新建类User:
package entity;
public class User {
private String username;
private String sex;
private String age;
public User(){
}
public User(String age) {
this.age = age;
}
private User(String username,String sex){
this.username = username;
this.sex = sex;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public void sysPrintUserNameSex(String username,String sex){
System.out.println("调用公有方法sysPrintUserNameSex：username=" + username + ";sex=" + sex);
}
private void sysPrintUserName(String username,String age){
System.out.println("调用私有方法sysPrintUserName：username=" + username + ";age=" + age);
}
private static void getInfo(String username){
System.out.println("私有的一个参数的静态方法getInfo：" + username);
}
private static void getInfo(String username,String sex){
System.out.println("私有的多个参数的静态方法getInfo：username=" + username + ";sex=" + sex);
}
public static void pubGetInfo(String username){
System.out.println("公有的一个参数的静态方法pubGetInfo：" + username);
}
public static void pubGetInfo(String username,String sex){
System.out.println("公有的多个参数的静态方法getInfo：username=" + username + ";sex=" + sex);
}
@Override
public String toString() {
return "User{" +
"username='" + username + '\'' +
", sex='" + sex + '\'' +
", age='" + age + '\'' +
'}';
}
}
新建接口 Mapper , Mapper2
package dao;
public interface Mapper {
void connectionJDBC();
}
package dao;
public interface Mapper2 {
void connectionJDBC1();
}
接口实现类
package impl;
import dao.Mapper;
import dao.Mapper2;
public class UserMapperImpl implements Mapper, Mapper2 {
//连接数据库方法
@Override
public void connectionJDBC(){
System.out.println("Mapper进行数据库操作 CURD");
}
@Override
public void connectionJDBC1() {
System.out.println("Mapper2进行数据库操作 CURD");
}
}
Java反射方法Demo示例
import entity.User;
import impl.UserMapperImpl;
import java.lang.reflect.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ReflectDemo {
public static void main(String[] args) {
//获取类对象的三种方法
//1.Class.forName("全路径（包名+类名）");
//2.使用.class ,需要导入类包（import）
//3.使用getClass()获取类对象
try {
/**
* .class 获取类对象（常用）:
* Class<User> clazz = User.class;
*/
/**
* getClass() 方法获取类对象:
* Class<? extends User> clazz = new User().getClass();
*/
//Class.forName方式获取类对象(常用)
Class<?> clazz = Class.forName("entity.User");
//********************获取/全名 /类名 /包名************************
System.out.println("全名：" + clazz.getName() + ";包名:" + clazz.getPackage() + ";类名：" + clazz.getSimpleName());
//********************获取所有的公共的构造方法*************************
Constructor<?>[] constructors = clazz.getConstructors();
List<Constructor<?>> constructors1 = Arrays.asList(constructors);
System.out.println("所有的公共构造方法:" + constructors1);
//********************获取所有的构造方法(公有 + 私有)*************************
Constructor<?>[] declaredConstructors = clazz.getDeclaredConstructors();
List<Constructor<?>> constructors2 = Arrays.asList(declaredConstructors);
System.out.println("所有的构造方法(公有 + 私有):" + constructors2);
//********************根据参数类型获取公共的构造方法*************************
Constructor<?> constructor1 = clazz.getConstructor(String.class);
Object o1 = constructor1.newInstance("根据参数类型获取公共的构造方法创建的实例");
System.out.println(o1);
System.out.println("根据参数类型获取公共的构造方法:" + constructor1);
System.out.println("构造方法类型：" + Modifier.toString(constructor1.getModifiers()));
//********************根据参数类型获取所有的构造方法*************************
Constructor<?> declaredConstructor = clazz.getDeclaredConstructor(String.class, String.class);
declaredConstructor.setAccessible(true);
Object o2 = declaredConstructor.newInstance("私有构造方法实例", "私有构造方法实例");
System.out.println(o2);
System.out.println("根据参数类型获取所有的构造方法(公共+私有):" + declaredConstructor);
System.out.println("构造方法类型：" + Modifier.toString(declaredConstructor.getModifiers()));
//*********************获取公共的无参构造方法************************
Constructor<?> constructor = clazz.getConstructor();
//*********************根据无参构造方法创建类实例*************************
Object user = constructor.newInstance();
//*********************根据方法名称和参数类型获取公共方法*********************************
