RESTEasy - 文件下载示例

原文： https://howtodoinjava.com/resteasy/resteasy-file-download-example/

RESTEasy 是 JBOSS 提供的 JAX-RS 规范的实现，用于构建 RESTful Web 服务和 RESTful Java 应用。 RESTEasy 与 HTTP 媒体类型结合使用，以特定格式（例如图像，pdf 或文本）提供响应。

为响应而支持多种媒体类型的配置的核心组件是@Produces注解。 可以在此链接中找到此类媒体类型的完整列表。

出于演示目的，我将展示下载一个图像，一个文本和一个 pdf 文件的示例。 同样，您可以构建其他媒体类型（文件类型）。

1）创建一个 Maven 项目

mvn archetype:generate -DgroupId=com.howtodoinjava -DartifactId=RESTfulDemoApplication 
-DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false
mvn eclipse:eclipse -Dwtpversion=2.0

2）更新pom.xml文件中的 jax-rs 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>
    <!-- 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>
  </dependencies>
  <build>
    <finalName>RESTfulDemoApplication</finalName>
  </build>
</project>

3）在@Produces注解中创建具有相应媒体类型的服务类和 API

package com.howtodoinjava.service;
import java.io.File;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.Response.Status;
@Path("/file-management")
public class FileServer
{
    @GET
    @Path("/{fileName}/text")
    @Produces("text/plain")
    public Response getFileInTextFormat(@PathParam("fileName") String fileName) 
    {
        System.out.println("File requested is : " + fileName);
        //Put some validations here such as invalid file name or missing file name
        if(fileName == null || fileName.isEmpty())
        {
            ResponseBuilder response = Response.status(Status.BAD_REQUEST);
            return response.build();
        }
        //Prepare a file object with file to return
        File file = new File("c:/demoTxtFile.txt");
        ResponseBuilder response = Response.ok((Object) file);
        response.header("Content-Disposition", "attachment; filename="howtodoinjava.txt"");
        return response.build();
    }
    @GET
    @Path("/{fileName}/pdf")
    @Produces("application/pdf")
    public Response getFileInPDFFormat(@PathParam("fileName") String fileName) 
    {
        System.out.println("File requested is : " + fileName);
        //Put some validations here such as invalid file name or missing file name
        if(fileName == null || fileName.isEmpty())
        {
            ResponseBuilder response = Response.status(Status.BAD_REQUEST);
            return response.build();
        }
        //Prepare a file object with file to return
        File file = new File("c:/demoPDFFile.pdf");
        ResponseBuilder response = Response.ok((Object) file);
        response.header("Content-Disposition", "attachment; filename="howtodoinjava.pdf"");
        return response.build();
    }
    @GET
    @Path("/{fileName}/image")
    @Produces("image/jpeg")
    public Response getFileInJPEGFormat(@PathParam("fileName") String fileName) 
    {
        System.out.println("File requested is : " + fileName);
        //Put some validations here such as invalid file name or missing file name
        if(fileName == null || fileName.isEmpty())
        {
            ResponseBuilder response = Response.status(Status.BAD_REQUEST);
            return response.build();
        }
        //Prepare a file object with file to return
        File file = new File("c:/demoJpegFile.jpeg");
        ResponseBuilder response = Response.ok((Object) file);
        response.header("Content-Disposition", "attachment; filename="howtodoinjava.jpeg"");
        return response.build();
    }
}

4）将要下载的文件放在参考位置

我正在引用“c:/<文件>”中的文件。 在运行此示例之前，从下载链接中的分发文件夹复制文件，并将其粘贴到c:中。

5）测试应用

以下是在浏览器中显示的用于请求 URL 的下载窗口的快照：

http://localhost:8080/RESTfulDemoApplication/file-management/demoTxtFile/text

http://localhost:8080/RESTfulDemoApplication/file-management/demoPDFFile/pdf

http://localhost:8080/RESTfulDemoApplication/file-management/demoJpegFile/image

如果要下载以上示例的源代码，请遵循以下给定的链接。

祝您学习愉快！