如何在Spring MVC应用程序中显示上传的图像

Question

如何在Spring MVC应用程序中显示上传的图像

我有Spring MVC应用程序,我想将用户图像上传到resources/uploads文件夹中.显然,我想在我的网站上提供服务.但是当我试图sample.png放入resources文件夹时,仅仅是出于测试目的,网络服务器回答了"not found".我重新建立项目和图片变得可访问.我删除了图片,它仍然可以访问.我重新构建项目和服务器应答它应该("未找到").

这个奇怪的行为是什么？资源是否被构建到最终的jar文件中？这是否意味着,在重建项目之前,所有上传的用户图片都无法访问？如果是这样,我完全不应该将上传的文件放到资源文件夹中,那么我应该在哪里放置它们？为什么会这样,我该如何服务这些照片？

非常感谢你.

context.xml中:

<!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->

    <!-- Enables the Spring MVC @Controller programming model -->
    <annotation-driven>
        <message-converters>
          <beans:bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
              <beans:property name="objectMapper" ref="customObjectMapper"/>
          </beans:bean>
      </message-converters>
    </annotation-driven>

    <!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
    <resources mapping="/resources/**" location="/resources/" />


    <!-- mustache.java -->
    <beans:bean id="viewResolver" class="org.springframework.web.servlet.view.mustache.MustacheViewResolver">
        <beans:property name="cache" value="false" />
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".mustache" />
        <beans:property name="templateLoader">
            <beans:bean class="org.springframework.web.servlet.view.mustache.MustacheTemplateLoader" />
        </beans:property>
    </beans:bean>


    <!-- Standard template engine -->
    <!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
    <!--
    <beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <beans:property name="prefix" value="/WEB-INF/views/" />
        <beans:property name="suffix" value=".jsp" />
    </beans:bean>
    -->

    <context:component-scan base-package="com.me.myproject" />


    <!-- JDBC Data Source. It is assumed you have MySQL running on localhost port 3306 with 
       username root and blank password. Change below if it's not the case -->
      <beans:bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <beans:property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <beans:property name="url" value="jdbc:mysql://localhost:3306/myproject"/>
    <beans:property name="username" value="someone"/>
    <beans:property name="password" value="something"/>
    <beans:property name="validationQuery" value="SELECT 1"/>
  </beans:bean>


  <!-- FlyWay -->
  <beans:bean id="flyway" class="com.googlecode.flyway.core.Flyway" init-method="migrate">
    <beans:property name="dataSource" ref="myDataSource"/>
  </beans:bean>

  <!-- Hibernate Session Factory -->
  <beans:bean id="mySessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean" depends-on="flyway">
    <beans:property name="dataSource" ref="myDataSource"/>
    <beans:property name="packagesToScan">
      <beans:array>
        <beans:value>com.me.myproject</beans:value>
      </beans:array>
    </beans:property>
    <beans:property name="hibernateProperties">
        <beans:value>
           hibernate.dialect=org.hibernate.dialect.MySQLDialect
          hibernate.hbm2ddl.auto=validate
        </beans:value>
      </beans:property>
    </beans:bean>

  <!-- Hibernate Transaction Manager -->
  <beans:bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <beans:property name="sessionFactory" ref="mySessionFactory"/>
  </beans:bean>

  <!-- Activates annotation based transaction management -->
  <tx:annotation-driven transaction-manager="transactionManager"/>


</beans:beans>

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web.xml中:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">





    <!-- The definition of the Root Spring Container shared by all Servlets and Filters -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/root-context.xml</param-value>
    </context-param>

    <!-- Creates the Spring Container shared by all Servlets and Filters -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- Processes application requests -->
    <servlet>
        <servlet-name>appServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>appServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

</web-app>

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Answer 1

Lor*_*ton 11

这是一个准备好使用的图像上传/下载控制器,完全用于此目的:

首先,我们需要通过简单的表单(admin.jsp)上传图像:

