@Service用於標注業務層組件 ： 將當前類注冊為spring的Bean
@Controller用於標注控制層組件（如struts中的action）
@Repository用於標注數據訪問組件，即DAO組件
@Component泛指組件，當組件不好歸類的時候，我們可以使用這個注解進行標注。： 將當前類注冊為spring的Bean
實例：
DemoService ：文件：
package ch2.el;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
//注入：當前類是spring管理的一個bean
//等效（可根據需要選擇）:@Service=@Component=@Repository=@Controller
@Service
public class DemoService {
//注入普通字符串
@Value("其他類的屬性")
private String another;
public String getAnother()
{
return another;
}
public void setAnother(String another)
{
this.another = another;
}
}
test.txt文件：
wwwweeebbfddfd
test.propeties文件：
book.author=wangyunfei book.name=spring boot
ResourceConfig文件：
package ch2.el;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
//聲明當前類是一個配置類
@Configuration
//自動掃描ch2.el包下的所有@Service,@Component,@Repository和@Controller注冊為Bean;
@ComponentScan("ch2.el")
public class ResourceConfig {
}
Eiconfig文件：
package ch2.el;
import org.apache.commons.io.IOUtils;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.env.Environment;
import org.springframework.core.io.Resource;
//聲明當前類是一個配置類
@Configuration
//自動掃描包下的所有@Service,@Component,@Repository和@Controller注冊為Bean;
@ComponentScan("ch2.el")
//注入配置文件
@PropertySource("classpath:ch2/el/test.propeties")
public class ElConfig {
//將FunctionService類的實體Bean注入到UseFunctionService中,讓UseFunctionService擁有FunctionService的功能
//等效注解: @Autowire=@Inject=@Resource
//注入文字
@Value("I love you")
private String normal;
//注入操作系統屬性
@Value("#{systemProperties['os.name']}")
private String osName;
//注入表達式結果
@Value("#{ T(java.lang.Math).random() * 100.0 }")
private double randomNumber;
//注入其他Bean屬性
@Value("#{demoService.another}")
private String fromAnother;
//注入文件資源
@Value("classpath:ch2/el/test.txt")
private Resource testFile;
//注入網址資源
@Value("http://www.baidu.com")
private Resource testUrl;
//注入配置文件
@Value("${book.name}")
private String bookName;
//注入配置文件
@Autowired
private Environment environment;
//注入配置文件
@Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigure()
{
return new PropertySourcesPlaceholderConfigurer();
}
public void outputResource()
{
try {
System.out.println(normal);
System.out.println(osName);
System.out.println(randomNumber);
System.out.println(fromAnother);
System.out.println(testFile);
System.out.println(testUrl);
System.out.println(IOUtils.toString(testUrl.getInputStream()));
System.out.println(bookName);
System.out.println(environment.getProperty("book.author"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Main文件：
package ch2.el;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Main {
public static void main(String[] args)
{
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ResourceConfig.class);
ElConfig resourceElconfig = context.getBean(ElConfig.class);
resourceElconfig.outputResource();
context.close();
}
}