【SSM框架】为集合类型属性赋值

news2024/11/28 6:36:35

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🍒系列专栏：SSM框架

1.为集合类型属性赋值

①为List集合类型属性赋值

②为Map集合类型属性赋值

2.p命名空间

3.引入外部属性文件

1.为集合类型属性赋值

①为List集合类型属性赋值

在 Clazz 类中添加以下代码：

private List<Student> students;
public List<Student> getStudents() {
return students;
}
public void setStudents(List<Student> students) {
this.students = students;
}

方法1：配置bean：

若为Set集合类型属性赋值，只需要将其中的list标签改为set标签即可

    <bean id="clazzTwo" class="com.atguigu.spring.pojo.Clazz">
        <property name="clazzId" value="1"></property>
        <property name="clazzName" value="计算机科学与技术"></property>
        <property name="students">
            <list>
                <ref bean="studentOne"></ref>
                <ref bean="studentTwo"></ref>
                <ref bean="studentThree"></ref>
            </list>
        </property>
    </bean>

    <bean id="studentOne" class="com.atguigu.spring.pojo.Student">
        <property name="id" value="1001"></property>
        <property name="name" value="赵1"></property>
        <property name="age" value="22"></property>
        <property name="sex" value="女"></property>

        <property name="hobbies">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>打豆豆</value>
            </array>
        </property>
    </bean>
    <bean id="studentTwo" class="com.atguigu.spring.pojo.Student">
        <property name="id" value="1002"></property>
        <property name="name" value="赵2"></property>
        <property name="age" value="24"></property>
        <property name="sex" value="女"></property>

        <property name="hobbies">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>打豆豆</value>
            </array>
        </property>
    </bean>

    <bean id="studentThree" class="com.atguigu.spring.pojo.Student">
        <property name="id" value="1004"></property>
        <property name="name" value="赵3"></property>
        <property name="age" value="21"></property>
        <property name="sex" value="女"></property>

        <property name="hobbies">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>打豆豆</value>
            </array>
        </property>

        
    </bean>

测试：

    @org.junit.Test
    public void testHelloWorld(){

        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        Clazz clazzTwo = ac.getBean("clazzTwo", Clazz.class);
        System.out.println(clazzTwo);

方法2：配置一个集合类型的bean，需要使用util 的约束-

    <bean id="clazzTwo" class="com.atguigu.spring.pojo.Clazz">
        <property name="clazzId" value="1"></property>
        <property name="clazzName" value="计算机科学与技术"></property>
        <property name="students" ref="studentsList">
        </property>
    </bean>

    <util:list id="studentsList">
        <ref bean="studentOne"></ref>
        <ref bean="studentTwo"></ref>
        <ref bean="studentThree"></ref>
    </util:list>

效果一样的：

②为Map集合类型属性赋值

创建教师类Teacher：

public class Teacher {
    private Integer tid;
    private String tname;

    public Teacher() {
    }

    public Teacher(Integer tid, String tname) {
        this.tid = tid;
        this.tname = tname;
    }

    public Integer getTid() {
        return tid;
    }

    public void setTid(Integer tid) {
        this.tid = tid;
    }

    public String getTname() {
        return tname;
    }

    public void setTname(String tname) {
        this.tname = tname;
    }

    @Override
    public String toString() {
        return "Teacher{" +
                "tid=" + tid +
                ", tname='" + tname + '\'' +
                '}';
    }
}

在Student类中添加以下代码：

private Map<String, Teacher> teacherMap;
public Map<String, Teacher> getTeacherMap() {
return teacherMap;
}
public void setTeacherMap(Map<String, Teacher> teacherMap) {
this.teacherMap = teacherMap;
}

方法1：配置bean（ 引用集合类型的 bean ）：

    <bean id="student" class="com.atguigu.spring.pojo.Student">
        <property name="id" value="1004"></property>
        <property name="name" value="赵六"></property>
        <property name="age" value="26"></property>
        <property name="sex" value="女"></property>

        <property name="clazz">
            <!-- 在一个bean中再声明一个bean就是内部bean -->
            <!-- 内部bean只能用于给属性赋值，不能在外部通过IOC容器获取，因此可以省略id属性 -->
            <bean id="clazzInner" class="com.atguigu.spring.pojo.Clazz">
                <property name="clazzId" value="2"></property>
                <property name="clazzName" value="软件工程"></property>
            </bean>
        </property>

        <property name="hobbies">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>打豆豆</value>
            </array>
        </property>
        <property name="teacherMap">
            <map>
                <entry key="1" value-ref="teacherOne"></entry>
                <entry key="2" value-ref="teacherTwo"></entry>
            </map>
        </property>
    </bean>


    <bean id="teacherOne" class="com.atguigu.spring.pojo.Teacher">
        <property name="tid" value="11111"></property>
        <property name="tname" value="小王"></property>

    </bean>
    <bean id="teacherTwo" class="com.atguigu.spring.pojo.Teacher">
        <property name="tid" value="22222"></property>
        <property name="tname" value="小李"></property>

    </bean>

测试：

    public void testHelloWorld(){

        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        Student student = ac.getBean("student", Student.class);
        System.out.println(student);


    }

方法2：配置bean（util:map):

    <bean id="student" class="com.atguigu.spring.pojo.Student">
        <property name="id" value="1004"></property>
        <property name="name" value="赵六"></property>
        <property name="age" value="26"></property>
        <property name="sex" value="女"></property>

        <property name="clazz">
            <!-- 在一个bean中再声明一个bean就是内部bean -->
            <!-- 内部bean只能用于给属性赋值，不能在外部通过IOC容器获取，因此可以省略id属性 -->
            <bean id="clazzInner" class="com.atguigu.spring.pojo.Clazz">
                <property name="clazzId" value="2"></property>
                <property name="clazzName" value="软件工程"></property>
            </bean>
        </property>

        <property name="hobbies">
            <array>
                <value>吃饭</value>
                <value>睡觉</value>
                <value>打豆豆</value>
            </array>
        </property>
        <property name="teacherMap" ref="teacherMap">
        </property>
    </bean>

    <util:map id="teacherMap">
        <entry key="1" value-ref="teacherOne"></entry>
        <entry key="2" value-ref="teacherTwo"></entry>
    </util:map>

2.p命名空间

引入p命名空间后，可以通过以下方式为bean的各个属性赋值

    <bean id="studentT" class="com.atguigu.spring.pojo.Student" p:name="李王" p:id="1009" p:teacherMap-ref="teacherMap">

    </bean>

3.引入外部属性文件

①加入依赖

<!-- MySQL驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.16</version>
</dependency>
<!-- 数据源 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.31</version>
</dependency>

②创建外部属性文件

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm? serverTimezone=UTC
jdbc.username=root
jdbc.password=root

③引入属性文件

 <context:property-placeholder location="jdbc.properties"></context:property-placeholder>

④配置 bean

<?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:context="http://www.springframework.org/schema/context"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-4.2.xsd">


    <context:property-placeholder location="jdbc.properties"></context:property-placeholder>
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
        <property name="url" value="${jdbc.url}"/>
        <property name="driverClassName" value="${jdbc.driver}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    
</bean>




</beans>

⑤测试

public void test(){
ClassPathXmlApplicationContext ioc = new ClassPathXmlApplicationContext("spring-datasource.xml");
DruidDataSource bean = ioc.getBean(DruidDataSource.class);
try {
System.out.println(bean.getConnection());
} catch (SQLException throwables) {
throwables.printStackTrace();
}

}