Dao.java

package com.icss.dao;

import java.util.ArrayList;
import java.util.List;
import javax.crypto.spec.DESKeySpec;

import com.icss.DBHelper.DBHelper;
import com.icss.entity.DownloadInfo;

 import android.content.Context;
 import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;


 /**
  *
  * 一个业务类
  */
 public class Dao {
     private DBHelper dbHelper;

     public Dao(Context context) {
         dbHelper = new DBHelper(context);
         
     }

     /**
      * 查看数据库中是否有数据
      */
     public boolean isHasInfors(String urlstr) {
         SQLiteDatabase database = dbHelper.getReadableDatabase();
        String sql = "select count(*)  from download_info where url=?";
         Cursor cursor = database.rawQuery(sql, new String[] { urlstr });
         cursor.moveToFirst();
         int count = cursor.getInt(0);
        cursor.close();
         return count == 0;
     }

     /**
      * 保存 下载的具体信息
      */
     public void saveInfos(List<DownloadInfo> infos) {
         SQLiteDatabase database = dbHelper.getWritableDatabase();
         for (DownloadInfo info : infos) {
             String sql = "insert into download_info(thread_id,start_pos, end_pos,compelete_size,url) values (?,?,?,?,?)";
           Object[] bindArgs = { info.getThreadId(), info.getStartPos(),
                     info.getEndPos(), info.getCompeleteSize(), info.getUrl() };
             database.execSQL(sql, bindArgs);
         }
     }

     /**
      * 得到下载具体信息
      */
     public List<DownloadInfo> getInfos(String urlstr) {
         List<DownloadInfo> list = new ArrayList<DownloadInfo>();
         SQLiteDatabase database = dbHelper.getReadableDatabase();
         String sql = "select thread_id, start_pos, end_pos,compelete_size,url from download_info where url=?";
         Cursor cursor = database.rawQuery(sql, new String[] { urlstr });
         while (cursor.moveToNext()) {
             DownloadInfo info = new DownloadInfo(cursor.getInt(0),
                     cursor.getInt(1), cursor.getInt(2), cursor.getInt(3),
                    cursor.getString(4));
             list.add(info);
         }
         cursor.close();
         return list;
     }

     /**
     * 更新数据库中的下载信息
      */
     public void updataInfos(int threadId, int compeleteSize, String urlstr) {
         SQLiteDatabase database = dbHelper.getReadableDatabase();
         String sql = "update download_info set compelete_size=? where thread_id=? and url=?";
         Object[] bindArgs = { compeleteSize, threadId, urlstr };
        database.execSQL(sql, bindArgs);
     }
     /**
      * 关闭数据库
      */
     public void closeDb() {
         dbHelper.close();
    }

     /**
     * 下载完成后删除数据库中的数据
      */
     public void delete(String url) {
        SQLiteDatabase database = dbHelper.getReadableDatabase();
         database.delete("download_info", "url=?", new String[] { url });
         database.close();
     }
 }