Webview从资源目录加载html

Question

我正在尝试从assets目录加载一个html页面。我尝试了这个，但它失败了。

public class ViewWeb extends Activity {  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        WebView wv;  
        wv = (WebView) findViewById(R.id.webView1);  
        wv.loadUrl("file:///android_asset/aboutcertified.html");   // fails here
        setContentView(R.layout.webview);  
    }  
}

我在LogCat中没有任何明显的错误...

Answer 1

您在设置“内容”视图之前获取WebView，因此wv可能为null。

public class ViewWeb extends Activity {  
        @Override  
        public void onCreate(Bundle savedInstanceState) {  
            super.onCreate(savedInstanceState);
            setContentView(R.layout.webview);  
            WebView wv;  
            wv = (WebView) findViewById(R.id.webView1);  
            wv.loadUrl("file:///android_asset/aboutcertified.html");   // now it will not fail here
        }  
    }

Answer 2

无论何时创建活动，都必须在超级调用后添加setcontentview（您的布局）。因为setcontentview将xml绑定到您的活动中，所以这就是您获得nullpointerexception的原因。

 setContentView(R.layout.webview);  
 webView = (WebView) findViewById(R.id.webView1);
 wv.loadUrl("file:///android_asset/xyz.html");

Answer 3

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        WebView wb = new WebView(this);
        wb.loadUrl("file:///android_asset/index.html");
        setContentView(wb);
    }


keep your .html in `asset` folder

Answer 4

从这里下载源代码（Open html file from assets android）

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:background="#FFFFFF"
 android:layout_height="match_parent">

<WebView
 android:layout_width="match_parent"
 android:id="@+id/webview"
 android:layout_height="match_parent"
 android:layout_margin="10dp"></WebView>
</RelativeLayout>

main activity.Java

package com.deepshikha.htmlfromassets;
 import android.app.ProgressDialog;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {

WebView webview;
 ProgressDialog progressDialog;

@Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 init();
 }

private void init(){
 webview = (WebView)findViewById(R.id.webview);
 webview.loadUrl("file:///android_asset/download.html");
 webview.requestFocus();

progressDialog = new ProgressDialog(MainActivity.this);
 progressDialog.setMessage("Loading");
 progressDialog.setCancelable(false);
 progressDialog.show();

webview.setWebViewClient(new WebViewClient() {

public void onPageFinished(WebView view, String url) {
 try {
 progressDialog.dismiss();
 } catch (Exception e) {
 e.printStackTrace();
 }
 }
 });
 }
 }