android之sqlite实现增删改查

1、 Sqlite 实现简单的增删改查主界面：功能实现：1） 增加数据：2） 全部显示3） 清除显示4） 全部删除5）：ID删除6)ID查询：7）ID更新：主要代码段：DBOpenHelper.javapackage com.chen.dao;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;public class DBOpenHelper exten

2、ds SQLiteOpenHelper private static final int VERSION=2;/版本 private static final String DBNAME=user.db;/数据库名字/创建数据库public DBOpenHelper(Context context) super(context, DBNAME, null, VERSION);Override/* * 创建表 */public void onCreate(SQLiteDatabase db) db.execSQL(create table if not exists u_user(_id int

3、eger primary key,name varchar(20),age integer,tall varchar(5); /版本被更新时执行Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) UserDAO.javapackage com.chen.dao;import java.util.ArrayList;import java.util.List;import com.chen.modl.User;import android.content.Context;import a

4、ndroid.database.Cursor;import android.database.sqlite.SQLiteDatabase;public class UserDAO private DBOpenHelper helper; /写入 ，不然会是出错，是空指针 public UserDAO(Context context) helper=new DBOpenHelper(context); /* * 添加用户信息 */ public void add(User user) SQLiteDatabase db=helper.getWritableDatabase(); String s

5、ql=Insert into u_user(_id,name,age,tall) values(?,?,?,?); db.execSQL(sql, new Object user.getId(),user.getName(),user.getAge(),user.getTall() ); db.close(); /* * 删除用户信息 */ public void delete(Integer.id) if(id.length0) StringBuffer sb=new StringBuffer(); for(int i=0;iid.length;i+) sb.append(?).append

6、(,); sb.deleteCharAt(sb.length()-1); SQLiteDatabase database=helper.getWritableDatabase(); String sql=delete from u_user where _id in (+sb+); database.execSQL(sql, (Object)id); /* * 删除表里的全部数据 */public void delelteall() SQLiteDatabase database=helper.getWritableDatabase(); String sql = delete from u_

7、user; database.execSQL(sql); /* * 用户修改 */ public void update(User user) SQLiteDatabase db=helper.getWritableDatabase();/写入数据库中注意！不能放在外面 String sql=update u_user set name=?,age=?,tall=? where _id=?; db.execSQL(sql, new Object user.getName(),user.getAge(),user.getTall(),user.getId() ); /* * 查找用户信息 */

8、public User find(int userid) SQLiteDatabase db=helper.getWritableDatabase();/写入数据库中注意！不能放在外面 String sql=select _id,name,age,tall from u_user where _id=?; Cursor cursor=db.rawQuery(sql, new String String.valueOf(userid) ); if(cursor.moveToNext() return new User( cursor.getInt(cursor.getColumnIndex(_i

9、d), cursor.getString(cursor.getColumnIndex(name), cursor.getInt(cursor.getColumnIndex(age), cursor.getString(cursor.getColumnIndex(tall) ); return null; /* * 显示用户 */public Cursor select() SQLiteDatabase db = helper.getReadableDatabase();Cursor cursor = db.query(u_user,null, null, null, null,null, _i

10、d desc);return cursor;MainActivity.javapackage com.chen.database;/* * writer:ManMan * Email:1015082527 * */import com.chen.dao.UserDAO;import com.chen.modl.User;import android.app.Activity;import android.database.Cursor;import android.os.Bundle;import android.util.Log;import android.view.View;import

11、 android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.ListView;import android.widget.SimpleCursorAdapter;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity implements OnClickListenerpriv

12、ate static final String TAG = Add;private EditText edname,edage,edtall,id;private Button add,deleteshow,show,iddelete,idupdate,idshow,deleteall;private TextView tedatashow;private ListView datashow; /* Called when the activity is first created. */ Override public void onCreate(Bundle savedInstanceSt

13、ate) super.onCreate(savedInstanceState); setContentView(R.layout.main); edname = (EditText)findViewById(R.id.edname); edage = (EditText)findViewById(R.id.edage); edtall = (EditText)findViewById(R.id.edtall); id = (EditText)findViewById(R.id.id); tedatashow = (TextView)findViewById(R.id.tedatashow);

