spring ioc---基於註解的配置(beans包@Autowired,@Qualifier,@Required,@Value)
| 註解 | 釋義 | 說明 | 原始碼註解說明(包含部分) |
| @Autowired | 自動裝配 | 1,通常在屬性和setter方法上使用 2,註解值required,某些情況可取代@Required,預設值是true. |
Marks a constructor, field, setter method or config method as to be autowired by Spring's dependency injection facilities. This is an alternative to the JSR-330 |
| @Qualifier |
限定符 | 限定注入的bean值 |
This annotation may be used on a field or parameter as a qualifier forcandidate beans when autowiring. It may also be used to annotate other custom annotations that can then in turn be used as qualifiers. |
| @Required | 必需的 | 1,必須注入標註的依賴項 2,通常使用在setter方法上 |
Marks a method (typically a JavaBean setter method) as being 'required': that is, the setter method must be configured to be dependency-injected with a value. |
| @Value | 賦值 | 1,接收String型別,依據標註的型別自動轉換 2,標註的屬性可沒有setter方法 |
Annotation at the field or method/constructor parameter level that indicates a default value expression for the affected argument. |
| @Lookup[✘] | 查詢 | DI中方法注入依賴bean時使用,標記的預設值即依賴的bean名稱 | An annotation that indicates 'lookup' methods, to be overridden by the container to redirect them back to the |
| @Configurable[✘] | 可配置的 | 類級別的註解,與AspectJ註解驅動一起使用 | Marks a class as being eligible for Spring-driven configuration.Typically used with the AspectJ |
備忘,此測試中,只測試註解autowired,qualifier和required,及value.
類物件
package siye;
import java.util.ArrayList;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Required;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component("member")
public class MemberCls
{
// 使用value,可以沒有setter方法.
@Value("jack")
private String name;
@Value("34")
private int age;
@Value("0")
private int sex;
// autowired,qualifier和required的組合使用
// 在屬性的級別上.
@Autowired(required = true)
@Qualifier("arrayList")
private ArrayList<?> list;
public void setList(ArrayList<?> list)
{
this.list = list;
}
public ArrayList<?> getList()
{
return list;
}
// autowired,qualifier和required的組合使用.
// 在setter方法的級別上
private String description;
// @Qualifier("desc")
@Autowired
@Required
public void setDescription(@Qualifier("desc") String description)
{
this.description = description;
}
public String getDescription()
{
return description;
}
@Override
public String toString()
{
return "User [name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
}
配置類
package siye;
import java.util.ArrayList;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan("siye")
public class ConfigClass
{
@Bean("arrayList")
@SuppressWarnings("serial")
public ArrayList<?> getList()
{
return new ArrayList<Integer>()
{
{
add(0);
add(1);
add(2);
}
};
}
@Bean("desc")
public String getDesc()
{
return new String("this's_test_class");
}
}
測試類
package siye;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class UnitTest
{
public static void main(String[] args)
{
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext();
context.register(ConfigClass.class);
context.refresh();
MemberCls obj = context.getBean("member", MemberCls.class);
// autowired,qualifier和required在屬性級別上
System.out.println(obj.getList());
// autowired,qualifier和required在setter方法級別上
System.out.println(obj.getDescription());
// 驗證value註解
System.out.println(obj);
context.close();
}
}