10_Android中通过HttpUrlConnection访问网络，Handler和多线程使用，读取网络html代码并显示在界面上，ScrollView组件的使用



1. 编写如下项目：

2 编写Android清单文件

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.itheima28.htmldemo"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="19" />

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

<application

android:allowBackup="true"

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name="com.itheima28.htmldemo.MainActivity"

android:label="@string/app_name" >

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

</application>

</manifest>

3 编写布局文件activity_main.xml

<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" >

<LinearLayout

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:orientation="horizontal">

<EditText

android:id="@+id/et_url"

android:layout_width="0dip"

android:text="http://www.baidu.com"

android:layout_height="wrap_content"

android:singleLine="true"

android:layout_weight="1"/>

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:onClick="getHtml"

android:text="GO"/>

</LinearLayout>

<ScrollView

android:layout_width="fill_parent"

android:layout_height="fill_parent">

<TextView

android:id="@+id/tv_html"

android:layout_width="fill_parent"

android:layout_height="fill_parent"/>

</ScrollView>

</LinearLayout>

4 编写Activity的类MainActivity如下：

package com.itheima28.htmldemo;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import android.app.Activity;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.text.TextUtils;

import android.util.Log;

import android.view.View;

import android.widget.EditText;

import android.widget.TextView;

import android.widget.Toast;

public class MainActivity extends Activity {

private static final String TAG = "MainActivity";

private static final int SUCCESS = 0;

protected static final int ERROR = 1;

private EditText etUrl;

private TextView tvHtml;

private Handler handler = new Handler() {

@Override

public void handleMessage(Message msg) {

super.handleMessage(msg);

switch (msg.what) {

case SUCCESS:

tvHtml.setText((String) msg.obj);

break;

case ERROR:

Toast.makeText(MainActivity.this, "访问失败", 0).show();

break;

default:

break;

}

}

};

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

etUrl = (EditText) findViewById(R.id.et_url);

tvHtml = (TextView) findViewById(R.id.tv_html);

}

public void getHtml(View v) {

final String url = etUrl.getText().toString();

new Thread(new Runnable() {

@Override

public void run() {

// 请求网络

String html = getHtmlFromInternet(url);

if(!TextUtils.isEmpty(html)) {

// 更新textview的显示了

Message msg = new Message();

msg.what = SUCCESS;

msg.obj = html;

handler.sendMessage(msg);

} else {

Message msg = new Message();

msg.what = ERROR;

handler.sendMessage(msg);

}

}

}).start();

}

/**

* 根据给定的url访问网络, 抓去html代码

* @param url

* @return

*/

protected String getHtmlFromInternet(String url) {

try {

URL mURL = new URL(url);

HttpURLConnection conn = (HttpURLConnection) mURL.openConnection();

conn.setRequestMethod("GET");

conn.setConnectTimeout(10000);

conn.setReadTimeout(5000);

//         conn.connect();

int responseCode = conn.getResponseCode();

if(responseCode == 200) {

InputStream is = conn.getInputStream();

String html = getStringFromInputStream(is);

return html;

} else {

Log.i(TAG, "访问失败: " + responseCode);

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

/**

* 根据流返回一个字符串信息

* @param is

* @return

* @throws IOException

*/

private String getStringFromInputStream(InputStream is) throws IOException {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len = -1;

while((len = is.read(buffer)) != -1) {

baos.write(buffer, 0, len);

}

is.close();

String html = baos.toString();  // 把流中的数据转换成字符串, 采用的编码是: utf-8

String charset = "utf-8";

if(html.contains("gbk") || html.contains("gb2312")

|| html.contains("GBK") || html.contains("GB2312")) {       // 如果包含gbk, gb2312编码, 就采用gbk编码进行对字符串编码

charset = "gbk";

}

html = new String(baos.toByteArray(), charset);  // 对原有的字节数组进行使用处理后的编码名称进行编码

baos.close();

return html;

}

}