问题
I'm trying to convert a SVG image into JPEG as shown in https://xmlgraphics.apache.org/batik/using/transcoder.html#createImage example. Here is the code:
public void saveAsjpeg() throws Exception {
// Create a JPEG transcoder
JPEGTranscoder t = new JPEGTranscoder();
// Set the transcoding hints.
t.addTranscodingHint(JPEGTranscoder.KEY_QUALITY, new Float(.8));
// Create the transcoder input.
String svgURI = new File(inputFilePath).toURL().toString();
TranscoderInput input = new TranscoderInput(svgURI);
// Create the transcoder output.
OutputStream ostream = new FileOutputStream(outputFilePath);
TranscoderOutput output = new TranscoderOutput(ostream);
// Save the image.
t.transcode(input, output);
// Flush and close the stream.
ostream.flush();
ostream.close();
System.exit(0);
}
Below is my pom.xml. I'm trying in spring boot project:
<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.4.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-transcoder</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-codec</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-svgpp</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-rasterizer</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-squiggle</artifactId>
<version>1.8</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>xmlgraphics-commons</artifactId>
<version>2.1</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-ttf2svg</artifactId>
<version>1.8</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<executions>
<execution>
<id>attach-sources</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<executions>
<execution>
<id>attach-javadocs</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
I'm getting following exception:
org.apache.batik.transcoder.TranscoderException: null
Enclosed Exception:
null
at org.apache.batik.transcoder.image.ImageTranscoder.transcode(Unknown Source)
at org.apache.batik.transcoder.XMLAbstractTranscoder.transcode(Unknown Source)
at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(Unknown Source)
at SaveToJPEG.saveAsjpeg(SaveToJPEG.java:31)
at SaveToJPEG.main(SaveToJPEG.java:42)
I've several issues here:
- Why the exception stacktrace says "Unknown Source" and exception is so uninformative? I googled on this and read that if the jars don't have sources attached to them, the exception can be uninformative. I've put the plugin code in the pom to add the source. But this is not working.
- What is wrong in the batik code for it for not converting the svg image to jpeg?
回答1:
I don't know who published this artifact but it has solved this problem for me
<dependency>
<groupId>fr.avianey.apache-xmlgraphics</groupId>
<artifactId>batik</artifactId>
<version>1.8</version>
</dependency>
These classes are included with this artifact
- org.apache.batik.ext.awt.image.codec.imageio.ImageIOPNGImageWriter
- org.apache.batik.ext.awt.image.codec.imageio.ImageIOTIFFImageWriter
- org.apache.batik.ext.awt.image.codec.imageio.ImageIOJPEGImageWriter
回答2:
This is a bug inside Apache Batik 1.8, referenced in BATIK-1136.
The issue is the following: the JPEGTranscoder is using the Service Provider API to acquire an instance of an ImageWriter that handles the "image/jpeg" format. However, the class configured in the artifact batik-codec inside META-INF/services points a class org.apache.batik.ext.awt.image.codec.imageio.ImageIOJPEGImageWriter that apparently wasn't released in the final package (since it exists in the source code).
As such, there are 2 solutions.
Downgrade
Downgrade to version 1.7 with:
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-transcoder</artifactId>
<version>1.7</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>batik-codec</artifactId>
<version>1.7</version>
</dependency>
<dependency>
<groupId>org.apache.xmlgraphics</groupId>
<artifactId>xmlgraphics-commons</artifactId>
<version>2.1</version>
</dependency>
The classes were correctly released in this version.
Copy necessary classes
Copy the necessary classes from Apache Batik into your own sources. Inside a package org.apache.batik.ext.awt.image.codec.imageio, create the two following classes.
First, ImageIOImageWriter:
package org.apache.batik.ext.awt.image.codec.imageio;
import java.awt.image.RenderedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Iterator;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.event.IIOWriteWarningListener;
import javax.imageio.metadata.IIOInvalidTreeException;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.stream.ImageOutputStream;
import org.apache.batik.ext.awt.image.spi.ImageWriter;
import org.apache.batik.ext.awt.image.spi.ImageWriterParams;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class ImageIOImageWriter implements ImageWriter, IIOWriteWarningListener {
private String targetMIME;
/**
* Main constructor.
