以编程的方式使用SQLite数据库 执行CRUD（创建 读取 更新 删除）操作

DBAdapter数据库辅助类

package com.databses;  

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;  

public class DBAdapter {  

    static final String KEY_ROWID = "_id";
    static final String KEY_NAME = "name";
    static final String KEY_EMAIL = "email";
    static final String TAG = "DBAdapter";  

    static final String DATABASE_NAME = "mydb";
    static final String DATABASE_TABLE = "contacts";
    static final int DATABASE_VERSION = 1;
    final Context context;  

    //创建表sql语句
    static final String DATABASE_CREATE = "create table contacts (_id integer primary key autoincrement,name text not null,email text not null)";  

    SQLiteDatabase db;
    DatabaseHelper dBHelper;  

    public DBAdapter(Context context){
        this.context = context;
        dBHelper = new DatabaseHelper(context);
    }  

    //数据库辅助类 继承SQLiteOpenHelper
    private static class DatabaseHelper extends SQLiteOpenHelper{
        public DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }  

        //创建数据库
        @Override
        public void onCreate(SQLiteDatabase db) {
            try {
                db.execSQL(DATABASE_CREATE);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        //升级数据库版本
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w(TAG, "upgrading db from version "+oldVersion+"to"+newVersion+",which will destory all old data");
            db.execSQL("drop table if exists contacts");
            onCreate(db);
        }
    }  

    //打开数据库
    public DBAdapter open() throws SQLException
    {
        db = dBHelper.getWritableDatabase();
        return this;
    }  

    //关闭数据库
    public void close(){
        dBHelper.close();
    }  

    //插入一条联系人记录
    public long insertContact(String name,String email){
        ContentValues initalValues = new ContentValues();
        initalValues.put(KEY_NAME,name);
        initalValues.put(KEY_EMAIL, email);
        return db.insert(DATABASE_TABLE, null, initalValues);
    }  

    //删除一条记录
    public boolean deleteContact(long rowId){
        return db.delete(DATABASE_TABLE,KEY_ROWID+"="+rowId,null)>0;
    }  

    //查询所有联系人
    public Cursor getAllContacts()
    {
        return db.query(DATABASE_TABLE, new String[]{KEY_ROWID,KEY_NAME,KEY_EMAIL},null, null, null, null, null, null);
    }  

    //查询一条记录
    public Cursor getContact(long rowId) throws SQLException{
        Cursor cursor = db.query(true, DATABASE_TABLE, new String[]{KEY_ROWID,KEY_NAME,KEY_EMAIL}, KEY_ROWID+"="+rowId, null, null, null, null, null);
        if(cursor != null){
            cursor.moveToFirst();
        }
        return cursor;
    }  

    //更新一个联系人
    public boolean updateContact(long rowId,String name,String email){
        ContentValues contentValues = new ContentValues();
        contentValues.put(KEY_NAME, name);
        contentValues.put(KEY_EMAIL, email);
        return db.update(DATABASE_TABLE, contentValues, KEY_ROWID+"="+KEY_ROWID, null)>0;
    }
}  

DatabaseActivity

package com.databses;  

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;  

public class DatabasesActivity extends Activity {  

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_databases);
        DBAdapter dbAdapter = new DBAdapter(this);  

        dbAdapter.open();
        dbAdapter.insertContact("weiwei", "[email protected]");
        dbAdapter.insertContact("Jackson", "[email protected]");  

    }  

}  

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