2------一个简单的Spring项目

导入依赖

至于要弄清楚，每次需要导入哪些包，可以查看如下网站

https://juejin.im/entry/58ae5f5f2f301e0068ee6f9a

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>5.2.1.RELEASE</version>
        </dependency>
</dependencies>

编写实体类

package demo1.com.sicheng.entity;




public class Hello {

    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Hello(String name) {
        this.name = name;
    }

    public Hello() {
    }

    @Override
    public String toString() {
        return "Hello{" +
                "name='" + name + '\'' +
                '}';
    }
}

配置xml文件

<?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">
   
    <bean id="hello" class="demo1.com.sicheng.entity.Hello">
        <property name="name" value="hello"/>
    </bean>
</beans>

编写测试类

import demo1.com.sicheng.entity.Hello;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringTest {

    @Testo
    public void HelloTest(){
        ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
        Hello hello = (Hello)context.getBean("hello");
        System.out.println(hello.toString());
    }
}

需要注意的

输出hello啦！！！

想不到吧，就是这么简单！！！

每一个实体类都可以去xml文件中，注册一下。

上述可以看出：

name，通过set方法注入了，D：dependency，依赖
是通过无参构造方法构造的hello实体类
Hello类被注入到了spring

修改一下xml文件

<?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">
   
    <bean id="hello" class="demo1.com.sicheng.entity.Hello">
        <constructor-arg name="name" value="1"/>
    </bean>
</beans>

可以看出上述，hello实体类是通过有参构造方法构造的。

spring创建实体类的几种方法

类Hello

package demo1.com.sicheng.entity;

public class Hello {

    private String name;
    private Person person;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }

    public Hello() {
    }

    public Hello(String name, Person person) {
        this.name = name;
        this.person = person;
    }

    @Override
    public String toString() {
        return "Hello{" +
                "name='" + name + '\'' +
                ", person=" + person +
                '}';
    }
}

类Person

package demo1.com.sicheng.entity;

public class Person {

    private int age;

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Person(int age) {
        this.age = age;
    }

    public Person() {
    }

    @Override
    public String toString() {
        return "Person{" +
                "age=" + age +
                '}';
    }
}