安卓——WebView

example.html文件的位置

以下是代码

example.html

打开百度

AndroidManifest.xml

activity_main.xml

MainActivity

package com.example.lenovo.webview;

import android.app.Activity;
import android.app.ProgressDialog;
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 MainActivity extends Activity {
    private WebView webView;
    private String url="http://2014.qq.com/";
    private ProgressDialog dialog;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView=(WebView)findViewById(R.id.webview);
        init();
    }

    private void init() {
        //WebView加载本地资源
        //webView.loadUrl("file:///android_asset/example.html");
        //webView加载web资源
        webView.loadUrl(url);

        //覆盖WebView请求系统浏览器或者第三方浏览器打开网页，在WebView自己里面打开
        webView.setWebViewClient(new WebViewClient(){
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {

            //返回true在自己里面打开，返回false在第三方或者系统浏览器中打开
            view.loadUrl(url);
            return true;

        }
    });
        //WebViewClient帮助webview处理一些页面的控制和请求通知
        //启用JavaScript
        WebSettings settings=webView.getSettings();
        settings.setJavaScriptEnabled(true);

        //webView优先加载缓存
        webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);

        //打开一个网页是加载一个对话框,提示用户当前加载了白分之几
        webView.setWebChromeClient(new WebChromeClient(){
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                //newProgress是1%-100%
                if(newProgress==100){

                    closedialogue();
                }
                else{
                    openDialogue(newProgress);
                }
            }
            public void closedialogue(){

                if(dialog!=null&&dialog.isShowing()) {
                    dialog.dismiss();
                    dialog = null;
                }
            }
            private void  openDialogue(int newProgress){
                if(dialog==null){
                    dialog=new ProgressDialog(MainActivity.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(this,webView.getUrl(),Toast.LENGTH_SHORT).show();
            if(webView.canGoBack())
            {
                webView.goBack();
                return true;
            }
            else
                System.exit(0);//程序退出
        }

        return super.onKeyDown(keyCode, event);
    }
}