android 自定义WebView实现网页加载

现在的实际项目中一般是少不了混合开发的，通常加载页面我们都需要一个WebView，为了美观我们还需要一个用于显示当前加载进度的进度条。接下来就看看我们自定义的WebView：

**
 * Created by SerryWang
 * on 2018/8/23
 */
public class ProgressWebView extends WebView {

    private ProgressBar progressBar;
    private Context context;
    public ProgressWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
        progressBar = new ProgressBar(context,null,android.R.attr.progressBarStyleHorizontal);
        progressBar.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,3));//设置宽高属性
        addView(progressBar);
        //设置内部加载器
        setWebChromeClient(new MyWebChromeClient(context,progressBar));
        setWebViewClient(new MyWebViewClient());
    }
}

代码说明：

我们将一个progressBar添加到我们的WebView中去。可是哪里可以监听加载进度的变化了，这个时候我们就要重写WebChromeClient;
WebChromeClient:

/**
 * Created by SerryWang
 * on 2018/8/23
 */
public class MyWebChromeClient extends WebChromeClient {

    private Context context;
    private ProgressBar progressBar;


    public MyWebChromeClient(Context context, ProgressBar progressBar){
        this.context = context;
        this.progressBar = progressBar;
    }


    //监听进度的回调
    @Override
    public void onProgressChanged(WebView view, int newProgress) {
        if(newProgress == 100){
            progressBar.setVisibility(View.GONE);
        }else{

            if(progressBar.getVisibility() == View.GONE){
                progressBar.setVisibility(View.VISIBLE);
                progressBar.setProgress(newProgress);
            }
        }
        super.onProgressChanged(view, newProgress);
    }
}

可以看到构造方法中接收progressBar,在onProgressChanged中实现对进度的监听。
于此同事为了不使用外部浏览器，我们还要重写WebViewClient.
WebViewClient:

/**
 * Created by SerryWang
 * on 2018/8/23
 */
public class MyWebViewClient extends WebViewClient {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
        view.loadUrl(request.getUrl().toString());
        return true;
    }
}

最后记得防止WebView的内存泄漏，所以应该伴随Activity或者Fragment的生命周期。

public class WebActivity extends AppCompatActivity {

    private LinearLayout mLinearLayout;
    private AgentWeb mAgentWeb;
    private ToolBarView toolBarView;
    private WebView webView;
    private ProgressWebView progressWebView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web);
        initView();
        LoadUrl();
    }

    private void LoadUrl() {
        progressWebView.getSettings().setJavaScriptEnabled(true);
        progressWebView.loadUrl("file:///android_asset/detaillss/index.html");
    }

    private void initView() {

        mLinearLayout = findViewById(R.id.mLinearLayout);
        toolBarView   = findViewById(R.id.WebTool);
        progressWebView = findViewById(R.id.Web);
        toolBarView.setmNavigationTip(Constant.Toolbar_Title);

    }

    @Override
    protected void onPause() {

        if(progressWebView!=null){
            progressWebView.pauseTimers();
            progressWebView.onPause();
        }

        super.onPause();
    }

    @Override
    protected void onResume() {
        if(progressWebView != null){
            progressWebView.onResume();
        }
        super.onResume();
    }

    @Override
    protected void onDestroy() {
       if(progressWebView != null){
           progressWebView.stopLoading();
           progressWebView.removeAllViews();
           progressWebView.setWebViewClient(null);
           progressWebView.setWebChromeClient(null);
           unregisterForContextMenu(progressWebView);
           progressWebView.destroy();
       }
        super.onDestroy();
    }
}