org.apache.fop.fo.flow.ExternalGraphic 捕获并记录我想自己处理的 ImageException
org.apache.fop.fo.flow.ExternalGraphic catches and logs ImageException I want to handle myself
出于测试目的,我正在将图像转换为 pdf。
为了确保图像与以后的打印过程兼容,我在上传过程中运行进行了快速测试打印。
我正在使用转换器创建一个简单的 Test-PDF。当我尝试打印格式不兼容的图像时,转换器的 ImageManager 抛出 ImageException,从 preloadImage() 函数开始:
public ImageInfo preloadImage(String uri, Source src)
throws ImageException, IOException {
Iterator iter = registry.getPreloaderIterator();
while (iter.hasNext()) {
ImagePreloader preloader = (ImagePreloader)iter.next();
ImageInfo info = preloader.preloadImage(uri, src, imageContext);
if (info != null) {
return info;
}
}
throw new ImageException("The file format is not supported. No ImagePreloader found for "
+ uri);
}
扔给:
public ImageInfo needImageInfo(String uri, ImageSessionContext session, ImageManager manager)
throws ImageException, IOException {
//Fetch unique version of the URI and use it for synchronization so we have some sort of
//"row-level" locking instead of "table-level" locking (to use a database analogy).
//The fine locking strategy is necessary since preloading an image is a potentially long
//operation.
if (isInvalidURI(uri)) {
throw new FileNotFoundException("Image not found: " + uri);
}
String lockURI = uri.intern();
synchronized (lockURI) {
ImageInfo info = getImageInfo(uri);
if (info == null) {
try {
Source src = session.needSource(uri);
if (src == null) {
registerInvalidURI(uri);
throw new FileNotFoundException("Image not found: " + uri);
}
info = manager.preloadImage(uri, src);
session.returnSource(uri, src);
} catch (IOException ioe) {
registerInvalidURI(uri);
throw ioe;
} catch (ImageException e) {
registerInvalidURI(uri);
throw e;
}
putImageInfo(info);
}
return info;
}
}
扔给 :
public ImageInfo getImageInfo(String uri, ImageSessionContext session)
throws ImageException, IOException {
if (getCache() != null) {
return getCache().needImageInfo(uri, session, this);
} else {
return preloadImage(uri, session);
}
}
最终它被捕获并记录在 ExternalGraphic.class:
/** {@inheritDoc} */
public void bind(PropertyList pList) throws FOPException {
super.bind(pList);
src = pList.get(PR_SRC).getString();
//Additional processing: obtain the image's intrinsic size and baseline information
url = URISpecification.getURL(src);
FOUserAgent userAgent = getUserAgent();
ImageManager manager = userAgent.getFactory().getImageManager();
ImageInfo info = null;
try {
info = manager.getImageInfo(url, userAgent.getImageSessionContext());
} catch (ImageException e) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageError(this, url, e, getLocator());
} catch (FileNotFoundException fnfe) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageNotFound(this, url, fnfe, getLocator());
} catch (IOException ioe) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageIOError(this, url, ioe, getLocator());
}
if (info != null) {
this.intrinsicWidth = info.getSize().getWidthMpt();
this.intrinsicHeight = info.getSize().getHeightMpt();
int baseline = info.getSize().getBaselinePositionFromBottom();
if (baseline != 0) {
this.intrinsicAlignmentAdjust
= FixedLength.getInstance(-baseline);
}
}
}
这样我就无法在使用转换器的代码中访问它。
我尝试使用自定义 ErrorListener,但转换器仅将 fatalErrors 注册到 ErrorListener。
有没有办法在不修改库代码的情况下访问异常并自己处理?
这比我想象的要容易。在调用转换之前,我向正在使用的 Fop 的用户代理注册了一个 Costum EventListener。这个 Listener 只存储触发了哪种事件的信息,所以如果是 ImageError 我可以抛出异常。
我的听众:
import org.apache.fop.events.Event;
import org.apache.fop.events.EventListener;
public class ImageErrorListener implements EventListener
{
private String eventKey = "";
private boolean imageError = false;
@Override
public void processEvent(Event event)
{
eventKey = event.getEventKey();
if(eventKey.equals("imageError")) {
imageError = true;
}
}
public String getEventKey()
{
return eventKey;
}
public void setEventKey(String eventKey)
{
this.eventKey = eventKey;
}
public boolean isImageError()
{
return imageError;
}
public void setImageError(boolean imageError)
{
this.imageError = imageError;
}
}
侦听器的使用:
// Start XSLT transformation and FOP processing
ImageErrorListener imageListener = new ImageErrorListener();
fop.getUserAgent().getEventBroadcaster().addEventListener(imageListener);
if (res != null)
{
transformer.transform(xmlDomStreamSource, res);
}
if(imageListener.isImageError()) {
throw new ImageException("");
}
fop 是 Fop 类型,xmlDomStreamSource 是我要转换的 xml-Source,res 是我的 SAXResult。
出于测试目的,我正在将图像转换为 pdf。
为了确保图像与以后的打印过程兼容,我在上传过程中运行进行了快速测试打印。
我正在使用转换器创建一个简单的 Test-PDF。当我尝试打印格式不兼容的图像时,转换器的 ImageManager 抛出 ImageException,从 preloadImage() 函数开始:
public ImageInfo preloadImage(String uri, Source src)
throws ImageException, IOException {
Iterator iter = registry.getPreloaderIterator();
while (iter.hasNext()) {
ImagePreloader preloader = (ImagePreloader)iter.next();
ImageInfo info = preloader.preloadImage(uri, src, imageContext);
if (info != null) {
return info;
}
}
throw new ImageException("The file format is not supported. No ImagePreloader found for "
+ uri);
}
扔给:
public ImageInfo needImageInfo(String uri, ImageSessionContext session, ImageManager manager)
throws ImageException, IOException {
//Fetch unique version of the URI and use it for synchronization so we have some sort of
//"row-level" locking instead of "table-level" locking (to use a database analogy).
