Java content type binary

Class ContentType

@Contract(threading=IMMUTABLE) public final class ContentType extends Object implements Serializable

Content type information consisting of a MIME type and an optional charset. This class makes no attempts to verify validity of the MIME type. The input parameters of the create(String, String) method, however, may not contain characters , , reserved by the HTTP specification.

Field Summary

Fields

Modifier and Type	Field and Description
static ContentType	APPLICATION_ATOM_XML
static ContentType	APPLICATION_FORM_URLENCODED
static ContentType	APPLICATION_JSON
static ContentType	APPLICATION_NDJSON

Method Summary

Generates textual representation of this content type which can be used as the value of a Content-Type header.

Methods inherited from class java.lang.Object

Field Detail

APPLICATION_ATOM_XML

APPLICATION_FORM_URLENCODED

public static final ContentType APPLICATION_FORM_URLENCODED

APPLICATION_JSON

APPLICATION_NDJSON

APPLICATION_OCTET_STREAM

APPLICATION_PDF

APPLICATION_SOAP_XML

APPLICATION_SVG_XML

APPLICATION_XHTML_XML

APPLICATION_XML

APPLICATION_PROBLEM_JSON

APPLICATION_PROBLEM_XML

APPLICATION_RSS_XML

IMAGE_BMP

IMAGE_GIF

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Java Web Services Binary Data Transfer Example (base64 encoding)

In this tutorial, we are going to provide an example of a web services-based application that transfers binary data (e.g. content of an arbitrary file) using base64 encoding/decoding approach. The web services library to be used is JAX-WS (Java API for XML Web Services) which is a built-in technology in Java EE family and is also available in Java SE 6 or later.

1. Understand how to transfer binary data via web services

In the approach employed by this article, the binary data is embedded directly in the SOAP envelop using base64 text encoding. In other words, the raw binary data is converted to an encoded String which is value of an XML element in the SOAP message. Upon receiving the SOAP message, the receiver decodes the encoded String in order to re-construct the original binary data.

The following picture depicts this process:

This approach is the simplest way and is only suitable for transferring a small amount of binary data. It becomes very inefficient when transferring a large amount of binary data because the base64 text encoding technique bloats the data by a factor of 1.33x (UTF-8 text encoding) or 2.66x (UTF-16 text encoding) of the original size. Also, the encoding/decoding process slows down the application performance.

This approach is also often referred as “by value” or “inline attachment” method. Now, let’s go through an example application that is used to transfer small binary files.

2. Code the Web Service Endpoint Interface

package net.codejava.ws.binary.server; import javax.jws.WebMethod; import javax.jws.WebService; /** * A web service endpoint interface. * @author www.codejava.net * */ @WebService public interface FileTransferer

This endpoint defines two web methods, upload() and download() which allows the client to upload/download a file by sending/receiving a chunk of bytes.

3. Code the Web Service Endpoint Implementation

package net.codejava.ws.binary.server; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import javax.jws.WebMethod; import javax.jws.WebService; import javax.xml.ws.WebServiceException; /** * A web service implementation of an endpoint interface. * @author www.codejava.net * */ @WebService public class FileTransfererImpl implements FileTransferer < @WebMethod public void upload(String fileName, byte[] imageBytes) < String filePath = "e:/Test/Server/Upload/" + fileName; try < FileOutputStream fos = new FileOutputStream(filePath); BufferedOutputStream outputStream = new BufferedOutputStream(fos); outputStream.write(imageBytes); outputStream.close(); System.out.println("Received file: " + filePath); >catch (IOException ex) < System.err.println(ex); throw new WebServiceException(ex); >> @WebMethod public byte[] download(String fileName) < String filePath = "e:/Test/Server/Download/" + fileName; System.out.println("Sending file: " + filePath); try < File file = new File(filePath); FileInputStream fis = new FileInputStream(file); BufferedInputStream inputStream = new BufferedInputStream(fis); byte[] fileBytes = new byte[(int) file.length()]; inputStream.read(fileBytes); inputStream.close(); return fileBytes; >catch (IOException ex) < System.err.println(ex); throw new WebServiceException(ex); >> >

As we can see, the upload() method saves the received bytes array to file specified by the given fileName ; and the download() method reads the requested file and returns its content as a bytes array.

