JAVA基础知识|反射

package com.my.po;/**
* description:{description}
* author:jyy
* date:2018-02-06 16:28
* modify:{modify}
*/
public interface InterFace {
void read();
}

package com.my.po;/**
* description:{description}
* author:jyy
* date:2018-02-03 13:20
* modify:{modify}
*/
public class Person implements InterFace { private String id; private String name; public String age; //构造函数1
public Person() { } //构造函数2
public Person(String id) {
this.id = id;
} //构造函数3
public Person(String id, String name) {
this.id = id;
this.name = name;
} public String getId() {
return id;
} public void setId(String id) {
this.id = id;
} public String getName() {
return name;
} public void setName(String name) {
this.name = name;
} public String getAge() {
return age;
} public void setAge(String age) {
this.age = age;
} /**
* 静态方法
*/
public static void update() { } @Override
public void read() { }
}

//第一种方法：forName
try {
Class<?> class1 = Class.forName("com.my.po.Person");
System.out.println( class1 );
} catch (ClassNotFoundException e) {
e.printStackTrace();
} //第二张方法：class
Class<?> class2 = Person.class;
System.out.println( class2 ); //第三种方法：getClass
Person person = new Person();
Class<?> class3 = person.getClass(); System.out.println( class3 );

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //getMethods()获取当前类及其父类所有的public方法
Method[] methods1 = class1.getMethods();
for (Method method : methods1) {
System.out.println(method);
}
System.out.println("=================="); //getDeclaredMethods()获取当前类所有的方法，包括private、protected修饰的方法，但不可以获取父类的方法
Method[] methods2 = class1.getDeclaredMethods();
for (Method method : methods2) {
System.out.println(method);
} } catch (ClassNotFoundException e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //获取所有的接口
Class<?>[] interfaces = class1.getInterfaces(); for (Class<?> class2 : interfaces) {
System.out.println(class2);
} } catch (ClassNotFoundException e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //获取父类
Class<?> superClass = class1.getSuperclass(); System.out.println(superClass); } catch (ClassNotFoundException e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //getConstructors()获取当前类所有的公有构造器
Constructor<?>[] constructors1 = class1.getConstructors() ; for (Constructor<?> constructor : constructors1) {
System.out.println( constructor );
}
System.out.println("================");
//getDeclaredConstructors获取当前类所有的构造器，不包括父类构造器
Constructor<?>[] constructors2 = class1.getDeclaredConstructors() ;
for (Constructor<?> constructor : constructors2) {
System.out.println( constructor );
} } catch (ClassNotFoundException e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //getDeclaredFields()取得当前类的全部属性，包括private、protected修饰的属性
Field[] field1 = class1.getDeclaredFields(); for (Field field : field1) {
System.out.println( field );
} System.out.println("=================="); //getFields()取得当前类和父类所有public修饰的属性
Field[] field2 = class1.getFields(); for (Field field : field2) {
System.out.println( field );
} } catch (ClassNotFoundException e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //创建实例化：相当于 new 了一个对象
Object object = class1.newInstance(); //向下转型
Person person;
if (object instanceof Person) {
person = (Person) object;
person.setAge("20");
System.out.println(person.getAge());
} } catch (Exception e) {
e.printStackTrace();
}

try {
//创建类
Class<?> class1 = Class.forName("com.my.po.Person"); //创建实例
Object obj = class1.newInstance();
Person person;
if (obj instanceof Person) {
person = (Person) obj;
} else {
person = null;
} //给id,name,age赋值
Field idField = class1.getDeclaredField("id");
idField.setAccessible(true);//打破私有属性封装
idField.set(person, "1001");
Field nameField = class1.getDeclaredField("name");
nameField.setAccessible(true);//打破私有属性封装
nameField.set(person, "李明");
Field ageField = class1.getDeclaredField("age");
ageField.setAccessible(true);//打破私有属性封装
ageField.set(person, "30"); //通过执行方法给id,name,age赋值
Method setNameMethod = class1.getDeclaredMethod("setName", String.class);
setNameMethod.invoke(person, "王立"); //查询属性值
String id = (String) idField.get(person);
System.out.println(id);
String name = (String) nameField.get(person);
System.out.println(name); } catch (Exception e) {
e.printStackTrace();
}

public class Bird { public void fly() {
System.out.println("小鸟正在飞");
}
}
public class Dragonfly { public void fly() {
System.out.println("蜻蜓正在飞");
}
}

try {
//读取配置文件
ResourceBundle resource = ResourceBundle.getBundle("configure");
String className = resource.getString("animal.forclass");
String methodName = resource.getString("animal.method"); //获取类
Class<?> class1 = Class.forName(className);
//根据方法名称，获取方法对象
Method m = class1.getMethod(methodName);
//获取构造器
Constructor<?> constructor = class1.getDeclaredConstructor();
//根据构造器，实例化出对象
Object obj = constructor.newInstance();
//调用对象的指定方法
m.invoke(obj); } catch (Exception e) {
e.printStackTrace();
}