안드로이드 데이터베이스 크래킹

저는 안드로이드 개발을 처음 사용하고 rss xml 파일을 읽고 데이터베이스에 저장하고 로컬에서 액세스 할 수있는 앱을 만들고있었습니다. 내가이 작업을 수행함에 따라 코드가 충돌하고 왜 그럴 수 없는지를 알 수 있습니다. 나는 어떤 것을 시도했지만 아무데도 가지 못하고있다. 어떤 도움을 주셔서 감사합니다. 감사합니다안드로이드 데이터베이스 크래킹

LayoutFile (maintwo.xml)

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:orientation="vertical" android:layout_width="match_parent" 
android:layout_height="match_parent"> 
<TextView 
    android:id="@+id/textView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="I&apos;m screen 2 (main2.xml)" 
    android:textAppearance="?android:attr/textAppearanceLarge" /> 
</LinearLayout>

활동 파일 (ActivityTwo.java)

import android.app.Activity; 
import android.os.Bundle; 
import android.widget.Button; 
import android.widget.TextView; 

import java.util.ArrayList; 
public class ActivityTwo extends Activity{ 

    //private DatabaseHelper helper; 
    private TextView tv; 
    private ArrayList<String> strings = new ArrayList<String>(); 
    private HandleXML handleXML; 
    //DatabaseHelper helper; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.maintwo); 
     tv = (TextView)findViewById(R.id.textView1); 
     //helper = new DatabaseHelper(this); 
     //storeToDB(); 
     //writeToFile(); 
     getFromXML(); 
    } 
    /*public void storeToDB() { 
     helper = new DatabaseHelper(this); 
     helper.insertContact("Something", "123"); 
     helper.insertContact("Another", "456"); 
    } 
    public void writeToFile() { 
     strings = helper.getAllContacts(); 
     String x = strings.get(0); 
     String y = strings.get(2); 
     tv.setText(x + " " + y); 
    }*/ 
    public void getFromXML() { 
     handleXML = new HandleXML("http://examplewebsite/file.xml"); 
     handleXML.fetchXML(); 
     strings = handleXML.getAll(); 
     //strings = helper.getAllContacts(); 
     String x = strings.get(0); 
     tv.setText(x); 
    } 
}

RSS 리더 (HandleXML.java)

import java.io.InputStream; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.util.ArrayList; 

import org.xmlpull.v1.XmlPullParser; 
import org.xmlpull.v1.XmlPullParserFactory; 

import android.app.Activity; 
import android.content.Context; 
import android.util.Log; 

public class HandleXML extends Activity{ 

    private String title = "title"; 
    private String link = "link"; 
    private String description = "description"; 
    private DatabaseHelper helper; 

    private String urlString = null; 
    private XmlPullParserFactory xmlFactoryObject; 
    public volatile boolean parsingComplete = true; 
    public HandleXML(String url){ 
     helper = new DatabaseHelper(this); 
     this.urlString = url; 
    } 
    public ArrayList<String> getAll() { 
     return helper.getAllContacts(); 
    } 
    /*public String getTitle(){ 
     return title; 
    } 
    public String getLink(){ 
     return link; 
    } 
    public String getDescription(){ 
     return description; 
    }*/ 
    public void parseXMLAndStoreIt(XmlPullParser myParser) { 
     int event; 
     int i =0; 
     String text=null; 
     try { 
      event = myParser.getEventType(); 
      while (event != XmlPullParser.END_DOCUMENT) { 
       String name=myParser.getName(); 
       switch (event){ 
        case XmlPullParser.START_TAG: 
         break; 
        case XmlPullParser.TEXT: 
         text = myParser.getText(); 
         break; 
        case XmlPullParser.END_TAG: 
         if(name.equals("title")){ 
          title = text; 
         } 
         else if(name.equals("link")){ 
          link = text; 
         } 
         else if(name.equals("description")){ 
          description = text; 
         } 
         else{ 
         } 
         break; 
       } 
       helper.insertContact(title + i, "123"); 
       i++; 
       event = myParser.next(); 
      } 
      parsingComplete = false; 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 
    } 
    public void fetchXML(){ 
     Thread thread = new Thread(new Runnable(){ 
      @Override 
      public void run() { 
       try { 
        URL url = new URL(urlString); 
        HttpURLConnection conn = (HttpURLConnection) url.openConnection(); 
        conn.setReadTimeout(10000 /* milliseconds */); 
        conn.setConnectTimeout(15000 /* milliseconds */); 
        conn.setRequestMethod("GET"); 
        conn.setDoInput(true); 
        // Starts the query 
        conn.connect(); 
        InputStream stream = conn.getInputStream(); 
        xmlFactoryObject = XmlPullParserFactory.newInstance(); 
        XmlPullParser myparser = xmlFactoryObject.newPullParser(); 
        myparser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false); 
        myparser.setInput(stream, null); 
        parseXMLAndStoreIt(myparser); 
        stream.close(); 
       } catch (Exception e) { 
       } 
      } 
     }); 
     thread.start(); 
    } 
}

