简单使用URLConnection、HttpURLConnection和HttpClient访问网络资源
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：
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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 // 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( // 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( // 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 // 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(); } } } } 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 // 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( // 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( // 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 // 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：
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<?xml version="1.0" encoding="utf-8"?> 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> <?xml version="1.0" encoding="utf-8"?> 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：
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<uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.INTERNET" /> |