 <form method="POST" action="uploadFile" enctype="multipart/form-data">
    File to upload: <input type="file" name="file" >
    <br />
    Name: <input type="text" name="name" >
    <br />
    <br />
    <input type="submit" value="Upload">
</form>
<c:if test="${not empty message}">
    ${message} <!-- here would be a message with a result of processing -->
</c:if>

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现在我们需要一个控制器,它可以将图像上传到服务器并在以后的jsp页面显示它们:

package com.pizza.controllers;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;

@Controller
public class FileUploadController {

    private static final String PIZZA_IMAGES = "pizzaImages";
    private static final String TOMCAT_HOME_PROPERTY = "catalina.home";
    private static final String TOMCAT_HOME_PATH = System.getProperty(TOMCAT_HOME_PROPERTY);
    private static final String PIZZA_IMAGES_PATH = TOMCAT_HOME_PATH + File.separator + PIZZA_IMAGES;

    private static final File PIZZA_IMAGES_DIR = new File(PIZZA_IMAGES_PATH);
    private static final String PIZZA_IMAGES_DIR_ABSOLUTE_PATH = PIZZA_IMAGES_DIR.getAbsolutePath() + File.separator;

    private static final String FAILED_UPLOAD_MESSAGE = "You failed to upload [%s] because the file because %s";
    private static final String SUCCESS_UPLOAD_MESSAGE = "You successfully uploaded file = [%s]";

    @RequestMapping(value = "/uploadFile", method = RequestMethod.POST)
    public ModelAndView uploadFileHandler(@RequestParam("name") String name,
                                      @RequestParam("file") MultipartFile file) {
        ModelAndView modelAndView = new ModelAndView("admin");

        if (file.isEmpty()) {
            modelAndView.addObject("message", String.format(FAILED_UPLOAD_MESSAGE, name, "file is empty"));
        } else {
            createPizzaImagesDirIfNeeded();
            modelAndView.addObject("message", createImage(name, file));
        }

        return modelAndView;
    }

    private void createPizzaImagesDirIfNeeded() {
        if (!PIZZA_IMAGES_DIR.exists()) {
            PIZZA_IMAGES_DIR.mkdirs();
        }
    }

    private String createImage(String name, MultipartFile file) {
        try {
            File image = new File(PIZZA_IMAGES_DIR_ABSOLUTE_PATH + name);
            BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(image));
            stream.write(file.getBytes());
            stream.close();

            return String.format(SUCCESS_UPLOAD_MESSAGE, name);
        } catch (Exception e) {
            return String.format(FAILED_UPLOAD_MESSAGE, name, e.getMessage());
        }
    }

    @RequestMapping(value = "/image/{imageName}")
    @ResponseBody
    public byte[] getImage(@PathVariable(value = "imageName") String imageName) throws IOException {
        createPizzaImagesDirIfNeeded();

        File serverFile = new File(PIZZA_IMAGES_DIR_ABSOLUTE_PATH + imageName + ".jpg");

        return Files.readAllBytes(serverFile.toPath());
    }

}

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现在让我们测试一下我们的上传功能.选择图像并为其指定名称(包括扩展名).稍后(Upload按钮点击后)此图像将显示在{Tomcat.dir}/pizzaImages文件夹中:

让我们检查图像显示功能.为此,我们只需要<img>在我们需要显示图像的平台中包含一个标记(这就是Spring MVC的工作原理):

<img src="/image/11" />

PS所以你看,它很简单.

Answer 2

gip*_*ani 2

您必须将文件保存到外部文件夹中。

例如，我创建一个类似的目录/home/webappFolder/，并在其中创建一些其他子目录。例如，我存储上传数据的存储库目录..我放置 jasper 报告文件的报告子目录..等

/home/webappFolder/repo
/home/webappFolder/report
/home/webappFolder/logs

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正如您可以在问题中发布的 xml 中看到的那样：

<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->

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在资源中，您提供静态资源。

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