1.反射
person.java
package zh.javaBean.demo;
public class Person {
private String name;
private int age;
public Person() {
}
public Person(String name, int age) {
this.name = name;
this.age = 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;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
ClassDemo.java
package zh.javaBean.demo;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import org.junit.Test;
/**
* 反射
*
* @author ZH
*
*/
public class ClassDemo {
@Test
public void test1() throws Exception {
Class<?> clazz = Class.forName("zh.javaBean.demo.Person");
// 使用无参构方法数创建对象，要求类具有无参构造方法
Person person = (Person) clazz.newInstance();
System.out.println(person);// Person [name=null, age=0]
// 获取私有属性，再设置访问权限，最后修改属性值
Field nameField = clazz.getDeclaredField("name");
nameField.setAccessible(true);
nameField.set(person, "小龙女");
Field ageField = clazz.getDeclaredField("age");
ageField.setAccessible(true);
ageField.set(person, 18);
System.out.println(person);// Person [name=小龙女, age=18]
}
@Test
public void test2() throws Exception {
Class<?> clazz = Class.forName("zh.javaBean.demo.Person");
// 获取无参构造方法
Constructor<?> NoParamCons = clazz.getConstructor(null);
Person person1 = (Person) NoParamCons.newInstance(null);
// 获取指定带参构造方法
Constructor<?> paramCons = clazz
.getConstructor(String.class, int.class);
Person person2 = (Person) paramCons.newInstance("小龙女", 19);
// 获取指定方法
Method toStringMethed = clazz.getMethod("toString", null);
// 调用不同对象的方法
String result1 = (String) toStringMethed.invoke(person1, null);
String result2 = (String) toStringMethed.invoke(person2, null);
System.out.println(result1);//Person [name=null, age=0]
System.out.println(result2);//Person [name=小龙女, age=19]
}
}
2.内省
person.java
package zh.javaBean.demo;
public class Person {
private String name;
private int age;
public Person() {
}
public Person(String name, int age) {
this.name = name;
this.age = 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;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
IntrospectorDemo.java
package zh.javaBean.demo;
import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import org.junit.Test;
/**
* 内省
*
* @author ZH
*
*/
public class IntrospectorDemo {
@Test
public void test1() throws Exception {
Person person = new Person("姬如雪", 20);
// 获取BeanInfo
BeanInfo beanInfo = Introspector.getBeanInfo(person.getClass());
// 获取属性描述器
PropertyDescriptor[] propertyDescriptors = beanInfo
.getPropertyDescriptors();
for (PropertyDescriptor descriptor : propertyDescriptors) {
System.out.println(descriptor.getName() + ","
+ descriptor.getPropertyType());
}
}
@Test
public void test2() throws Exception {
Person person = new Person("姬如雪", 20);
System.out.println(person);// Person [name=姬如雪, age=20]
// 获取name的属性描述器
PropertyDescriptor pd1 = new PropertyDescriptor("name",
person.getClass());
// 获取属性的写方法
Method writeMethod = pd1.getWriteMethod();
writeMethod.invoke(person, "雪儿");
System.out.println(person);// Person [name=雪儿, age=20]
// 获取属性描述器
PropertyDescriptor pd2 = new PropertyDescriptor("age",
person.getClass());
// 获取属性的读方法
Method readMethod = pd2.getReadMethod();
Integer age = (Integer) readMethod.invoke(person, null);
System.out.println(age);// 20
}
}
3.BeanUtils
导入beanUtils.jar和logging.jar
person.java
package zh.javaBean.demo;
public class Person {
private String name;
private int age;
public Person() {
}
public Person(String name, int age) {
this.name = name;
this.age = 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;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
BeanUtilsDemo.java
package zh.javaBean.demo;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.beanutils.BeanUtils;
public class BeanUtilsDemo {
public static void main(String[] args) throws Exception {
Person person = new Person("小仙女", 21);
// 获取属性
String name = BeanUtils.getProperty(person, "name");
String ageString = BeanUtils.getProperty(person, "age");
int age = Integer.parseInt(ageString);
System.out.println(name + "," + age);// 小仙女,21
// 设置属性
BeanUtils.setProperty(person, "name", "慕容仙");
BeanUtils.setProperty(person, "age", 22);
System.out.println(person);// Person [name=慕容仙, age=22]
// 和Map集合一起使用
Person p = new Person();
Map<String, String> map = new HashMap<String, String>();
map.put("name", "小鱼儿");
map.put("age", "23");
// 为属性赋值
BeanUtils.populate(p, map);
System.out.println(p);// Person [name=小鱼儿, age=23]
}
}