基于XML方式的Bean管理

基于XML方式的Bean管理

1、创建对象

<bean id="user" class="com.qianchen.User"> </bean>
<!--创建User对象-->
<!--    
在 bean 标签有很多属性，介绍常用的属性：
id 属性：唯一标识
class 属性：类全路径（包类路径）
创建对象时候，默认是执行无参数构造方法完成对象创建
-->

2、使用set方法注入属性

package com.qianchen;
//创建类，定义属性和对应的 set 方法
public class User {
    private String name;
​
    public void setName(String name) {
        this.name = name;
    }
}

<bean id="user" class="com.qianchen.User">
    <property name="name" value="root"/>
</bean>
<!--set方法注入属性-->
<!--使用 property 完成属性注入
name：类里面属性名称
value：向属性注入的值
-->

3、使用有参构造函数注入属性

package com.qianchen;
//创建类，定义属性，创建属性对应的有参数构造方法
public class User {
    private String name;
    private String password;
​
    public User(String name, String password) {
        this.name = name;
        this.password = password;
    }
}

<bean id="user" class="com.qianchen.User">
    <!--有参数构造注入属性-->
    <constructor-arg name="name" value="root"></constructor-arg>
    <constructor-arg name="password" value="123456"></constructor-arg>
</bean>

4、其他类型属性的注入

• null

<property name="name">
    <null></null>
</property>

• 注入属性-外部bean

（1）创建两个类 People 类和 User 类 （2）在 User 调用 People 里面的方法 （3）在 spring 配置文件中进行配置

package com.qianchen;
​
public class People {
    public void eat(){
        System.out.println("eat...");
    }
}

package com.qianchen;
//创建类，定义属性，创建属性对应的有参数构造方法
public class User {
​
    private People people;
​
    public void setPeople(People people) {
        this.people = people;
    }
    public void eat(){
        people.eat();
    }
}

<bean id="people" class="com.qianchen.People">
</bean>
<bean id="user" class="com.qianchen.User">
    <property name="people" ref="people"> </property>
</bean>

• 注入属性-内部bean

package com.qianchen;

public class School {
    private String name;

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

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

package com.qianchen;

public class Student {
    private String name;
    private School school;

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

    public void setSchool(School school) {
        this.school = school;
    }

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

<bean class="com.qianchen.Student" id="student">
    <property name="name" value="root"> </property>
    <property name="school">
        <bean id="school" class="com.qianchen.School">
            <property name="name" value="常宁大学"> </property>
        </bean>

    </property>
</bean>

• 注入属性-级联赋值

(1)第一种写法

沿用上面的School、Student类

<bean id="school" class="com.qianchen.School">
    <property name="name" value="常宁大学"> </property>
</bean>
<bean class="com.qianchen.Student" id="student">
    <property name="name" value="root"> </property>
    <property name="school" ref="school"> </property>
</bean>

(2)第二种写法

为Student类增加getSchool方法

public School getSchool() {
    return school;
}

<bean id="school" class="com.qianchen.School">
</bean>
<bean class="com.qianchen.Student" id="student">
    <property name="name" value="root"> </property>
    <property name="school" ref="school"> </property>
    <property name="school.name" value="常宁大学"> </property>
</bean>

5、xml 注入集合属性

package com.qianchen;

import java.util.*;

public class Student {
    private List<String> studentName;//学生姓名
    private Set<Integer>  id;//学号
    private Map<String,String> teacher;//各科老师
    private String[]   subject;//学科

    public void setStudentName(List<String> studentName) {
        this.studentName = studentName;
    }

    public void setId(Set<Integer> id) {
        this.id = id;
    }

    public void setTeacher(Map<String, String> teacher) {
        this.teacher = teacher;
    }

    public void setSubject(String[] subject) {
        this.subject = subject;
    }

    @Override
    public String toString() {
        return "Student{" +
                "studentName=" + studentName +
                ", id=" + id +
                ", teacher=" + teacher +
                ", subject=" + Arrays.toString(subject) +
                '}';
    }
}

<bean class="com.qianchen.Student" id="student">
    <!--数组类型属性注入-->
    <property name="subject">
        <array>
            <value>数学</value>
            <value>语文</value>
            <value>体育</value>
        </array>
    </property>
    <!--list 类型属性注入-->
    <property name="studentName">
        <list>
            <value>张三</value>
            <value>李四</value>
            <value>王五</value>
        </list>
    </property>
    <!--map 类型属性注入-->
    <property name="teacher">
        <map>
            <entry key="语文老师" value="孔子"> </entry>
            <entry key="数学老师" value="祖之冲"> </entry>
            <entry key="体育老师" value="姚明"> </entry>
        </map>
    </property>
    <!--set 类型属性注入-->
    <property name="id">
        <set>
            <value>1</value>
            <value>2</value>
            <value>3</value>
        </set>
    </property>
</bean>

在集合里面设置对象类型值

package com.qianchen;

public class Subject {
    private String subName;

    public void setSubName(String subName) {
        this.subName = subName;
    }

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

package com.qianchen;

import java.util.Arrays;

public class Student {

    private Subject[] subject;//学科

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

    @Override
    public String toString() {
        return "Student{" +
                "subject=" + Arrays.toString(subject) +
                '}';
    }
}

<bean id="sub1" class="com.qianchen.Subject">
    <property name="subName" value="数学"> </property>
</bean>
<bean id="sub2" class="com.qianchen.Subject">
    <property name="subName" value="语文"> </property>
</bean>

<bean class="com.qianchen.Student" id="student">
    <property name="subject">
        <array>
            <ref bean="sub1"></ref>
            <ref bean="sub2"></ref>
        </array>
    </property>
</bean>