三、数据库 和工具类

1.创建数据库
public class Mysqlite extends SQLiteOpenHelper {
public Mysqlite( Context context) {
super(context, “bw.db”, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(“create table person(uniquekey varchar(20),title varchar(20),date varchar(20),category varchar(20),author_name varchar(20),url varchar(20),thumbnail_pic_s varchar(20),thumbnail_pic_s02 varchar(20),thumbnail_pic_s03 varchar(20))”);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
2.Dao层
public class Dao {
private final SQLiteDatabase db;
public Dao(Context context){
Mysqlite mysqlite=new Mysqlite(context);
db = mysqlite.getWritableDatabase();
}
public long add(String table, String nullColumnHack, ContentValues values) {
return db.insert(table,nullColumnHack,values);
}
public long delete(String table, String whereClause, String[] whereArgs) {
return db.delete(table,whereClause,whereArgs);
}
public long update(String table, ContentValues values, String whereClause, String[] whereArgs){
return db.update(table, values, whereClause, whereArgs);
}
public Cursor query(String table, String[] columns, String selection,
String[] selectionArgs, String groupBy, String having,
String orderBy) {
return db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
}
}
3.HttpUtils类
public class HttpUtils {
private static HttpURLConnection connection;
public static String httpGet(String strUrl) {
try {
URL url = new URL(strUrl);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod(“GET”);
connection.setConnectTimeout(5000);
connection.setReadTimeout(5000);
InputStream stream = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
StringBuilder builder = new StringBuilder();
String str = “”;
while ((str = reader.readLine()) != null) {
builder.append(str);
}
connection.disconnect();
return builder.toString();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public static boolean isNetworkConnected(Context context) {
if (context != null) {
ConnectivityManager mconnectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo info = mconnectivityManager.getActiveNetworkInfo();
if (info != null) {
return info.isAvailable();
}
}
return false;
}
public static void httpAsyncTask(String strUrl, final CallBackString backString) {
new AsyncTask<String, Integer, String>() {
@Override
protected String doInBackground(String… strings) {
return httpGet(strings[0]);
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
backString.getData(s);
}
}.execute(strUrl);
}
public interface CallBackString {
void getData(String s);
}
}