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Spring——Bean管理-xml方式进行属性注入_xml注入bean

作者：不正经 | 2024-02-16 03:44:21

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xml注入bean

constructor-arg：通过构造函数注入

用name标签属性：不按照顺序也会自动匹配

使用index标签属性：index的值为参数的顺序，默认从0开始

使用type标签属性：要和参数数据类型严格一致

5、注入集合属性——数组、List集合、Map集合、Set集合

抽取公共部分

Spring系列文章

一、xml方式创建对象


<!--    配置User对象创建-->
<!--    id是取得别名，通过id别名可以把类找到-->
<bean id="user" class="com.atguigu.spring5.User"></bean>

id：唯一标识，不能加特殊符号
class：类全路经（包类路径）
name：可以加特殊符号

二、xml方式注入属性

DI：依赖注入，就是注入属性

第①种方式注入：set方法注入


package com.atguigu.spring5.Book;
 
public class Book {
    private String bname;
    private String bauthor;
    public void setBname(String bname){
        this.bname=bname;
    }
 
    public void setBauthor(String bauthor){
        this.bauthor=bauthor;
    }
 
    public static void main(String[] args) {
        Book book = new Book();
        book.setBname("abc");
    }
 
    public void testDemo(){
        System.out.println(bname+"---"+bauthor);
    }
}


<?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">
 
<!--    2.set方法注入属性-->
    <bean id="book" class="com.atguigu.spring5.Book.Book">
<!--        使用propterty完成属性注入-->
<!--        name：类里面属性名称-->
<!--        value：向属性注入的值-->
        <property name="bname" value="追风筝的人"></property>
        <property name="bauthor" value="卡勒德·胡赛尼"></property>
    </bean>
</beans>


package com.atguigu.spring5.Book;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class BoolTestMain {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("Booktest.xml");
        Book book = context.getBean("book", Book.class);
        System.out.println(book);
        book.testDemo();
    }
}

我们还可以通过另一种方式简化写法—p名称空间注入


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
 
	<bean id="books" class="com.atguigu.spring5.Book.Book" p:bname="朝花夕拾" p:bauthor="鲁迅"></bean>
 
</beans>

第②种方式注入：有参构造函数注入


public class Orders {
    //    有参数构造注入属性
    private String oname;
    private String address;
    private double money;
 
    public Orders(String oname, String address, double money) {
        this.oname = oname;
        this.address = address;
        this.money = money;
    }
 
    public void show() {
        System.out.println(oname + "---" + address + "---" + money);
    }
}

constructor-arg：通过构造函数注入

使用value标签属性：默认按照constructor-arg标签的顺序


<constructor-arg value="电脑"></constructor-arg>
<constructor-arg value="China"></constructor-arg>

用name标签属性：不按照顺序也会自动匹配


<constructor-arg name="oname" value="电脑"></constructor-arg>
<constructor-arg name="address" value="China"></constructor-arg>

使用index标签属性：index的值为参数的顺序，默认从0开始


 <!--index="0"：有参构造的第一个属性-->
<constructor-arg index="0" value="电脑"></constructor-arg>
<constructor-arg index="1" value="China"></constructor-arg>

使用type标签属性：要和参数数据类型严格一致

（如果数据类型一致，按照constructor-arg标签的顺序匹配）


<constructor-arg type="double" value="23"></constructor-arg>
<constructor-arg type="java.lang.String" value="电脑"></constructor-arg>
<constructor-arg type="java.lang.String" value="China"></constructor-arg>

三、xml注入其他类型属性

1、字面量--null值


<constructor-arg name="oname" value="朝花夕拾"/>
<constructor-arg name="oauthor" value="鲁迅"/>
<constructor-arg name="address" >
            <null></null>
</constructor-arg>

2、含有特殊符号

&lt；&gt；
把带特殊符号内容写到!CDATA


  <!--        1、使用&lt;&gt;先进行转义-->
<property name="bauthor" value="鲁迅"></property>
<property name="bname" value="&lt;&gt;朝花夕拾>>"></property>
 
<!--        2、使用!CDATA-->
<property name="bauthor">
		<value><![CDATA[<<南京>>]]></value>
</property>

3、注入属性-外部bean

通过ref属性将进行注入


public class School {
    //创建School类型属性，生成set方法
    private Teacher teacher;
 
    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }
}


<!--    注入外部bean-->
<bean id="school" class="com.atguigu.spring5.propertyTest.School">
        <property name="teacher" ref="teachers"></property>
</bean>
 
<bean id="teachers" class="com.atguigu.spring5.propertyTest.Teacher"></bean>

4、注入属性-内部bean

什么是内部bean？

在某一个bean中定义另一个bean作为属性

什么时候使用内部bean？

如果School类中的某个属性的数据类型是另一个类Book，则可以把这个类Book定义在属性的内部

如何使用内部bean？


public class School {
    //创建School类型属性，生成set方法
    private Teacher teacher;
 
