Spring EL

百聯達發表於2017-02-16
Spring
一:說明

Spring EL-Spring表示式語言，支援在xml和註解中使用表示式，類似於JSP的EL表示式語言。

Spring 開發中經常涉及呼叫各種資源的情況，包含普通檔案，網址，配置檔案，系統環境變數等。 我們可以使用Spring的表示式語言實現資源的注入。

二：程式碼例項


點選(此處)摺疊或開啟

  1. @Service
  2. public class DemoService {
  3.     @Value("其他類的屬性")
  4.     private String another;

  6.     /**
  7.      * @return the another
  8.      */
  9.     public String getAnother() {
  10.         return another;
  11.     }

  13.     /**
  14.      * @param another
  15.      * the another to set
  16.      */
  17.     public void setAnother(String another) {
  18.         this.another = another;
  19.     }

  21. }


點選(此處)摺疊或開啟

  1. @Configuration
  2. @ComponentScan("com.gemdale")
  3. @PropertySource("classpath:com/gemdale/gmap/spring/boot/demo/el/test.properties")
  4. public class ElConfig {
  5.     @Value("I love youe!")
  6.     private String normal;

  8.     @Value("#{systemProperties['os.name']}")
  9.     private String osName;

  11.     @Value("#{ T(java.lang.Math).random() * 100.0 }")
  12.     private double randomNumber;

  14.     @Value("#{demoService.another}")
  15.     private String fromAnother;

  17.     @Value("classpath:com/gemdale/gmap/spring/boot/demo/el/test.txt")
  18.     private Resource testFile;

  20.     @Value("")
  21.     private Resource testUrl;

  23.     @Value("${book.name}")
  24.     private String bookName;

  26.     @Autowired
  27.     private Environment environment;

  29.     @Bean
  30.     public static PropertySourcesPlaceholderConfigurer propertyConfigure() {
  31.         return new PropertySourcesPlaceholderConfigurer();
  32.     }

  34.     public void outputResource() {
  35.         try {
  36.             System.out.println(normal);
  37.             System.out.println(osName);
  38.             System.out.println(randomNumber);
  39.             System.out.println(fromAnother);
  40.             System.out.println(IOUtils.toString(testFile.getInputStream()));
  41.             System.out.println(IOUtils.toString(testUrl.getInputStream()));
  42.             System.out.println(bookName);
  43.             System.out.println(environment.getProperty("book.author"));
  44.         }
  45.         catch (Exception e) {
  46.            e.printStackTrace();
  47.         }
  48.     }
  49. }

點選(此處)摺疊或開啟

  1. public class Start {
  2.     public static void main(String[] args) throws Exception {

  4.         AnnotationConfigApplicationContext configApplicationContext = new AnnotationConfigApplicationContext(
  5.                 ElConfig.class);
  6.         ElConfig resourceService = configApplicationContext.getBean(ElConfig.class);
  7.         resourceService.outputResource();

  9.         configApplicationContext.close();
  10.     }
  11. }



點選(此處)摺疊或開啟

  1. book.author=GH
  2. book.name=spring boot


來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/28624388/viewspace-2133687/，如需轉載，請註明出處，否則將追究法律責任。

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