Android数据库操作代码,Java代码库,德仔网

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【Java】 Android数据库操作
作者:烨鑫 / 发布于2016/9/20/ 685
Android数据库操作
数据库的建立
package my.pack;  
import android.app.ListActivity;  
import android.os.Bundle;  
import android.view.View;  
import android.widget.AdapterView;  
import android.widget.ArrayAdapter;  
import android.widget.ListView;  
import android.widget.TextView;  
import android.widget.Toast;  
import android.widget.AdapterView.OnItemClickListener;  
import android.app.Activity;  
import android.os.Bundle;  
import android.widget.*;  
import java.util.*;  
import android.content.Context;  
import android.database.*;  
import android.database.sqlite.*;  
import android.database.sqlite.SQLiteDatabase.CursorFactory;  
  
public class MyDatabaseHelper extends SQLiteOpenHelper  
{  
    private static final String DB_NAME = "Notepad_1.db";  
    private static final int DB_VERSION = 1;  
    private static final String TABLE_NAME = "Table_1";  
    MyDatabaseHelper(Context context)   
    {    
        super(context, DB_NAME, null, DB_VERSION);    
    }    
    @Override    
    public void onCreate(SQLiteDatabase db)   
    {    
        String Sql = "CREATE TABLE Table_1 ('Time' varchar(200) not null,'Title' varchar (200) not null,'Content' text ,primary key(Title));";  
        db.execSQL(Sql);  
    }    
    @Override    
    public void onUpgrade(SQLiteDatabase db, int oldVersion,   int newVersion)   
    {     
    }     
}  




数据库操作帮组类（选择、插入、删除、）


package my.pack;  
  
import java.util.ArrayList;  
import java.util.HashMap;  
import java.util.List;  
  
import android.content.Context;  
import android.database.Cursor;  
import android.database.SQLException;  
import android.database.sqlite.SQLiteDatabase;  
  
public class MySqlHelper {  
    public MyDatabaseHelper mOpenHelper;   
    public SQLiteDatabase db;   
    //构造函数  
    MySqlHelper(Context context)  
    {  
        mOpenHelper = new MyDatabaseHelper(context);   
    }  
    //选择  
    public int SelectItem(String mytitle)  
    {  
        db = mOpenHelper.getReadableDatabase();   
        //String col[] = {"Time","Title","Content"};  
        //String Sql = "where 'Title' = " + mytitle;  
        //Cursor cur = db.query("Table_1",col,Sql,null,null,null,null);  
        Cursor cur = db.rawQuery("SELECT * FROM Table_1 WHERE Title=?", new String[] { mytitle});    
        int num = cur.getCount();  
        cur.close();  
        db.close();  
        return num;  
    }  
    //插入  
    public void InsertItem(String mytime,String mytitle,String mycontent)  
    {  
        db = mOpenHelper.getWritableDatabase();   
        String Sql= "insert into Table_1 values('" + mytime +"', '" + mytitle +"', '" + mycontent+"' )";  
        try  
        {  
            db.execSQL(Sql);  
            //setTitle("Yes");  
        }  
        catch(SQLException e)  
        {  
            //setTitle(Sql);  
        }  
        db.close();  
    }  
    //显示  
    public ArrayList<HashMap<String, Object>> ShowItem()  
    {  
        ArrayList<HashMap<String, Object>> listItem = new ArrayList<HashMap<String, Object>>();    
  
        db = mOpenHelper.getReadableDatabase();   
        String col[] = {"Time","Title","Content"};  
        Cursor cur = db.query("Table_1",col,null,null,null,null,"Time desc"); //按时间降序  
        int num = cur.getCount();  
        //setTitle(Integer.toString(num) + " 条记录");  
        cur.moveToFirst();  
        for(int i=0;i<num;i++)  
        {  
            HashMap<String, Object> map = new HashMap<String, Object>();    
            map.put("ItemTitle", cur.getString(1));    
            map.put("ItemText", cur.getString(0));    
            listItem.add(map);    
            cur.moveToNext();  
        }  
        cur.close();  
        db.close();  
        return listItem;  
    }  
    //删除Item  
    public void DeleteItem(String mytitle)  
    {  
        try  
        {  
            db = mOpenHelper.getWritableDatabase();   
            db.delete("Table_1","Title = '"+mytitle + "'",null);  
            //setTitle("删除Title为" + mytitle +"的记录");  
            db.close();  
        }  
        catch(SQLException e)  
        {}  
    }  
    //删除表项  
    public void DeleteTable(String mytable)  
    {  
        try  
        {  
            db = mOpenHelper.getWritableDatabase();   
            String Sql = "drop table " +mytable;  
            db.execSQL(Sql);  
            db.close();  
            //setTitle("已删除" + mytable +"表项");  
        }  
        catch(SQLException e)  
        {}  
    }  
}  



删除数据库

**删除数据库  
final File file = this.getDatabasePath(DB_NAME);  
file.delete();
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