【Spring 框架 03】DI 依赖注入，spring 菜鸟教程 pdf

public class AccountDao {

public void add(){

System.out.println("AccountDao.add>>>>>>>>>");

}

}

3.spring.xml 配置

标签内 name 表示传入参数的名字

标签内 ref 表示中的 id

<?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="accountDao" class="com.lcySpring.dao.AccountDao"></bean>

<bean id="accountService" class="com.lcySpring.service.AccountService">

<constructor-arg name="accountDao" ref="accountDao"></constructor-arg>

</bean>

</beans>

三.p 标签和 c 标签

1.简化< property >使用 p 标签

这里我们创建一个类存在 set 方法

public class UserService {

private String username;

private int age;

public void show(){

System.out.println("姓名："+username+" 年龄："+age);

}

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

}

配置 spring.xml 为变量赋值

<?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="userService" class="com.lcySpring.service.UserService">

<property name="username" value="mlrcj"></property>

<property name="age" value="21"></property>

</bean>

</beans>

通过设置 value 属性成功传入参数

但是这样写太麻烦了我们可以使用 p 标签

在 spring.xml 中配置命名空间加入 p 插件功能(p:是写在< bean >里面的)

<?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="userService" class="com.lcySpring.service.UserService"

p:username="lmrcj"

p:age="21"

</bean>

</beans>

2.简化< constructor-arg >使用 c 标签

和 p 标签的功能差不多，但是它还可以提供索引赋值

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:c="http://www.springframework.org/schema/c"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans.xsd">

<bean id="accountService" class="com.lcySpring.service.AccountService"

c:aname="aaaaaaaaaaa"

c:money="100000000000"

</bean>

<bean id="accountService02" class="com.lcySpring.service.AccountService"

c:_0="bbbbbbbbbbbbbb"

c:_1="10000000000000"

</bean>

关于 Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/c]报错

可以参考这篇文章

文章链接

四.集合注入

1.集合 list 注入

构建一个含集合的 java 类

public class CollectionService {

private List list;

p

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ublic void setList(List list) {

this.list = list;

}

public void show(){

System.out.println(list);

}

}

配置 xml 文件

<?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="collectionService" class="com.lcySpring.service.CollectionService">

<property name="list">

<list>

<value>a</value>

<value>b</value>

<value>c</value>

<value>d</value>

</list>

</property>

</bean>

</beans>

编写测试类，检测成功注入

2.集合 set 注入

直接将 xml 中 list 配置改为 set 就好了

<?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="collectionService" class="com.lcySpring.service.CollectionService">

<property name="set">

<set>

<value>a</value>

<value>b</value>

<value>c</value>

<value>d</value>

</set>

</property>

</bean>

</beans>

3.map 类型属性注入