* @param mime the MIME type of the image format
*/
public ImageIOImageWriter(String mime) {
this.targetMIME = mime;
}
/**
* @see ImageWriter#writeImage(java.awt.image.RenderedImage, java.io.OutputStream)
*/
public void writeImage(RenderedImage image, OutputStream out) throws IOException {
writeImage(image, out, null);
}
/**
* @see ImageWriter#writeImage(java.awt.image.RenderedImage, java.io.OutputStream, ImageWriterParams)
*/
public void writeImage(RenderedImage image, OutputStream out,
ImageWriterParams params)
throws IOException {
Iterator iter;
iter = ImageIO.getImageWritersByMIMEType(getMIMEType());
javax.imageio.ImageWriter iiowriter = null;
try {
iiowriter = (javax.imageio.ImageWriter)iter.next();
if (iiowriter != null) {
iiowriter.addIIOWriteWarningListener(this);
ImageOutputStream imgout = null;
try {
imgout = ImageIO.createImageOutputStream(out);
ImageWriteParam iwParam = getDefaultWriteParam(iiowriter, image, params);
ImageTypeSpecifier type;
if (iwParam.getDestinationType() != null) {
type = iwParam.getDestinationType();
} else {
type = ImageTypeSpecifier.createFromRenderedImage(image);
}
//Handle metadata
IIOMetadata meta = iiowriter.getDefaultImageMetadata(
type, iwParam);
//meta might be null for some JAI codecs as they don't support metadata
if (params != null && meta != null) {
meta = updateMetadata(meta, params);
}
//Write image
iiowriter.setOutput(imgout);
IIOImage iioimg = new IIOImage(image, null, meta);
iiowriter.write(null, iioimg, iwParam);
} finally {
if (imgout != null) {
imgout.close();
}
}
} else {
throw new UnsupportedOperationException("No ImageIO codec for writing "
+ getMIMEType() + " is available!");
}
} finally {
if (iiowriter != null) {
iiowriter.dispose();
}
}
}
/**
* Returns the default write parameters for encoding the image.
* @param iiowriter The IIO ImageWriter that will be used
* @param image the image to be encoded
* @param params the parameters for this writer instance
* @return the IIO ImageWriteParam instance
*/
protected ImageWriteParam getDefaultWriteParam(
javax.imageio.ImageWriter iiowriter, RenderedImage image,
ImageWriterParams params) {
ImageWriteParam param = iiowriter.getDefaultWriteParam();
if ((params != null) && (params.getCompressionMethod() != null)) {
param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
param.setCompressionType(params.getCompressionMethod());
}
return param;
}
/**
* Updates the metadata information based on the parameters to this writer.
* @param meta the metadata
* @param params the parameters
* @return the updated metadata
*/
protected IIOMetadata updateMetadata(IIOMetadata meta, ImageWriterParams params) {
final String stdmeta = "javax_imageio_1.0";
if (meta.isStandardMetadataFormatSupported()) {
IIOMetadataNode root = (IIOMetadataNode)meta.getAsTree(stdmeta);
IIOMetadataNode dim = getChildNode(root, "Dimension");
IIOMetadataNode child;
if (params.getResolution() != null) {
child = getChildNode(dim, "HorizontalPixelSize");
if (child == null) {
child = new IIOMetadataNode("HorizontalPixelSize");
dim.appendChild(child);
}
child.setAttribute("value",
Double.toString(params.getResolution().doubleValue() / 25.4));
child = getChildNode(dim, "VerticalPixelSize");
if (child == null) {
child = new IIOMetadataNode("VerticalPixelSize");
dim.appendChild(child);
}
child.setAttribute("value",
Double.toString(params.getResolution().doubleValue() / 25.4));
}
try {
meta.mergeTree(stdmeta, root);
} catch (IIOInvalidTreeException e) {
throw new RuntimeException("Cannot update image metadata: "
+ e.getMessage());
}
}
return meta;
}
/**
* Returns a specific metadata child node
* @param n the base node
* @param name the name of the child
* @return the requested child node
*/
protected static IIOMetadataNode getChildNode(Node n, String name) {
NodeList nodes = n.getChildNodes();
for (int i = 0; i < nodes.getLength(); i++) {
Node child = nodes.item(i);
if (name.equals(child.getNodeName())) {
return (IIOMetadataNode)child;
}
}
return null;
}
/**
* @see ImageWriter#getMIMEType()
*/
public String getMIMEType() {
return this.targetMIME;
}
/**
* @see javax.imageio.event.IIOWriteWarningListener#warningOccurred(javax.imageio.ImageWriter, int, java.lang.String)
*/
public void warningOccurred(javax.imageio.ImageWriter source,
int imageIndex, String warning) {
System.err.println("Problem while writing image using ImageI/O: "
+ warning);
}
}
and then ImageIOJPEGImageWriter:
package org.apache.batik.ext.awt.image.codec.imageio;
import java.awt.image.RenderedImage;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOInvalidTreeException;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.metadata.IIOMetadataNode;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import org.apache.batik.ext.awt.image.codec.imageio.ImageIOImageWriter;
import org.apache.batik.ext.awt.image.spi.ImageWriterParams;
public class ImageIOJPEGImageWriter extends ImageIOImageWriter {
private static final String JPEG_NATIVE_FORMAT = "javax_imageio_jpeg_image_1.0";
/**
* Main constructor.
