学会使用SQLite存储数据和删除数据等基本操作

首先还是写一个XML界面：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <EditText
        android:id="@+id/bookname"
        android:hint="输入名称"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"

        >
    </EditText>
    <EditText
        android:id="@+id/author"
        android:hint="输入密码"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        >
    </EditText>
    <ListView
        android:id="@+id/bookslist"

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        >
    </ListView>
</LinearLayout>

2.书写Java代码实现功能：

package com.example.zhoushasha.sqlitedatabasedemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class  MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
    private BooksDB mBooksDB;
    private Cursor mCursor;
    private EditText BookName;
    private EditText BookAuthor;
    private ListView BooksList;

    private int BOOK_ID = 0;
    protected final static int MENU_ADD = Menu.FIRST;
    protected final static int MENU_DELETE = Menu.FIRST + 1;
    protected final static int MENU_UPDATE = Menu.FIRST + 2;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout);
        setUpViews();
    }

    public void setUpViews() {
        mBooksDB = new BooksDB(this);
        mCursor = mBooksDB.select();

        BookName =(EditText)findViewById(R.id.bookname);
        BookAuthor = (EditText) findViewById(R.id.author);
        BooksList = (ListView) findViewById(R.id.bookslist);

        BooksList.setAdapter(new BooksListAdapter(this, mCursor));
        BooksList.setOnItemClickListener(this);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        menu.add(Menu.NONE, MENU_ADD, 0, "ADD");
        menu.add(Menu.NONE, MENU_DELETE, 0, "DELETE");
        menu.add(Menu.NONE, MENU_DELETE, 0, "UPDATE");
        return true;
    }

    public boolean onOptionsItemSelected(MenuItem item) {
        super.onOptionsItemSelected(item);
        switch (item.getItemId()) {
            case MENU_ADD:
                add();
                break;
            case MENU_DELETE:
                delete();
                break;
            case MENU_UPDATE:
                update();
                break;
        }
        return true;
    }

    public void add() {
        String bookname = BookName.getText().toString();
        String author = BookAuthor.getText().toString();
//书名和作者都不能为空，或者退出
        if (bookname.equals("") || author.equals("")) {
            return;
        }
        mBooksDB.insert(bookname, author);
        mCursor.requery();
        BooksList.invalidateViews();
        BookName.setText("");
        BookAuthor.setText("");
        Toast.makeText(this, "Add Successed!", Toast.LENGTH_SHORT).show();
    }

    public void delete() {
        if (BOOK_ID == 0) {
            return;
        }
        mBooksDB.delete(BOOK_ID);
        mCursor.requery();
        BooksList.invalidateViews();
        BookName.setText("");
        BookAuthor.setText("");
        Toast.makeText(this, "Delete Successed!", Toast.LENGTH_SHORT).show();
    }

    public void update() {
        String bookname = BookName.getText().toString();
        String author = BookAuthor.getText().toString();
//书名和作者都不能为空，或者退出
        if (bookname.equals("") || author.equals("")) {
            return;
        }
        mBooksDB.update(BOOK_ID, bookname, author);
        mCursor.requery();
        BooksList.invalidateViews();
        BookName.setText("");
        BookAuthor.setText("");
        Toast.makeText(this, "Update Successed!", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

        mCursor.moveToPosition(position);
        BOOK_ID = mCursor.getInt(0);
        BookName.setText(mCursor.getString(1));
        BookAuthor.setText(mCursor.getString(2));

    }

    public class BooksListAdapter extends BaseAdapter {
        private Context mContext;
        private Cursor mCursor;

        public BooksListAdapter(Context context, Cursor cursor) {

            mContext = context;
            mCursor = cursor;
        }

        @Override
        public int getCount() {
            return mCursor.getCount();
        }

        @Override
        public Object getItem(int position) {
            return null;
        }

        @Override
        public long getItemId(int position) {
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            TextView mTextView = new TextView(mContext);
            mCursor.moveToPosition(position);
            mTextView.setText(mCursor.getString(1) + "___" + mCursor.getString(2));
            return mTextView;
        }

    }
}

3.创建一个新类bookDB.java类继承：

package com.example.zhoushasha.sqlitedatabasedemo;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class BooksDB extends SQLiteOpenHelper {
    private final static String DATABASE_NAME = "BOOKS.db";
    private final static int DATABASE_VERSION = 1;
    private final static String TABLE_NAME = "books_table";
    public final static String BOOK_ID = "book_id";
    public final static String BOOK_NAME = "book_name";
    public final static String BOOK_AUTHOR = "book_author";

    public BooksDB(Context context) {
// TODO Auto-generated constructor stub
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    //创建table
    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql = "CREATE TABLE " + TABLE_NAME + " (" + BOOK_ID
                + " INTEGER primary key autoincrement, " + BOOK_NAME + " text, "+ BOOK_AUTHOR +" text);";
        db.execSQL(sql);
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        String sql = "DROP TABLE IF EXISTS " + TABLE_NAME;
        db.execSQL(sql);
        onCreate(db);
    }

    public Cursor select() {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db
                .query(TABLE_NAME, null, null, null, null, null, null);
        return cursor;
    }
    //增加操作
    public long insert(String bookname,String author)
    {
        SQLiteDatabase db = this.getWritableDatabase();
/* ContentValues */
        ContentValues cv = new ContentValues();
        cv.put(BOOK_NAME, bookname);
        cv.put(BOOK_AUTHOR, author);
        long row = db.insert(TABLE_NAME, null, cv);
        return row;
    }
    //删除操作
    public void delete(int id)
    {
        SQLiteDatabase db = this.getWritableDatabase();
        String where = BOOK_ID + " = ?";
        String[] whereValue ={ Integer.toString(id) };
        db.delete(TABLE_NAME, where, whereValue);
    }
    //修改操作
    public void update(int id, String bookname,String author)
    {
        SQLiteDatabase db = this.getWritableDatabase();
        String where = BOOK_ID + " = ?";
        String[] whereValue = { Integer.toString(id) };

        ContentValues cv = new ContentValues();
        cv.put(BOOK_NAME, bookname);
        cv.put(BOOK_AUTHOR, author);
        db.update(TABLE_NAME, cv, where, whereValue);
    }
}