Spring入门（二）——DI
- 2020 年 3 月 11 日
- 笔记
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");
