Spring ： constructor-arg property 注入

最新推荐文章于 2024-06-18 11:28:14 发布

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本文详细介绍了Spring框架中两种主要的依赖注入方式：构造函数注入和setter注入。通过具体的代码示例和XML配置文件展示了如何使用这两种注入方式来初始化Bean。

1、说明

constructor-arg：通过构造函数注入。
property：通过setter对应的方法注入。

2、constructor-arg的使用示例

(1)、Model代码：

public class Student
 {

    private Integer
 id;

    private String
 name;

    private List<String>
 dream;

    private Map<String,
 Integer> score;

    private boolean graduation;

                                                                                                                                                                           

    public Student()
 {

                                                                                                                                                                           

    }

                                                                                                                                                                           

    public Student(Integer
 id, String name, List<String> dream,

            Map<String,
 Integer> score, boolean graduation)
 {

        this.id
 = id;

        this.name
 = name;

        this.dream
 = dream;

        this.score
 = score;

        this.graduation
 = graduation;

    }

                                                                                                                                                                           

    @Override

    public String
 toString() {

        return "Student
 [id=" +
 id + ",
 name=" +
 name + ",
 dream=" +
 dream

                + ",
 score=" +
 score + ",
 graduation=" +
 graduation + "]";

    }

                                                                                                                                                                           

}

(2)、xml配置：

<bean id="student" class="com.rc.sp.Student">

    <constructor-arg name="id" value="1"/>

    <constructor-arg name="name" value="student"/>

    <constructor-arg name="dream">

        <list>

            <value>soldier</value>

            <value>scientist</value>

            <value>pilot</value>

        </list>

    </constructor-arg>

    <constructor-arg name="score">

        <map>

            <entry key="math" value="90"/>

            <entry key="english" value="85"/>

        </map>

    </constructor-arg>

    <constructor-arg name="graduation" value="false"/>

</bean>

说明：<constructor-arg name="id" value="1"/>也可以改成<constructor-arg index="0" value="1"/>方式；boolean的值既可以用0/1填充，也可以用true/false填充。

3、property的使用示例

(1)、Model代码：

public class Teacher
 {

    private Integer
 id;

    private String
 name;

    public Integer
 getId() {

        return id;

    }

    public void setId(Integer
 id) {

        this.id
 = id;

    }

    public String
 getName() {

        return name;

    }

    public void setName(String
 name) {

        this.name
 = name;

    }

    @Override

    public String
 toString() {

        return "Teacher
 [id=" +
 id + ",
 name=" +
 name + "]";

    }

}

(2)、xml配置：

<bean id="teacher" class="com.rc.sp.Teacher">

    <property name="id" value="1"></property>

    <property name="name" value="teacher"></property>

</bean>

4、Test

(1)、测试代码：

public class Run
 {

    public static void main(String[]
 args) {

        ApplicationContext
 context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        Student
 student = (Student) context.getBean("student");

        System.out.println(student);

        Teacher
 teacher = (Teacher) context.getBean("teacher");

        System.out.println(teacher);

    }

}