Android包含了常用于嵌入式系統(tǒng)的SQLite，免去了開發(fā)者自己移植安裝的功夫。SQLite 支持多數(shù) SQL92 標(biāo)準(zhǔn)，很多常用的SQL命令都能在SQLite上面使用，除此之外Android還提供了一系列自定義的方法去簡化對SQLite數(shù)據(jù)庫的操作。不過有跨平臺需求的程序就建議使用標(biāo)準(zhǔn)的SQL語句，畢竟這樣容易在多個平臺之間移植。
先貼出本文程序運行的結(jié)果：
本文主要講解了SQLite的基本用法，如：創(chuàng)建數(shù)據(jù)庫，使用SQL命令查詢數(shù)據(jù)表、插入數(shù)據(jù)，關(guān)閉數(shù)據(jù)庫，以及使用GridView實現(xiàn)了一個分頁欄(關(guān)于GridView的用法)，用于把數(shù)據(jù)分頁顯示。
分頁欄的pagebuttons.xml的源碼如下：
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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:paddingBottom="4dip"
android:layout_width="fill_parent">
<TextView android:layout_width="wrap_content"
android:layout_below="@+id/ItemImage" android:layout_height="wrap_content"
android:text="TextView01" android:layout_centerHorizontal="true"
android:id="@+id/ItemText">
</TextView>
</RelativeLayout>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:paddingBottom="4dip"
android:layout_width="fill_parent">
<TextView android:layout_width="wrap_content"
android:layout_below="@+id/ItemImage" android:layout_height="wrap_content"
android:text="TextView01" android:layout_centerHorizontal="true"
android:id="@+id/ItemText">
</TextView>
</RelativeLayout>
main.xml的源碼如下：
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<?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">
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:id="@+id/btnCreateDB"
android:text="創(chuàng)建數(shù)據(jù)庫"></Button>
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:text="插入一串實驗數(shù)據(jù)" android:id="@+id/btnInsertRec"></Button>
<Button android:layout_height="wrap_content" android:id="@+id/btnClose"
android:text="關(guān)閉數(shù)據(jù)庫" android:layout_width="fill_parent"></Button>
<EditText android:text="@+id/EditText01" android:id="@+id/EditText01"
android:layout_width="fill_parent" android:layout_height="256dip"></EditText>
<GridView android:id="@+id/gridview" android:layout_width="fill_parent"
android:layout_height="32dip" android:numColumns="auto_fit"
android:columnWidth="40dip"></GridView>
</LinearLayout>
<?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">
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:id="@+id/btnCreateDB"
android:text="創(chuàng)建數(shù)據(jù)庫"></Button>
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:text="插入一串實驗數(shù)據(jù)" android:id="@+id/btnInsertRec"></Button>
<Button android:layout_height="wrap_content" android:id="@+id/btnClose"
android:text="關(guān)閉數(shù)據(jù)庫" android:layout_width="fill_parent"></Button>
<EditText android:text="@+id/EditText01" android:id="@+id/EditText01"
android:layout_width="fill_parent" android:layout_height="256dip"></EditText>
<GridView android:id="@+id/gridview" android:layout_width="fill_parent"
android:layout_height="32dip" android:numColumns="auto_fit"
android:columnWidth="40dip"></GridView>
</LinearLayout>
本文程序源碼如下：
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package com.testSQLite;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.GridView;
import android.widget.SimpleAdapter;
public class testSQLite extends Activity {
/** Called when the activity is first created. */
Button btnCreateDB, btnInsert, btnClose;
EditText edtSQL;//顯示分頁數(shù)據(jù)
SQLiteDatabase db;
int id;//添加記錄時的id累加標(biāo)記，必須全局
static final int PageSize=10;//分頁時，每頁的數(shù)據(jù)總數(shù)
private static final String TABLE_NAME = "stu";
private static final String ID = "id";
private static final String NAME = "name";
SimpleAdapter saPageID;// 分頁欄適配器