//The fine locking strategy is necessary since preloading an image is a potentially long
//operation.
if (isInvalidURI(uri)) {
throw new FileNotFoundException("Image not found: " + uri);
}
String lockURI = uri.intern();
synchronized (lockURI) {
ImageInfo info = getImageInfo(uri);
if (info == null) {
try {
Source src = session.needSource(uri);
if (src == null) {
registerInvalidURI(uri);
throw new FileNotFoundException("Image not found: " + uri);
}
info = manager.preloadImage(uri, src);
session.returnSource(uri, src);
} catch (IOException ioe) {
registerInvalidURI(uri);
throw ioe;
} catch (ImageException e) {
registerInvalidURI(uri);
throw e;
}
putImageInfo(info);
}
return info;
}
}
扔给 :
public ImageInfo getImageInfo(String uri, ImageSessionContext session)
throws ImageException, IOException {
if (getCache() != null) {
return getCache().needImageInfo(uri, session, this);
} else {
return preloadImage(uri, session);
}
}
最终它被捕获并记录在 ExternalGraphic.class:
/** {@inheritDoc} */
public void bind(PropertyList pList) throws FOPException {
super.bind(pList);
src = pList.get(PR_SRC).getString();
//Additional processing: obtain the image's intrinsic size and baseline information
url = URISpecification.getURL(src);
FOUserAgent userAgent = getUserAgent();
ImageManager manager = userAgent.getFactory().getImageManager();
ImageInfo info = null;
try {
info = manager.getImageInfo(url, userAgent.getImageSessionContext());
} catch (ImageException e) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageError(this, url, e, getLocator());
} catch (FileNotFoundException fnfe) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageNotFound(this, url, fnfe, getLocator());
} catch (IOException ioe) {
ResourceEventProducer eventProducer = ResourceEventProducer.Provider.get(
getUserAgent().getEventBroadcaster());
eventProducer.imageIOError(this, url, ioe, getLocator());
}
if (info != null) {
this.intrinsicWidth = info.getSize().getWidthMpt();
this.intrinsicHeight = info.getSize().getHeightMpt();
int baseline = info.getSize().getBaselinePositionFromBottom();
if (baseline != 0) {
this.intrinsicAlignmentAdjust
= FixedLength.getInstance(-baseline);
}
}
}
这样我就无法在使用转换器的代码中访问它。
我尝试使用自定义 ErrorListener,但转换器仅将 fatalErrors 注册到 ErrorListener。
有没有办法在不修改库代码的情况下访问异常并自己处理?
这比我想象的要容易。在调用转换之前,我向正在使用的 Fop 的用户代理注册了一个 Costum EventListener。这个 Listener 只存储触发了哪种事件的信息,所以如果是 ImageError 我可以抛出异常。
我的听众:
import org.apache.fop.events.Event;
import org.apache.fop.events.EventListener;
public class ImageErrorListener implements EventListener
{
private String eventKey = "";
private boolean imageError = false;
@Override
public void processEvent(Event event)
{
eventKey = event.getEventKey();
if(eventKey.equals("imageError")) {
imageError = true;
}
}
public String getEventKey()
{
return eventKey;
}
public void setEventKey(String eventKey)
{
this.eventKey = eventKey;
}
public boolean isImageError()
{
return imageError;
}
public void setImageError(boolean imageError)
{
this.imageError = imageError;
}
}
侦听器的使用:
// Start XSLT transformation and FOP processing
ImageErrorListener imageListener = new ImageErrorListener();
fop.getUserAgent().getEventBroadcaster().addEventListener(imageListener);
if (res != null)
{
transformer.transform(xmlDomStreamSource, res);
}
if(imageListener.isImageError()) {
throw new ImageException("");
}
fop 是 Fop 类型,xmlDomStreamSource 是我要转换的 xml-Source,res 是我的 SAXResult。