java – Android：将网页的HTML读入字符串

发布时间：2020-12-15 04:56:26 所属栏目：Java 来源：网络整理

导读：我是 Android开发的新手,我正在尝试阅读网页的HTML并将其存储在下面的字符串(“myHTML”)中,并将其显示在应用程序上. 但是,只要运行,应用程序就会结束.我一直在网上搜索这个原因,并且发现一些文章说由于其“昂贵”的性质,无法在应用程序的主UI线程中完成互联

我是 Android开发的新手,我正在尝试阅读网页的HTML并将其存储在下面的字符串(“myHTML”)中,并将其显示在应用程序上.

但是,只要运行,应用程序就会结束.我一直在网上搜索这个原因,并且发现一些文章说由于其“昂贵”的性质,无法在应用程序的主UI线程中完成互联网访问.有没有人遇到过类似的问题？我会很感激有关这个问题的任何进一步信息…在初学者级别:)

这是程序：

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.regex.*;
import java.net.*;
import java.io.*;

/*
   * Gets A webpage's HTML and saves to a string
   */
public String WebPageToHTML(String Webpage) throws   IOException{
  URL x = new URL(Webpage);
    BufferedReader in = new BufferedReader(
          new InputStreamReader(
          x.openStream()));
    String y = "";
    String inputLine;
    while ((inputLine = in.readLine()) != null)
       y = y.concat(inputLine);
     in.close();
  return y;     
}

public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      TextView tv = new TextView(this);

       String FirstAddress = "http://www.google.com";
       String myHTML = "";
  try {
    myHTML = WebPageToHTML(FirstAddress);
  } catch (IOException e) {
    e.printStackTrace();
  }    
      tv.setText(myHTML);
      setContentView(tv);
}

logcat的：

12-29 14:41:44.441: E/AndroidRuntime(540): java.lang.RuntimeException: Unable to start activity ComponentInfo{my.first.app/my.first.app.WhatHaveIMissedActivity}: android.os.NetworkOnMainThreadException
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.os.Looper.loop(Looper.java:137)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread.main(ActivityThread.java:4424)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.lang.reflect.Method.invokeNative(Native Method)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.lang.reflect.Method.invoke(Method.java:511)
12-29 14:41:44.441: E/AndroidRuntime(540):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-29 14:41:44.441: E/AndroidRuntime(540):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-29 14:41:44.441: E/AndroidRuntime(540):  at dalvik.system.NativeStart.main(Native Method)
12-29 14:41:44.441: E/AndroidRuntime(540): Caused by: android.os.NetworkOnMainThreadException
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.net.InetAddress.lookupHostByName(InetAddress.java:391)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.net.InetAddress.getAllByName(InetAddress.java:220)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
12-29 14:41:44.441: E/AndroidRuntime(540):  at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
12-29 14:41:44.441: E/AndroidRuntime(540):  at java.net.URL.openStream(URL.java:462)
12-29 14:41:44.441: E/AndroidRuntime(540):  at my.first.app.WhatHaveIMissedActivity.WebPageToHTML(WhatHaveIMissedActivity.java:71)
12-29 14:41:44.441: E/AndroidRuntime(540):  at my.first.app.WhatHaveIMissedActivity.onCreate(WhatHaveIMissedActivity.java:99)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.Activity.performCreate(Activity.java:4465)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-29 14:41:44.441: E/AndroidRuntime(540):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
12-29 14:41:44.441: E/AndroidRuntime(540):  ... 11 more

解决方法

您可以使用HttpClient来请求此信息.它将同步完成,但您也可以发出异步请求.

String myUri = "http://www.whatever.com";
HttpClient httpClient = new DefaultHttpClient();
HttpGet get = new HttpGet(myUri);

HttpResponse response = httpClient.execute(get);

// Build up result
String bodyHtml = EntityUtils.toString(response.getEntity());

您还需要将以下内容添加到应用程序的清单文件中.

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

关于如何使用AsyncTask包装它的一个很好的线程是：Common class for AsyncTask in Android?

（编辑：李大同）

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