如何使用光标适配器在 android 中创建简单的 SQLite 数据库？

Question

嗨，我是 android 编程的新手，我想在 android 应用程序中使用 sqlite 数据库来处理一些与数据库相关的东西。我正在开发应用程序，就像它会从家里扫描一些 wifi 设备到那里供应商 ID 应该在列表视图中显示在按下列表中的任何项目时它应该向该受尊敬的设备发送一些 udp 消息在得到对 udp 消息的响应时它应该再次创建一个列表视图那个回应。我已经实现了与 Udp 相关的东西并扫描了与 wifi 设备相关的东西，但剩下的就是在获取设备后，我需要存储该设备以获取更多与 udp 相关的东西并维护数据库，任何人都可以有最好的建议。

lass IP_Channal_DB extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "note.db";
    private static final String Table_NAME = "Ip_channal_Table";
    private static final String Col_1 = "ID";
    private static final String Col_2 = "IP_Address";
    private static final String Col_3 = "Flag";
    private static final String Col_4 = "Channal_1";
    private static final String Col_5 = "Channal_2";
    private static final String Col_6 = "Channal_3";
    private static final String Col_7 = "Channal_4";

    private static final int SCHEMA_VERSION = 1;

    private static final String DATABASE_CREATE = "CREATE TABLE " + Table_NAME + " (" + Col_1 + " integer PRIMARY KEY autoincrement," + Col_2 + "TEXT," + Col_3 + "TEXT," + Col_4 + "TEXT," + Col_5 + "TEXT," + Col_6 + "TEXT," + Col_7 + "TEXT,)";


    public IP_Channal_DB(Context context) {

        super(context, DATABASE_NAME, null, SCHEMA_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.v("MainActivity","creating table");
        db.execSQL(DATABASE_CREATE);
        //db.execSQL("CREATE TABLE "+Table_NAME+"("+Col_1+" INTEGER PRIMARY KEY AUTOINCREMENT,"+Col_2+" TEXT,"+Col_3+"INTEGER,"+Col_4+" TEXT,"+Col_5+" TEXT,"+Col_6+" TEXT,"+Col_7+" TEXT);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
   /* public Cursor getAll_IP()
    {
        return (getReadableDatabase().rawQuery("SELECT "+Col_1+", "+Col_2+" FROM "+Table_NAME,null));
    }*/
   public Cursor getAll_IP()
    {
        SQLiteDatabase db=this.getReadableDatabase();
        Cursor cur=db.rawQuery("SELECT "+Col_1+" as _id, "+Col_2+" from "+Table_NAME,new String [] {});

        return cur;
    }

}

和logcat窗口是

03-31 14:39:36.547 1681-1681/com.example.admin.myhome E/SQLiteLog: (1) no such table: Ip_channal_Table
03-31 14:39:36.557 1681-1681/com.example.admin.myhome E/AndroidRuntime: FATAL EXCEPTION: main
                                                                        Process: com.example.admin.myhome, PID: 1681
                                                                        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.admin.myhome/com.example.admin.myhome.MainActivity}: android.database.sqlite.SQLiteException: no such table: Ip_channal_Table (code 1): , while compiling: SELECT ID as _id, IP_Address from Ip_channal_Table
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2348)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2410)
                                                                            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4019)
                                                                            at android.app.ActivityThread.access$900(ActivityThread.java:151)
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                            at android.os.Looper.loop(Looper.java:135)
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5345)
                                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                                            at java.lang.reflect.Method.invoke(Method.java:372)
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:947)
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:742)
                                                                         Caused by: android.database.sqlite.SQLiteException: no such table: Ip_channal_Table (code 1): , while compiling: SELECT ID as _id, IP_Address from Ip_channal_Table
                                                                            at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
                                                                            at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
                                                                            at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
                                                                            at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
                                                                            at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
                                                                            at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
                                                                            at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
                                                                            at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1316)
                                                                            at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1255)
                                                                            at com.example.admin.myhome.IP_Channal_DB.getAll_IP(NoteHolder.java:52)
                                                                            at com.example.admin.myhome.MainActivity$override.onCreate(MainActivity.java:131)
                                                                            at com.example.admin.myhome.MainActivity$override.access$dispatch(MainActivity.java)
                                                                            at com.example.admin.myhome.MainActivity.onCreate(MainActivity.java:0)
                                                                            at android.app.Activity.performCreate(Activity.java:6012)
                                                                            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2292)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2410) 
                                                                            at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:4019) 
                                                                            at android.app.ActivityThread.access$900(ActivityThread.java:151) 
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1319) 
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                            at android.os.Looper.loop(Looper.java:135) 
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5345) 
                                                                            at java.lang.reflect.Method.invoke(Native Method) 
                                                                            at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:947) 
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:742) 

Answer 1

我开发了一个在我的主应用程序中使用的示例项目。希望对你也有帮助。

DataBaseHandler.java

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

import java.util.ArrayList;

public class DataBaseHandler extends SQLiteOpenHelper {

    public String BooksTable="Books";
    public String Book_Id="id";
    public String BookAuther="BookAuther";
    public String BookTitle="BookTitle";

    private  final int DB_Version=1;
    public DataBaseHandler(Context context,String DBName,int DBVersion){
        super(context, DBName,null,DBVersion);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("Create Table " + BooksTable + "(" + Book_Id + " INTEGER PRIMARY KEY, " + BookAuther + " Text, " + BookTitle + " Text);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
    public void addBook(Book book){
        SQLiteDatabase db=this.getWritableDatabase();
        ContentValues cv=new ContentValues();
        cv.put(Book_Id,book.getId());
        cv.put(BookAuther,book.getAuthor());
        cv.put(BookTitle,book.getTitle());

        db.insert(BooksTable, null, cv);
        db.close();
    }

    public ArrayList<Book> fetchAllBooks(){
        ArrayList<Book> booksList = new ArrayList<Book>();
        SQLiteDatabase db=this.getReadableDatabase();
        Cursor c= db.query(BooksTable, null, null, null, null, null, null);
        c.moveToFirst();
        while (!c.isAfterLast()){
            Book book = new Book();
            book.setId(c.getInt(0));
            book.setAuthor(c.getString(1));
            book.setTitle(c.getString(2));
            booksList.add(book);
            c.moveToNext();
        }
        db.close();
        return booksList;
    }
}

Book.java

public class Book {
private int id;
private String author;
private String title;

public void setId(int id) {
    this.id = id;
}

public void setAuthor(String author) {
    this.author = author;
}

public void setTitle(String title) {
    this.title = title;
}

public int getId() {
    return id;
}

public String getAuthor() {
    return author;
}

public String getTitle() {
      return title;
    }
}

MainActivity.java

DataBaseHandler db=new DataBaseHandler(getApplicationContext(),"DB_Name",1);
Book book=new Book();
book.setId(1);
book.setTitle("My Title");
book.setAuthor("Name of Author");
db.addBook(book);