Android(安卓)数据库SQLiteDatabase的使用！！

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：

[java] view plain copy

packagecom.android.tutor;
importandroid.content.ContentValues;
importandroid.content.Context;
importandroid.database.Cursor;
importandroid.database.sqlite.SQLiteDatabase;
importandroid.database.sqlite.SQLiteOpenHelper;
publicclassBooksDBextendsSQLiteOpenHelper{
privatefinalstaticStringDATABASE_NAME="BOOKS.db";
privatefinalstaticintDATABASE_VERSION=1;
privatefinalstaticStringTABLE_NAME="books_table";
publicfinalstaticStringBOOK_ID="book_id";
publicfinalstaticStringBOOK_NAME="book_name";
publicfinalstaticStringBOOK_AUTHOR="book_author";
publicBooksDB(Contextcontext){
//TODOAuto-generatedconstructorstub
super(context,DATABASE_NAME,null,DATABASE_VERSION);
}
//创建table
@Override
publicvoidonCreate(SQLiteDatabasedb){
Stringsql="CREATETABLE"+TABLE_NAME+"("+BOOK_ID
+"INTEGERprimarykeyautoincrement,"+BOOK_NAME+"text,"+BOOK_AUTHOR+"text);";
db.execSQL(sql);
}
@Override
publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){
Stringsql="DROPTABLEIFEXISTS"+TABLE_NAME;
db.execSQL(sql);
onCreate(db);
}
publicCursorselect(){
SQLiteDatabasedb=this.getReadableDatabase();
Cursorcursor=db
.query(TABLE_NAME,null,null,null,null,null,null);
returncursor;
}
//增加操作
publiclonginsert(Stringbookname,Stringauthor)
{
SQLiteDatabasedb=this.getWritableDatabase();
/*ContentValues*/
ContentValuescv=newContentValues();
cv.put(BOOK_NAME,bookname);
cv.put(BOOK_AUTHOR,author);
longrow=db.insert(TABLE_NAME,null,cv);
returnrow;
}
//删除操作
publicvoiddelete(intid)
{
SQLiteDatabasedb=this.getWritableDatabase();
Stringwhere=BOOK_ID+"=?";
String[]whereValue={Integer.toString(id)};
db.delete(TABLE_NAME,where,whereValue);
}
//修改操作
publicvoidupdate(intid,Stringbookname,Stringauthor)
{
SQLiteDatabasedb=this.getWritableDatabase();
Stringwhere=BOOK_ID+"=?";
String[]whereValue={Integer.toString(id)};
ContentValuescv=newContentValues();
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:

[java] view plain copy

<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns: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:

[java] view plain copy

packagecom.android.tutor;
importandroid.app.Activity;
importandroid.content.Context;
importandroid.database.Cursor;
importandroid.os.Bundle;
importandroid.view.Menu;
importandroid.view.MenuItem;
importandroid.view.View;
importandroid.view.ViewGroup;
importandroid.widget.AdapterView;
importandroid.widget.BaseAdapter;
importandroid.widget.EditText;
importandroid.widget.ListView;
importandroid.widget.TextView;
importandroid.widget.Toast;
publicclassSQLiteDatabaseDemoextendsActivityimplementsAdapterView.OnItemClickListener{
privateBooksDBmBooksDB;
privateCursormCursor;
privateEditTextBookName;
privateEditTextBookAuthor;
privateListViewBooksList;
privateintBOOK_ID=0;
protectedfinalstaticintMENU_ADD=Menu.FIRST;
protectedfinalstaticintMENU_DELETE=Menu.FIRST+1;
protectedfinalstaticintMENU_UPDATE=Menu.FIRST+2;
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setUpViews();
}
publicvoidsetUpViews(){
mBooksDB=newBooksDB(this);
mCursor=mBooksDB.select();
BookName=(EditText)findViewById(R.id.bookname);
BookAuthor=(EditText)findViewById(R.id.author);
BooksList=(ListView)findViewById(R.id.bookslist);
BooksList.setAdapter(newBooksListAdapter(this,mCursor));
BooksList.setOnItemClickListener(this);
}
@Override
publicbooleanonCreateOptionsMenu(Menumenu){
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");
returntrue;
}
publicbooleanonOptionsItemSelected(MenuItemitem)
{
super.onOptionsItemSelected(item);
switch(item.getItemId())
{
caseMENU_ADD:
add();
break;
caseMENU_DELETE:
delete();
break;
caseMENU_UPDATE:
update();
break;
}
returntrue;
}
publicvoidadd(){
Stringbookname=BookName.getText().toString();
Stringauthor=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,"AddSuccessed!",Toast.LENGTH_SHORT).show();
}
publicvoiddelete(){
if(BOOK_ID==0){
return;
}
mBooksDB.delete(BOOK_ID);
mCursor.requery();
BooksList.invalidateViews();
BookName.setText("");
BookAuthor.setText("");
Toast.makeText(this,"DeleteSuccessed!",Toast.LENGTH_SHORT).show();
}
publicvoidupdate(){
Stringbookname=BookName.getText().toString();
Stringauthor=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,"UpdateSuccessed!",Toast.LENGTH_SHORT).show();
}
@Override
publicvoidonItemClick(AdapterView<?>parent,Viewview,intposition,longid){
mCursor.moveToPosition(position);
BOOK_ID=mCursor.getInt(0);
BookName.setText(mCursor.getString(1));
BookAuthor.setText(mCursor.getString(2));
}
publicclassBooksListAdapterextendsBaseAdapter{
privateContextmContext;
privateCursormCursor;
publicBooksListAdapter(Contextcontext,Cursorcursor){
mContext=context;
mCursor=cursor;
}
@Override
publicintgetCount(){
returnmCursor.getCount();
}
@Override
publicObjectgetItem(intposition){
returnnull;
}
@Override
publiclonggetItemId(intposition){
return0;
}
@Override
publicViewgetView(intposition,ViewconvertView,ViewGroupparent){
TextViewmTextView=newTextView(mContext);
mCursor.moveToPosition(position);
mTextView.setText(mCursor.getString(1)+"___"+mCursor.getString(2));
returnmTextView;
}
}
}

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：

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