1. DI
Dependency Injection，依赖注入。当对象里有属性或对象的时候，就需要为这些属性或对象赋值
2. 流程
这里介绍两种方式
- set方法
- 注解方式
2.1 set方法
Bean准备
package bean;
import bean.Question;
public class User {
private String name;
private String email;
private String password;
private Question question;
/**
* 省略了getters/setters
* @author Howl
*/
//set方法
public void setQuestion(Question question) {
this.question = question;
}
//构造函数
public User(String name, String email, String password) {
super();
this.name = name;
this.email = email;
this.password = password;
}
}
package bean;
import java.sql.Timestamp;
import java.util.Date;
public class Question {
private int id;
private Timestamp time;
private String content;
/**
* 省略了getters/setters
* @author Howl
*/
//构造函数
public Question(int id, Timestamp time, String content) {
super();
this.id = id;
this.time = time;
this.content = content;
}
}
applictionContext.xml配置
<!--创建User对象-->
<bean id="User" class="User">
<!-- 依赖注入,setting自动注入 -->
<property name="Question" ref="Question"/>
</bean>
<!--创建Question对象-->
<bean id="Question" class="Question"></bean>
获取对象
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
//直接获取
User user = ac.getBean("User");
2.2 注解方式
注解准备
package bean;
import bean.Question;
@Component
public class User {
private String name;
private String email;
private String password;
private Question question;
/**
* 省略了getters/setters
* @author Howl
*/
//set方法
@Autowired
public void setQuestion(Question question) {
this.question = question;
}
//构造函数
public User(String name, String email, String password) {
super();
this.name = name;
this.email = email;
this.password = password;
}
}
获取对象
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
//直接获取
User user = ac.getBean("User");