Spring IoC注入方式(设置注入\构造注入+p命名空间注入)+单例模式+对象声明周期+反射方式复制对象

本文链接：https://blog.youkuaiyun.com/crazyo2jam/article/details/99313660

首先我们要有一个实体类,属性都以包装类命名(int写成Integer),设置注入必有set\get访问器,构造注入必有构造方法,

public class Student {
     Integer id;
     String  name;
     Integer age;
     Boolean sex;
     Date    Brithday;
     
	public Student() {
		super();
	}
	public Student(Integer id, String name, Integer age, Boolean sex, Date brithday) {
		super();
		this.id = id;
		this.name = name;
		this.age = age;
		this.sex = sex;
		Brithday = brithday;
	}
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
//其他属性构造方法......

------------------设置注入--------------------------

{
  
   <bean id="stu" class="emtity.Student"> 
       <property name="id" value="15"></property>
       <property name="name" value="小明"></property>
       <property name="age"   value="19"></property>
       <property name="brithday" value="1999-12-12"></property>
   </bean>//基本类型赋值
   
   <bean  id="userdao" class="dao.UserDaolmpl"> </bean>
   <bean id="userservice" class="service.UserServicelmpl"> 
      	 <property name="student"  ref="stu"></property>
   </bean>//把上面id="stu"赋值后的对象赋值给 id="userservice"类内为name="student"属性
}

------------------构造注入--------------------------

 <bean id="stu2" class="emtity.Student">
    <constructor-arg index="0" value="1"/>
    <constructor-arg index="1" value="小明"/>
    <constructor-arg index="2" value="15"/>
    <constructor-arg index="3" value="true"/>
    <constructor-arg index="4" value="1999-12-12"/>
 </bean>
 一个constructor-arg 相当于一个属性  index为参数下标 value为值  type可以设置类型(用的不多)

------------------p命名空间注入--------------------------

 <bean id="stu3" class="emtity.Student" p:id="2" p:name="小张" p:age="20"></bean>
 <bean id="userservice" class="service.UserServicelmpl" p:dao-ref="stu3"></bean>  
  xmlns:p="http://www.springframework.org/schema/p"   //在头部添加一句话

------------------集合赋值--------------------------

list\set\map\Properties\Arrays赋值方法

 <bean id="stu4" class="emtity.Student">
      <property name="list">
      		<list>
      		     <value>List1</value>
      		     <value>List2</value>
      		     <ref bean="stu"/>
      		</list>
      </property>
      
      <property name="set">
      		<set>
      		    <value>set1</value>
      		    <value>set2</value>
      		    <ref bean="stu"/>
      		</set>
      </property>
      
      <property name="str">
      		<array>
      			<value>Array1</value>
      			<value>Array2</value>
      		</array>
      </property>
      
      <property name="map">
      		<map>
      			<entry  key="001" value="张三"></entry>
      			<entry  key="002" value="张四"></entry>
      			<entry  key="003" value-ref="stu"></entry>
      		</map>
      </property>
      
      <property name="props">
            <props>
                <prop key="004">张五</prop>
                <prop key="005">张六</prop>
            </props>
      </property>
      
 </bean>

------------------单例模式--------------------------

在Spring框架内创建的对象默认为单例模式,运行过程中只要是同一id的对象操作的都是一对象
在bean标签内添加 scope=“prototype”,解放单例模式,每次拿到的对象都是不同的

      <bean id="stu" class="emtity.Student">
		Student stu=(Student)factory.getBean("stu");
		Student stu2=(Student)factory.getBean("stu2");
		System.out.println(stu==stu2);//结果为true

      <bean id="stu" class="emtity.Student"  scope="prototype"> 
		Student stu=(Student)factory.getBean("stu");
		Student stu2=(Student)factory.getBean("stu2");
		System.out.println(stu==stu2);//结果为false

------------------对象声明周期--------------------------

对象创建后不会主动的销毁,想在创建调用后销毁则在bean标签内的init-method="" destroy-method=""为创建前执行,销毁前执行,ConfigurableApplicationContext类创建对象,最后使用registerShutdownHook();方法销毁

    ----- entity.Student类
		public void init() {
			System.out.println("init");
		}
		public void destroy() {
			System.out.println("destroy");
		}
    ----- ApplicationContext.xml
     <bean id="stu" class="emtity.Student" init-method="init" destroy-method="destroy"> 
       <property name="id" value="15"></property>
       <property name="name" value="小明"></property>
       <property name="age"   value="19"></property>
       <property name="brithday" value="1999-12-12"></property>
     </bean>
     -----test测试类  
     	BeanFactory factory=new ClassPathXmlApplicationContext("ApplicationContext.xml");
		Student stu=(Student)factory.getBean("stu");
		System.out.println(stu.getName());
		输出  init > 小明
        -----销毁对象使用
       ConfigurableApplicationContext factory=new ClassPathXmlApplicationContext("ApplicationContext.xml");
		Student stu=(Student)factory.getBean("stu");
		System.out.println(stu.getName());
	    factory.registerShutdownHook();
	   输出  init > 小明 > destroy

------------------反射方式复制对象--------------------------

          
		Student s = new Student(131, "小张", 13,false, new Date());
	    Student s2=(Student)copyForObject(s);

private static Object copyForObject(Object obj) throws NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
		//获得原有对象的class信息
		Class clazz=obj.getClass();
		//获得原有对象的无参构造方法
		Constructor constructor=clazz.getConstructor(new Class[] {});//参数列表给一个空数组
		//通过无参构造方法创建新对象   target为返回对象
		Object target = constructor.newInstance(new Object[] {});
		//获取原对象的属性
		Field[] fields=clazz.getDeclaredFields();
		//每个属性有set\get两个方法,并且有一定规律,
		for(Field f:fields) {
			//获得set\get方法名称=获取属性名.字符串截取(截取从一位开始前开始到第二位前结束,包前不包后)             
			String setmethodName="set"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1);
			String getmethodName="get"+f.getName().substring(0,1).toUpperCase()+f.getName().substring(1);
		    //查询get                                     属性名        参数(为空)
			Method getMethod = clazz.getDeclaredMethod(getmethodName, new Class[] {});
			//查询set                                     属性名        参数类型
			Method setMethod = clazz.getDeclaredMethod(setmethodName,f.getType());
            //调用原有对象的get方法  赋给新对象的set方法
			Object result=getMethod.invoke(obj, new Object[] {});
			//将属性通过set方法赋值给新对象
			setMethod.invoke(target, result);
		}
		
		return target;
		
	}