Android example source code file (BridgeInflater.java)

This example Android source code file (BridgeInflater.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, attributeset, bridgecontext, bridgeinflater, bridgexmlblockparser, classnotfoundexception, content, file, inflateexception, io, iprojectcallback, kxmlparser, layoutinflater, object, override, string, util, utilities, utils, view

The BridgeInflater.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view;

import com.android.layoutlib.api.IProjectCallback;
import com.android.layoutlib.api.IResourceValue;
import com.android.layoutlib.bridge.Bridge;
import com.android.layoutlib.bridge.BridgeConstants;
import com.android.layoutlib.bridge.BridgeContext;
import com.android.layoutlib.bridge.BridgeXmlBlockParser;

import org.kxml2.io.KXmlParser;
import org.xmlpull.v1.XmlPullParser;

import android.content.Context;
import android.util.AttributeSet;

import java.io.File;
import java.io.FileReader;

/**
 * Custom implementation of {@link LayoutInflater} to handle custom views. 
 */
public final class BridgeInflater extends LayoutInflater {
    
    private final IProjectCallback mProjectCallback;

    /**
     * List of class prefixes which are tried first by default.
     * <p/>
     * This should match the list in com.android.internal.policy.impl.PhoneLayoutInflater.
     */ 
    private static final String[] sClassPrefixList = {
        "android.widget.",
        "android.webkit."
    };

    protected BridgeInflater(LayoutInflater original, Context newContext) {
        super(original, newContext);
        mProjectCallback = null;
    }
    
    /**
     * Instantiate a new BridgeInflater with an {@link IProjectCallback} object.
     * 
     * @param context The Android application context.
     * @param projectCallback the {@link IProjectCallback} object.
     */
    public BridgeInflater(Context context, IProjectCallback projectCallback) {
        super(context);
        mProjectCallback = projectCallback;
        mConstructorArgs[0] = context;
    }

    @Override
    public View onCreateView(String name, AttributeSet attrs) throws ClassNotFoundException {
        View view = null;

        try {
            // First try to find a class using the default Android prefixes
            for (String prefix : sClassPrefixList) {
                try {
                    view = createView(name, prefix, attrs);
                    if (view != null) {
                        break;
                    }
                } catch (ClassNotFoundException e) {
                    // Ignore. We'll try again using the base class below.
                }
            }
    
            // Next try using the parent loader. This will most likely only work for
            // fully-qualified class names.
            try {
                if (view == null) {
                    view = super.onCreateView(name, attrs);
                }
            } catch (ClassNotFoundException e) {
                // Ignore. We'll try again using the custom view loader below.
            }
    
            // Finally try again using the custom view loader
            try {
                if (view == null) {
                    view = loadCustomView(name, attrs);
                }
            } catch (ClassNotFoundException e) {
                // If the class was not found, we throw the exception directly, because this
                // method is already expected to throw it.
                throw e;
            }
        } catch (Exception e) {
            // Wrap the real exception in a ClassNotFoundException, so that the calling method
            // can deal with it.
            ClassNotFoundException exception = new ClassNotFoundException("onCreateView", e);
            throw exception;
        }
        
        setupViewInContext(view, attrs);
        
        return view;
    }
    
    @Override
    public View createViewFromTag(String name, AttributeSet attrs) {
        View view = null;
        try {
            view = super.createViewFromTag(name, attrs);
        } catch (InflateException e) {
            // try to load the class from using the custom view loader
            try {
                view = loadCustomView(name, attrs);
            } catch (Exception e2) {
                // Wrap the real exception in an InflateException so that the calling
                // method can deal with it.
                InflateException exception = new InflateException();
                if (e2.getClass().equals(ClassNotFoundException.class) == false) { 
                    exception.initCause(e2);
                } else {
                    exception.initCause(e);
                }
                throw exception;
            }
        }
        
        setupViewInContext(view, attrs);
        
        return view;
    }
    
    @Override
    public View inflate(int resource, ViewGroup root) {
        Context context = getContext();
        if (context instanceof BridgeContext) {
            BridgeContext bridgeContext = (BridgeContext)context;
            
            IResourceValue value = null;

            String[] layoutInfo = Bridge.resolveResourceValue(resource);
            if (layoutInfo != null) {
                value = bridgeContext.getFrameworkResource(BridgeConstants.RES_LAYOUT,
                        layoutInfo[0]);
            } else {
                layoutInfo = mProjectCallback.resolveResourceValue(resource);
                
                if (layoutInfo != null) {
                    value = bridgeContext.getProjectResource(BridgeConstants.RES_LAYOUT,
                            layoutInfo[0]);
                }
            }

            if (value != null) {
                File f = new File(value.getValue());
                if (f.isFile()) {
                    try {
                        KXmlParser parser = new KXmlParser();
                        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
                        parser.setInput(new FileReader(f));
                        
                        BridgeXmlBlockParser bridgeParser = new BridgeXmlBlockParser(
                                parser, bridgeContext, false);
                        
                        return inflate(bridgeParser, root);
                    } catch (Exception e) {
                        bridgeContext.getLogger().error(e);
                        // return null below.
                    }
                }
            }
        }
        return null;
    }
    
    private View loadCustomView(String name, AttributeSet attrs) throws ClassNotFoundException,
            Exception{
        if (mProjectCallback != null) {
            // first get the classname in case it's not the node name
            if (name.equals("view")) {
                name = attrs.getAttributeValue(null, "class");
            }
            
            mConstructorArgs[1] = attrs;

            Object customView = mProjectCallback.loadView(name, mConstructorSignature,
                    mConstructorArgs);
            
            if (customView instanceof View) {
                return (View)customView;
            }
        }

        return null;
    }
    
    
    
    private void setupViewInContext(View view, AttributeSet attrs) {
        if (getContext() instanceof BridgeContext) {
            BridgeContext bc = (BridgeContext) getContext();
            if (attrs instanceof BridgeXmlBlockParser) {
                Object viewKey = ((BridgeXmlBlockParser) attrs).getViewKey();
                if (viewKey != null) {
                    bc.addViewKey(view, viewKey);
                }
            }
        }
    }

    @Override
    public LayoutInflater cloneInContext(Context newContext) {
        return new BridgeInflater(this, newContext);
    }
}