網絡連接——WebView

Android提供了一個WebView控件，可以用它在自定義的應用程序中嵌入一個瀏覽器，展示各種網頁。
首先佈置一個簡單的佈局，用來顯示網絡連接的類型，顯示一個網頁

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button_netConnect"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="獲取網絡連接信息"/>
    <TextView
        android:id="@+id/textview_netInfo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="網絡連接的信息"/>
    <ProgressBar
        android:id="@+id/progressbar"
        android:layout_width="match_parent"
        android:layout_height="20dp"
        style="@style/Widget.AppCompat.ProgressBar.Horizontal"/>
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <WebView
            android:id="@+id/webview"
            android:layout_width="match_parent"
            android:layout_height="match_parent"></WebView>
        <TextView
            android:id="@+id/text_error"
            android:visibility="gone"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="加載失敗"/>
    </FrameLayout>
</LinearLayout>

package com.example.administrator.mynetworkconnect;

import android.app.Activity;
import android.graphics.Bitmap;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import org.w3c.dom.Text;

public class MainActivity extends Activity implements View.OnClickListener
{
    private Button mButton_getNetInfo;
    private TextView mTextViewgetInfo;
    private WebView mWebView;
    private TextView mTextViewError;
    private ProgressBar mProgressBar;
    private ConnectivityManager mConnectivityManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mButton_getNetInfo= (Button) findViewById(R.id.button_netConnect);
        mTextViewgetInfo= (TextView) findViewById(R.id.textview_netInfo);
        mButton_getNetInfo.setOnClickListener(this);
        mWebView= (WebView) findViewById(R.id.webview);
        mTextViewError= (TextView) findViewById(R.id.text_error);
        mProgressBar= (ProgressBar) findViewById(R.id.progressbar);
        //getSetting方法可以設置一些瀏覽器的屬性
        mWebView.getSettings().setJavaScriptEnabled(true);//使WebView支持JavaScript腳本
        //mWebView.getSettings().setBuiltInZoomControls(true);
        mWebView.setWebChromeClient(new WebChromeClient(){
            //設置進度條在加載網頁過程中的過程
            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                super.onProgressChanged(view, newProgress);
                mProgressBar.setProgress(newProgress);
            }
        });
        //當網頁跳轉的時候仍在當前WebView中。
        mWebView.setWebViewClient(new WebViewClient(){
            //當加載網頁失敗時使用自定義的界面
            @Override
            public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
                super.onReceivedError(view, errorCode, description, failingUrl);
                mWebView.setVisibility(View.GONE);

                Toast.makeText(getApplicationContext(),"找不到網頁",Toast.LENGTH_LONG).show();
                mTextViewError.setVisibility(View.VISIBLE);
                mTextViewError.setText("網頁加載失敗");
            }
            //在網頁加載完成後使得進度條消失
            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);
                mProgressBar.setVisibility(View.GONE);
            }
            //在網頁開始加載時使進度條顯示
            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);
                mProgressBar.setVisibility(View.VISIBLE);
            }
        });
        //傳入需要加載的網頁的URL
        mWebView.loadUrl("http://www.ncwu.com");
        //ConnectivityManager主要管理和網絡連接相關的操作 
        mConnectivityManager= (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode==KeyEvent.KEYCODE_BACK){
            if (mWebView.canGoBack()){
                mWebView.goBack();
                return true;
            }else {
                finish();
            }
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.button_netConnect:
                NetworkInfo info=mConnectivityManager.getActiveNetworkInfo();
                if (info!=null&&info.isConnected()){
                    Toast.makeText(getApplicationContext(),"網絡已連接",Toast.LENGTH_LONG).show();
                    mTextViewgetInfo.setText("網絡連接的方式爲："+info.getTypeName());
                }else{
                    Toast.makeText(getApplicationContext(),"網絡未連接",Toast.LENGTH_LONG).show();
                    mTextViewgetInfo.setText("無網絡連接");
                }
                break;
            default:
                break;
        }
    }
}

點擊第一個按鈕可以獲取到連接到的網絡的類型是WiFi或者其他，進度條顯示正在加載。