android 系统浏览器 源码-Android 最最最简单的浏览器代码

    import android.app.Activity;
    import android.app.ProgressDialog;
    import android.os.Bundle;
    import android.view.KeyEvent;
    import android.view.View;
    import android.webkit.WebChromeClient;
    import android.webkit.WebSettings;
    import android.webkit.WebView;
    import android.webkit.WebViewClient;
    import android.widget.Button;
    import android.widget.EditText;
    import android.widget.Toast;
    public class MainActivity extends Activity {
        private String url = null;
        private WebView webView;
        private ProgressDialog dialog;
        private EditText text;
        private Button button;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Toast.makeText(this,"欢迎使用简易浏览器_by sorgs",Toast.LENGTH_SHORT).show(); //弹出欢迎
            init();
        }
        private void init() {
            webView = (WebView) findViewById(R.id.webview);
            text = (EditText) findViewById(R.id.text);
            button = (Button) findViewById(R.id.button);
            webView.loadUrl(url);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    String str = text.getText().toString();  //去获取text中输入的网址
                    url = "http://"+ str;
                    webView.loadUrl(url);            //设置到webView中去
                }
            });
            //覆盖WebView默认通过第三方或者是系统浏览器打开网页的行为，使网页可以再WebView中打开
            webView.setWebViewClient(new WebViewClient() {
                @Override
                public boolean shouldOverrideUrlLoading(WebView view, String url) {
                    //返回值是true的时候控制网页在WebView中去打开，如果为false调用系统浏览器或者第三方浏览器打开
                    view.loadUrl(url);
                    return true;
                }//WebViewClient帮助WebView去处理一些页面控制和请求通知
            });
            //启用支持javaScript
            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,关闭ProgressDialog
                        closeDialo();
                    } else {
                        //网页正在加载，打开ProgressDialog
                        openDialog(newProgress);
                        text.setText(webView.getUrl()); //实时显示当前网址
                        text.requestFocus();           //把输入焦点放在调用这个方法的控件上
                        text.setSelectAllOnFocus(true); //点击之后就被全选
                    }
                }
                private void closeDialo() {
                    if (dialog != null && dialog.isShowing()) {
                        dialog.dismiss();
                        dialog = null;
                    }
                }
                private void openDialog(int newProgress) {
                    if (dialog == null) {
                        dialog = new ProgressDialog(MainActivity.this);
                        dialog.setTitle("加载中...");
                        dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                        dialog.setProgress(newProgress);
                        dialog.show();
                    } else {
                        dialog.setProgress(newProgress);
                    }
                }
            });
        }
        @Override //改写物理按键——返回的逻辑
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            if(keyCode == KeyEvent.KEYCODE_BACK){
                if(webView.canGoBack()){
                    webView.goBack();   //返回上一页面
                    return true;
                }else {
                    System.exit(0);
                }
            }
            return super.onKeyDown(keyCode,event);
        }
    }