在配置類中使用@PropertySource注解讀取外部的資源配置文件：
使用@Value注入表達式：
1.注入普通字符
@Value("注入普通字符")
2.注入操作系統屬性
@Value(#{SystemProperties['os.name']})
3.表達式
@Value(#T(java.lang.Math).random()*100.0)
4.其他Bean的屬性
@Value("#{其他Bean的name.其他Bean的屬性}")
5. 文件資源
@Value("classpath:其他文件的路徑")
6.網址資源
@Value("www.baidu.com")
7.其他配置文件的屬性,注意這個使用$，而不是#
@Value("${book.name}")
test.properties
1 book.author=zhangsan 2 book.name=spring boot
test.txt中文本任意
配置類SpringConfig.java
package config; import org.apache.commons.io.IOUtils; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.*; import org.springframework.core.env.Environment; import org.springframework.core.io.Resource; import repository.dao.UserDAO; import service.DemoService; import service.FunctionService; import service.UseFunctionService; import java.io.IOException; @Configuration @ComponentScan(basePackages = "main.java.com.example.demo") @PropertySource(value={"test.properties"}) public class SpringConfig { @Bean // 通過該注解來表明是一個Bean對象，相當於xml中的<bean> public DemoService demoService(){ return new DemoService(); // 直接new對象做演示 } @Value("注入普通字符串")// 注入普通字符串 private String normal; @Value("#{systemProperties['os.name']}")// 注入操作系統屬性 private String osName; @Value("#{T(java.lang.Math).random() * 100.0 }")// 注入表達式結果 private double randomNumber; @Value("#{demoService.another}")// 注入其他Bean屬性 private String fromAnother; @Value("classpath:test.txt")// 注入文件資源 private Resource testFile; @Value("https://www.baidu.com")// 注入網址資源 private Resource testUrl; @Value("${book.name}")// 注入配置文件【注意是$符號】 private String bookName; @Autowired// Properties可以從Environment獲得 private Environment environment;//屬性文件 @Override public String toString() { try { return "ELConfig [normal=" + normal + ", osName=" + osName + ", randomNumber=" + randomNumber + ", fromAnother=" + fromAnother + ", testFile=" + IOUtils.toString(testFile.getInputStream()) + ", testUrl=" + IOUtils.toString(testUrl.getInputStream()) + ", bookName=" + bookName + ", environment=" + environment.getProperty("book.name") + "]"; } catch (IOException e) { e.printStackTrace(); return null; } } }
測試類
1 import config.SpringConfig; 2 import org.springframework.context.annotation.AnnotationConfigApplicationContext; 3 import repository.entity.User; 4 import service.DemoService; 5 import service.UseFunctionService; 6 import service.UserService; 7 8 import java.util.List; 9 10 public class Main { 11 12 public static void main(String[] args) { 13 // 通過Java配置來實例化Spring容器 14 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class); 15 16 SpringConfig config=context.getBean(SpringConfig.class); 17 System.out.println(config.toString()); 18 // 銷毀該容器 19 context.destroy(); 20 } 21 }
輸出結果
SpringConfig [
normal=注入普通字符串,
osName=Windows 10,
randomNumber=90.51228169713467,
fromAnother=其他類的屬性,
testFile=測試文本,
testUrl=<!DOCTYPE html> //百度登錄首頁的html文本
信息: Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@728938a9: startup date [Thu Dec 07 15:55:23 CST 2017]; root of context hierarchy
<!--STATUS OK--><html> <head><meta http-equiv=content-type content=text/html;charset=utf-8><meta http-equiv=X-UA-Compatible content=IE=Edge><meta content=always name=referrer><link rel=stylesheet type=text/css href=https://ss1.bdstatic.com/5eN1bjq8AAUYm2zgoY3K/r/www/cache/bdorz/baidu.min.css><title>百度一下，你就知道</title></head> <body link=#0000cc> <div id=wrapper> <div id=head> <div class="head_wrapper"> <div class="s_form"> <div class="s_form_wrapper"> <div id=lg> <img hidefocus=true src=//www.baidu.com/img/bd_logo1.png width=270 height=129> </div> <form id=form name=f action=//www.baidu.com/s class="fm"> <input type=hidden name=bdorz_come value=1> <input type=hidden name=ie value=utf-8> <input type=hidden name=f value=8> <input type=hidden name=rsv_bp value=1> <input type=hidden name=rsv_idx value=1> <input type=hidden name=tn value=baidu><span class="bg s_ipt_wr"><input id=kw name=wd class="s_ipt" value maxlength=255 autocomplete=off autofocus=autofocus></span><span class="bg s_btn_wr"><input type=submit id=su value=百度一下 class="bg s_btn" autofocus></span> </form> </div> </div> <div id=u1> <a href=http://news.baidu.com name=tj_trnews class="mnav">新聞</a> <a href=https://www.hao123.com name=tj_trhao123 class="mnav">hao123</a> <a href=http://map.baidu.com name=tj_trmap class="mnav">地圖</a> <a href=http://v.baidu.com name=tj_trvideo class="mnav">視頻</a> <a href=http://tieba.baidu.com name=tj_trtieba class="mnav">貼吧</a> <noscript> <a href=http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u=http%3A%2F%2Fwww.baidu.com%2f%3fbdorz_come%3d1 name=tj_login class="lb">登錄</a> </noscript> <script>document.write('<a href="http://www.baidu.com/bdorz/login.gif?login&tpl=mn&u='+ encodeURIComponent(window.location.href+ (window.location.search === "" ? "?" : "&")+ "bdorz_come=1")+ '" name="tj_login" class="lb">登錄</a>');
</script> <a href=//www.baidu.com/more/ name=tj_briicon class="bri" style="display: block;">更多產品</a> </div> </div> </div> <div id=ftCon> <div id=ftConw> <p id=lh> <a href=http://home.baidu.com>關於百度</a> <a href=http://ir.baidu.com>About Baidu</a> </p> <p id=cp>©2017 Baidu <a href=http://www.baidu.com/duty/>使用百度前必讀</a> <a href=http://jianyi.baidu.com/ class="cp-feedback">意見反饋</a> 京ICP證030173號 <img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>
bookName=spring boot,
environment=spring boot]