安卓数据持久化：文件存储、SharedPreferences存储以及数据库存储

C:\Users\Administrator>adb shell
root@generic_x86:/ # cd /data/data/com.example.databasetest/databases/
cd /data/data/com.example.databasetest/databases/
root@generic_x86:/data/data/com.example.databasetest/databases # ls
ls
BookStore.db
BookStore.db-journal
root@generic_x86:/data/data/com.example.databasetest/databases # sqlite3 BookSto
re.db
BookStore.db                                                                 <
SQLite version 3.7.11 2012-03-20 11:35:50
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .table
.table
android_metadata  book
sqlite> .schema
.schema
CREATE TABLE android_metadata (locale TEXT);
CREATE TABLE book(id integer primary key autoincrement,author textprice realpage
s integername text);
sqlite> .exit
.exit
root@generic_x86:/data/data/com.example.databasetest/databases # exit
exit

@Override
      public void onUpgrade(SQLiteDatabase db, int oldVersion, intnewVersion) {
            // TODO Auto-generated method stub
            db.execSQL( "drop table if exists book" );
            db.execSQL( "drop table if exists category" );
           onCreate( db);
     }

public long insert (String table, String nullColumnHack, ContentValues values)

Button addData =(Button) findViewById(R.id. add_data);
      addData.setOnClickListener( new OnClickListener() {         
            @Override
            public void onClick(View v) {
                 // TODO Auto-generated method stub
                SQLiteDatabase dbOperate= dbHelper.getWritableDatabase();
                ContentValues values= new ContentValues();
            //下面没有给表中的id赋值，因为在建表的时候，id是默认自动增长的
                 //添加第一条记录到Book
                 values.put( "name", "安卓入门之路" );
                 values.put( "author", "hl174");
                 values.put( "pages", 800);
                 values.put( "price", 50);               
                 dbOperate.insert( "book", null, values);
                
                 values.clear();
                
                 //插入第二条记录到book
                 values.put( "name", "安卓精通" );
                 values.put( "author", "hl174");
                 values.put( "pages", 700);
                 values.put( "price", 45);     
              dbOperate.insert( "book", null, values);
           }
     });

//更新数据
     Button updateData=(Button) findViewById(R.id. update_data);
      updateData.setOnClickListener( new OnClickListener() {
            @Override
            public void onClick(View v) {
                 // TODO Auto-generated method stub
                SQLiteDatabase db= dbHelper.getWritableDatabase();
                ContentValues values= new ContentValues();
                 values.put( "price", 10000);
                
        db.update( "book", values, "name=?", new String[]{"安卓入门之路" });
           }
     });

//删除数据
     Button deleteData=(Button) findViewById(R.id. delete_data);
      deleteData.setOnClickListener( new OnClickListener() {      
            @Override
            public void onClick(View v) {
                 // TODO Auto-generated method stub
                SQLiteDatabase db= dbHelper.getWritableDatabase();
                 //删除页数大于500的记录
                 db.delete( "book", "pages>?", new String[]{"500" });
           }
     });

public void onClick(View v ) {
          // TODO Auto-generated method stub
       SQLiteDatabase db= dbHelper.getWritableDatabase();
        //查询book表中的所有数据
 Cursor cursor=  db.query( "book", null, null, null, null, null, null);
   if( cursor.moveToFirst()){
          do{
             //遍历cursor对象，取出数据并打印
         String name= cursor.getString( cursor.getColumnIndex( "name"));
       String author= cursor.getString( cursor.getColumnIndex( "author"));
     int pages= cursor.getInt( cursor.getColumnIndex( "pages"));
     double price= cursor.getDouble( cursor.getColumnIndex( "price"));
                           
         Log. d("MainActivity" , "书名是:" +name );
         Log. d("MainActivity" , "书的作者是:" +author );
         Log. d("MainActivity" ,"书的页数是：" +pages );
         Log. d("MainActivity" , "书的价钱是：" +price );
          } while( cursor.moveToNext());
         }
     cursor.close();
    }
  });

public abstract int getColumnIndex (String columnName)