spring的依賴注入是指在spring創建對象的過程中,將對象的依賴屬性通過配置進行注入,我們先寫個bean:
public class User {
private String username;
private String password;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User [username=" + username + ", password=" + password + "]";
}
}
bean寫好了,我們繼續寫配置文件:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--id是bean的唯一標識-->
<bean id="user" class="com.adwo.User">
<!--name是對象的屬性名-->
<!--value是對該屬性設置值-->
<property name="password" value="3344"></property>
</bean>
</beans>
下面寫測試用例:
public static void main(String[] args) {
String path="beans.xml";
ApplicationContext app = new ClassPathXmlApplicationContext(path);
User user =(User) app.getBean("user");
user.setUsername("33");
System.out.println(user);
}
//打印
User [username=33, password=3344]
在這裏我們可以看到打印的語句,既包含了我們手動設置的user.setUsername(“33”);也包含了在配置文件中的,也就是說配置文件中的property的作用就是user.setPassword(“3344”);