Android 实现带进度条的WebView的实例

//加载本地资源
loadUrl("file:///android_asset/example.html");
//加载网络资源
loadUrl("http://baidu.com");

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

  <item android:id="@android:id/progress">
    <clip>
      <shape>
        <solid android:color="#31CE15"/>
        <corners android:radius="2dp"/>
      </shape>
    </clip>
  </item>

</layer-list>

/**
 * 带进度条的WebView
 * @Author GQ
 */
public class ProgressWebView extends WebView {

  private ProgressBar progressbar;
  private Context mContext;

  public ProgressWebView(Context context,AttributeSet attrs) {
    super(context,attrs);
    this.mContext = context;
    progressbar = new ProgressBar(context,null,android.R.attr.progressBarStyleHorizontal);
    progressbar.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,5,0));

    Drawable drawable = context.getResources().getDrawable(R.drawable.view_progress_webview);
    progressbar.setProgressDrawable(drawable);
    addView(progressbar);

    //主要处理解析，渲染网页等浏览器做的事情
    setWebViewClient(new WebViewClient() {
      @Override
      public void onReceivedError(WebView view,int errorCode,String description,String failingUrl) {
        super.onReceivedError(view,errorCode,description,failingUrl);
        //加载失败时候,显示自定义的页面
        if (errorListener != null) {
          errorListener.onError();
        }
      }
    });
    //辅助WebView处理Javascript的对话框，网站图标，网站title，加载进度等
    setWebChromeClient(new WebChromeClient());

    getSettings().setSupportZoom(true);//是否可以缩放
    getSettings().setBuiltInZoomControls(true);
    getSettings().setJavaScriptEnabled(true);//支持JS
    getSettings().setLayoutAlgorithm(WebSettings.LayoutAlgorithm.NARROW_COLUMNS);
    getSettings().setUseWideViewPort(true);
    getSettings().setLoadWithOverviewMode(true);
    getSettings().setSaveFormData(true);
    getSettings().setDomStorageEnabled(true);

    //优先使用缓存
    getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);

    //禁用长按
    setOnLongClickListener(new OnLongClickListener() {
      @Override
      public boolean onLongClick(View view) {
        return true;
      }
    });

    //如果在浏览器下载,调用浏览器默认下载+通知栏
    setDownloadListener(new DownloadListener() {
      @Override
      public void onDownloadStart(String url,String userAgent,String contentDisposition,String mimetype,long contentLength) {
        Uri uri = Uri.parse(url);
        Intent intent = new Intent(Intent.ACTION_VIEW,uri);
        mContext.startActivity(intent);
      }
    });
  }


  public class WebChromeClient extends android.webkit.WebChromeClient {
    @Override
    public void onProgressChanged(WebView view,int newProgress) {
      if (newProgress == 100) {
        progressbar.setVisibility(GONE);
      } else {
        if (progressbar.getVisibility() == GONE)
          progressbar.setVisibility(VISIBLE);
        progressbar.setProgress(newProgress);
      }
      super.onProgressChanged(view,newProgress);
    }

    @Override
    public void onReceivedTitle(WebView view,String title) {
      super.onReceivedTitle(view,title);
      if (titleListener != null)
        titleListener.getTitle(title);
    }

  }


  @Override
  protected void onScrollChanged(int l,int t,int oldl,int oldt) {
    LayoutParams lp = (LayoutParams) progressbar.getLayoutParams();
    lp.x = l;
    lp.y = t;
    progressbar.setLayoutParams(lp);
    super.onScrollChanged(l,t,oldl,oldt);
  }

  private TitleListener titleListener;

  public interface TitleListener {
    void getTitle(String title);
  }

  public void setOnTitleListener(TitleListener titleListener) {
    this.titleListener = titleListener;
  }

  private ErrorListener errorListener;

  public interface ErrorListener {
    void onError();
  }

  public void setOnErrorListener(ErrorListener errorListener) {
    this.errorListener = errorListener;
  }

}

/**
* 公共WebView
*/
public class BasicWebActivity extends Activity {

  protected ProgressWebView progressWebView;
  private TextView title;//标题栏
  private TextView tv_none;//加载失败显示文字

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

    title = (TextView) findViewById(R.id.title);
    tv_none = (TextView) findViewById(R.id.tv_none);
    progressWebView = (ProgressWebView) findViewById(R.id.progressWebView);

    String url = getIntent().getStringExtra("url");
    progressWebView.setOnTitleListener(new ProgressWebView.TitleListener() {
      @Override
      public void getTitle(String title) {
        title.setText(title);
      }
    });
    progressWebView.setOnErrorListener(new ProgressWebView.ErrorListener() {
      @Override
      public void onError() {
        tv_none.setText("url资源失效");
      }
    });
    //加载网页
    progressWebView.loadUrl(url);
  }

 //重写返回键
  @Override
  public boolean onKeyDown(int keyCode,KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
      if (progressWebView.canGoBack()) {
        progressWebView.goBack();//返回上一层页面
        return true;
      } else {
        finish();//关闭页面
      }
    }
    return super.onKeyDown(keyCode,event);
  }
}