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Spring IoC创建对象
==================

1 实体类

在/src/main/java/cn.tedu.springioc.beans目录下创建Subject.java文件：

public class Subject {
    private String name;

    public String getName() {
        return name;
    }

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

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

在/src/main/java/cn.tedu.springioc.beans目录下创建Student.java文件：

public class Student {
    private String number;
    private String name;
    private String gender;
    private int age;
    private Date enrollment;
    private Subject subject;

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public String getName() {
        return name;
    }

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

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public int getAge() {
        return age;
    }

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

    public Date getEnrollment() {
        return enrollment;
    }

    public void setEnrollment(Date enrollment) {
        this.enrollment = enrollment;
    }

    public Subject getSubject() {
        return subject;
    }

    public void setSubject(Subject subject) {
        this.subject = subject;
    }

    @Override
    public String toString() {
        return "Student{" +
            "number='" + number + '\'' +
            ", name='" + name + '\'' +
            ", gender='" + gender + '\'' +
            ", age=" + age +
            ", enrollment=" + enrollment +
            ", subject=" + subject +
            '}';
    }
}

2 以传统方式创建对象

在/src/main/java/cn.tedu.springioc.test目录下创建TraditionTest.java文件：

public class TraditionTest {
    public static void main(String[] args) {
        // 以传统方式创建对象
        Student sa = new Student();
        sa.setNumber("1001");
        sa.setName("张飞");
        sa.setGender("男");
        sa.setAge(20);
        sa.setEnrollment(new Date());
        Subject subject = new Subject();
        subject.setName("Java");
        sa.setSubject(subject);
        System.out.println(sa);
    }
}

运行测试：

Student{number='1001', name='张飞', gender='男', age=20, enrollment=Wed Feb 09 09:37:46 CST 2022, subject=Subject{name='Java'}}

例程：SpringIoC

3 通过Spring获取对象

在/src/main/resources/applicationContext.xml文件中添加：

<beans ...>
    ...
    <bean id="sb" class="cn.tedu.springioc.beans.Student" />
    ...
</beans>

在/src/main/java/cn.tedu.springioc.test目录下创建SpringTest.java文件：

public class SpringTest {
    public static void main(String[] args) {
        // 初始化Spring容器
        ClassPathXmlApplicationContext context =
            new ClassPathXmlApplicationContext("applicationContext.xml");
        // 通过Spring获取对象
        Student sb = context.getBean("sb", Student.class);
        System.out.println(sb);
    }
}

运行测试：

Student{number='null', name='null', gender='null', age=0, enrollment=null, subject=null}

例程：SpringIoC

4 通过Spring配置初值

<beans ...>
    ...
    <bean id="sc" class="cn.tedu.springioc.beans.Student" autowire="byName">
        <property name="number" value="1001" />
        <property name="name" value="张飞" />
        <property name="gender" value="男" />
        <property name="age" value="20" />
        <property name="enrollment" ref="enrollment" />
    </bean>
    <bean id="enrollment" class="java.util.Date" />
    <bean id="subject" class="cn.tedu.springioc.beans.Subject">
        <property name="name" value="Java" />
    </bean>
    ...
</beans>

public class SpringTest {
    public static void main(String[] args) {
        ...
        // 通过Spring配置初值
        Student sc = context.getBean("sc", Student.class);
        System.out.println(sc);
        ...
    }
}

运行测试：

Student{number='1001', name='张飞', gender='男', age=20, enrollment=Wed Feb 09 09:43:25 CST 2022, subject=Subject{name='Java'}}

例程：SpringIoC