Android example source code file (FileLoader.java)

This example Android source code file (FileLoader.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

allow/block, android, can't, caught, fileloader, http, illegalaccessexception, illegalargumentexception, indicates, internet, io, net, network, override, r, securityexception, string, type_asset, type_res, typedvalue

The FileLoader.java Android example source code

/*
 * Copyright (C) 2007 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.webkit;

import com.android.internal.R;

import android.content.res.AssetManager;
import android.net.http.EventHandler;
import android.net.http.Headers;
import android.util.Log;
import android.util.TypedValue;

import java.io.File;
import java.io.FileInputStream;
import java.lang.reflect.Field;

/**
 * This class is a concrete implementation of StreamLoader that uses a
 * file or asset as the source for the stream.
 *
 */
class FileLoader extends StreamLoader {

    private String mPath;  // Full path to the file to load
    private int mType;  // Indicates the type of the load
    private boolean mAllowFileAccess; // Allow/block file system access

    // used for files under asset directory
    static final int TYPE_ASSET = 1;
    // used for files under res directory
    static final int TYPE_RES = 2;
    // generic file
    static final int TYPE_FILE = 3;

    private static final String LOGTAG = "webkit";

    /**
     * Construct a FileLoader with the file URL specified as the content
     * source.
     *
     * @param url Full file url pointing to content to be loaded
     * @param loadListener LoadListener to pass the content to
     * @param asset true if url points to an asset.
     * @param allowFileAccess true if this WebView is allowed to access files
     *                        on the file system.
     */
    FileLoader(String url, LoadListener loadListener, int type,
            boolean allowFileAccess) {
        super(loadListener);
        mType = type;
        mAllowFileAccess = allowFileAccess;

        // clean the Url
        int index = url.indexOf('?');
        if (mType == TYPE_ASSET) {
            mPath = index > 0 ? URLUtil.stripAnchor(
                    url.substring(URLUtil.ASSET_BASE.length(), index)) :
                    URLUtil.stripAnchor(url.substring(
                            URLUtil.ASSET_BASE.length()));
        } else if (mType == TYPE_RES) {
            mPath = index > 0 ? URLUtil.stripAnchor(
                    url.substring(URLUtil.RESOURCE_BASE.length(), index)) :
                    URLUtil.stripAnchor(url.substring(
                            URLUtil.RESOURCE_BASE.length()));
        } else {
            mPath = index > 0 ? URLUtil.stripAnchor(
                    url.substring(URLUtil.FILE_BASE.length(), index)) :
                    URLUtil.stripAnchor(url.substring(
                            URLUtil.FILE_BASE.length()));
        }
    }

    private String errString(Exception ex) {
        String exMessage = ex.getMessage();
        String errString = mContext.getString(R.string.httpErrorFileNotFound);
        if (exMessage != null) {
            errString += " " + exMessage;
        }
        return errString;
    }

    @Override
    protected boolean setupStreamAndSendStatus() {
        try {
            if (mType == TYPE_ASSET) {
                try {
                    mDataStream = mContext.getAssets().open(mPath);
                } catch (java.io.FileNotFoundException ex) {
                    // try the rest files included in the package
                    mDataStream = mContext.getAssets().openNonAsset(mPath);
                }
            } else if (mType == TYPE_RES) {
                // get the resource id from the path. e.g. for the path like
                // drawable/foo.png, the id is located at field "foo" of class
                // "<package>.R$drawable"
                if (mPath == null || mPath.length() == 0) {
                    Log.e(LOGTAG, "Need a path to resolve the res file");
                    mLoadListener.error(EventHandler.FILE_ERROR, mContext
                            .getString(R.string.httpErrorFileNotFound));
                    return false;

                }
                int slash = mPath.indexOf('/');
                int dot = mPath.indexOf('.', slash);
                if (slash == -1 || dot == -1) {
                    Log.e(LOGTAG, "Incorrect res path: " + mPath);
                    mLoadListener.error(EventHandler.FILE_ERROR, mContext
                            .getString(R.string.httpErrorFileNotFound));
                    return false;
                }
                String subClassName = mPath.substring(0, slash);
                String fieldName = mPath.substring(slash + 1, dot);
                String errorMsg = null;
                try {
                    final Class<?> d = mContext.getApplicationContext()
                            .getClassLoader().loadClass(
                                    mContext.getPackageName() + ".R$"
                                            + subClassName);
                    final Field field = d.getField(fieldName);
                    final int id = field.getInt(null);
                    TypedValue value = new TypedValue();
                    mContext.getResources().getValue(id, value, true);
                    if (value.type == TypedValue.TYPE_STRING) {
                        mDataStream = mContext.getAssets().openNonAsset(
                                value.assetCookie, value.string.toString(),
                                AssetManager.ACCESS_STREAMING);
                    } else {
                        errorMsg = "Only support TYPE_STRING for the res files";
                    }
                } catch (ClassNotFoundException e) {
                    errorMsg = "Can't find class:  "
                            + mContext.getPackageName() + ".R$" + subClassName;
                } catch (SecurityException e) {
                    errorMsg = "Caught SecurityException: " + e;
                } catch (NoSuchFieldException e) {
                    errorMsg = "Can't find field:  " + fieldName + " in "
                            + mContext.getPackageName() + ".R$" + subClassName;
                } catch (IllegalArgumentException e) {
                    errorMsg = "Caught IllegalArgumentException: " + e;
                } catch (IllegalAccessException e) {
                    errorMsg = "Caught IllegalAccessException: " + e;
                }
                if (errorMsg != null) {
                    mLoadListener.error(EventHandler.FILE_ERROR, mContext
                            .getString(R.string.httpErrorFileNotFound));
                    return false;
                }
            } else {
                if (!mAllowFileAccess) {
                    mLoadListener.error(EventHandler.FILE_ERROR,
                            mContext.getString(R.string.httpErrorFileNotFound));
                    return false;
                }

                mDataStream = new FileInputStream(mPath);
                mContentLength = (new File(mPath)).length();
            }
            mLoadListener.status(1, 1, 200, "OK");

        } catch (java.io.FileNotFoundException ex) {
            mLoadListener.error(EventHandler.FILE_NOT_FOUND_ERROR, errString(ex));
            return false;

        } catch (java.io.IOException ex) {
            mLoadListener.error(EventHandler.FILE_ERROR, errString(ex));
            return false;
        }
        return true;
    }

    @Override
    protected void buildHeaders(Headers headers) {
        // do nothing.
    }
}