4. Code the Server Program for Web Services

package net.codejava.ws.binary.server; import javax.xml.ws.Endpoint; /** * A simple web service server. * @author www.codejava.net * */ public class WebServiceServer < public static void main(String[] args) < String bindingURI = "http://localhost:9898/codejava/fileService"; FileTransferer service = new FileTransfererImpl(); Endpoint.publish(bindingURI, service); System.out.println("Server started at: " + bindingURI); >>

Server started at: http://localhost:9898/codejava/fileService

The server is now waiting for request. Next, we are going to generate the web service client code.

5. Generating Client Code for Web Services

It’s recommended to use the wsimport tool in order to generate web services client code in Java. Execute the following command at the command prompt:

wsimport -keep -p net.codejava.ws.binary.client http://localhost:9898/codejava/fileService?wsdl

The wsimport tool generates necessary client code and puts .java source files under the package net.codejava.ws.binary.client . Here’s the list of generated files:

Download.java
DownloadResponse.java
FileTransfererImpl.java
FileTransfererImplService.java
ObjectFactory.java
package-info.java
Upload.java
UploadResponse.java

6. Coding the Client Program for Web Services

package net.codejava.ws.binary.client; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; /** * A client program that connects to a web service in order to upload * and download files. * @author www.codejava.net * */ public class WebServiceClient < public static void main(String[] args) < // connects to the web service FileTransfererImplService client = new FileTransfererImplService(); FileTransfererImpl service = client.getFileTransfererImplPort(); String fileName = "binary.png"; String filePath = "e:/Test/Client/Upload/" + fileName; File file = new File(filePath); // uploads a file try < FileInputStream fis = new FileInputStream(file); BufferedInputStream inputStream = new BufferedInputStream(fis); byte[] imageBytes = new byte[(int) file.length()]; inputStream.read(imageBytes); service.upload(file.getName(), imageBytes); inputStream.close(); System.out.println("File uploaded: " + filePath); >catch (IOException ex) < System.err.println(ex); >// downloads another file fileName = "camera.png"; filePath = "E:/Test/Client/Download/" + fileName; byte[] fileBytes = service.download(fileName); try < FileOutputStream fos = new FileOutputStream(filePath); BufferedOutputStream outputStream = new BufferedOutputStream(fos); outputStream.write(fileBytes); outputStream.close(); System.out.println("File downloaded: " + filePath); >catch (IOException ex) < System.err.println(ex); >> >

As we can see, this client program connects to the web service then uploads an image file to the service, and finally downloads another image file from the service.

7. Test binary data transfer with web services

File uploaded: e:/Test/Client/Upload/binary.png File downloaded: E:/Test/Client/Download/camera.png

Received file: e:/Test/Server/Upload/binary.png Sending file: e:/Test/Server/Download/camera.png

Using a monitoring tool such asTCP/IP Monitor in Eclipse IDE, we can spot the SOAP messages delivered along with the request and response as follows:

GET /codejava/fileService?wsdl HTTP/1.1 User-Agent: Java/1.7.0_17 Host: localhost:9898 Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2 Connection: keep-alive POST /codejava/fileService HTTP/1.1 Accept: text/xml, multipart/related Content-Type: text/xml; charset=utf-8 SOAPAction: "http://server.binary.ws.codejava.net/FileTransfererImpl/uploadRequest" User-Agent: JAX-WS RI 2.2.4-b01 Host: localhost:9898 Connection: keep-alive Content-Length: 1971    binary.png iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAMAAAAoLQ9TAA.

HTTP/1.1 200 OK Transfer-encoding: chunked Content-type: text/xml;charset=utf-8 Date: Fri, 11 Oct 2013 02:48:45 GMT -- WSDL XML (ommitted for saving space). HTTP/1.1 200 OK Transfer-encoding: chunked Content-type: text/xml; charset=utf-8 Date: Fri, 11 Oct 2013 02:48:45 GMT

POST /codejava/fileService HTTP/1.1 Accept: text/xml, multipart/related Content-Type: text/xml; charset=utf-8 SOAPAction: "http://server.binary.ws.codejava.net/FileTransfererImpl/downloadRequest" User-Agent: JAX-WS RI 2.2.4-b01 Host: localhost:9898 Connection: keep-alive Content-Length: 218    camera.png

HTTP/1.1 200 OK Transfer-encoding: chunked Content-type: text/xml; charset=utf-8 Date: Fri, 11 Oct 2013 02:48:45 GMT    iVBORw0KGgoAAAANSUhEUgAAABAAA.

About the Author:

Nam Ha Minh is certified Java programmer (SCJP and SCWCD). He started programming with Java in the time of Java 1.4 and has been falling in love with Java since then. Make friend with him on Facebook and watch his Java videos you YouTube.

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