上手spring

IDEA创建一个Maven项目，加入所需要的依赖：

<dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>5.2.5.RELEASE</version>
</dependency>

所谓的spring容器，我的理解就是帮助程序员new对象，程序中所有的对象都可以交给spring容器去创建管理。只要把需要创建对象的类加入到spring的xml文件中去即可。

这里我们先创建一个pojo：

package spring.beans;

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

public class People {
    private String name;
    private int age;
    private String[] hobby;
    private List job;
    private Map score;
    private String wife;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public String[] getHobby() {
        return hobby;
    }

    public void setHobby(String[] hobby) {
        this.hobby = hobby;
    }

    public List getJob() {
        return job;
    }

    public void setJob(List job) {
        this.job = job;
    }

    public Map getScore() {
        return score;
    }

    public void setScore(Map score) {
        this.score = score;
    }

    public String getWife() {
        return wife;
    }

    public void setWife(String wife) {
        this.wife = wife;
    }

    @Override
    public String toString() {
        return "People{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", hobby=" + Arrays.toString(hobby) +
                ", job=" + job +
                ", score=" + score +
                ", wife='" + wife + '\'' +
                '}';
    }
}

然后在新建一个beans.xml文件来管理bean。文件名可随便取即可：

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="student" class="spring.beans.Student">
            <property name="name" value="小明"/>
    </bean>
　　<!--这里的bean的功能相当于People people = new People()。property就是给类中属性赋值-->
    <bean id="people" class="spring.beans.People">
        <property name="name" value="小王"/>
        <property name="age" value="21"/>
        <property name="hobby">
            <array>
                <value>红楼梦</value>
                <value>三国演义</value>
                <value>水浒传</value>
                <value>西游记</value>
            </array>
        </property>
        <property name="job">
            <list>
                <value>程序员</value>
                <value>销售</value>
            </list>
        </property>
        <property name="score">
            <map>
                <entry key="weight" value="100"/>
                <entry key="height" value="180"/>
            </map>
        </property>
        <property name="wife">
            <null/>
        </property>
    </bean>

</beans>

这样就可以测试了：

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import spring.beans.People;
import spring.beans.Student;

public class TextSpring {
    public static void main(String[] args) {
　　　　　//通过 new ClassPathXmlApplicationContext("beans.xml")来获取spring的配置文件，返回一个ApplicationContext;
        ApplicationContext app = new ClassPathXmlApplicationContext("beans.xml");
　　　　 //getBean("people");  获取beans.xml文件中由spring容器创建好的对象People。
        People p = (People) app.getBean("people");
        System.out.printf(p.toString());
    }
}