如何在webapp文件夹中上传图像

问题描述

我正在尝试使用ServletContext将图像文件上传到/webapp/foto/上的文件夹照片，但是每次我遇到NullPointerExceptions

I'm trying to upload image files to folder photos on /webapp/foto/ using ServletContext, but every time I got NullPointerExceptions

我该怎么做?

这是UploadFile.class，其中NPE在CONTAINER_ROOT变量上上升.

Here is the UploadFile.class where NPE is rising on CONTAINER_ROOT variable.

@Component
public class UploadFile {

    @Autowired
    HttpServletRequest httpServletRequest;

    private String CONTAINER_ROOT = httpServletRequest.getSession().getServletContext().getRealPath("/");

    private String DIR_NAME = "foto";

    private String UPLOAD_DIR = CONTAINER_ROOT + File.separator + DIR_NAME;

    private Logger logManager = LogManager.getLogger(this.getClass());


    public String getUploadedPath(MultipartFile file) {
        return upload(file);
    }

    private String upload(MultipartFile file) {

        if (!file.isEmpty()) try {
            byte[] bytes = file.getBytes();
            String fileName = file.getOriginalFilename();
            File dir = new File(UPLOAD_DIR);

            if (!dir.exists()) dir.mkdirs();

            File fileOnServer = new File(dir.getAbsolutePath() + File.separator + fileName);
            BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(fileOnServer));
            outputStream.write(bytes);
            outputStream.close();

            logManager.warn("UPLOADED FILE LOCATION: " + fileOnServer.getAbsolutePath());

            return fileOnServer.getPath();
        }
        catch (IOException e) {
            logManager.error("Error trying to upload file to location, or file is empty!", e.getMessage());
        }
        return null;
    }

}

这就是我在Controller上使用的方式:

And this is how I use on Controller:

Foto savedFoto = this.fotoRepository.save(new Foto(this.uploadFile.getUploadedPath(file)，savedImovel));

Stacktrace:

The Stacktrace:

    Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [br.com.agenciadsw.morenoimoveis.util.UploadFile]: Constructor threw exception; nested exception is java.lang.NullPointerException
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:164)
28-Aug-2014 11:02:16.409 WARNING [RMI TCP Connection(2)-127.0.0.1] org.apache.catalina.loader.WebappClassLoader.clearReferencesJdbc The web application [] registered the JDBC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1069)
    ... 71 more
Caused by: java.lang.NullPointerException
    at br.com.agenciadsw.morenoimoveis.util.UploadFile.<init>(UploadFile.java:26)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
    at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:148)
    ... 73 more

这里是 web.xml :

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
            http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <display-name>MorenoImoveis</display-name>


        <servlet>
            <servlet-name>dispacher</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            <init-param>
                <param-name>contextClass</param-name>
                <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
            </init-param>
            <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                br.com.agenciadsw.morenoimoveis.cfg.PersistenceConfigurer
                br.com.agenciadsw.morenoimoveis.cfg.SecurityConfigurer
                br.com.agenciadsw.morenoimoveis.cfg.WebMvcConfigurer
            </param-value>
        </init-param>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispacher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            br.com.agenciadsw.morenoimoveis.cfg.PersistenceConfigurer
            br.com.agenciadsw.morenoimoveis.cfg.SecurityConfigurer
            br.com.agenciadsw.morenoimoveis.cfg.WebMvcConfigurer
        </param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>


    <filter>
        <filter-name>encodingFilter</filter-name>
        <filter-class>org.springframework.web.filter.CharacterEncodingFilter
        </filter-class>
        <init-param>
            <param-name>encoding</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>encodingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

推荐答案

您可以将图像上传到项目外部的文件夹中.我有用的几张图片

You could upload image in folder outside the project. I useful for several image

try {
            byte[] bytes = file.getBytes();

            // Creating the directory to store file
            File dir = new File(Utils.getFolderStoreImage(request.getSession().getServletContext().getRealPath("/")));
            if (!dir.exists())
                dir.mkdirs();
            // Create the file on server
            serverFile = new File(Utils.getFolderStoreImage(request.getServletContext().getRealPath("/"))+System.currentTimeMillis()+"-"+UUID.randomUUID().toString()+".jpg");
            BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(serverFile));
            stream.write(bytes);
            stream.close();
        } catch (Exception e) {
            result.rejectValue("image", "error when upload image");
            return "product/add";
        }

Utils.java

Utils.java

public class Utils {
public static String getFolderStoreImage(String webContentRoot) {
    if (webContentRoot.endsWith("\\")){
        webContentRoot = webContentRoot.substring(0,webContentRoot.length() - 1);
        }
    String folder = webContentRoot.substring(0, webContentRoot.lastIndexOf("\\") + 1) + "upload\\";
    return folder;
}

}

这篇关于如何在webapp文件夹中上传图像的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！