java之spring之对象的创建

痛定思痛。 2021-10-18 09:26 310阅读 0赞

首先提供目录结构如下：

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下面提供各文件代码，以供参考：

UserDynamicFactory.java

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1 package cn.sxt.factory;
     2 
     3 import cn.sxt.vo.User;
     4 
     5 /**
     6  *     ��̬��������������
     7  *
     8  */
     9 public class UserDynamicFactory {
    10     public User createUser(String name,int age){
    11         return new User(name,age);
    12     }
    13 }

UserFactory.java

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1 package cn.sxt.factory;
     2 
     3 import cn.sxt.vo.User;
     4 /**
     5  * 
     6  */
     7 public class UserFactory {
     8     public static User createUser(String name,int age){
     9         return new User(name,age);
    10     }
    11 }

User.java

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1 package cn.sxt.vo;
     2 
     3 
     4 public class User {
     5     private String name;
     6     private int age;
     7     public User() {
     8     }
     9     public User(String name, int age) {
    10         super();
    11         this.name = name;
    12         this.age = age;
    13     }
    14     public String getName() {
    15         return name;
    16     }
    17     public void setName(String name) {
    18         this.name = name;
    19     }
    20     public int getAge() {
    21         return age;
    22     }
    23     public void setAge(int age) {
    24         this.age = age;
    25     }
    26     @Override
    27     public String toString() {
    28         return "User [name=" + name + ", age=" + age + "]";
    29     }
    30 }

beans.xml

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1 <?xml version="1.0" encoding="UTF-8"?>
     2 <beans xmlns="http://www.springframework.org/schema/beans"
     3     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     4     xsi:schemaLocation="http://www.springframework.org/schema/beans
     5         http://www.springframework.org/schema/beans/spring-beans.xsd">
     6     
     7     <bean id="u1" class="cn.sxt.vo.User">
     8         
     9         <constructor-arg index="0" value="张三疯"/>
    10         <constructor-arg index="1" value="33"/>
    11     </bean>
    12     <bean id="u2" class="cn.sxt.vo.User">
    13         
    14         <constructor-arg name="name" value="张三疯"/>
    15         <constructor-arg name="age" value="33"/>
    16     </bean>
    17     <bean id="u3" class="cn.sxt.vo.User">
    18         
    19         <constructor-arg type="java.lang.String" value="张三疯"/>
    20         <constructor-arg type="int" value="33"/>
    21     </bean>
    22     <bean id="u4" class="cn.sxt.vo.User">
    23         <property name="name" value="张无忌"/>
    24         <property name="age" value="23"/>
    25     </bean>
    26     
    27     <bean id="u5" class="cn.sxt.factory.UserFactory" factory-method="createUser">
    28         <constructor-arg type="java.lang.String" value="张三疯"/>
    29         <constructor-arg type="int" value="33"/>
    30     </bean>
    31     
    32     <bean id="factory" class="cn.sxt.factory.UserDynamicFactory"/>
    33     <bean id="u6" factory-bean="factory" factory-method="createUser">
    34         <constructor-arg type="java.lang.String" value="张三疯"/>
    35         <constructor-arg type="int" value="33"/>
    36     </bean>
    37 </beans>

SpringTest.java

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1 package cn.sxt.spring;
     2 
     3 import org.junit.Test;
     4 import org.springframework.context.ApplicationContext;
     5 import org.springframework.context.support.ClassPathXmlApplicationContext;
     6 
     7 import cn.sxt.vo.User;
     8 
     9 public class SpringTest {
    10     @Test
    11     public void testHello(){
    12         //��������
    13         ApplicationContext ac = new ClassPathXmlApplicationContext("beans.xml");
    14         User u=(User)ac.getBean("u6");
    15         System.out.println(u);
    16     }
    17 }

一.通过构造方法来创建对象

1. 通过参数下标来设置参数的值

<bean id="u1" class="cn.sxt.vo.User">
            
            <constructor-arg index="0" value="张三疯"/>
            <constructor-arg index="1" value="33"/>
        </bean>

2.通过参数名称来设置

3.通过参数类型来设置

二. 通过无参构造方法来创建对象

注意：需要提供无参构造器，并且属性要有对应的set方法

三. 通过静态工厂来创建对象

静态工厂类：

/**
     * 静态工厂方法 
     *     通过静态工厂来创建对象
     */
    public class UserFactory {
        public static User createUser(String name,int age){
            return new User(name,age);
        }
    }

配置文件

<bean id="u5" class="cn.sxt.factory.UserFactory" factory-method="createUser">
            <constructor-arg type="java.lang.String" value="张三疯"/>
            <constructor-arg type="int" value="33"/>
        </bean>

四.通过动态工厂来创建对象

动态工厂类

/**
     *     动态工厂来创建对象
     *
     */
    public class UserDynamicFactory {
        public User createUser(String name,int age){
            return new User(name,age);
        }
    }

配置文件

<bean id="factory" class="cn.sxt.factory.UserDynamicFactory"/>
        <bean id="u6" factory-bean="factory" factory-method="createUser">
            <constructor-arg type="java.lang.String" value="张三疯"/>
            <constructor-arg type="int" value="33"/>
        </bean>

转载于:https://www.cnblogs.com/Vincent-yuan/p/11247789.html

[1182288-20190725235453562-806008429.png]: /images/20211018/37e14fa6e4e6492aa6f4a3a0c665624f.png
[ContractedBlock.gif]: https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif
[ExpandedBlockStart.gif]: /images/20211018/eac299acb2b8425fbd7ce1ab5d4bf142.png