파일

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.DatabaseUtils; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 

import java.util.ArrayList; 
import java.util.HashMap; 

public class DatabaseHelper extends SQLiteOpenHelper { 

    public static final String DATABASE_NAME = "MyDBName.db"; 
    public static final String CONTACTS_TABLE_NAME = "contacts"; 
    public static final String CONTACTS_COLUMN_ID = "id"; 
    public static final String CONTACTS_COLUMN_NAME = "name"; 
    public static final String CONTACTS_COLUMN_PHONE = "phone"; 

    private HashMap hp; 

    public DatabaseHelper(Context context) { 
     super(context, DATABASE_NAME , null, 1); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     db.execSQL("create table contacts " + "(id integer primary key, name text,phone text)"); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS contacts"); 
     onCreate(db); 
    } 

    public boolean insertContact (String name, String phone) 
    { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     ContentValues contentValues = new ContentValues(); 

     contentValues.put("name", name); 
     contentValues.put("phone", phone); 

     db.insert("contacts", null, contentValues); 
     return true; 
    } 

    public Cursor getData(int id){ 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor res = db.rawQuery("select * from contacts where id="+id+"", null); 
     return res; 
    } 

    public int numberOfRows(){ 
     SQLiteDatabase db = this.getReadableDatabase(); 
     int numRows = (int) DatabaseUtils.queryNumEntries(db, CONTACTS_TABLE_NAME); 
     return numRows; 
    } 

    public boolean updateContact (Integer id, String name, String phone) 
    { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     ContentValues contentValues = new ContentValues(); 
     contentValues.put("name", name); 
     contentValues.put("phone", phone); 
     db.update("contacts", contentValues, "id = ? ", new String[] { Integer.toString(id) }); 
     return true; 
    } 

    public Integer deleteContact (Integer id) 
    { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     return db.delete("contacts", 
       "id = ? ", 
       new String[] { Integer.toString(id) }); 
    } 

    public ArrayList getAllContacts() 
    { 
     ArrayList array_list = new ArrayList(); 
     //hp = new HashMap(); 
     SQLiteDatabase db = this.getReadableDatabase(); 
     Cursor res = db.rawQuery("select * from contacts", null); 
     res.moveToFirst(); 
     while(res.isAfterLast() == false){ 
      array_list.add(res.getString(res.getColumnIndex(CONTACTS_COLUMN_NAME))); 
      res.moveToNext(); 
     } 
     return array_list; 
    } 
}

충돌 보고서

01-23 20:33:10.124 19847-19847/com.varvaniweb.example.helloworld E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    Process: com.varvaniweb.example.helloworld, PID: 19847 
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.varvaniweb.example.helloworld/com.varvaniweb.example.helloworld.ActivityTwo}: java.lang.NullPointerException 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
      at android.app.ActivityThread.access$800(ActivityThread.java:135) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:136) 
      at android.app.ActivityThread.main(ActivityThread.java:5021) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:515) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) 
      at dalvik.system.NativeStart.main(Native Method) 
    Caused by: java.lang.NullPointerException 
      at android.content.ContextWrapper.openOrCreateDatabase(ContextWrapper.java:256) 
      at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:224) 
      at android.database.sqlite.SQLiteOpenHelper.getReadableDatabase(SQLiteOpenHelper.java:188) 
      at com.varvaniweb.example.helloworld.DatabaseHelper.getAllContacts(DatabaseHelper.java:87) 
      at com.varvaniweb.example.helloworld.HandleXML.getAll(HandleXML.java:33) 
      at com.varvaniweb.example.helloworld.ActivityTwo.getFromXML(ActivityTwo.java:45) 
      at com.varvaniweb.example.helloworld.ActivityTwo.onCreate(ActivityTwo.java:29) 
      at android.app.Activity.performCreate(Activity.java:5231) 
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1090) 
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159) 
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
            at android.app.ActivityThread.access$800(ActivityThread.java:135) 
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
            at android.os.Handler.dispatchMessage(Handler.java:102) 
            at android.os.Looper.loop(Looper.java:136) 
            at android.app.ActivityThread.main(ActivityThread.java:5021) 
            at java.lang.reflect.Method.invokeNative(Native Method) 
            at java.lang.reflect.Method.invoke(Method.java:515) 
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643) 
            at dalvik.system.NativeStart.main(Native Method)

출처

2015-01-24 Hzakv

문제는 당신이 만드는됩니다 (DatabaseHelper.java)를 DB를 생성하는 데 사용되는 Activity 자신 (HandleXML) 및 사용하여 그 context을 같은 귀하의 DatabaseHelper :

handleXML = new HandleXML("http://examplewebsite/file.xml");

내부 HandleXML :

public HandleXML(String url) { 
    helper = new DatabaseHelper(this); // <-- PROBLEM: this does not have Context info 
    this.urlString = url; 
}

당신이해야 결코가 인스턴스화되지 응용 프로그램 구성 요소 자신. 그렇게하는 것은 시스템의 책임이며, 그렇게하는 과정에서 시스템은 사용자를 대신하여 만드는 앱 및 구성 요소에 대한 정보를 첨부합니다. 직접 만들었으므로 데이터베이스를 열 때 필요한 Context 정보가 필요하지 않습니다.

handleXML = new HandleXML(this, "http://examplewebsite/file.xml");

출처

2015-01-24 02:02:27 Karakuri

당신을 감사합니다

public class HandleXML { ... public HandleXML(Context context, String url) { helper = new DatabaseHelper(context); this.urlString = url; } ... }

이처럼 ActivityTwo에 전화 : 그것은 활동을 연장하지 않는 대신 DatabaseHelper에 전달하는 상황을 부여되도록

은 HandleXML 클래스를 변경

고마워요 !!!!!!! – Hzakv

안드로이드 데이터베이스 크래킹

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