Android 数据库SQLiteDatabase的使用！！

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转载自：http://blog.csdn.net/android_tutor/article/details/5654124

大家好，好久没有更新博客了，最近由于身体不适让大家久等了，好了，直接进入主题~

Android 提供了三种数据存储方式，第一种是文件存储;第二种是SharedPreferences存储;第三种就是数据库SQLiteDatabase存储。

文件存储我就不用多说了，而SharedPreferences可以存取简单的数据(int,double,float.etc)，它经常用于数据缓存，因为它读取存储简单。详细可以参见本系列。Android高手进阶教程(七)之----Android 中Preferences的使用!

今天我们将讲一下SQLiteDatabase的使用。而掌握SqliteDatabase，将会我们接下来掌握ContentProvider打下良好的基石。

为了让大家更好的掌握，我们手把手完成该节的Demo。

第一步：新建一个Android工程，命名为SQLiteDatabaseDemo.

第二步:创建一个新的类BooksDB.java这个类要继承于android.database.sqlite.SQLiteOpenHelper抽象类，我们要实现其中两个方法：onCreate(),onUpdate.具体代码如下：

package com.android.tutor;
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);
      }
}

 

 

第三步:修改main.xml布局如下，由两个EditText和一个ListView组成，代码如下:

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

第四步:修改SQLiteDatabaseDemo.java代码如下:

package com.android.tutor;
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 SQLiteDatabaseDemo extends Activity 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.main);
        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;
        }

    }
}

第五步:运行程序效果如下:

 

 

 

   

 

第六步：查看我们所建的数据库。有两种方法：第一种用命令查看：adb shell ls data/data/com.android.tutor/databases。

另一种方法是用DDMS查看，在data/data下面对应的应用程序的包名 下会有如下数据库，如图所示：