内省(Introspector) 是Java 语言对 JavaBean 类属性、事件的一种缺省处理方法
目的：主要用于传递数据信息，这种类中的方法主要用于访问私有的字段（且方法名符合某种命名规则）
package day02.introspector;
public class Person {
public String name;
public int age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getHigh() {
return high;
}
public void setHigh(String high) {
this.high = high;
}
public String high;
public int getAb() {
return age;
}
}
//使用内省操作bean的属性
package day02.introspector;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method; import org.junit.Test;
//使用内省操作bean的属性
public class Demo1 {
//得到bean的所有属性
@Test
public void Test() throws IntrospectionException{
BeanInfo info= Introspector.getBeanInfo(Person.class,Object.class);//拿到bean自己的属性
PropertyDescriptor[] psd=info.getPropertyDescriptors();//得到属性描述器
for(PropertyDescriptor pd:psd){
System.out.println(pd.getName());
}
} //操作bean的属性：age
@Test
public void Test2() throws IntrospectionException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
Person p=new Person();
PropertyDescriptor pd=new PropertyDescriptor("age",Person.class);
//得到属性的写方法，为属性赋值
Method method=pd.getWriteMethod();
method.invoke(p,23);
//获得属性值
method=pd.getReadMethod();
System.out.println(method.invoke(p, null));
// System.out.println(p.getAge());
} }
以上代码可以运行后体验下
//高级点的操作：bean的操作属性类型
@Test
public void Test3 () throws IntrospectionException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
Person p=new Person();
PropertyDescriptor pd=new PropertyDescriptor("age",Person.class);
System.out.println(pd.getPropertyType());
}
get set数据
注册日期转换器
@Test
public void test2() throws IllegalAccessException, InvocationTargetException {
String name = "aaaa";
String high = "232";
String age = "34";
String birthday = "1995-12-10";
// String today="1996-12-10";
// ConvertUtils.register(new DateLocaleConverter(), Date.class);//方法之二：有bug，不要用！
Person p = new Person();
// 为了让日期赋到bean的birthday的属性上。我们给beanuntils注册一个日期转换器
ConvertUtils.register(new Converter() {
@Override
public Object convert(Class arg0, Object value) {
if (value == null) {
return null;
}
if (!(value instanceof String)) {
System.out.println("no");
throw new ConversionException("只转String");
}
String str = (String) value;
if (str.trim().equals("")) {
return null;
}
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
try {
return df.parse(str);
} catch (ParseException e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);// 异常链不能断
}
}
}, Date.class);
BeanUtils.setProperty(p, "name", name);
BeanUtils.setProperty(p, "high", high);// 只支持8种基本类型自动转型
BeanUtils.setProperty(p, "age", age);// 只支持8种基本类型自动转型
BeanUtils.setProperty(p, "birthday", birthday);//通过转化器成功 System.out.println(p.getName());
System.out.println(p.getHigh());
System.out.println(p.getAge());
System.out.println(p.getBirthday());
// Date date=p.getToday();
// System.out.println(date.toLocaleString());
}
用map
//用map来添数据
@Test
public void test5() throws IllegalAccessException, InvocationTargetException{
Map map=new HashMap();
map.put("name", "aaaa");
map.put("high", "123");
map.put("age", "23");
map.put("birthday", "1995-12-10");
ConvertUtils.register(new DateLocaleConverter(), Date.class);
Person p=new Person();
BeanUtils.populate(p, map);
System.out.println(p.getName());
System.out.println(p.getHigh());
System.out.println(p.getAge());
System.out.println(p.getBirthday());
}