}
	
	@Test
	public void test3() throws Exception{
		Student stu = new Student();
		//注册类型转换器
		ConvertUtils.register(new DateLocaleConverter(), Date.class);
		BeanUtils.setProperty(stu, "birthday", "1990-11-12"); //给属性赋值
		String s = BeanUtils.getProperty(stu, "birthday");
		
		System.out.println(s);
	}
	
	@Test
	public void test4() throws Exception{
		Student stu = new Student();
		//注册类型转换器
		ConvertUtils.register(new Converter() {
			
			public Object convert(Class type, Object value) {
				SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
				if(value instanceof String){
					String v = (String) value;
					try {
						return sdf.parse(v);
					} catch (ParseException e) {
						throw new RuntimeException(e);
					}
				}
				return null;
			}
		}, Date.class);
		
		BeanUtils.setProperty(stu, "birthday", "1995-11-12"); //给属性赋值
		String s = BeanUtils.getProperty(stu, "birthday");
		
		System.out.println(s);
	}
	
	@Test
	public void test5() throws Exception{
		//
		Map m = new HashMap();
		m.put("name", "张三"); //key名一定要与对象中的变量名一致
		m.put("age", "18"); //key名一定要与对象中的变量名一致
		m.put("birthday", "1992-05-12"); //key名一定要与对象中的变量名一致
		
		Student stu = new Student();
		
		ConvertUtils.register(new DateLocaleConverter(), Date.class);
		BeanUtils.populate(stu, m); //将Map属性自动放到Bean中
		
		System.out.println(stu.getName());
	}
	
	
}