spring的DI(依赖注入)

依赖注入(Dependency Injection)：在Spring创建这个对象的过程中，将这个对象所依赖的属性注入进去。（依赖关系的管理以后都交给spring来维护，在当前类需要用到其他类的对象，由spring为我们提供，我们只需要在配置文件中说明。依赖关系的维护，就称之为依赖注入）

依赖注入的能注入的数据：

• 基本类型和String
• 其他bean类型（在配置文件中或者注解配置过的bean）
• 复杂类型/集合类型

注入的方式：

1. 使用构造函数提供
2. 使用set方法提供
3. 使用注解提供

构造函数：

public interface AccountService {
    void saveAccount();
}
public class AccountServiceImpl implements AccountService {

    private String name;
    private Integer age;
    private Date birthday;

    public AccountServiceImpl(String name, Integer age, Date birthday) {
        this.name = name;
        this.age = age;
        this.birthday = birthday;
    }

    public void saveAccount() {
        System.out.println("service中的saveAccount方法执行了。。。"+name+","+age+","+birthday);
    }
}
public class Client {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        AccountService as = (AccountService) ac.getBean("accountService");
        as.saveAccount();
    }
}

使用set方法提供：

public interface AccountService {
    void saveAccount();
}
public class AccountServiceImpl implements AccountService {

    private String name;
    private Integer age;
    private Date birthday;

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public void saveAccount() {
        System.out.println("service中的saveAccount方法执行了。。。"+name+","+age+","+birthday);
    }
}
public class Client {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        AccountService as = (AccountService) ac.getBean("accountService");
        as.saveAccount();
    }
}

    
        
            
                AAA
            
        
        
            
                HELLO
                WORLD
            
        
        
            
                AAA
                BBB
                CCC
            
        
        
            
                
                
            
        
        
            
        
    

public interface AccountService {
    void saveAccount();
}
public class AccountServiceImpl3 implements AccountService {

    private String[] myStrs;
    private List myList;
    private Set mySet;
    private Map myMap;
    private Properties myProps;

    public void setMyStrs(String[] myStrs) {
        this.myStrs = myStrs;
    }

    public void setMyList(List myList) {
        this.myList = myList;
    }

    public void setMySet(Set mySet) {
        this.mySet = mySet;
    }

    public void setMyMap(Map myMap) {
        this.myMap = myMap;
    }

    public void setMyProps(Properties myProps) {
        this.myProps = myProps;
    }


    public void saveAccount() {
        System.out.println(Arrays.toString(myStrs));
        System.out.println(myList);
        System.out.println(mySet);
        System.out.println(myMap);
        System.out.println(myProps);
    }
}
public class Client {
    public static void main(String[] args) {
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        AccountService as = (AccountService) ac.getBean("accountService3");
        as.saveAccount();
    }
}