java可以通过反射机制获取类的各种信息和创建类的实例,就算将构造方法用private修饰,也可以创建,通过反射能创建很多强大的功能,算是写框架的常用方法和技巧
这里只介绍通过反射获取类的各种信息
实验类
package learn.reflect;
public class UserBean {
private Integer id;
private String usrname;
private String phone;
public UserBean(Integer id, String usrname, String phone) {
super();
this.id = id;
this.usrname = usrname;
this.phone = phone;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsrname() {
return usrname;
}
public void setUsrname(String usrname) {
this.usrname = usrname;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
}
启动类
package learn.reflect;
public class Main {
public static void main(String[] args) {
Class u = null;
try {
// 运行时加载以编译好的xxx.class文件,默认路径在classPath
u = Class.forName("learn.reflect.UserBean");
System.out.println("找到xxx.class文件");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 获取class后,能获取该类的一切信息进行判断或查看,有很多getxxx方法和isxxx方法
System.out.println("class文件和包路径: " + u.getName());
System.out.println(u.getComponentType());
System.out.println(u.getCanonicalName());
System.out.println(u.getModifiers());
System.out.println(u.getSimpleName());
System.out.println(u.getTypeName());
System.out.println(u.getAnnotatedInterfaces());
System.out.println(u.getAnnotatedSuperclass());
System.out.println(u.getAnnotations());
System.out.println(u.getConstructors());
System.out.println(u.getDeclaredAnnotations());
System.out.println(u.getFields());
System.out.println(u.getMethods());
System.out.println();
u.getMethods();
}
}