在android里如何利用WebView实现和javascript通信

1、为确保有权限访问网页，在AndroidManifest.xml里面添加代码如下：

<uses-permission android:name="android.permission.INTERNET"/>

2、在res/layout/main.xml里添加

<WebView  android:layout_height="fill_parent"  android:layout_width="fill_parent"  android:id="@+id/webview" />

3、activity 里面添加

package com.phoneplus;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.widget.Toast;

public class DemoActivity extends Activity {
     WebView webView;
     String  url = "http://10.254.58.32/demo/gradeplan/activitydetail.php?v=1";
    private WebSettings settings;
     
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       //测试WebView
        webView = (WebView) findViewById(R.id.webview);
        webView.getSettings().setSavePassword(false);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.getSettings().setUseWideViewPort(true);  
        webView.getSettings().setLoadWithOverviewMode(true);  
        webView.getSettings().setBuiltInZoomControls(true);   
        webView.getSettings().setSupportZoom(true);  
        display(webView);
        //显示网页
        webHtml(url);
        webView.setWebChromeClient(new MyWebChromeClient());
     }
    
    class MyWebChromeClient extends WebChromeClient{
        @Override
        public boolean onJsAlert(WebView view, String url, String message, JsResult result){           
    
            Log.d("==message==",message);
            Log.d("==url==",url);
            Log.d("==JsResult==",result.toString());
 
            result.confirm();
            return true;            
        }
        
    }
    
    /**  直接网页显示   */   
    private void webHtml(String url) {   
        try {   
            webView.loadUrl(url);   
        } catch (Exception ex) {  
            ex.printStackTrace();  
        }   
    }  
     
    /**
     * 分辨率自适应
     * @param webView
     */
    private void display(WebView webView){
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        int width = (int) (dm.widthPixels * dm.density);

        if ( Build.VERSION.SDK_INT >= 14 && width >= 480 ) {
            webView.setInitialScale(100);
        }else if ( Build.VERSION.SDK_INT ==14 && width >= 320 ) {
            webView.setInitialScale(67);
        }else if ( Build.VERSION.SDK_INT == 14 && width < 320 ) {
            webView.setInitialScale(50);
        }else {
            webView.setInitialScale(1);
        }
    }
}

 4、HTML里面

 <script type="text/javascript">  
        
     function get_activity(str_flag){  
        <?php 
            //android
            if( $_GET['v'] == '1'){ 
                echo 'alert(str_flag); ';
            }
            //ios
            else {
                echo 'document.location = str_flag;';
            }
        ?>
      }  
</script>