URL的openConnection方法将返回一个URLConnection，该对象表示应用程序和URL之间的通信连接。程序可以通过它的实例向该URL发送请求，读取URL引用的资源。

下面通过一个简单示例来演示：

Activity：

package com.home.urlconnection;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import java.net.URLConnection;

import java.util.ArrayList;

import java.util.List;

import org.apache.http.HttpEntity;

import org.apache.http.HttpResponse;

import org.apache.http.client.ClientProtocolException;

import org.apache.http.client.HttpClient;

import org.apache.http.client.entity.UrlEncodedFormEntity;

import org.apache.http.client.methods.HttpPost;

import org.apache.http.impl.client.DefaultHttpClient;

import org.apache.http.message.BasicNameValuePair;

import org.apache.http.util.EntityUtils;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.webkit.WebView;

import android.widget.Button;

import android.widget.TextView;

public class MainActivity extends Activity implements OnClickListener {

	private Button urlConnectionBtn;

	private Button httpUrlConnectionBtn;

	private Button httpClientBtn;

	private TextView showTextView;

	private WebView webView;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		init();

	}

	private void init() {

		urlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_urlconnection);

		httpUrlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_httpurlconnection);

		httpClientBtn = (Button) findViewById(R.id.test_url_main_btn_httpclient);

		showTextView = (TextView) findViewById(R.id.test_url_main_tv_show);

		webView = (WebView) findViewById(R.id.test_url_main_wv);

		urlConnectionBtn.setOnClickListener(this);

		httpUrlConnectionBtn.setOnClickListener(this);

		httpClientBtn.setOnClickListener(this);

	}

	@Override

	public void onClick(View v) {

		if (v == urlConnectionBtn) {

			try {

				// 直接使用URLConnection对象进行连接

				URL url = new URL("http://192.168.1.100:8080/myweb/hello.jsp");

				// 得到URLConnection对象

				URLConnection connection = url.openConnection();

				InputStream is = connection.getInputStream();

				byte[] bs = new byte[1024];

				int len = 0;

				StringBuffer sb = new StringBuffer();

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

					String str = new String(bs, 0, len);

					sb.append(str);

				}

				showTextView.setText(sb.toString());

			} catch (Exception e) {

				e.printStackTrace();

			}

		}

		if (v == httpUrlConnectionBtn) {

			// 直接使用HttpURLConnection对象进行连接

			try {

				URL url = new URL(

						"http://192.168.1.100:8080/myweb/hello.jsp?username=abc");

				// 得到HttpURLConnection对象

				HttpURLConnection connection = (HttpURLConnection) url

						.openConnection();

				// 设置为GET方式

				connection.setRequestMethod("GET");

				if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {

					// 得到响应消息

					String message = connection.getResponseMessage();

					showTextView.setText(message);

				}

			} catch (Exception e) {

				e.printStackTrace();

			}

		}

		if (v == httpClientBtn) {

			try {

				// 使用ApacheHttp客户端进行连接(重要方法)

				HttpClient client = new DefaultHttpClient();

				// 如果是Get提交则创建HttpGet对象，否则创建HttpPost对象

				// POST提交的方式

				HttpPost httpPost = new HttpPost(

						"http://192.168.1.100:8080/myweb/hello.jsp");

				// 如果是Post提交可以将参数封装到集合中传递

				List dataList = new ArrayList();

				dataList.add(new BasicNameValuePair("username", "abc"));

				dataList.add(new BasicNameValuePair("pwd", "123"));

				// UrlEncodedFormEntity用于将集合转换为Entity对象

				httpPost.setEntity(new UrlEncodedFormEntity(dataList));

				// GET提交的方式

				// HttpGet httpGet = new

				// HttpGet("http://192.168.1.100:8080/myweb/hello.jsp?username=abc&pwd=321");

				// 获取相应消息

				HttpResponse httpResponse = client.execute(httpPost);

				// 获取消息内容

				HttpEntity entity = httpResponse.getEntity();

				// 把消息对象直接转换为字符串

				String content = EntityUtils.toString(entity);

				// 显示在TextView中

				// showTextView.setText(content);

				// 通过webview来解析网页

				webView.loadDataWithBaseURL(null, content, "text/html",

						"utf-8", null);

				// 直接根据url来进行解析

				// webView.loadUrl(url);

			} catch (ClientProtocolException e) {

				e.printStackTrace();

			} catch (IOException e) {

				e.printStackTrace();

			}

		}

	}

}

上面使用到的url是部署在笔者本机的web应用，这里不再给出，大家可以换成自己的web应用即可。
布局XML：

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

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

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical" >

    <Button

        android:id="@+id/test_url_main_btn_urlconnection"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="使用URLConnection连接" />

    <Button

        android:id="@+id/test_url_main_btn_httpurlconnection"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="使用HttpURLConnection连接" />

    <Button

        android:id="@+id/test_url_main_btn_httpclient"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="使用Apache客户端连接" />

    <TextView

        android:id="@+id/test_url_main_tv_show"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content" />

    <WebView

        android:id="@+id/test_url_main_wv"

        android:layout_width="match_parent"

        android:layout_height="match_parent" />

</LinearLayout>

权限：

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