Question

我正在实现一个从在线mysql获取数据的应用程序，并在mysql lite表中存储包含2列

通知

日期

我想在列表视图中显示通知列，在右侧显示相关日期列

我得到了什么

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:orientation="vertical"
   tools:context=".ListActivity" >

   <ListView
      android:id="@+id/mobile_list"
      android:layout_width="match_parent"
      android:layout_height="wrap_content" >
   </ListView>

</LinearLayout>

MainActivity.java

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);

      ArrayAdapter adapter = new ArrayAdapter<String>(this, 
         R.layout.activity_listview, mobileArray);

      ListView listView = (ListView) findViewById(R.id.mobile_list);
      listView.setAdapter(adapter);
   }

Answer 1

这样做：

DatabaseHelper.java 类：只需在路径和dbname中更改包名称。

  package Your package name;

 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;

 import android.content.Context;
 import android.database.SQLException;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteException;
 import android.database.sqlite.SQLiteOpenHelper;


public class DataBaseHelper extends SQLiteOpenHelper{

  //The Android's default system path of your application database.
private static String DB_PATH = "/data/data/your package name/databases/";

 private static String DB_NAME = " your database name";

 private SQLiteDatabase myDataBase; 

 private final Context myContext;

   /**
  * Constructor
      * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
  * @param context
  */
     public DataBaseHelper(Context context) {

    super(context, DB_NAME, null, 1);
     this.myContext = context;
}   

       /**
         * Creates a empty database on the system and rewrites it with your own database.
      * */
       public void createDataBase() throws IOException{

      boolean dbExist = checkDataBase();

     if(dbExist){
        //do nothing - database already exist
    //  Toast.makeText(myContext, "already exist", Toast.LENGTH_LONG).show();
     else{

            //By calling this method and empty database will be created into the default system path
           //of your application so we are gonna be able to overwrite that database with our database.
            this.getReadableDatabase();

    try {

        copyDataBase();

    } catch (IOException e) {

        //throw new Error("Error copying database");

    }
}

 }

    /**
       * Check if the database already exist to avoid re-copying the file each time you open the application.
   * @return true if it exists, false if it doesn't
   */
    private boolean checkDataBase(){

    SQLiteDatabase checkDB = null;

      try{
            String myPath = DB_PATH + DB_NAME;
       checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
//  Toast.makeText(myContext, "already exist", Toast.LENGTH_LONG).show();
}catch(SQLiteException e){

    //database does't exist yet.
    //Toast.makeText(myContext, "not already exist", Toast.LENGTH_LONG).show();
}

if(checkDB != null){

    checkDB.close();

  }

  return checkDB != null ? true : false;
 }

   /**
   * Copies your database from your local assets-folder to the just created empty database in the
   * system folder, from where it can be accessed and handled.
   * This is done by transfering bytestream.
   * */
  private void copyDataBase() throws IOException{

    //Open your local db as the input stream
    InputStream myInput = myContext.getAssets().open(DB_NAME);

     // Path to the just created empty db
      String outFileName = DB_PATH + DB_NAME;

//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);

//transfer bytes from the Input file to the output file
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
    myOutput.write(buffer, 0, length);
}

//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();

}

 public void openDataBase() throws SQLException{

//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}

 @Override
  public synchronized void close() {

    if(myDataBase != null)
        myDataBase.close();

    super.close();

 }

@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub

 }

@Override
 public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
 // TODO Auto-generated method stub

}



  // Add your public helper methods to access and get content from the database.
  // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
   // to you to create adapters for your views.

 }

您的 MainActivity.java ：选择方法从数据库中选择网址;

  public void select()
{
//this is select command code
 //--------------------------------------------------
  DataBaseHelper myDbHelper = new DataBaseHelper(getApplicationContext());

  try 
  {
 myDbHelper.createDataBase(); 
 } catch (IOException ioe ) {
  throw new Error("Unable to create database");


 }
  database = this.openOrCreateDatabase("your database name", MODE_PRIVATE, null); 
  Cursor crs;
  crs= database.rawQuery("select * from tablename ", null);
 while(crs.moveToNext())
 {
   array.add(crs.getString(index of column));
  // example  : array.add(crs.getString(1));
   level = crs.getInt(4);
   System.out.println("=="+level);

      }
crs.close();
database.close();
}

现在调用oncreate中的Select Method并设置List adapter;

           Select();
          list.setAdapter(new ArrayAdapter(getapplicationContext,android.R.layout.simple_list_item_1,array));

这是从数据库中选择数据的全部内容。希望这会对你有所帮助。

在列表视图上显示表列

1 个答案: