第二章spring

ApplicationContext与BeanFactory区别

BeanFactory 采取延迟加载，第一次getBean时才会初始化Bean
ApplicationContext是对BeanFactory扩展，提供了更多功能（直接创建了对象）国际化处理，事件传递，Bean自动装配，各种不同应用层的Context实现

依赖注入概述

三种形式：构造函数注入，属性注入（常用），接口注入（并未实现）

构造函数注入：

public class C {
    private D d;    
    public C(D d)
    {
        this.d = d;
    }
    public void test()
    {
        System.out.println(d);
    }
}

public class D {

}

 <!-- 构造函数注入 -->
     <bean id="c" class="com.fcx.test.C">
        <!-- 构造器注入定义变量 名字 ，ref也是名，构造器里面名 -->
       <constructor-arg name="d" ref="d"></constructor-arg>
       <!--  <property name="d" ref="d"></property> -->
   </bean>

    @Test
    public void test4()
    {
        //启动String的容器
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //从容器获取A对象
        C c = context.getBean(C.class);
        c.test();
    }

值注入：

public class ValueInject {
    
    private String username;
    private String password;
      public void setUsername(String username) {
        this.username = username;
    }
    public void setPassword(String password) {
        this.password = password;
    }
        public void showInfo() {
        System.out.println(username);
        System.out.println(password);
    }
}

<bean id="valueInjection" class="com.fcx.test.ValueInject">
<property name="username" value="root"></property>
<property name="password" value="root"></property>
</bean>

    @Test
    public void test5()
    {
        //1.启动spring的容器
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从容器获取A对象
        ValueInject v = context.getBean(ValueInject.class);
        
        v.showInfo();
    }

集合注入：

public class ValueInject {
    
    private String username;
    private String password;
    private List<String> list;
    private Set<String> set;
    private HashMap<String, String> map;
    //p里都是名值对,还可以直接读取.propertis文件
    private Properties p;
    

    public void setList(List<String> list) {
        this.list = list;
    }
    public void setSet(Set<String> set) {
        this.set = set;
    }
    public void setMap(HashMap<String, String> map) {
        this.map = map;
    }
    public void setP(Properties p) {
        this.p = p;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
    //java8新特性
    public void showInfo()
    {
        System.out.println(username);
        System.out.println(password);
        //遍历list
        /*for(String str:list)
        {
            System.out.println(str);
        }*/
        list.forEach(str->{
            System.out.println(str);
        });
    
        //遍历set
        /*for(String str:set)
        {
            System.out.println(str);
        }*/     
        set.forEach(str->{
            System.out.println(str);
        });
        //遍历map
        /*Set<Entry<String, String>> entries =  map.entrySet();
        for(Entry<String, String> entry: entries)
        {
            System.out.println(entry.getKey()+"\t"+entry.getValue());   
        }*/
        
        map.forEach((k,v)->{            
            System.out.println(k+"\t"+v);           
        });

        //遍历p
        /*Set<Entry<Object, Object>> items = p.entrySet();
        for(Entry<Object, Object> item: items)
        {
            System.out.println(item.getKey()+"\t"+item.getValue());
        }*/
        
        p.forEach((k,v)->{
            System.out.println(k+"\t"+v);
        });
        
    }
}

   <bean id="valueInjection" class="com.fcx.test.ValueInject">
        <property name="username" value="root"></property>
        <property name="password" value="root"></property>
        <property name="list">
            <list>
                <value>aa</value>
                <value>bb</value>
                <value>cc</value>
            </list>
        </property>
         <property name="set">
            <list>
                <value>ee</value>
                <value>ff</value>
                <value>gg</value>
            </list>
        </property>
         <property name="map">
            <map>
                <entry key="driver" value="com.mysql.driver">
                </entry>
                <entry key="username" value="root">
                </entry>
                <entry key="password" value="root">
                </entry>
            </map>
        </property>
        <property name="p">
            <props>
               <prop key="driver">com.mysql.driver</prop>
               <prop key="username">root</prop>
               <prop key="password">root</prop>
            </props>
        </property>
   </bean>

    @Test
    public void test5()
    {
        //1.启动spring的容器
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从容器获取A对象
        ValueInject v = context.getBean(ValueInject.class);
        
        v.showInfo();
    }