sqlite简单使用

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这是一个用sqlite存储的简单的记事本，主要实现数据的增加和删除功能。

xml样式

主界面 mainlayout.xml<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" ><LinearLayout android:layout_width="match_parent"    android:layout_height="40dp">    <EditText          android:id="@+id/edcontent"        android:layout_width="wrap_content"        android:layout_height="match_parent"        android:gravity="top"        android:hint="   好记性不如烂笔头       "       android:textColorHint="#ff22ff"/>    <Button        android:id="@+id/addbtn"         android:layout_width="80dp"        android:layout_height="match_parent"        android:text="add"/></LinearLayout>  <ListView         android:id="@+id/listview"        android:layout_width="match_parent"        android:layout_height="wrap_content"        ></ListView></LinearLayout>

listview样式 celllayout.xml<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <LinearLayout              android:layout_width="match_parent"                android:layout_height="wrap_content"               android:orientation="vertical" >        <TextView   android:id="@+id/content"            android:layout_width="wrap_content"            android:layout_height="wrap_content"             android:layout_weight="2" />           <TextView   android:id="@+id/time"            android:layout_width="match_parent"            android:layout_height="match_parent"             android:layout_weight="3" />    </LinearLayout></LinearLayout>

java代码

DB操作NotesDB.javapackage note;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;public class NotesDB extends SQLiteOpenHelper{    public static final String TABLE_NAME = "notes";    public static final String CONTENT = "content";    public static final String ID = "_id";    public static final String TIME = "time";    public NotesDB(Context context) {        super(context, "notes", null, 1);    }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL("CREATE TABLE " + TABLE_NAME + " (" + ID                + " INTEGER PRIMARY KEY AUTOINCREMENT," + CONTENT                + " TEXT NOT NULL," + TIME + " TEXT NOT NULL)");    }    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {    }}

设置listview适配器MyAdapter.javapackage note;import com.example.note.R;import com.example.note.R.layout;import android.R.string;import android.content.Context;import android.database.Cursor;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.LinearLayout;import android.widget.TextView;public class MyAdapter extends  BaseAdapter{    private  Context context;    private  Cursor  cursor;  private   LinearLayout Layout;   public  MyAdapter( Context context, Cursor  cursor){       this.context=context;       this.cursor=cursor;   }    @Override    public int getCount() {        // TODO Auto-generated method stub        return cursor.getCount();    }    @Override    public Object getItem(int arg0) {        // TODO Auto-generated method stub        return cursor.getPosition();    }    @Override    public long getItemId(int arg0) {        // TODO Auto-generated method stub        return arg0;    }    @Override    public View getView(int arg0, View arg1, ViewGroup arg2) {        // TODO Auto-generated method stub        LayoutInflater inflater =LayoutInflater.from(context);        Layout =(LinearLayout) inflater.inflate(R.layout.celllayout, null);        TextView contenttv=(TextView) Layout.findViewById(R.id.content);        TextView timetv= (TextView) Layout.findViewById(R.id.time);        cursor.moveToPosition(arg0);        String   content= cursor.getString(cursor.getColumnIndex("content"));        String   time= cursor.getString(cursor.getColumnIndex("time"));        contenttv.setText(content);        timetv.setText(time);        return Layout;    }}

主界面MianActivity.javaimport java.text.SimpleDateFormat;import java.util.Date;import com.example.note.R;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ListView;public class MianActivity  extends Activity  implements OnClickListener{    private NotesDB notesDB;    private  SQLiteDatabase dbwrite=null;    private  SQLiteDatabase dbReader=null;    private  EditText ed;    private  Button  addbtn;    private ListView  lv;    private MyAdapter adapter;    private Cursor mcursor ;    private  int  id;        @Override    protected void onCreate(Bundle savedInstanceState) {        // TODO Auto-generated method stub        super.onCreate(savedInstanceState);        setContentView(R.layout.mainlayout);             notesDB=new NotesDB(this);            dbwrite =notesDB.getWritableDatabase();            lv=(ListView) findViewById(R.id.listview);            ed= (EditText) findViewById(R.id.edcontent);            addbtn=(Button) findViewById(R.id.addbtn);            addbtn.setOnClickListener(this);            dbReader=notesDB.getReadableDatabase();            lv.setOnItemClickListener(new OnItemClickListener() {                @Override                public void onItemClick(AdapterView<?> arg0, View arg1,                        int arg2, long arg3) {                    mcursor=dbReader.query(NotesDB.TABLE_NAME, null, null, null, null, null, null);                        mcursor.moveToPosition(arg2);                      id = mcursor.getInt(0);                        dbwrite.delete(NotesDB.TABLE_NAME,                                "_id=" + id, null);                      selectDB();                }            });         }        public void addDb(){            ContentValues cv = new ContentValues();            cv.put(NotesDB.CONTENT, ed.getText().toString());            cv.put(NotesDB.TIME, getTime());            dbwrite.insert(NotesDB.TABLE_NAME, null, cv);            ed.setText("");        }        private String getTime() {            SimpleDateFormat format = new SimpleDateFormat("yyyy年MM月dd日  HH:mm:ss");            Date curDate = new Date();            String str = format.format(curDate);            return str;        }        @Override        public void onClick(View arg0) {            switch (arg0.getId()) {            case R.id.addbtn:                if (ed.getText()==null){}                else{                addDb();}                break;            default:                break;            }            selectDB();        }        public void  selectDB(){            Cursor cursor=dbReader.query(NotesDB.TABLE_NAME, null, null, null, null, null, null);            adapter=new MyAdapter(this, cursor);            lv.setAdapter(adapter);        }       @Override    protected void onResume() {        super.onResume();        selectDB();    }}

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