We have a reporting aplication that by default generates pdf outputs, but you can write your own classes to generate any other output format. This way I have generated xls files using apache poi 10.0. But, now came a request to generate xlsx file. When I try to create a workbook with this code:
XSSFWorkbook wbTemplate=new XSSFWorkbook()
I got the error:
java.lang.NoSuchMethodError: org.apache.xmlbeans.XmlOptions.setSaveAggressiveNamespaces()Lorg/apache/xmlbeans/XmlOptions;
I have discovered that the application already uses a very old version of the xmlbeans file that of course doesn't contain the above method. First I tryed to replace the xml bean file with a newer version just in case I have luck, but the application freezes.
My next idea is to use classLoader and when the app runs my class to generate the xlsx file I load the above method. To do so I have implemented this solution found on the internet:
URL[] classLoaderUrls = new URL[]{new URL("file:/C:/HOME/Installs/Apache POI/poi-3.10/ooxml-lib/xmlbeans-2.6.0.jar")};
URLClassLoader urlClassLoader = new URLClassLoader(classLoaderUrls);
Class<?> beanClass = urlClassLoader.loadClass("org.apache.xmlbeans.XmlOptions");
Constructor<?> constructor = beanClass.getConstructor();
Object beanObj = constructor.newInstance();
Method[] m=beanClass.getMethods();
Method method = beanClass.getMethod("setSaveAggressiveNamespaces");
method.invoke(beanObj);
But what a surprise when it wants to get the "setSaveAggressiveNamespaces" method name I got again the error that this function doesn't exist. Then I have written into a file all the function names of this class and it is true, that name doesn't exist. But exist another one called "setSaveAggresiveNamespaces" with one S! If I invoke this it works, but of course when I wan't to create the XSSF workbook I still get the message that the setSaveAggressiveNamespaces (with double SS) doesn't exist. But the setSaveAggressiveNamespaces should be in the class since this is coming with the apache poi package.
What can I do in this case to make it work? The application runs under java 1.6
Thanks in advance for the answers.
UPDATE
Axel, this is how I load now the class:
public void customClassLoader() throws Exception
{
URL[] classLoaderUrls = new URL[]{new URL("file:/C:/HOME/Installs/Apache POI/poi-3.10/ooxml-lib/xmlbeans-2.3.0.jar")};
URLClassLoader urlClassLoader = new URLClassLoader(classLoaderUrls,null);
Class<?> beanClass = urlClassLoader.loadClass("org.apache.xmlbeans.XmlOptions");
log("RESOURCES:" +beanClass.getResource("/org/apache/xmlbeans/XmlOptions.class"));
Constructor<?> constructor = beanClass.getConstructor();
Object beanObj = constructor.newInstance();
Method[] m=beanClass.getMethods();
for (int i=0;i<m.length;++i)
log("QQQ:" +String.valueOf(i)+".: "+ m[i].getName());
Method method = beanClass.getMethod("setSaveAggressiveNamespaces");
method.invoke(beanObj);
}
And then I call the above function at the first row of the class that generates the report. There is nothing before it.
The RESOURCE is written in the log as: "RESOURCES:jar:file:/C:/HOME/Installs/Apache POI/poi-3.10/ooxml-lib/xmlbeans-2.3.0.jar!/org/apache/xmlbeans/XmlOptions.class"
URLClassLoader(java.net.URL[]) states:
Constructs a new URLClassLoader for the specified URLs using the default delegation parent ClassLoader.
So the default delegation parent ClassLoader will also be used and so the org.apache.xmlbeans.XmlOptions will be loaded from there if found and not from the additional given URL.
So we need not using the default delegation parent ClassLoader. URLClassLoader(java.net.URL[], null) is doing this.
Example:
import java.net.URL;
import java.net.URLClassLoader;
import java.lang.reflect.Constructor;
public class UseURLClassLoader {
public static void main(String[] args) throws Exception {
URL[] classLoaderUrls;
URLClassLoader urlClassLoader;
Class<?> beanClass;
classLoaderUrls = new URL[]{new URL("file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/ooxml-lib/xmlbeans-2.6.0.jar")};
urlClassLoader = new URLClassLoader(classLoaderUrls); //default delegation parent ClassLoader is used
beanClass = urlClassLoader.loadClass("org.apache.xmlbeans.XmlOptions");
System.out.println(beanClass.getResource("/org/apache/xmlbeans/XmlOptions.class")); //class is loaded using default parent class loader
URL context = new URL("file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/");
classLoaderUrls = new URL[] {
new URL(context, "poi-3.10.1-20140818.jar"),
new URL(context, "poi-ooxml-3.10.1-20140818.jar"),
new URL(context, "poi-ooxml-schemas-3.10.1-20140818.jar"),
// maybe others also necessary
new URL(context, "lib/commons-codec-1.5.jar"),
// maybe others also necessary
new URL(context, "ooxml-lib/xmlbeans-2.6.0.jar")
// maybe others also necessary
};
for (int i = 0; i < classLoaderUrls.length; i++) {
System.out.println(classLoaderUrls[i]);
}
urlClassLoader = new URLClassLoader(classLoaderUrls, null); //set default parent class loader null
beanClass = urlClassLoader.loadClass("org.apache.xmlbeans.XmlOptions");
System.out.println(beanClass.getResource("/org/apache/xmlbeans/XmlOptions.class")); //class is loaded using this class loader
}
}
For me called as follows:
axel@arichter:~/Dokumente/JAVA/poi/poi-4.0.0$ java -cp .:./*:./lib/*:./ooxml-lib/* UseURLClassLoader
it produces:
jar:file:/home/axel/Dokumente/JAVA/poi/poi-4.0.0/ooxml-lib/xmlbeans-3.0.1.jar!/org/apache/xmlbeans/XmlOptions.class
file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/poi-3.10.1-20140818.jar
file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/poi-ooxml-3.10.1-20140818.jar
file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/poi-ooxml-schemas-3.10.1-20140818.jar
file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/lib/commons-codec-1.5.jar
file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/ooxml-lib/xmlbeans-2.6.0.jar
jar:file:/home/axel/Dokumente/JAVA/poi/poi-3.10.1/ooxml-lib/xmlbeans-2.6.0.jar!/org/apache/xmlbeans/XmlOptions.class
So at first the class is loaded using default parent class loader. For me it loads org.apache.xmlbeans.XmlOptions farther from the newer xmlbeans-3.0.1.jar. For you it loads farther from the older xmlbeans-1.*.jar. That is because those jars are in class path of the default parent class loader.
The second code part then sets the default parent class loader null and so class is loaded only using this class loader.
But messing around with the class loaders is a mess. As implied in my code, having the default parent class loader set null, we need giving the current class loader all the needed class sources. This often becomes very expensive. So not having the old jars in the class path will always be the better solution than messing around with the class loaders.