Android sqlite本地数据库

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futureflsl 2024-10-23 11:42:35 博主文章分类：android

文章标签 SQL android sqlite 文章分类 Python 后端开发

做任何开发都会用的数据库， Android 也一样，Android一般都要用的两个数据库本地数据库和远程数据库，本地数据库就是sqlite，远程数据库的话，我一般用的是 MySQL ，这次先了解下本地数据库sqlite，一般数据库类型为varchar(20) 如果你输入个大于20位的数据时，会报错，不能插入吧，但是sqlite里就不一样了，他就可以，这是sqlite的特色之一吧应该是。下来就看看sqlite的 crud：

MainActivity

package com.example.sqlite;  
  
import android.os.Bundle;  
import android.app.Activity;  
import android.view.Menu;  
import android.widget.TextView;  
  
public class MainActivity extends Activity {  
  
@Override  
public void onCreate(Bundle savedInstanceState) {  
super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        TextView t;  
          
new DBOpenHelter(this);  
    }  
  
@Override  
public boolean onCreateOptionsMenu(Menu menu) {  
        getMenuInflater().inflate(R.menu.activity_main, menu);  
return true;  
    }  
}

PersonService

package com.example.sqlite;  
  
import com.example.bean.Person;  
  
import android.content.Context;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
  
public class PersonService {  
private DBOpenHelter dbOpenHelper;  
      
public PersonService(Context context){  
          
this.dbOpenHelper=new DBOpenHelter(context);  
    }  
public void save(Person person){  
        SQLiteDatabase db=dbOpenHelper.getWritableDatabase();  
new StringBuilder(128);   //这个没用  
"insert ");                      //这个没用  
"insert into person(name,phone) values(?,?)",new Object[]{person.getName(),person.getPhone()});  
        db.close();  
    }  
public Person find(Integer id){  
new Person();  
        SQLiteDatabase db=dbOpenHelper.getReadableDatabase();  
"select * from testpersion wehre name=?",new String[]{id.toString()});  
while(cursor.moveToNext()){  
int personid=cursor.getInt(cursor.getColumnIndex("id"));  
        }  
return person;  
    }  
}

DBOpenHelter

package com.example.sqlite;

 import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 import android.database.sqlite.SQLiteOpenHelper;

 public class DBOpenHelter extends SQLiteOpenHelper{

     public DBOpenHelter(Context context) {
         super(context, "itcast.db", null, 1);
     }

     @Override
     public void onCreate(SQLiteDatabase db) {
         db.execSQL("CREATE TABLE testpersion(persionid integer primary key autoincrement,name varchar(20))");
     }

     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
         // TODO Auto-generated method stub
         db.execSQL("ALTER TABLE testpersion ADD phone VARCHAR(12) NULL");
     }

 }

MainActivity

package com.example.sqlite;  
  
import android.os.Bundle;  
import android.app.Activity;  
import android.view.Menu;  
import android.widget.TextView;  
  
public class MainActivity extends Activity {  
  
@Override  
public void onCreate(Bundle savedInstanceState) {  
super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        TextView t;  
          
new DBOpenHelter(this);  
    }  
  
@Override  
public boolean onCreateOptionsMenu(Menu menu) {  
        getMenuInflater().inflate(R.menu.activity_main, menu);  
return true;  
    }  
}

PersonService

package com.example.sqlite;  
  
import com.example.bean.Person;  
  
import android.content.Context;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
  
public class PersonService {  
private DBOpenHelter dbOpenHelper;  
      
public PersonService(Context context){  
          
this.dbOpenHelper=new DBOpenHelter(context);  
    }  
public void save(Person person){  
        SQLiteDatabase db=dbOpenHelper.getWritableDatabase();  
new StringBuilder(128);   //这个没用  
"insert ");                      //这个没用  
"insert into person(name,phone) values(?,?)",new Object[]{person.getName(),person.getPhone()});  
        db.close();  
    }  
public Person find(Integer id){  
new Person();  
        SQLiteDatabase db=dbOpenHelper.getReadableDatabase();  
"select * from testpersion wehre name=?",new String[]{id.toString()});  
while(cursor.moveToNext()){  
int personid=cursor.getInt(cursor.getColumnIndex("id"));  
        }  
return person;  
    }  
}

DBOpenHelter

package com.example.sqlite;

 import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 import android.database.sqlite.SQLiteOpenHelper;

 public class DBOpenHelter extends SQLiteOpenHelper{

     public DBOpenHelter(Context context) {
         super(context, "itcast.db", null, 1);
     }

     @Override
     public void onCreate(SQLiteDatabase db) {
         db.execSQL("CREATE TABLE testpersion(persionid integer primary key autoincrement,name varchar(20))");
     }

     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
         // TODO Auto-generated method stub
         db.execSQL("ALTER TABLE testpersion ADD phone VARCHAR(12) NULL");
     }

 }