spring入门 IOC创建对象--来自狂神

古城微笑少年丶 2022-09-15 12:56 25阅读 0赞

## User ##

package com.liu.pojo;
    
    public class User {
        
        private String name;
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public void show(){
        
            System.out.println("name="+name);
        }
    
        @Override
        public String toString() {
        
            return "User{" +
                    "name='" + name + '\'' +
                    '}';
        }
    }

## applicationContext.xml ##

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans.xsd">
    
    无参构造默认赋值
       <bean id="user" class="com.liu.pojo.User">
           <property name="name" value="向阳"/>
       </bean>
    
    </beans>

## MyTest ##

import com.liu.pojo.User;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    public class MyTest {
        
        public static void main(String[] args) {
        
        //获取ApplicationContext;拿到spring容器；
            ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
            //容器在手天下我有，需要啥就get啥
            User user = (User)context.getBean("user");
            System.out.println(user.toString());
        }
    }

## pom.xml
    <?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>org.example</groupId>
        <artifactId>myliu-02</artifactId>
        <version>1.0-SNAPSHOT</version>
    
    
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>5.3.10</version>
            </dependency>
            
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>5.3.10</version>
                <scope>test</scope>
            </dependency>
        </dependencies>
    
    </project>

--------------------

如果User中存在有参构造

package com.liu.pojo;
    
    public class User {
        
        private String name;
    
        private User(String name){
        
            this.name=name;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public void show(){
        
            System.out.println("name="+name);
        }
    
        @Override
        public String toString() {
        
            return "User{" +
                    "name='" + name + '\'' +
                    '}';
        }
    }

applicationcontext.xml

1.还可以用下标赋值

2.类型赋值

无参构造默认赋值