基于HTTP登录系统的扩展（SQLIte数据库部分）

下午在家写android程序。把数据库部分通过写代码方式实践了一下：

注意：产生的数据库文件New.db在windows下边查找不到，需要借助DDMS.找到data/data/com.example/databases，然后进行导数据

核心代码如下：

package com.example;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.graphics.Color;
import android.os.Bundle;
import android.view.KeyEvent;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
/**
* 针对SQLite数据库进行操作
* @author 码农小江
*
*/
public class Five extends Activity{
private static int miscount = 1;
/*数据库对象*/
private SQLiteDatabase mSqLiteDatabase = null;
/*数据库名*/
private  final static String DATABASE_NAME = "New.db";
/*表名*/
private  final static String TABLE_NAME = "PHP";
/*表中字段*/
private  final static String TABLE_ID = "_id";
private  final static String TABLE_NUM = "num";
private  final static String TABLE_DATA = "data";
public   ListView  m_ListView;
public  LinearLayout m_LinearLayout;

/*创建表的SQL语句*/
private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME +
"(" + TABLE_ID + " INTEGER PRIMARY KEY, "
+  TABLE_NUM + " INTERGER, "
+  TABLE_DATA + " TEXT)";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

//创建LinearLayout线性布局
m_LinearLayout = new LinearLayout(this);
//设置LinearLayout布局的属性
m_LinearLayout.setOrientation(LinearLayout.VERTICAL);
m_LinearLayout.setBackgroundColor(android.graphics.Color.BLACK);
//创建ListView对象
m_ListView = new ListView(this);
LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
m_ListView.setBackgroundColor(Color.BLACK);
//添加m_listView到m_LinerLayout中
m_LinearLayout.addView(m_ListView,param);
//设置主显页面
setContentView(m_LinearLayout);

//打开已经存在的数据库
mSqLiteDatabase = this.openOrCreateDatabase(DATABASE_NAME, MODE_PRIVATE, null);
//获取数据库的Cursor
try{
//在数据库中创建一个表
mSqLiteDatabase.execSQL(CREATE_TABLE);

}catch(Exception e){
UpdataAdapter();
}
}
public boolean onKeyUp(int keyCode, KeyEvent event){
switch(keyCode){
case KeyEvent.KEYCODE_DPAD_LEFT:
AddData();
break;

case KeyEvent.KEYCODE_DPAD_RIGHT:
DeleteData();
break;

case KeyEvent.KEYCODE_1:
UpData();
break;

case KeyEvent.KEYCODE_2:
DeleteTable();
break;

case KeyEvent.KEYCODE_3:
DeleteDatabase();
break;

}
return true;
}

/**
* 删除数据库
*/
public void DeleteDatabase(){
this.deleteDatabase(DATABASE_NAME);
this.finish();
}

/**
* 删除表操作
*/
public void DeleteTable(){
mSqLiteDatabase.execSQL("DROP TABLE " + TABLE_NAME);
this.finish();
}

/**
* 更新一条数据操作
*/
public void UpData(){
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miscount);
cv.put(TABLE_DATA, " 修改后的数据 " + miscount);
//更新数据库
mSqLiteDatabase.update(TABLE_NAME, cv, TABLE_NUM + " = " + Integer.toString(miscount-1), null);
UpdataAdapter();
}
/**
* 向表中添加一条数据
*/
public void AddData(){
ContentValues cv = new ContentValues();
cv.put(TABLE_NUM, miscount);
cv.put(TABLE_DATA, " 测试数据库数据 " + miscount);
/*插入数据*/
mSqLiteDatabase.insert(TABLE_NAME, null, cv);
miscount++;
UpdataAdapter();
}

/**
* 从表中删除一个指定的数据
*/
public void DeleteData(){
//删除数据
mSqLiteDatabase.execSQL(" DELETE FROM " + TABLE_NAME + " WHERE _id = " + Integer.toString(miscount));
miscount--;
if(miscount < 0){
miscount = 0;
}
UpdataAdapter();
}

/**
* 更新视图显示
*/
public void UpdataAdapter(){
//获取数据库的cursor
Cursor cur = mSqLiteDatabase.query(TABLE_NAME, new String[]{TABLE_ID,TABLE_NUM,TABLE_DATA},
null, null, null, null, null);
miscount = cur.getCount();
if(cur != null && cur.getCount() >= 0){
ListAdapter adapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2,
cur, new String[]{TABLE_NUM,TABLE_DATA}, new int[]{android.R.id.text1,android.R.id.text2});
m_ListView.setAdapter(adapter);
}
}
/**
* 按键处理
*/
public boolean onKeyDown(int keyCode, KeyEvent event ){
if(keyCode == KeyEvent.KEYCODE_BACK){
mSqLiteDatabase.close();
this.finish();
return true;
}
return super.onKeyDown(keyCode, event);
}
}