AboutActivity.java

package com.sunfusheng.StickyHeaderListView.ui;

import android.content.Context;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

import com.sunfusheng.StickyHeaderListView.R;

import butterknife.Bind;
import butterknife.ButterKnife;

/**
 * Created by sunfusheng on 16/4/24.
 */
public class AboutActivity extends AppCompatActivity {

    @Bind(R.id.toolbar)
    Toolbar toolbar;
    @Bind(R.id.webView)
    WebView webView;

    private WebSettings settings;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_about);
        ButterKnife.bind(this);

        initView();
    }

    private void initView() {
        initToolBar(toolbar, true, "关于 (V" + getVersionName(this) + ")");

        settings = webView.getSettings();
        settings.setJavaScriptEnabled(true); //如果访问的页面中有Javascript，则WebView必须设置支持Javascript
        settings.setJavaScriptCanOpenWindowsAutomatically(true);
        settings.setSupportZoom(true); //支持缩放
        settings.setBuiltInZoomControls(true); //支持手势缩放
        settings.setDisplayZoomControls(false); //是否显示缩放按钮

        // >= 19(SDK4.4)启动硬件加速，否则启动软件加速
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            webView.setLayerType(View.LAYER_TYPE_HARDWARE, null);
            settings.setLoadsImagesAutomatically(true); //支持自动加载图片
        } else {
            webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
            settings.setLoadsImagesAutomatically(false);
        }

        settings.setUseWideViewPort(true); //将图片调整到适合WebView的大小
        settings.setLoadWithOverviewMode(true); //自适应屏幕
        settings.setDomStorageEnabled(true);
        settings.setSaveFormData(true);
        settings.setSupportMultipleWindows(true);
        settings.setAppCacheEnabled(true);
        settings.setCacheMode(WebSettings.LOAD_DEFAULT); //优先使用缓存

        webView.setHorizontalScrollbarOverlay(true);
        webView.setHorizontalScrollBarEnabled(false);
        webView.setOverScrollMode(View.OVER_SCROLL_NEVER); // 取消WebView中滚动或拖动到顶部、底部时的阴影
        webView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY); // 取消滚动条白边效果
        webView.requestFocus();

        webView.loadUrl("file:///android_asset/about.html");
        webView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                view.loadUrl(url);
                return true;
            }
        });
    }

    // 获取当前应用的版本号
    public static String getVersionName(Context context) {
        try {
            PackageManager packageManager = context.getPackageManager();
            PackageInfo packInfo = packageManager.getPackageInfo(context.getPackageName(),0);
            String version = packInfo.versionName;
            if (!TextUtils.isEmpty(version)) {
                return version;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public void initToolBar(Toolbar toolbar, boolean homeAsUpEnabled, String title) {
        toolbar.setTitle(title);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        if (actionBar != null) {
            actionBar.setDisplayHomeAsUpEnabled(homeAsUpEnabled);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK && webView.canGoBack()) {
            webView.goBack();//返回上一页面
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

}