无法生成HTTPConnection

Question

我是android开发的新手，我正在尝试制作HTTPConnection。我创建了两个文件，一个是ParsingActivity.java(主活动文件)，另一个是XMLParser.java (用于设置HTTPRClient请求)。

ParserActivity.java

package ok.done;

import android.app.Activity;
import android.os.Bundle;

public class ParsingActivity extends Activity {

    String URL = "http://api.androidhive.info/pizza/?format=xml";
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        System.out.println("t1==========>"+URL);


        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL);

        System.out.println("t2==========>"+xml);
    }
}

XMLParsing.java

package ok.done;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

public class XMLParser {

    // constructor
    public XMLParser() {

    }

    public String getXmlFromUrl(String url) {
        String xml = null;

        System.out.println("t3==========>"+xml);
        System.out.println("t4==========>"+url);

        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            System.out.println("t5==========>"+url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity);

            System.out.println("t6==========>"+xml);

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return xml;
    }

}

我还在AndroidManifest.xml中添加了权限

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="ok.done"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:label="@string/app_name"
            android:name=".ParsingActivity" >
            <intent-filter >
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>


</manifest>

我的System.out.println的LogCat结果是

对于t1==========>http://api.androidhive.info/pizza/?format=xml t3==========>null t4==========>http://api.androidhive.info/pizza/?format=xml t5==========>null t6==========>null t2==========>null

但是如果在这个简单的代码中一切都是完美的，那么对于t6的结果，t2就是xml文件描述。

任何人请建议我应该做什么或任何其他链接，这将有助于我创建XML解析型应用程序。

提前谢谢。

Answer 1

是否确定http服务器在触发后提供了有效的xml。为了确保在web浏览器上触发url，如果服务器提供了xml，您将获得xml内容。