Java Webservice Upload File Example

In this tutorial I am going to show you how we can upload file using REST or RESTful web service.

The most important concept in REST is resources, which are identified by global IDs — typically using URIs. Client applications use HTTP methods (GET/ POST/ PUT/ DELETE) to manipulate the resource or collection of resources. A RESTful Web service is implemented using HTTP and the principles of REST. Typically, a RESTful Web service should define the following aspects:

The base/root URI for the Web service such as http://<host>/<appcontext/contextpath>/<url pattern>/<resources>.
The MIME type of the response data supported, which are JSON/XML/TEXT/HTML etc.
The set of operations supported by the service. (for example, POST, GET, PUT or DELETE).

Prerequisites
Eclipse, JDK 1.8, JAX-RS jars 2.23.2
Have maven installed and configured
JAX-RS dependencies in pom.xml

For this tutorial we will create a web maven project in Eclipse. If you already have an idea on how to create a maven project in Eclipse will be great otherwise I will tell you here how to create a maven project in Eclipse.

Step 1. Create a web maven project in Eclipse

Go to File -> New -> Other. On popup window under Maven select Maven Project. Then click on Next. Select the workspace location – either default or browse the location. Click on Next. Now in next window select the row as highlighted from the below list of archtypes and click on Next button.

maven-arctype-webapp
Now enter the required fields (Group Id, Artifact Id) as shown below
Group Id : com.roytuts
Artifact Id : rest
Step 2. Modify the pom.xml file as shown below.

<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.roytuts</groupId> 	<artifactId>rest</artifactId> 	<packaging>war</packaging> 	<version>0.0.1-SNAPSHOT</version> 	<name>rest Maven Webapp</name> 	<url>http://maven.apache.org</url> 	<properties> 		<java.version>1.8</java.version> 		<jersey.version>2.23.2</jersey.version> 	</properties> 	<dependencies> 		<dependency> 			<groupId>org.glassfish.jersey.containers</groupId> 			<artifactId>jersey-container-servlet</artifactId> 			<version>${jersey.version}</version> 		</dependency> 	</dependencies> 	<build> 		<finalName>rest</finalName> 		<plugins> 			<plugin> 				<groupId>org.apache.maven.plugins</groupId> 				<artifactId>maven-compiler-plugin</artifactId> 				<configuration> 					<source>${java.version}</source> 					<target>${java.version}</target> 				</configuration> 			</plugin> 		</plugins> 	</build> </project>

Step 3. If you see JRE System Library[J2SE-1.5] then change the version by below process

Do right-click on the project and go to Build -> Configure build path, under Libraries tab click on JRE System Library[J2SE-1.5], click on Edit button and select the appropriate jdk 1.8 from the next window. Click on Finish then Ok.

Step 4. Modify web.xml file to use the jersey servlet

<!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>REST Service</display-name> 	<servlet> 		<servlet-name>REST</servlet-name> 		<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class> 		<init-param> 			<param-name>jersey.config.server.provider.packages</param-name> 			<param-value>com.roytuts.rest.resources</param-value> 		</init-param> 		<load-on-startup>1</load-on-startup> 	</servlet> 	<!-- Map /rest/* to Jersey --> 	<servlet-mapping> 		<servlet-name>REST</servlet-name> 		<url-pattern>/*</url-pattern> 	</servlet-mapping> </web-app>

Step 5. Create a REST resource class as shown below

package com.roytuts.rest.resources; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import javax.ws.rs.Consumes; import javax.ws.rs.GET; import javax.ws.rs.POST; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.core.Context; import javax.ws.rs.core.HttpHeaders; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import javax.ws.rs.core.Response; import javax.ws.rs.core.Response.ResponseBuilder; @Path("/file") public class RestService { 	@POST 	@Path("/upload") 	@Consumes(MediaType.APPLICATION_OCTET_STREAM) 	@Produces(MediaType.TEXT_PLAIN) 	public Response sendFile(@Context HttpHeaders headers, InputStream fileInputStream) { 		MultivaluedMap<String, String> map = headers.getRequestHeaders(); 		String fileName = getFileName(map); 		OutputStream out = null; 		String filePath = "D:/" + fileName; 		try { 			out = new FileOutputStream(new File(filePath)); 			byte[] buf = new byte[1024]; 			int len; 			while ((len = fileInputStream.read(buf)) > 0) { 				out.write(buf, 0, len); 			} 		} catch (Exception e) { 			e.printStackTrace(); 		} finally { 			try { 				out.close(); 				fileInputStream.close(); 			} catch (IOException e) { 				e.printStackTrace(); 			} 		} 		return Response.status(Response.Status.OK).entity("File '" + filePath + "' uploaded successfully") 				.type(MediaType.TEXT_PLAIN).build(); 	} 	private String getFileName(MultivaluedMap<String, String> headers) { 		String[] contentDisposition = headers.getFirst("Content-Disposition").split(";"); 		for (String filename : contentDisposition) { 			if ((filename.trim().startsWith("filename"))) { 				String[] name = filename.split("="); 				String finalFileName = name[1].trim().replaceAll(""", ""); 				return finalFileName; 			} 		} 		return ""; 	} }

In the above class, the file will be uploaded to the directory D:

Step 6. Create a main class which will be used for testing the file upload fucntionality

package com.roytuts.rest.test; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.InputStream; import javax.ws.rs.client.Client; import javax.ws.rs.client.ClientBuilder; import javax.ws.rs.client.Entity; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.Response; public class RestTest { 	public static void main(String[] args) { 		try { 			File file = new File("D:/Documents/JavaJ2EE.doc"); 			InputStream fileInStream = new FileInputStream(file); 			String contentDisposition = "attachment; filename="" + file.getName() + """; 			Client client = ClientBuilder.newClient(); 			Response response = client.target("http://localhost:8080/rest/file").path("upload").request() 					.header("Content-Disposition", contentDisposition) 					.post(Entity.entity(fileInStream, MediaType.APPLICATION_OCTET_STREAM)); 			System.out.println(response.readEntity(String.class)); 		} catch (FileNotFoundException e) { 			e.printStackTrace(); 		} 	} }

Step 7. Now run the application on Tomcat 8. Run the above main class. Make sure you have a file JavaJ2EE.doc under D:Documents directory because this file will be uploaded using the REST service. Once the file is uploaded to D: drive then you will see the following output

Thanks for reading.

mccoycrong1963.blogspot.com

Source: https://roytuts.com/upload-file-using-rest-webservice/

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