A customer asked me to prepare a sample Android project which converts docx to HTML.<\/p>\n
The result is AndroidDocxToHtml<\/a><\/p>\n Since docx4j relies heavily on JAXB, the key to getting it working was getting JAXB – the reference implementation – to run on Android.<\/p>\n Android presents us with a number of challenges:<\/p>\n Ill-advised or mistaken usage of a core class (java.* or javax.*)<\/strong><\/p>\n You’ll get this message if you try to add a jar containing classes in java.* or the following javax packages:<\/p>\n Android doesn’t provide javax.xml.bind, and it won’t let you add it yourself. \u00a0It forces you to re-package it. \u00a0Just like on Google AppEngine, until Google eventually added it.<\/p>\n OK, done that; see https:\/\/github.com\/plutext\/jaxb-2_2_5_1\/tree\/android2<\/a> (the 2 in android2 is meaningless)<\/p>\n Repackaging is easy enough; the problem with it is that any library which uses the repackaged code, must also be changed. \u00a0In the case of docx4j, this means a new branch, and ongoing maintenance.<\/p>\n JAXB uses JAXP 1.3 DatatypeFactory, but\u00a0Android doesn’t provide it<\/strong><\/p>\n com.sun.xml.bind invokes javax.xml.datatype.DatatypeFactory.newInstance, whereupon Android \u00a0throws\u00a0\u00a0javax.xml.datatype.DatatypeConfigurationException: Provider org.apache.xerces.jaxp.datatype.DatatypeFactoryImpl not found.<\/p>\n Easy solution: jar it up and provide it.<\/p>\n JAXB uses javax.activation.DataHandler<\/strong><\/p>\n Easy solution: use the activation and additionnal jars from http:\/\/code.google.com\/p\/javamail-android\/downloads\/list<\/a><\/p>\n Dalvik \u00a0limit of 65536 method references per dex file<\/strong><\/p>\n This is more an issue running docx4j on Android than one related to JAXB, but it is worth noting. \u00a0We’re running very close to this limit. \u00a0Vote for the issue at http:\/\/code.google.com\/p\/android\/issues\/detail?id=7147<\/a><\/p>\n Also, you may need to give Eclipse more heap space\u00a0\u00a0(symptom is ‘you get Unable to execute dex: Java heap space’). \u00a0 In\u00a0eclipse.ini,\u00a0I used:<\/p>\n -Xms256m<\/p>\n -Xmx4096m<\/p>\n In Eclipse, Windows > Preferences > General > Show Heap Status gives you an entry on the bottom row which is useful.<\/p>\n Just when I thought it would all work…<\/strong><\/p>\n I found that my XML was not unmarshalling, because it contains namespaces, and for some reason the objects in my JAXB were being read as not having any.<\/p>\n The problem is that Android doesn’t support package annotations: http:\/\/code.google.com\/p\/android\/issues\/detail?id=16149<\/a> (vote), but JAXB needs to read them. \u00a0For example:<\/p>\n I ended up devising a simple minded way to tell JAXB about these programmatically. \u00a0See Context.java<\/a>. \u00a0 Hmmm, I probably should have created my own RuntimeInlineAnnotationReader implementation (Google ‘JAXBIntroductions’).<\/p>\n\n