package com.example.datebasetest; import android.content.ContentValues; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.Toast; public class MainActivity extends AppCompatActivity {
      private Button btn;     private DatabaseHelper dbHelper;     private Button addButton;     private Button updateData;     private Button deleteData;     private Button queryData;     @Override     protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         btn = (Button)findViewById(R.id.create_database);         dbHelper = new DatabaseHelper(this,"BookStore.db",null,2);         addButton = (Button)findViewById(R.id.add_data);         updateData = (Button)findViewById(R.id.update_data);         deleteData = (Button)findViewById(R.id.delete_data);         queryData = (Button)findViewById(R.id.query_data);         btn.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  dbHelper.getWritableDatabase();             }         });         addButton.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  SQLiteDatabase db = dbHelper.getWritableDatabase();                 ContentValues values = new ContentValues();                 values.put("name","wz");                 values.put("author","xx");                 values.put("price",1.0);                 values.put("pages",156);                 db.insert("Book",null,values);                 values.clear();                 values.put("name","wz2");                 values.put("author","xx2");                 values.put("price",2.0);                 values.put("pages",122);                 db.insert("Book",null,values);             }         });         updateData.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  SQLiteDatabase db = dbHelper.getWritableDatabase();                 ContentValues values = new ContentValues();                 values.put("price",10.99);                 db.update("Book", values, "name=?", new String[]{"wz"});             }         });         deleteData.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  SQLiteDatabase db = dbHelper.getWritableDatabase();                 db.delete("Book", "pages > ?", new String[]{"120"});                 Toast.makeText(MainActivity.this,"删除成功",Toast.LENGTH_SHORT).show();             }         });         queryData.setOnClickListener(new View.OnClickListener() {
              @Override             public void onClick(View v) {
                  SQLiteDatabase db = dbHelper.getWritableDatabase();                 Cursor cursor = db.query("Book",null,null,null,null,null,null);                 if(cursor.moveToFirst()){
                      do{
                          String name = cursor.getString(cursor.getColumnIndex("name"));                         String author = cursor.getString(cursor.getColumnIndex("author"));                         int pages = cursor.getInt(cursor.getColumnIndex("pages"));                         double price = cursor.getDouble(cursor.getColumnIndex("price"));                         Log.d("Message","name"+name);                         Log.d("Message","author"+author);                         Log.d("Message","pages"+pages);                         Log.d("Message","price"+price);                     }while(cursor.moveToNext());                 }                 cursor.close();             }         });     } }