ApkUtils.java

/**
 * 
 */
package org.odk.collect.android.utilities;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

import org.javarosa.core.util.PrefixTree;
import org.javarosa.core.util.externalizable.Externalizable;
import org.javarosa.core.util.externalizable.PrototypeFactory;

import android.content.Context;
import dalvik.system.DexFile;

/**
 * @author ctsims
 *
 */
public class ApkUtils {
    private static PrototypeFactory factory;


    public static PrototypeFactory getPrototypeFactory(Context c) {
        if(factory != null) {
            return factory;
        }
        
        PrefixTree tree = new PrefixTree();
        
        try {
        List<String> classes = getClasses("org.javarosa", c);
        for(String cl : classes) {
            //Log.i("CLASS", cl);
            tree.addString(cl);
        }
        
        //TODO: This was pulled from the source, should probably have a better
        //way to extend this utility
        classes = getClasses("org.commcare", c);
        for(String cl : classes) {
            //Log.i("CLASS", cl);
            tree.addString(cl);
        }
        } catch(Exception e) {
            throw new RuntimeException(e);
        }
        
        
        factory = new PrototypeFactory(tree);
        return factory;
        
    }
    
    /* Scans all classes accessible from the context class loader which belong to the given package and subpackages.
    *
    * @param packageName The base package
    * @return The classes
    * @throws ClassNotFoundException
    * @throws IOException
    */
   @SuppressWarnings("unchecked")
    private static List<String> getClasses(String packageName, Context c)
           throws IOException 
   {
       ArrayList<String> classNames = new ArrayList<String>();
       
       String zpath = c.getApplicationInfo().sourceDir;
       
       
       if(zpath == null) {
           zpath = "/data/app/org.odk.collect.apk";
       }
       
       DexFile df = new DexFile(new File(zpath));
       for(Enumeration<String> en = df.entries() ; en.hasMoreElements() ;) {
           String cn = en.nextElement();
           if(cn.startsWith(packageName) && !cn.contains(".test.")) {
               try{
                   Class prototype = Class.forName(cn);
                   if(prototype.isInterface()) {
                       continue;
                   }
                   boolean emptyc = false;
                   for(Constructor<?> cons : prototype.getConstructors()) {
                       if(cons.getParameterTypes().length == 0){
                           emptyc = true;
                       }
                   }
                   if(!emptyc) {
                       continue;
                   }
                   if(Externalizable.class.isAssignableFrom(prototype)) {
                       classNames.add(cn);
                   }
               } catch(Throwable e) {
                   //nothing should every make this crash
               }
           }
       }
       
       return classNames;
   }

}