Android 数据库SQLiteDatabase的使用

转自：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：