在 Spring Boot 中访问属性文件

Question

我正在创建一个简单的 Spring Boot 应用程序，我试图在其中访问外部 config.properties 文件。

IndexController.java

@Controller
public class IndexController {

    XmlOperation xmlOperation = new XmlOperation();

    @RequestMapping("/")
    public String greeting() {
        return "greeting";
    }

    @RequestMapping(params = "btnOpen", method = RequestMethod.POST)
    public String uploadFile(@RequestParam("file") MultipartFile file, Model model) {
        try {
            InputStream is = file.getInputStream();
            model.addAttribute("fileContent", xmlOperation.readXml(is));
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
        return "greeting";
    }
}

XmlOperation.java

@PropertySource("classpath:config.properties")
public class XmlOperation {

    @Autowired
    Environment env;

    public String readXml(InputStream is) throws IOException {
        System.out.println(env.getProperty("filepath"));
        StringWriter writer = new StringWriter();
        IOUtils.copy(is, writer, StandardCharsets.UTF_8);
        String fileContent = writer.toString();
        return fileContent;

    }

config.properties 文件位于src/main/resources。我无法从属性文件中获取值。

任何帮助将不胜感激......

Answer 1

src/main/resources 中的config.properties 文件还可以，但为什么要初始化：

XmlOperation xmlOperation = new XmlOperation();

在IndexController?而且我也不确定XmlOperation 是否是弹簧组件（问题中只有@PropertySource over XmlOperation）。

基本上我会将XmlOperation 设为spring @Component 并通过IoC 将此组件注入IndexController。

XmlOperation 中的public String readXml(InputStream is) 的行为类似于标准服务，我将创建属性 filepath 并使用 @Value 注释从配置文件 (config.properties) 中注入值。

---

完整示例：

@Controller
public class IndexController {

    @Autowired
    private XmlOperation xmlOperation;

    @RequestMapping("/")
    public String greeting() {
        return "greeting";
    }

    @RequestMapping(params = "btnOpen", method = RequestMethod.POST)
    public String uploadFile(@RequestParam("file") MultipartFile file, Model model) {
        try {
            InputStream is = file.getInputStream();
            model.addAttribute("fileContent", xmlOperation.readXml(is));
        } catch (IOException e) {
            System.out.println(e.getMessage());
        }
        return "greeting";
    }
}

---

@Component
@PropertySource("classpath:config.properties")
public class XmlOperation {

    // use this when XmlOperation is @Configuration bean and you want to create @Bean-s e.g
    // @Autowired
    // Environment env;

    // for your case inject property like this
    @Value("${filepath}")
    private String filepath;

    public String readXml(InputStream is) throws IOException {

        // dont use this
        //System.out.println(env.getProperty("filepath"));

        // rather this
        System.out.println(filepath);

        StringWriter writer = new StringWriter();
        IOUtils.copy(is, writer, StandardCharsets.UTF_8);
        String fileContent = writer.toString();
        return fileContent;

    }
}