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Android example source code file (WebStorage.java)

This example Android source code file (WebStorage.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, delete_all, get_origins, get_quota_origin, handler, hashmap, map, object, origin, os, return_quota_origin, return_usage_origin, string, update, util, utilities, utils, valuecallback, webstorage

The WebStorage.java Android example source code

/*
 * Copyright (C) 2009 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 android.os.Handler;
import android.os.Message;
import android.util.Log;

import java.util.Collection;
import java.util.Map;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

/**
 * Functionality for manipulating the webstorage databases.
 */
public final class WebStorage {

    /**
     * Encapsulates a callback function to be executed when a new quota is made
     * available. We primarily want this to allow us to call back the sleeping
     * WebCore thread from outside the WebViewCore class (as the native call
     * is private). It is imperative that this the setDatabaseQuota method is
     * executed once a decision to either allow or deny new quota is made,
     * otherwise the WebCore thread will remain asleep.
     */
    public interface QuotaUpdater {
        public void updateQuota(long newQuota);
    };

    // Log tag
    private static final String TAG = "webstorage";

    // Global instance of a WebStorage
    private static WebStorage sWebStorage;

    // Message ids
    static final int UPDATE = 0;
    static final int SET_QUOTA_ORIGIN = 1;
    static final int DELETE_ORIGIN = 2;
    static final int DELETE_ALL = 3;
    static final int GET_ORIGINS = 4;
    static final int GET_USAGE_ORIGIN = 5;
    static final int GET_QUOTA_ORIGIN = 6;

    // Message ids on the UI thread
    static final int RETURN_ORIGINS = 0;
    static final int RETURN_USAGE_ORIGIN = 1;
    static final int RETURN_QUOTA_ORIGIN = 2;

    private static final String ORIGINS = "origins";
    private static final String ORIGIN = "origin";
    private static final String CALLBACK = "callback";
    private static final String USAGE = "usage";
    private static final String QUOTA = "quota";

    private Map <String, Origin> mOrigins;

    private Handler mHandler = null;
    private Handler mUIHandler = null;

    static class Origin {
        String mOrigin = null;
        long mQuota = 0;
        long mUsage = 0;

        public Origin(String origin, long quota, long usage) {
            mOrigin = origin;
            mQuota = quota;
            mUsage = usage;
        }

        public Origin(String origin, long quota) {
            mOrigin = origin;
            mQuota = quota;
        }

        public Origin(String origin) {
            mOrigin = origin;
        }

        public String getOrigin() {
            return mOrigin;
        }

        public long getQuota() {
            return mQuota;
        }

        public long getUsage() {
            return mUsage;
        }
    }

    /**
     * @hide
     * Message handler, UI side
     */
    public void createUIHandler() {
        if (mUIHandler == null) {
            mUIHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    switch (msg.what) {
                        case RETURN_ORIGINS: {
                            Map values = (Map) msg.obj;
                            Map origins = (Map) values.get(ORIGINS);
                            ValueCallback<Map> callback = (ValueCallback) values.get(CALLBACK);
                            callback.onReceiveValue(origins);
                            } break;

                        case RETURN_USAGE_ORIGIN: {
                            Map values = (Map) msg.obj;
                            ValueCallback<Long> callback = (ValueCallback) values.get(CALLBACK);
                            callback.onReceiveValue((Long)values.get(USAGE));
                            } break;

                        case RETURN_QUOTA_ORIGIN: {
                            Map values = (Map) msg.obj;
                            ValueCallback<Long> callback = (ValueCallback) values.get(CALLBACK);
                            callback.onReceiveValue((Long)values.get(QUOTA));
                            } break;
                    }
                }
            };
        }
    }

    /**
     * @hide
     * Message handler, webcore side
     */
    public synchronized void createHandler() {
        if (mHandler == null) {
            mHandler = new Handler() {
                @Override
                public void handleMessage(Message msg) {
                    switch (msg.what) {
                        case SET_QUOTA_ORIGIN: {
                            Origin website = (Origin) msg.obj;
                            nativeSetQuotaForOrigin(website.getOrigin(),
                                                    website.getQuota());
                            } break;

                        case DELETE_ORIGIN: {
                            Origin website = (Origin) msg.obj;
                            nativeDeleteOrigin(website.getOrigin());
                            } break;

                        case DELETE_ALL:
                            nativeDeleteAllData();
                            break;

                        case GET_ORIGINS: {
                            syncValues();
                            ValueCallback callback = (ValueCallback) msg.obj;
                            Map origins = new HashMap(mOrigins);
                            Map values = new HashMap<String, Object>();
                            values.put(CALLBACK, callback);
                            values.put(ORIGINS, origins);
                            postUIMessage(Message.obtain(null, RETURN_ORIGINS, values));
                            } break;

                        case GET_USAGE_ORIGIN: {
                            syncValues();
                            Map values = (Map) msg.obj;
                            String origin = (String) values.get(ORIGIN);
                            ValueCallback callback = (ValueCallback) values.get(CALLBACK);
                            Origin website = mOrigins.get(origin);
                            Map retValues = new HashMap<String, Object>();
                            retValues.put(CALLBACK, callback);
                            if (website != null) {
                                long usage = website.getUsage();
                                retValues.put(USAGE, new Long(usage));
                            }
                            postUIMessage(Message.obtain(null, RETURN_USAGE_ORIGIN, retValues));
                            } break;

