Android中sqlite的学习

实现了增加数据，删除数据，跟查询。绑定Spinner控件跟ListView控件，实现点击列表删除选项。

package com.example.splite;
import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DbHelpe extends SQLiteOpenHelper {
    
    private static final int DATABASE_VERSION = 1; 
    private static final String DATABASE_NAME = "test";
    private static final String TABLE_LABELS = "labels";
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    SQLiteDatabase db;
    public DbHelpe(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }
    
    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        String sql = "CREATE TABLE " + TABLE_LABELS + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT)";
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS" + TABLE_LABELS);
        onCreate(db);
    }
    //增加
     public void insertLabel(String label){
         db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(KEY_NAME, label);
        db.insert(TABLE_LABELS, null, values);
        db.close(); // Closing database connection
        }
     //查找
     public List<String> getAllLabels(){
        List<String> labels = new ArrayList<String>();
 
        String selectQuery = "SELECT  * FROM " + TABLE_LABELS;
 
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
 
        if (cursor.moveToFirst()) {
            do {
             labels.add(cursor.getString(1));
            } while (cursor.moveToNext());
        }
        cursor.close();
        return labels;
    }
     //删除
     public void delete (String name){
         if(db==null)
        db=this.getReadableDatabase();
         String sql = "delete from labels where name='"+name+ "'";
         db.execSQL(sql);    
     }
}

主类里有一个方法，就是当点击添加数据按钮后，系统的文字输入框会自动隐藏，实现代码

InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(edittext.getWindowToken(), 0);

package com.example.splite;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.ScrollView;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends Activity implements OnItemClickListener {
    Spinner spinner;
    EditText edittext;
    Button   button;
    ScrollView scr;
    ListView list;
    Cursor mcursor;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);    
        list = (ListView)findViewById(R.id.listview);
        button = (Button)findViewById(R.id.btn_add);
        edittext = (EditText)findViewById(R.id.input_label);
        spinner = (Spinner)findViewById(R.id.spinner);
        list.setOnItemClickListener(this);
        button.setOnClickListener(new OnClickListener() {
            
            public void onClick(View v) {
                // TODO Auto-generated method stub
            String data = edittext.getText().toString().trim();
            if(data.trim().length()>0){
                DbHelpe db  = new DbHelpe(getApplicationContext());
                db.getWritableDatabase();
                int a = 0;
                a=db.getAllLabels().size();
                db.insertLabel(data);
                Log.d("ddd", db.getAllLabels().size()+"");
                if(db.getAllLabels().size()>a){
                    Toast.makeText(getApplicationContext(), "插入成功", Toast.LENGTH_SHORT).show();
                }else {
                    Toast.makeText(getApplicationContext(), "插入失败", Toast.LENGTH_SHORT).show();
                }
                Log.d("aa", a+"");
                edittext.setText("");
                InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(edittext.getWindowToken(), 0);
                loadData();
             }else {
                 Toast.makeText(getApplicationContext(), "请输入数据", Toast.LENGTH_SHORT).show();
                   }
            }
        });
          loadData();
    }
    
    public void loadData(){
        DbHelpe db  = new DbHelpe(getApplicationContext());
        List<String> data = db.getAllLabels();
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, data);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        ArrayAdapter<String> listadapter  =  new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, data);
        list.setAdapter(listadapter);
        
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
        // TODO Auto-generated method stub
        DbHelpe db  = new DbHelpe(getApplicationContext());
        db.getReadableDatabase();
        String data = arg0.getItemAtPosition(arg2).toString();
        Log.d("sss", data);
        db.delete(data);
        loadData();
    }
}