Spring IoC 詳解(下篇)

IoC 構造器注入

<!-- 聲明TelePhone -->
<bean id="phone" class="model.TelePhone">
    <!-- index指定構造器的第幾個參數，name指定參數名，value指定參數值 -->
    <constructor-arg name="cpu" index="0" value="高通"></constructor-arg>
    <constructor-arg name="ram" index="1" value="迅閃"></constructor-arg>
</bean>

測試方法：

    @org.junit.Test
    public void test5() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        TelePhone t = ac.getBean("phone",TelePhone.class);
        t.show();
    }

bean對應的java類 TelePhone.java

/**
 * 手機類，模擬構造器注入
 * @author haifeng
 *
 */
public class TelePhone {

    private String cpu;
    private String ram;


    public TelePhone() {
        super();
    }

    public TelePhone(String cpu, String ram) {
        this.cpu = cpu;
        this.ram = ram;
    }

    public void show() {
        System.out.println( "TelePhone [cpu:" + cpu + ", ram:" + ram + "]");
    }
}

SET方式注入對象：
注入的對象需要在beans中聲明,使用ref進行注入

<!-- 聲明Computer -->
<bean id="student" class="model.Student">
    <property name="name" value="haydn"></property>
    <property name="computer" ref="computer"></property>
    <property name="phone" ref="phone"></property>
</bean>

測試方法：

    @org.junit.Test
    public void test6() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu = ac.getBean("student",Student.class);
        stu.show();
    }

bean的對應JAVA類，Student.java

/**
 * student實體類，模擬注入類對象
 * @author haifeng
 *
 */
public class Student {

    private String name;
    private Computer computer;
    private TelePhone phone;



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



    public void setComputer(Computer computer) {
        this.computer = computer;
    }



    public void setPhone(TelePhone phone) {
        this.phone = phone;
    }



    public void show() {
        System.out.println("學生姓名：" + name);
        computer.show();
        phone.show();
    }

}

List set map propetries 注入

<!-- 注入集合 -->
    <bean id="message" class="bean.Message">
    <!-- 字符串注入null值，方式一：不寫該配置，方式2：不寫value,加個null標籤 -->
        <property name="name" ><null/></property>
        <property name="age" value="23"></property>
        <!-- 注入list -->
        <property name="friends">
            <list>
                <value>摩嚴</value>
                <value>白子畫</value>
                <value>殺阡陌</value>
                <value>花千骨</value>
                <value>洛十一</value>
                <value>糖寶</value>
            </list>
        </property>
        <!-- 注入set -->
        <property name="cities">
            <set>
                <value>北京</value>
                <value>上海</value>
            </set>
        </property>
        <!-- 注入MAP -->
        <property name="score">
            <map>
                <entry key="語文" value="98"> </entry>
                <entry key="數學" value="99"></entry>
                <entry key="英語" value="100"></entry>
            </map>
        </property>
        <!-- 注入配置文件 -->
        <property name="dbParams">
            <props>
                <prop key="url">localhost</prop>
                <prop key="username">root</prop>
                <prop key="password">123</prop>
            </props>
        </property>

        <!-- 表達式注入,類似EL表達式用#{bean對象名.屬性}標記， -->
        <property name="password" value="#{dbProps.password}"></property>
    </bean>

    <!-- spring標籤注入 ,其他bean中使用ref調用,set Map Propties都可以,使用時需要加入命名空間-->
    <util:list id="someList">
        <value>摩嚴</value>
        <value>白子畫</value>
        <value>殺阡陌</value>
        <value>花千骨</value>
        <value>洛十一</value>
        <value>糖寶</value>
    </util:list>
    <!-- 注入list -->
    <property name="friends" ref="someList"></property>

    <!-- 加載properties文件創建Properties對象,location="classpath:dbcp.properties" location表示指定文件路徑
    classpath表示絕對路徑 -->
    <util:properties id="dbProps" location="classpath:dbcp.properties">
    </util:properties>  

測試類JAVA代碼:

@org.junit.Test
    public void test7() {
        ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
        Message msg = ac.getBean("message",Message.class);
        msg.show();
    }

bean的對應JAVA類，Message.java

/**
 * 消息類，模擬各種類型對象注入
 * @author haifeng
 *
 */
public class Message {

    private String name;
    private int age;
    private List<String> friends;
    private Set<String> cities;
    private Map<String,Integer> score;
    private Properties dbParams;
    private String password;


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

    public void setFriends(List<String> friends) {
        this.friends = friends;
    }


    public void setCities(Set<String> cities) {
        this.cities = cities;
    }


    public void setScore(Map<String, Integer> score) {
        this.score = score;
    }


    public void setDbParams(Properties dbParams) {
        this.dbParams = dbParams;
    }



    public void setPassword(String password) {
        this.password = password;
    }
    public void show() {
        System.out.println( "Message [name:" + name + ", age:" + age +", friends"+
    friends.toString()+",cities:" +cities.toString()+",score:"+score.toString()+
    ",properties:"+dbParams.toString()+"password:"+password+"]");
    }
    /**
     * map的遍歷
     */
    public void showMap(){
        Set<Entry<String,Integer>> map = score.entrySet();
        for(Entry<String,Integer> e : map) {
            System.out.println(e.getKey()+e.getValue());
        }
    }

    /**
     * protries的遍歷
     */
    public void showProp(){
        Set<Object> keys = dbParams.keySet();
        for(Object o : keys) {
            System.out.println(dbParams.get(o));
        }
    }

}

自動裝配(bean對象注入簡配)
autowire:
byName:按名稱匹配，beanid名與setXXX名字匹配植入，否則不注入
byType:按類型匹配，bean的class與類型待注入的bean屬性類型一致時注入，否則不注入

<!-- 自動裝配,autowire：byName根據名稱,byType根據類型,不寫默認會自動裝配，但可讀性很差 -->
<!-- 自動裝配的bean的id需要和待注入的bean的屬性name一致,注入的名字需要和set方法的名字一致(不含set，首字母小寫) -->
<!-- byType和名字沒關係，根據類型自動裝配 -->
<!-- 但是byType的bean中有相同類型的bean出現則會出錯,而且還要以單例模式聲明要注入的bean -->
<bean id="student" class="model.Student" autowire="byName">
    <property name="name" value="haydn"></property>
</bean>