                        case GET_QUOTA_ORIGIN: {
                            syncValues();
                            Map values = (Map) msg.obj;
                            String origin = (String) values.get(ORIGIN);
                            ValueCallback callback = (ValueCallback) values.get(CALLBACK);
                            Origin website = mOrigins.get(origin);
                            Map retValues = new HashMap<String, Object>();
                            retValues.put(CALLBACK, callback);
                            if (website != null) {
                                long quota = website.getQuota();
                                retValues.put(QUOTA, new Long(quota));
                            }
                            postUIMessage(Message.obtain(null, RETURN_QUOTA_ORIGIN, retValues));
                            } break;

                        case UPDATE:
                            syncValues();
                            break;
                    }
                }
            };
        }
    }

    /*
     * When calling getOrigins(), getUsageForOrigin() and getQuotaForOrigin(),
     * we need to get the values from webcore, but we cannot block while doing so
     * as we used to do, as this could result in a full deadlock (other webcore
     * messages received while we are still blocked here, see http://b/2127737).
     *
     * We have to do everything asynchronously, by providing a callback function.
     * We post a message on the webcore thread (mHandler) that will get the result
     * from webcore, and we post it back on the UI thread (using mUIHandler).
     * We can then use the callback function to return the value.
     */

    /**
     * Returns a list of origins having a database
     */
    public void getOrigins(ValueCallback<Map> callback) {
        if (callback != null) {
            if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
                syncValues();
                callback.onReceiveValue(mOrigins);
            } else {
                postMessage(Message.obtain(null, GET_ORIGINS, callback));
            }
        }
    }

    /**
     * Returns a list of origins having a database
     * should only be called from WebViewCore.
     */
    Collection<Origin> getOriginsSync() {
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            update();
            return mOrigins.values();
        }
        return null;
    }

    /**
     * Returns the use for a given origin
     */
    public void getUsageForOrigin(String origin, ValueCallback<Long> callback) {
        if (callback == null) {
            return;
        }
        if (origin == null) {
            callback.onReceiveValue(null);
            return;
        }
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            syncValues();
            Origin website = mOrigins.get(origin);
            callback.onReceiveValue(new Long(website.getUsage()));
        } else {
            HashMap values = new HashMap<String, Object>();
            values.put(ORIGIN, origin);
            values.put(CALLBACK, callback);
            postMessage(Message.obtain(null, GET_USAGE_ORIGIN, values));
        }
    }

    /**
     * Returns the quota for a given origin
     */
    public void getQuotaForOrigin(String origin, ValueCallback<Long> callback) {
        if (callback == null) {
            return;
        }
        if (origin == null) {
            callback.onReceiveValue(null);
            return;
        }
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            syncValues();
            Origin website = mOrigins.get(origin);
            callback.onReceiveValue(new Long(website.getUsage()));
        } else {
            HashMap values = new HashMap<String, Object>();
            values.put(ORIGIN, origin);
            values.put(CALLBACK, callback);
            postMessage(Message.obtain(null, GET_QUOTA_ORIGIN, values));
        }
    }

    /**
     * Set the quota for a given origin
     */
    public void setQuotaForOrigin(String origin, long quota) {
        if (origin != null) {
            if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
                nativeSetQuotaForOrigin(origin, quota);
            } else {
                postMessage(Message.obtain(null, SET_QUOTA_ORIGIN,
                    new Origin(origin, quota)));
            }
        }
    }

    /**
     * Delete a given origin
     */
    public void deleteOrigin(String origin) {
        if (origin != null) {
            if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
                nativeDeleteOrigin(origin);
            } else {
                postMessage(Message.obtain(null, DELETE_ORIGIN,
                    new Origin(origin)));
            }
        }
    }

    /**
     * Delete all databases
     */
    public void deleteAllData() {
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            nativeDeleteAllData();
        } else {
            postMessage(Message.obtain(null, DELETE_ALL));
        }
    }

    /**
     * Sets the maximum size of the ApplicationCache.
     * This should only ever be called on the WebKit thread.
     * @hide Pending API council approval
     */
    public void setAppCacheMaximumSize(long size) {
        nativeSetAppCacheMaximumSize(size);
    }

    /**
     * Utility function to send a message to our handler
     */
    private synchronized void postMessage(Message msg) {
        if (mHandler != null) {
            mHandler.sendMessage(msg);
        }
    }

    /**
     * Utility function to send a message to the handler on the UI thread
     */
    private void postUIMessage(Message msg) {
        if (mUIHandler != null) {
            mUIHandler.sendMessage(msg);
        }
    }

    /**
     * Get the global instance of WebStorage.
     * @return A single instance of WebStorage.
     */
    public static WebStorage getInstance() {
      if (sWebStorage == null) {
          sWebStorage = new WebStorage();
      }
      return sWebStorage;
    }

    /**
     * @hide
     * Post a Sync request
     */
    public void update() {
        if (WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName())) {
            syncValues();
        } else {
            postMessage(Message.obtain(null, UPDATE));
        }
    }

    /**
     * Run on the webcore thread
     * set the local values with the current ones
     */
    private void syncValues() {
        Set<String> tmp = nativeGetOrigins();
        mOrigins = new HashMap<String, Origin>();
        for (String origin : tmp) {
            Origin website = new Origin(origin,
                                 nativeGetQuotaForOrigin(origin),
                                 nativeGetUsageForOrigin(origin));
            mOrigins.put(origin, website);
        }
    }

    // Native functions
    private static native Set nativeGetOrigins();
    private static native long nativeGetUsageForOrigin(String origin);
    private static native long nativeGetQuotaForOrigin(String origin);
    private static native void nativeSetQuotaForOrigin(String origin, long quota);
    private static native void nativeDeleteOrigin(String origin);
    private static native void nativeDeleteAllData();
    private static native void nativeSetAppCacheMaximumSize(long size);
}

Other Android examples (source code examples)

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