RESTEasy 文件上传 - HTML 表单示例 - 《HowToDoInJava 中文系列教程》

原文： https://howtodoinjava.com/resteasy/jax-rs-resteasy-file-upload-html-form-example/

在上一篇文章中，我们了解了有关在 JAX-RS RESTEasy 应用中上传文件的信息，其中使用HttpClient库构建了客户端来上传文件。该客户端是纯 Java 客户端，没有任何 UI 关联。在这篇文章中，我将构建相同的上传功能，但是这次，我们将有一个与之交互的 UI。

我们将文件上传到服务器的 UI 如下所示。

RESTEasy 文件上传 - HTML 表单示例 - 图1

JAX-RS RESTeasy 文件上传示例

让我们逐步制作应用：

1）使用 Maven 创建一个 Eclipse Web 项目进行依赖项管理

在此处学习操作方法

2）更新pom.xml中的项目依赖项

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.howtodoinjava</groupId>
  <artifactId>RESTfulDemoApplication</artifactId>
  <packaging>war</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>RESTfulDemoApplication Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <repositories>
       <repository>
      <id>jboss</id>
      <url>http://repository.jboss.org/maven2</url>
       </repository>
  </repositories>
  <dependencies>
      <!-- Junit support -->
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <!-- core library -->
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
         <artifactId>resteasy-jaxrs</artifactId>
        <version>2.3.1.GA</version>
    </dependency>
    <dependency>
        <groupId>net.sf.scannotation</groupId>
        <artifactId>scannotation</artifactId>
        <version>1.0.2</version>
    </dependency>
    <!-- JAXB provider -->
   <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>resteasy-jaxb-provider</artifactId>
        <version>2.3.1.GA</version>
    </dependency>    
    <!-- Multipart support -->
    <dependency>
        <groupId>org.jboss.resteasy</groupId>
        <artifactId>resteasy-multipart-provider</artifactId>
        <version>2.3.1.GA</version>
    </dependency>
    <!-- For better I/O control -->
    <dependency>
        <groupId>commons-io</groupId>
        <artifactId>commons-io</artifactId>
        <version>2.0.1</version>
    </dependency>
  </dependencies>
  <build>
    <finalName>RESTfulDemoApplication</finalName>
  </build>
</project>

3）更新web.xml文件以映射有效的 REST API

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
      <display-name>Archetype Created Web Application</display-name>
      <!-- Auto scan REST service -->
    <context-param>
        <param-name>resteasy.scan</param-name>
        <param-value>true</param-value>
    </context-param>
    <listener>
      <listener-class>
         org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
      </listener-class>
   </listener>
    <servlet>
        <servlet-name>resteasy-servlet</servlet-name>
        <servlet-class>
            org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
        </servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>resteasy-servlet</servlet-name>
        <url-pattern>/rest-ws/*</url-pattern>
    </servlet-mapping>
</web-app>

4）使用所需的用户界面更新index.jsp文件

<html>
    <body>
        <h1>JAX-RS File Upload Example</h1>
        <form action="rest-ws/upload-file" method="post" enctype="multipart/form-data">
            <p>
                File name : <input type="text" name="fileName" />
            </p>
            <p>
                Choose the file : <input type="file" name="selectedFile" />
            </p>
            <input type="submit" value="Upload" />
        </form>
        https://www.howtodoinjava.com
    </body>
</html>

5）创建具有映射到 HTML 表单的字段的FileUploadForm

package com.howtodoinjava.client.upload;
import javax.ws.rs.FormParam;
import org.jboss.resteasy.annotations.providers.multipart.PartType;
public class FileUploadForm {
    public FileUploadForm() {
    }
    private byte[] fileData;
    private String fileName;
    public String getFileName() {
        return fileName;
    }
    @FormParam("fileName")
    public void setFileName(String fileName) {
        this.fileName = fileName;
    }
    public byte[] getFileData() {
        return fileData;
    }
    @FormParam("selectedFile")
    @PartType("application/octet-stream")
    public void setFileData(byte[] fileData) {
        this.fileData = fileData;
    }
}

6）创建具有处理上传文件逻辑的 RESTful API

package com.howtodoinjava.client.upload;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.Response;
import org.jboss.resteasy.annotations.providers.multipart.MultipartForm;
@Path("/rest-ws")
public class DemoFileSaver_MultipartForm 
{
    @POST
    @Path("/upload-file")
    @Consumes("multipart/form-data")
    public Response uploadFile(@MultipartForm FileUploadForm form) {
        String fileName = form.getFileName() == null ? "Unknown" : form.getFileName() ;
        String completeFilePath = "c:/temp/" + fileName;
        try 
        {
            //Save the file
            File file = new File(completeFilePath);
            if (!file.exists()) 
            {
                file.createNewFile();
            }
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(form.getFileData());
            fos.flush();
            fos.close();
        } 
        catch (IOException e)
        {
            e.printStackTrace();
        }
        //Build a response to return
        return Response.status(200)
            .entity("uploadFile is called, Uploaded file name : " + fileName).build();
    }
}

7）测试应用

祝您学习愉快！