支持HTML5 SqlLite的AndroidApp

简介：

想要建立一个支持HTML5的Android App;

这个HTML5的程序需要使用本地存储，特别是sqllite;

用eclipse创建了一个app,这个app默认在res/layout建了两个描述界面的xml文件，一个调用另一个，下面的代码基于这种情况;

package com.example.helloweb;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebSettings;
import android.webkit.WebStorage.QuotaUpdater;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 为了支持HTML5使用数据库(sqlite)的本地存储
        String databasePath = getApplicationContext().getDir("database", Context.MODE_PRIVATE).getPath();

        if (savedInstanceState == null) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            fragment.setDatabasePath(databasePath);

            getFragmentManager().beginTransaction()
                    .add(R.id.container, fragment)
                    .commit();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     * 被实例化，作为子UI的类
     */
    public static class PlaceholderFragment extends Fragment {
        String databasePath;

        public PlaceholderFragment() {
        }

        // 拿到MainActivity生成的数据库路径
        public void setDatabasePath(String databasePath){
            this.databasePath = databasePath;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {

            View rootView = inflater.inflate(R.layout.fragment_main, container, false);

            // 通过IDE在子UI里拖进去一个webView,所以这里从rootView里查找
            WebView  webView = (WebView)rootView.findViewById(R.id.webView1);
            webView.setWebChromeClient(this.makeWebChromeClient());

            WebSettings webSettings = webView.getSettings();
            webSettings.setJavaScriptEnabled(true);
            webSettings.setDatabaseEnabled(true);
            webSettings.setDatabasePath(this.databasePath);

            // 可以加载本地和网络的资源，加载网络资源需要配置权限
            //webView.loadUrl("http://www.****.net/");
            webView.loadUrl("file:///android_asset/demo.html");
            return rootView;
        }

        private WebChromeClient makeWebChromeClient(){
            return new WebChromeClient(){
                @Override
                public void onExceededDatabaseQuota(
                    String url,
                    String databaseIdentifier,
                    long currentQuota,
                    long estimatedSize,
                    long totalUsedQuota,
                    QuotaUpdater quotaUpdater) {
                        quotaUpdater.updateQuota(5 * 1024 * 1024);
                    }
            };
        }
    }
}

配置app访问网络的权限（在AndroidManifest.xml文件里配置）

<?xml version="1.0" encoding="utf-8"?>
<manifest>

    <uses-permission android:name="android.permission.INTERNET" /> 

    <uses-sdk/>
    <application></application>

</manifest>

如果要使用HTML5的localStorage还是要设置databasepath和打开localStorage

webSettings.setDatabasePath(this.databasePath);
webSettings.setDomStorageEnabled(true);