Spring学习–3 EL和资源调用
目的:学习掌握EL和资源调用方法。
过程:通过编程学习实现。
工具:Spring tool suit
难度:一颗星
1、同classpath下编写test.txt和test.properties文件,前者内容自定,后者满足格式即可,如:
book.author=Cruise
book.name=spring boot
2、编写Service类
package com.el;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Service;
@Service
public class DemoService {
@Value("类成员属性值")
String member;
public void setMember(String member) {
this.member = member;
}
public String getMember() {
return member;
}
}
3、编写Configuration类
package com.el;
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.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;
@Configuration
@ComponentScan("com.el")
@PropertySource("classpath:com/el/test.properties") //注入配置文件需要使用该注解指定文件地址
public class ELConfig {
@Value("I love you!") //注入普通字符串
private String normal;
@Value("#{systemProperties['os.name']}") // 注入系统属性
private String osName;
@Value("#{T(java.lang.Math).random() * 100.0}") // 注入表达式结果
private double randomNumber;
@Value("#{demoService.member}") // 注入Bean属性
private String member;
@Value("classpath:com/el/test.txt") // 注入文件资源
private Resource testFile;
@Value("http://www.baidu.com") // 注入网络资源
private Resource testUrl;
@Value("${book.name}") // 注入配置文件
private String bookName;
@Autowired
private Environment environment;
/** 注入配置文件test.properties需要使用@PropertySource指定文件地址,若使用@Value注入,则要配置一个
* PropertySourcesPlaceholderConfigurer的Bean
* @return
*/
@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(member);
// 使用IOUtils需要在pom.xml中添加commons-io组件(groupId和artifactId均为commons-io)的依赖,使用该组件将InputStream转换成字符串。
System.out.println(IOUtils.toString(testFile.getInputStream()));
System.out.println(IOUtils.toString(testUrl.getInputStream()));
System.out.println(bookName);
System.out.println(environment.getProperty("book.author"));
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
4、编写启动类进行测试
package com.el;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
public class Bootrap {
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext(ELConfig.class);
ELConfig resourceService = context.getBean(ELConfig.class);
resourceService.outputResource();
context.close();
}
}