先眼熟WebView

package com.example.test;

import android.app.ProgressDialog;
import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.webkit.WebChromeClient;
import android.webkit.WebResourceRequest;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class Main2Activity extends AppCompatActivity {
private String url="http://www.baidu.com";
    private WebView webView;
    private ProgressDialog dialog;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

/*        Uri uri=Uri.parse(url);
        Intent intent=new Intent(Intent.ACTION_VIEW,uri);
        startActivity(intent);*/
        init();
    }
    private void init() {
        webView= (WebView) findViewById(R.id.webView);
        //webView.loadUrl("file:///android_asset/example.html");
        webView.loadUrl(url);
        //覆盖webview默认第三方或者系统浏览器打开网页的行为，使得网页可在webview打开
        webView.setWebViewClient(new WebViewClient(){
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
                //返回值是true的时候控制网页在Webview中打开，如果为false调用系统浏览器或三方浏览器打开
                view.loadUrl(url);
                return true;
            }
            //webviewClient帮助webview去处理一些页面控制或请求通知
        });
        //启用javaScrip
        WebSettings settings=webView.getSettings();
        settings.setJavaScriptEnabled(true);
        //WebView加载页面优先使用缓存加载
        settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
        webView.setWebChromeClient(new WebChromeClient(){
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                //newProgress 1-100之间的整数
                if (newProgress==100){
                    //网页加载完毕
                    closeDialog();
                }else {
                    //网页正在加载
                    openDialog(newProgress);
                }
            }
            private void closeDialog(){
                if (dialog!=null&&dialog.isShowing()){
                    dialog.dismiss();
                    dialog=null;
                }

            }
            private void openDialog(int newProgress) {
                if (dialog==null){
                    dialog=new ProgressDialog(Main2Activity.this);
                    dialog.setTitle("正在加载");
                    dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                    dialog.setProgress(newProgress);
                    dialog.show();
                }else {
                    dialog.setProgress(newProgress);
                }
            }
        });

    }
    //改写物理按键返回的逻辑
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode==KeyEvent.KEYCODE_BACK){
           // Toast.makeText(Main2Activity.this, webView.getUrl(), Toast.LENGTH_SHORT).show();
            if (webView.canGoBack()){
                webView.goBack();//返回上衣界面
                return true;
            }else {
                System.exit(0);
            }
        }
        return super.onKeyDown(keyCode, event);
    }
}