数据库Sqlite 的操作

1.创建数据库 extends SQLiteOpenHelper 需要继承SQLiteOpenHelper

package com.example.usersqllite.domain; 
  
import android.content.Context; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteDatabase.CursorFactory; 
import android.database.sqlite.SQLiteOpenHelper; 
  
public class UserSqlLiteHelp extends SQLiteOpenHelper { 
  
    public UserSqlLiteHelp(Context context) { 
        super(context, "User.db", null, 1); 
    } 
  
    // 创建数据库 初始化表结构 
    @Override
    public void onCreate(SQLiteDatabase db) { 
  
        db.execSQL("create table user ( id integer primary key autoincrement , name  varchar(20), age INTEGER  )"); 
    } 
  
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
  
    } 
  
}

2.数据的dao 增删改查

package com.example.usersqllite.dao; 
  
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 com.example.usersqllite.domain.User; 
import com.example.usersqllite.domain.UserSqlLiteHelp; 
  
public class UserDao { 
  
    private UserSqlLiteHelp help; 
  
    public UserDao(Context context) { 
        help = new UserSqlLiteHelp(context); 
    } 
  
    /** 
     * 添加数据 
     *  
     * @throws Exception 
     */
    public void insert() throws Exception { 
        SQLiteDatabase sb = help.getWritableDatabase(); 
        ContentValues values = new ContentValues(); 
  
        for (int i = 0; i < 30; i++) { 
            values.put("name", "aaa" + i); 
            values.put("age", 10 + i); 
            sb.insert("User", null, values); 
        } 
        sb.close(); 
  
    } 
  
    /** 
     * 删除数据 
     * @return  
     *  
     * @throws Exception 
     */
    public boolean delete(int id) throws Exception { 
        SQLiteDatabase sb = help.getWritableDatabase(); 
        int result = sb.delete("user", "id=?", new String[] { id + "" }); 
        sb.close(); 
        if(result>0) 
        { 
            return true; 
        }else
        { 
            return false; 
        } 
          
  
    } 
  
    /** 
     * 修改数据 
     *  
     * @throws Exception 
     */
    public boolean update(int id, String data) throws Exception { 
        SQLiteDatabase sb = help.getWritableDatabase(); 
        ContentValues values = new ContentValues(); 
  
        values.put("name", data); 
        int result = sb.update("user", values, "id=?", new String[] { id + "" }); 
  
        sb.close(); 
        if(result>0) 
        { 
            return true; 
        }else
        { 
            return false; 
        } 
          
    } 
  
    /** 
     * 查询数据 
     *  
     * @return 
     *  
     * @throws Exception 
     */
    public List<User> findAll() throws Exception { 
  
        SQLiteDatabase sb = help.getWritableDatabase(); 
        /** 
         * String table, String[] columns, String selection, String[] 
         * selectionArgs, String groupBy, String having, String orderBy) 
         */
  
        List<User> list = new ArrayList<User>(); 
        Cursor cursor = sb.query("user", new String[] { "id", "name", "age" }, 
                null, null, null, null, null, null); 
        while (cursor.moveToNext()) { 
            int id = cursor.getInt(cursor.getColumnIndex("id")); 
  
            String name = cursor.getString(cursor.getColumnIndex("name")); 
  
            int age = cursor.getInt(cursor.getColumnIndex("age")); 
  
            User user = new User(id, name, age); 
  
            list.add(user); 
            user = null; 
  
        } 
        sb.close(); 
        return list; 
  
    } 
  
}

来自为知笔记(Wiz)

posted on 2014-04-28 14:05 转折点人生阅读(200) 评论(0) 收藏举报