Method sysPrintUserNameSexMethod = clazz.getMethod("sysPrintUserNameSex",new Class[]{String.class,String.class});
sysPrintUserNameSexMethod.invoke(user,"李四","男");
System.out.println("方法类型：" + Modifier.toString(sysPrintUserNameSexMethod.getModifiers()));
System.out.println("方法所属类：" + sysPrintUserNameSexMethod.getDeclaringClass());
//*********************根据方法名称和参数类型获取指定的类成员方法（公共私有都可获取）**************************
Method method = clazz.getDeclaredMethod("sysPrintUserName", new Class[]{String.class,String.class});
//暴力访问 private方法 private方法需要设置setAccessible（true）为true的条件下才可访问
method.setAccessible(true);
method.invoke(user,"张三","21");
System.out.println("方法类型：" + Modifier.toString(method.getModifiers()));
//*****************根据方法名获取公有的静态方法****************
Method pubGetInfo = clazz.getMethod("pubGetInfo", String.class);
pubGetInfo.invoke(user,"王五");
System.out.println("方法类型：" + Modifier.toString(pubGetInfo.getModifiers()));
//*****************根据方法名获取多个参数公有的静态方法****************
Method overWritePubGetInfo = clazz.getDeclaredMethod("pubGetInfo", new Class[]{String.class,String.class});
overWritePubGetInfo.invoke(user,"王五","15");
System.out.println("方法类型：" + Modifier.toString(overWritePubGetInfo.getModifiers()));
//*****************根据方法名获取私有的静态方法****************
Method getInfo = clazz.getDeclaredMethod("getInfo", String.class);
getInfo.setAccessible(true);
getInfo.invoke(user,"王五");
//*****************根据方法名获取多个参数私有的静态方法****************
Method overWriteGetInfo = clazz.getDeclaredMethod("getInfo", new Class[]{String.class,String.class});
overWriteGetInfo.setAccessible(true);
overWriteGetInfo.invoke(user,"王五","15");
//*****************获取类的私有字段并修改值******************************
Field field = clazz.getDeclaredField("sex");
field.setAccessible(true);
System.out.println("字段所属类：" + field.getDeclaringClass());
//*********************获取的值********************************
Object o = field.get(o2);
System.out.println("通过反射获取username的值：" + o);
//*********************设置sex的值********************************
User user1 = (User) o2;
field.set(user1,"ABC");
System.out.println(user1.getSex());
//***************获取类实现的接口****************************
Class<?>[] interfaces = UserMapperImpl.class.getInterfaces();
List<Class<?>> classes = Arrays.asList(interfaces);
System.out.println("实现的接口：" + classes);
//***************获取第一个实现的接口***************************
Class<?> anInterface = UserMapperImpl.class.getInterfaces()[0];
System.out.println("实现的第一个接口：" + anInterface);
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InstantiationException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
}
}
}
执行结果
"C:\Program Files\Java\jdk1.8.0_152\bin\java.exe" "-javaagent:E:\IntelliJ IDEA 2020.1.2\lib\idea_rt.jar=56672:E:\IntelliJ IDEA 2020.1.2\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_152\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_152\jre\lib\rt.jar;D:\JavaStudy\out\production\JavaStudy" ReflectDemo
全名：entity.User;包名:package entity;类名：User
所有的公共构造方法:[public entity.User(java.lang.String), public entity.User()]
所有的构造方法(公有 + 私有):[private entity.User(java.lang.String,java.lang.String), public entity.User(java.lang.String), public entity.User()]
User{username='null', sex='null', age='根据参数类型获取公共的构造方法创建的实例'}
根据参数类型获取公共的构造方法:public entity.User(java.lang.String)
构造方法类型：public
User{username='私有构造方法实例', sex='私有构造方法实例', age='null'}
根据参数类型获取所有的构造方法(公共+私有):private entity.User(java.lang.String,java.lang.String)
构造方法类型：private
调用公有方法sysPrintUserNameSex：username=李四;sex=男
方法类型：public
方法所属类：class entity.User
调用私有方法sysPrintUserName：username=张三;age=21
方法类型：private
公有的一个参数的静态方法pubGetInfo：王五
方法类型：public static
公有的多个参数的静态方法getInfo：username=王五;sex=15
方法类型：public static
私有的一个参数的静态方法getInfo：王五
私有的多个参数的静态方法getInfo：username=王五;sex=15
字段所属类：class entity.User
通过反射获取username的值：私有构造方法实例
ABC
实现的接口：[interface dao.Mapper, interface dao.Mapper2]
实现的第一个接口：interface dao.Mapper
Process finished with exit code 0
网友评论