Android网络编程之httpclient
本文主要讲述如何通过HttpClient来访问网页内容。
1. 搭建web服务器环境:php+mySQL+apache,可以参考:关于Apache+MySQL+PHP在windows平台的整合
2. 测试访问局域网的web网页，需要在AndroidManifest.xml中添加internet权限：
<uses-permission android:name="android.permission.INTERNET"/>
3.解析来自web server的JSON数据
package json.http.andy;
/*
* @author:andy
* @date:2012.5.18
* Description:Demo to parse json from web server.
* */
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import org.apache.http.*;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class HttpClientActivity extends Activity {
private static final String TAG = "HTTPCLIENT";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.httpclient);
final TextView tv = (TextView)this.findViewById(R.id.textView_HTTPClient);
//http address
String httpurl = "http://10.0.2.2";
//定义Http Get请求
final HttpGet httpRequest = new HttpGet(httpurl);
//准备参数设置
HttpParams params = new BasicHttpParams();
//连接超时
HttpConnectionParams.setConnectionTimeout(params, 60*1000);
//Socket Timeout
HttpConnectionParams.setSoTimeout(params, 60*1000);
//Socket Buffer Size
HttpConnectionParams.setSocketBufferSize(params, 8192);//8K
//Redirecting to true
//HttpClientParams.setRedirecting(params, true);
HttpProtocolParams.setUserAgent(params, ACTIVITY_SERVICE);
//使用参数实例化HttpClient
final HttpClient httpclient = new DefaultHttpClient();
Log.v(TAG,"get httpclient");
Thread getThread = new Thread() {
@Override
public void run()
{
try
{
//执行Get请求，返回结果在httpResponse中
HttpResponse httpResponse = httpclient.execute(httpRequest);
Log.v(TAG,"creat http response object");
Log.v(TAG,"Response code:"+httpResponse.getStatusLine().getStatusCode());
if(httpResponse.getStatusLine().getStatusCode()==HttpStatus.SC_OK)
{
Log.v(TAG,"get result");
final String resultData = EntityUtils.toString(httpResponse.getEntity());
if(resultData != "")
{
Log.v(TAG,"result:"+resultData);
//tv.setText(resultData);//不能在UI线程之外刷UI
//可以这样刷
tv.post(new Runnable() {
public void run() {
tv.setText(resultData);
}
});
// Parse the JSON data.
try {
String text = "";
JSONArray jArray = new JSONArray(resultData);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
text += "id: " + json_data.getInt("id")
+ ", name: " + json_data.getString("name")
+ ", age: " + json_data.getInt("age")
+ ", homeaddr: "
+ json_data.getString("homeaddr")+"\n";
}
Log.v(TAG,text);
} catch (JSONException ex) {
Log.e(TAG,"Error parsing JSON data: " + ex.toString());
}
}
else
{
Log.e(TAG,"未读取到网页内容.");
}
}
else
{
httpResponse = null;
httpRequest.abort();
interrupted();
}
}
catch (ClientProtocolException e)
{
Log.e(TAG,"ClientProtocolException");
httpRequest.abort();
interrupted();
}
catch (IOException e)
{
Log.e(TAG, "IOException");
httpRequest.abort();
interrupted();
}
catch (Exception e)
{
Log.e(TAG, "Exception");
httpRequest.abort();
interrupted();
}
finally
{
if(httpclient != null )
{
httpclient.getConnectionManager().shutdown();
}
}
}
};
getThread.start();
//注意这里同样的R.id.Button_Back在不同的Activity中被注册成不同的功能
Button button_back = (Button)findViewById(R.id.Button_Back);
button_back.setOnClickListener(new Button.OnClickListener() {
@Override
public void onClick(View v)
{
Intent intent = new Intent();
intent.setClass(HttpClientActivity.this,HttpActivity.class);
startActivity(intent);
HttpClientActivity.this.finish();
}
});
}
}
得到结果显示如下（内容为php包装的JSON对象）：
附上web的源代码 index.php:
<?php
$conn = mysql_connect("localhost");
$t = mysql_select_db("test",$conn);
$q=mysql_query("SELECT * FROM staff",$conn);
while($e=mysql_fetch_assoc($q))
$output[]=$e;
print(json_encode($output));
mysql_close($conn);
?>
可以看出，我们如果需要访问远程数据接口，妥善的办法还是通过Web Server来访问数据库接口。
但是当把URL改成 http://www.google.com.hk/ 等internet网址时却出现无响应的情况，应该是超时所致，接下来我们来解决这个问题。
//分析下来，是由于公司网络必须设置proxy才能访问外网导致，因此增加proxy设置，解决此问题。
//设置代理
HttpHost proxy = new HttpHost("your proxy", 8888);
httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY,proxy);
//执行Get请求，返回结果在httpResponse中
HttpResponse httpResponse = httpclient.execute(httpRequest);