greenDao 在 qigsaw中报错Could not init DAOConfig

Posted 2022-01-22 许佳佳233

报错

org.greenrobot.greendao.DaoException: Could not init DAOConfig

场景

• 使用qigsaw
• 宿主模块依赖 greenDAO
• 插件模块使用了greenDAO
• 插件模块使用greenDAO报错：Could not init DAOConfig

原因

• greenDAO源码中通过反射的方式去调用Properties类
• 宿主模块加载greenDAO的ClassLoader是 PathClassLoader
• 插件模块加载AbstractDao实现类的ClassLoader是 QigsawClassLoader
• 由于QigsawClassLoader中没有加载DAOConfig，于是会报错。

排查方式

排查方式就是查看greenDAO源码，由于是插件化导致的崩溃，所以很快可以推断是ClassLoader的问题，验证后发现果然是。

    public DaoConfig(Database db, Class<? extends AbstractDao<?, ?>> daoClass) 
        this.db = db;
        try 
            this.tablename = (String) daoClass.getField("TABLENAME").get(null);
            Property[] properties = reflectProperties(daoClass);
            this.properties = properties;

            allColumns = new String[properties.length];

            List<String> pkColumnList = new ArrayList<String>();
            List<String> nonPkColumnList = new ArrayList<String>();
            Property lastPkProperty = null;
            for (int i = 0; i < properties.length; i++) 
                Property property = properties[i];
                String name = property.columnName;
                allColumns[i] = name;
                if (property.primaryKey) 
                    pkColumnList.add(name);
                    lastPkProperty = property;
                 else 
                    nonPkColumnList.add(name);
                
            
            String[] nonPkColumnsArray = new String[nonPkColumnList.size()];
            nonPkColumns = nonPkColumnList.toArray(nonPkColumnsArray);
            String[] pkColumnsArray = new String[pkColumnList.size()];
            pkColumns = pkColumnList.toArray(pkColumnsArray);

            pkProperty = pkColumns.length == 1 ? lastPkProperty : null;
            statements = new TableStatements(db, tablename, allColumns, pkColumns);

            if (pkProperty != null) 
                Class<?> type = pkProperty.type;
                keyIsNumeric = type.equals(long.class) || type.equals(Long.class) || type.equals(int.class)
                        || type.equals(Integer.class) || type.equals(short.class) || type.equals(Short.class)
                        || type.equals(byte.class) || type.equals(Byte.class);
             else 
                keyIsNumeric = false;
            

         catch (Exception e) 
            throw new DaoException("Could not init DAOConfig", e);
        
    

    private static Property[] reflectProperties(Class<? extends AbstractDao<?, ?>> daoClass)
            throws ClassNotFoundException, IllegalArgumentException, IllegalAccessException 
        Class<?> propertiesClass = Class.forName(daoClass.getName() + "$Properties");
        Field[] fields = propertiesClass.getDeclaredFields();

        ArrayList<Property> propertyList = new ArrayList<Property>();
        final int modifierMask = Modifier.STATIC | Modifier.PUBLIC;
        for (Field field : fields) 
            // There might be other fields introduced by some tools, just ignore them (see issue #28)
            if ((field.getModifiers() & modifierMask) == modifierMask) 
                Object fieldValue = field.get(null);
                if (fieldValue instanceof Property) 
                    propertyList.add((Property) fieldValue);
                
            
        

        Property[] properties = new Property[propertyList.size()];
        for (Property property : propertyList) 
            if (properties[property.ordinal] != null) 
                throw new DaoException("Duplicate property ordinals");
            
            properties[property.ordinal] = property;
        
        return properties;
    

解决方案

解决方案还是很多的，主要还是根据业务需要来。笔者就抛砖引玉写一些可能的方案：

1. 将插件中greenDAO的相关逻辑放到宿主模块中
2. 如果插件中greenDAO中逻辑不多，作为临时方案，可以将greenDAO调用到的类在宿主中重复定义一遍。（只能是临时方案）
3. 如宿主中没有使用greenDao的逻辑，可以改成插件直接依赖，而不要在宿主中加载。