如何在Android的WebView中加载HTML？

Question

您能告诉我如何在android的Web视图中加载html吗？

我执行以下步骤.i在资产文件夹中创建www文件夹，因为我粘贴了html，js和css文件。

请看图片。比我写xml代码。 和Java代码。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

   <WebView 
    android:id="@+id/webView1"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
/>       
</LinearLayout>

包com.example.test3;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;

public class MainActivity extends Activity {
    WebView web;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
         web = (WebView) findViewById(R.id.webView1);

            web.getSettings().setLoadsImagesAutomatically(true);
            web.getSettings().setJavaScriptEnabled(true);
            web.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
            web.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
            web.getSettings().setAppCacheEnabled(false);
            web.getSettings().setSaveFormData(false);
        web.loadUrl("file:///android_asset/www/parallel.html");

        setContentView(R.layout.activity_main);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);

        return true;
    }

}

错误

04-13 05:36:37.726: E/AndroidRuntime(868): FATAL EXCEPTION: main
04-13 05:36:37.726: E/AndroidRuntime(868): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test3/com.example.test3.MainActivity}: java.lang.NullPointerException
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.os.Looper.loop(Looper.java:137)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread.main(ActivityThread.java:5041)
04-13 05:36:37.726: E/AndroidRuntime(868):  at java.lang.reflect.Method.invokeNative(Native Method)
04-13 05:36:37.726: E/AndroidRuntime(868):  at java.lang.reflect.Method.invoke(Method.java:511)
04-13 05:36:37.726: E/AndroidRuntime(868):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-13 05:36:37.726: E/AndroidRuntime(868):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-13 05:36:37.726: E/AndroidRuntime(868):  at dalvik.system.NativeStart.main(Native Method)
04-13 05:36:37.726: E/AndroidRuntime(868): Caused by: java.lang.NullPointerException
04-13 05:36:37.726: E/AndroidRuntime(868):  at com.example.test3.MainActivity.onCreate(MainActivity.java:19)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.Activity.performCreate(Activity.java:5104)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
04-13 05:36:37.726: E/AndroidRuntime(868):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
04-13 05:36:37.726: E/AndroidRuntime(868):  ... 11 more

Answer 1

您应该移动setContentView(R.layout.activity_main); 在web = (WebView) findViewById(R.id.webView1);之前web = (WebView) findViewById(R.id.webView1);

更正如下：

WebView web;
@Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
    web = (WebView) findViewById(R.id.webView1);

    web.getSettings().setLoadsImagesAutomatically(true);
    web.getSettings().setJavaScriptEnabled(true);
    web.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
    web.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
    web.getSettings().setAppCacheEnabled(false);
    web.getSettings().setSaveFormData(false);
   web.loadUrl("file:///android_asset/www/parallel.html");
 }

在您的onCreate()方法中。

Answer 2

尝试这个..

setContentView(R.layout.activity_main); 必须在WebView初始化之前

WebView web;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
     web = (WebView) findViewById(R.id.webView1);

        web.getSettings().setLoadsImagesAutomatically(true);
        web.getSettings().setJavaScriptEnabled(true);
        web.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
        web.getSettings().setCacheMode(WebSettings.LOAD_NO_CACHE);
        web.getSettings().setAppCacheEnabled(false);
        web.getSettings().setSaveFormData(false);
    web.loadUrl("file:///android_asset/www/parallel.html");
}