*/
public ImageIOJPEGImageWriter() {
super("image/jpeg");
}
/** {@inheritDoc} */
@Override
protected IIOMetadata updateMetadata(IIOMetadata meta, ImageWriterParams params) {
//ImageIODebugUtil.dumpMetadata(meta);
if (JPEG_NATIVE_FORMAT.equals(meta.getNativeMetadataFormatName())) {
meta = addAdobeTransform(meta);
IIOMetadataNode root = (IIOMetadataNode)meta.getAsTree(JPEG_NATIVE_FORMAT);
IIOMetadataNode jv = getChildNode(root, "JPEGvariety");
if (jv == null) {
jv = new IIOMetadataNode("JPEGvariety");
root.appendChild(jv);
}
IIOMetadataNode child;
if (params.getResolution() != null) {
child = getChildNode(jv, "app0JFIF");
if (child == null) {
child = new IIOMetadataNode("app0JFIF");
jv.appendChild(child);
}
//JPEG gets special treatment because there seems to be a bug in
//the JPEG codec in ImageIO converting the pixel size incorrectly
//(or not at all) when using standard metadata format.
child.setAttribute("majorVersion", null);
child.setAttribute("minorVersion", null);
child.setAttribute("resUnits", "1"); //dots per inch
child.setAttribute("Xdensity", params.getResolution().toString());
child.setAttribute("Ydensity", params.getResolution().toString());
child.setAttribute("thumbWidth", null);
child.setAttribute("thumbHeight", null);
}
try {
meta.setFromTree(JPEG_NATIVE_FORMAT, root);
} catch (IIOInvalidTreeException e) {
throw new RuntimeException("Cannot update image metadata: "
+ e.getMessage(), e);
}
//ImageIODebugUtil.dumpMetadata(meta);
}
return meta;
}
private static IIOMetadata addAdobeTransform(IIOMetadata meta) {
// add the adobe transformation (transform 1 -> to YCbCr)
IIOMetadataNode root = (IIOMetadataNode)meta.getAsTree(JPEG_NATIVE_FORMAT);
IIOMetadataNode markerSequence = getChildNode(root, "markerSequence");
if (markerSequence == null) {
throw new RuntimeException("Invalid metadata!");
}
IIOMetadataNode adobeTransform = getChildNode(markerSequence, "app14Adobe");
if (adobeTransform == null) {
adobeTransform = new IIOMetadataNode("app14Adobe");
adobeTransform.setAttribute("transform" , "1"); // convert RGB to YCbCr
adobeTransform.setAttribute("version", "101");
adobeTransform.setAttribute("flags0", "0");
adobeTransform.setAttribute("flags1", "0");
markerSequence.appendChild(adobeTransform);
} else {
adobeTransform.setAttribute("transform" , "1");
}
try {
meta.setFromTree(JPEG_NATIVE_FORMAT, root);
} catch (IIOInvalidTreeException e) {
throw new RuntimeException("Cannot update image metadata: "
+ e.getMessage(), e);
}
return meta;
}
/** {@inheritDoc} */
@Override
protected ImageWriteParam getDefaultWriteParam(
ImageWriter iiowriter, RenderedImage image,
ImageWriterParams params) {
JPEGImageWriteParam param = new JPEGImageWriteParam(iiowriter.getLocale());
param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
param.setCompressionQuality(params.getJPEGQuality());
if (params.getCompressionMethod() != null
&& !"JPEG".equals(params.getCompressionMethod())) {
throw new IllegalArgumentException(
"No compression method other than JPEG is supported for JPEG output!");
}
if (params.getJPEGForceBaseline()) {
param.setProgressiveMode(JPEGImageWriteParam.MODE_DISABLED);
}
return param;
}
}
Keeping version 1.8 and adding above classes, the code will work as-is.
来源：https://stackoverflow.com/questions/37899651/convert-a-svg-image-to-a-jpeg-image-using-apache-batik