ArrayList<HashMap<String, String>> lstPageID;// 分頁欄的數(shù)據(jù)源，與PageSize和數(shù)據(jù)總數(shù)相關(guān)
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnCreateDB = (Button) this.findViewById(R.id.btnCreateDB);
btnCreateDB.setOnClickListener(new ClickEvent());
btnInsert = (Button) this.findViewById(R.id.btnInsertRec);
btnInsert.setOnClickListener(new ClickEvent());
btnClose = (Button) this.findViewById(R.id.btnClose);
btnClose.setOnClickListener(new ClickEvent());
edtSQL=(EditText)this.findViewById(R.id.EditText01);
GridView gridview = (GridView) findViewById(R.id.gridview);//分頁欄控件
// 生成動態(tài)數(shù)組，并且轉(zhuǎn)入數(shù)據(jù)
lstPageID = new ArrayList<HashMap<String, String>>();
// 生成適配器的ImageItem <====> 動態(tài)數(shù)組的元素，兩者一一對應(yīng)
saPageID = new SimpleAdapter(testSQLite.this, // 沒什么解釋
lstPageID,// 數(shù)據(jù)來源
R.layout.pagebuttons,//XML實現(xiàn)
new String[] { "ItemText" },
new int[] { R.id.ItemText });
// 添加并且顯示
gridview.setAdapter(saPageID);
// 添加消息處理
gridview.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
LoadPage(arg2);//根據(jù)所選分頁讀取對應(yīng)的數(shù)據(jù)
}
});
}
class ClickEvent implements View.OnClickListener {
@Override
public void onClick(View v) {
if (v == btnCreateDB) {
CreateDB();
} else if (v == btnInsert) {
InsertRecord(16);//插入16條記錄
RefreshPage();
}else if (v == btnClose) {
db.close();
}
}
}
/*
* 讀取指定ID的分頁數(shù)據(jù)
* SQL:Select * From TABLE_NAME Limit 9 Offset 10;
* 表示從TABLE_NAME表獲取數(shù)據(jù)，跳過10行，取9行
*/
void LoadPage(int pageID)
{
String sql= "select * from " + TABLE_NAME +
" Limit "+String.valueOf(PageSize)+ " Offset " +String.valueOf(pageID*PageSize);
Cursor rec = db.rawQuery(sql, null);
setTitle("當(dāng)前分頁的數(shù)據(jù)總數(shù):"+String.valueOf(rec.getCount()));
// 取得字段名稱
String title = "";
int colCount = rec.getColumnCount();
for (int i = 0; i < colCount; i++)
title = title + rec.getColumnName(i) + " ";
// 列舉出所有數(shù)據(jù)
String content="";
int recCount=rec.getCount();
for (int i = 0; i < recCount; i++) {//定位到一條數(shù)據(jù)
rec.moveToPosition(i);
for(int ii=0;ii<colCount;ii++)//定位到一條數(shù)據(jù)中的每個字段
{
content=content+rec.getString(ii)+" ";
}
content=content+"\r\n";
}
edtSQL.setText(title+"\r\n"+content);//顯示出來
rec.close();
}
/*
* 在內(nèi)存創(chuàng)建數(shù)據(jù)庫和數(shù)據(jù)表
*/
void CreateDB() {
// 在內(nèi)存創(chuàng)建數(shù)據(jù)庫
db = SQLiteDatabase.create(null);
Log.e("DB Path", db.getPath());
String amount = String.valueOf(databaseList().length);
Log.e("DB amount", amount);
// 創(chuàng)建數(shù)據(jù)表
String sql = "CREATE TABLE " + TABLE_NAME + " (" + ID
+ " text not null, " + NAME + " text not null " + ");";
try {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
db.execSQL(sql);
} catch (SQLException e) {}
}
/*
* 插入N條數(shù)據(jù)
*/
void InsertRecord(int n) {
int total = id + n;
for (; id < total; id++) {
String sql = "insert into " + TABLE_NAME + " (" + ID + ", " + NAME
+ ") values(''''''''" + String.valueOf(id) + "'''''''', ''''''''test'''''''');";
try {
db.execSQL(sql);
} catch (SQLException e) {
}
}
}
/*
* 插入之后刷新分頁
*/
void RefreshPage()
{
String sql = "select count(*) from " + TABLE_NAME;
Cursor rec = db.rawQuery(sql, null);
rec.moveToLast();
long recSize=rec.getLong(0);//取得總數(shù)
rec.close();
int pageNum=(int)(recSize/PageSize) + 1;//取得分頁數(shù)
lstPageID.clear();
for (int i = 0; i < pageNum; i++) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("ItemText", "No." + String.valueOf(i));
lstPageID.add(map);
}
saPageID.notifyDataSetChanged();
}
}
(審核編輯: 智匯小新)
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