14、datashow = (ListView)findViewById(R.id.datashow); add = (Button)findViewById(R.id.add); deleteshow = (Button)findViewById(R.id.deleteshow); show = (Button)findViewById(R.id.show); iddelete = (Button)findViewById(R.id.iddelete); idupdate = (Button)findViewById(R.id.idupdate); idshow = (Button)findVie

15、wById(R.id.idshow); deleteall = (Button)findViewById(R.id.deleteall); add.setOnClickListener(this); deleteshow.setOnClickListener(this); show.setOnClickListener(this); iddelete.setOnClickListener(this); idupdate.setOnClickListener(this); idshow.setOnClickListener(this); deleteall.setOnClickListener(

16、this); public void onClick(View v) /* * 添加数据 */if(v=add)if(!id.getText().toString().equals(null)&!edname.getText().toString().equals(null)&!edage.getText().toString().equals(null)&!edtall.getText().toString().equals(null)tryUserDAO userdao = new UserDAO(MainActivity.this); User user = new User(Integ

17、er.valueOf(id.getText().toString(), edname.getText().toString(),Integer.valueOf(edage.getText().toString(), edtall.getText().toString();userdao.add(user); Toast.makeText(MainActivity.this, 成功添加！, Toast.LENGTH_LONG) .show(); tedatashow.setText(新添数据为：+n+ID:+Integer.valueOf(id.getText().toString()+,+姓名

18、:+edname.getText().toString() +,+年龄:+Integer.valueOf(edage.getText().toString()+,+身高:+edtall.getText().toString()+, ); /设置为空 edage.setText(); edname.setText(); edtall.setText(); id.setText(); catch (Exception e) Log.i(TAG, 出错了);Log.i(TAG, e.getMessage(); else if(id.getText().toString().equals(null)

19、Toast.makeText(MainActivity.this, ID不能为空！, Toast.LENGTH_LONG) .show(); /* * 清除显示 */if(v=deleteshow)tedatashow.setText();/* * 全部显示 */if(v=show)try UserDAO userdao = new UserDAO(MainActivity.this); Cursor cursor = userdao.select(); /* * 构建Listview适配器 */ SimpleCursorAdapter adapter = new SimpleCursorAd

20、apter(this, R.layout.showuser, cursor, new String_id,name,age,tall , new intR.id.textView1,R.id.textView2,R.id.textView3,R.id.textView4); datashow.setAdapter(adapter); catch (Exception f) Log.e(err,f.getMessage(); Log.e(err,null, f.getCause();Toast.makeText(MainActivity.this, 显示不了, Toast.LENGTH_LONG

21、).show(); /* * ID删除 */if(v=iddelete)UserDAO userDAO=new UserDAO(MainActivity.this);/注意 不能放在外面userDAO.delete(Integer.valueOf(id.getText().toString(); Toast.makeText(MainActivity.this, 您成功删除了+Integer.valueOf(id.getText().toString(), Toast.LENGTH_LONG).show(); id.setText();/* * 全部删除 */if(v=deleteall)Us

22、erDAO userDAO=new UserDAO(MainActivity.this);/注意 不能放在外面userDAO.delelteall(); Toast.makeText(MainActivity.this, 您已经把数据全部删除了, Toast.LENGTH_LONG).show(); /* * ID更新 */if(v=idupdate)UserDAO userDAO=new UserDAO(MainActivity.this);/注意 不能放在外面User user=userDAO.find(Integer.valueOf(id.getText().toString();use

23、r.setName(edname.getText().toString();user.setAge(Integer.valueOf(edage.getText().toString();user.setTall(edtall.getText().toString();userDAO.update(user);Toast.makeText(MainActivity.this, 修改成功, Toast.LENGTH_LONG).show();/* * ID查询 */if(v=idshow)UserDAO userDAO=new UserDAO(MainActivity.this);/注意 不能放在外面User user=userDAO.find(Integer.valueOf(id.getText().toString();