java试图在tab窗口小部件中访问数据库

7 月 Questions & Answers 194

我确信我的代码结构是错误的，但我已经看了很长时间了

我已经设法让一个类能够访问我的数据库并返回数据，但是当我试图将这个类构建到我的选项卡小部件中时，它似乎不起作用

这就是我所说的班级：

// Create an Intent to launch an Activity for the tab (to be reused)
intent = new Intent().setClass(this, recipelist.class);

// Initialize a TabSpec for each tab and add it to the TabHost
spec = tabHost.newTabSpec("recipe").setIndicator("recipe", res.getDrawable(R.drawable.ic_tab_list)).setContent(intent);
tabHost.addTab(spec);

这是带有数据库代码的类：

package fridge.mate;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
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.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import 安卓.app.Activity;
import 安卓.os.Bundle;
import 安卓.util.Log;
import 安卓.widget.LinearLayout;
import 安卓.widget.TextView;

public class recipelist extends Activity {
   TextView txt;
   @Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);
    // Create a crude view - this should really be set via the layout resources  
    // but since its an example saves declaring them in the XML.  
    LinearLayout rootLayout = new LinearLayout(getApplicationContext());  
    txt = new TextView(getApplicationContext());  
    rootLayout.addView(txt);  
    setContentView(rootLayout);  

    // Set the text and call the connect function.  
    txt.setText("Connecting..."); 
  //call the method to run the data retreival
    txt.setText("gfgfgf..."); 
   }
public static final String KEY_121 = "http://www.bankruptcy.co.uk/1.php"; //i use my real ip here
private String getServerData(String returnString) {

       InputStream is = null;

       String result = "";
        //the year data to send
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("name","beans"));

        //http post
        try{
                HttpClient httpclient = new DefaultHttpClient();
                HttpPost httppost = new HttpPost(KEY_121);
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                HttpResponse response = httpclient.execute(httppost);
                HttpEntity entity = response.getEntity();
                is = entity.getContent();

        }catch(Exception e){
                Log.e("log_tag", "Error in http connection "+e.toString());
        }

        //convert response to string
        try{
                BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
                StringBuilder sb = new StringBuilder();
                String line = null;
                while ((line = reader.readLine()) != null) {
                        sb.append(line + "\n");
                }
                is.close();
                result=sb.toString();
        }catch(Exception e){
                Log.e("log_tag", "Error converting result "+e.toString());
        }
        //parse json data
        try{
                JSONArray jArray = new JSONArray(result);
                for(int i=0;i<jArray.length();i++){
                        JSONObject json_data = jArray.getJSONObject(i);
                        Log.i("log_tag","ID: "+json_data.getInt("ID")+
                                ", name: "+json_data.getString("name")+
                                ", servings: "+json_data.getString("servings")+
                                ", discription: "+json_data.getString("discription")
                        );
                        //Get an output to the screen
                        returnString += "\n\t" + jArray.getJSONObject(i); 
                        txt.setText("Connecting..."); 

                }
        }catch(JSONException e){
                Log.e("log_tag", "Error parsing data "+e.toString());
        }
        return returnString; 
    }    
}

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java试图在tab窗口小部件中访问数据库

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