    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }
 
    //部门
    private Book dept;
    public void setDept(Book dept) {
        this.dept = dept;
    }
}


public class Book {
    private String bname;
    private String bauthor;
 
    public void setBname(String bname) {
        this.bname = bname;
    }
}


 <!--    注入内部bean-->
<bean id="school" class="com.atguigu.spring5.propertyTest.School">
        <property name="teacher" ref="teachers"></property>
        <property name="dept" >
            <bean id="book" class="com.atguigu.spring5.Book.Book">
                <property name="bname" value="朝花夕拾"></property>
            </bean>
        </property>
</bean>

5、注入集合属性——数组、List集合、Map集合、Set集合


package com.atguigu.spring5.CollectionTypeTest;
 
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Set;
 
/**
 * @BelongsProject: 02-Spring
 * @BelongsPackage: com.atguigu.spring5.CollectionTypeTest
 * @Author: dengLiMei
 * @CreateTime: 2023-02-09  09:46
 * @Description: TODO
 * @Version: 1.0
 */
public class Student {
    //数组
    private String[] courses;
 
    //    List集合
    private List<String> lists;
 
    //Map集合
    private Map<String, String> maps;
 
    //Set集合
    private Set<String> sets;
 
    public void setSets(Set<String> sets) {
        this.sets = sets;
    }
 
    public Student() {
    }
 
    public void setCourses(String[] courses) {
        this.courses = courses;
    }
 
    public void setLists(List<String> lists) {
        this.lists = lists;
    }
 
    public void setMaps(Map<String, String> maps) {
        this.maps = maps;
    }
 
    public void show() {
        System.out.println(Arrays.toString(courses));
        System.out.println((lists));
        System.out.println((maps));
        System.out.println((sets));
    }
}


<?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="students" class="com.atguigu.spring5.CollectionTypeTest.Student">
        <!-- 数组-->
        <property name="courses">
            <array>
                <value>spring5</value>
                <value>springboot</value>
            </array>
        </property>
 
        <!--        List类型-->
        <property name="lists">
            <list>
                <value>springcloud</value>
                <value>springcloudAlibaba</value>
            </list>
        </property>
 
        <!--        Map集合-->
        <property name="maps">
            <map>
                <entry key="QQ" value="腾讯"></entry>
                <entry key="淘宝" value="阿里"></entry>
            </map>
        </property>
 
        <!--        Set集合-->
        <property name="sets">
            <set>
                <value>set-spring5</value>
                <value>set-springboot</value>
            </set>
        </property>
    </bean>
</beans>

输出结果：

如果一个类中包含了另一个类的实体对象，可以这样写


public class Course {
    //    课程名称
    private String cname;
 
    public void setCname(String cname) {
        this.cname = cname;
    }
}


package com.atguigu.spring5.CollectionTypeTest;
 
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Set;
 
public class Student2 {
    //实体对象-学生有多门课程
    private List<Course> courseList;
 
    public void setCourseList(List<Course> courseList) {
        this.courseList = courseList;
    }
 
    @Override
    public String toString() {
        return "Student2{" +
                "courseList=" + courseList +
                '}';
    }
}


<bean id="student2" class="com.atguigu.spring5.CollectionTypeTest.Student2">
        <property name="courseList">
            <list>
                <ref bean="course1"></ref>
                <ref bean="course2"></ref>
            </list>
        </property>
    </bean>
 
<!--    创建多个course对象-->
<bean id="course1" class="com.atguigu.spring5.CollectionTypeTest.Course">
        <property name="cname" value="spring5框架"></property>
</bean>
<bean id="course2" class="com.atguigu.spring5.CollectionTypeTest.Course">
        <property name="cname" value="MyBatis框架"></property>
</bean>


public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("CollectionTypeBeans.xml");
        Student2 students1 = context.getBean("student2", Student2.class);
        students1.show();
}

输出结果：

目前的问题：只能当前类使用，其他类不能用，接下来就是把集合属性抽取成公共部分让所有实体类都能够引入

抽取公共部分


public class Book {
    private List<String> list;
 
    public void setList(List<String> list) {
        this.list = list;
    }
 
    public void show(){
        System.out.println(list);
    }
}


<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                           http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">
 
    <!--    1、提取list集合类型属性注入-->
    <util:list id="bookList">
        <value>spring5</value>
        <value>springboot</value>
        <value>springcloud</value>
    </util:list>
 
    <!--    2、提取list集合类型属性注入使用-->
    <bean id="book" class="com.atguigu.spring5.CollectionTypeTest.Book">
        <property name="list" ref="bookList"></property>
    </bean>
</beans>


public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("CollectionTypeBeans.xml");
        Book book = context.getBean("book", Book.class);
        book.show();
}