Android數據庫相關代碼解讀(1)

在android 手機操作系統進行實際開發中，進場會應用到數據庫。而且在這一平台中對數據庫的應用方法比較簡單靈活。我們在這裡就為大家詳細介紹了相關方法，希望可以給大家帶來一些幫助。

昨天進行了GUI界面設計，感受了一下android初次設計的愉悅，今天接著學習其SQLite數據庫試用，將昨天的例子中數據存到數庫中，並讀取查看一下。 具體看代碼（原寫的有點問題，再改寫如下）：

1) android數據庫之庫操作類：

package com.topsun;   
import android.content.Context;   
import android.database.Cursor;   
import android.database.sqlite.SQLiteDatabase;   
import android.util.Log;   
public class DBHelper {   
private static final String TAG = "UserDB_DBHelper.Java";   
private static final String DataBaseName = "UserDB";   
SQLiteDatabase db;   
Context context;   
public DBHelper(Context context) {   
this.open(context);   
}   
private void createTabel() {   
// TODO Auto-generated method stub   
String sql = "";   
try {   
sql = "CREATE TABLE IF NOT EXISTS TestUser (ID INTEGER 
PRIMARY KEY autoincrement, NAME TEXT, SEX TEXT, AGES INTEGER)";   
this.db.execSQL(sql);   
Log.v(TAG, "Create Table TestUser ok");   
} catch (Exception e) {   
Log.v(TAG, "Create Table TestUser fail");   
} finally {   
//this.db.close();   
Log.v(TAG, "Create Table TestUser ");   
}   
}   
public boolean save(String name, String sex, Integer ages) {   
String sql = "insert into TestUser values
(null,'" + name + "','" + sex   
+ "'," + ages + ")";   
try {   
this.db.execSQL(sql);   
Log.v(TAG, "insert Table TestUser 1 record ok");   
return true;   
} catch (Exception e) {   
Log.v(TAG, "insert Table TestUser 1 record fail");   
return false;   
} finally {   
//this.db.close();   
Log.v(TAG, "insert Table TestUser ");   
}   
}   
public Cursor loadAll() {   
Cursor cur = db.query("TestUser", new String[] 
{ "ID", "NAME","SEX","AGES"}, null,   
null, null, null, null);   
return cur;   
}   
public void open(Context context){   
if (null == db || !this.db.isOpen()){   
this.context = context;   
this.db = context.openOrCreateDatabase(this.DataBaseName,   
context.MODE_PRIVATE, null);   
createTabel();   
Log.v(this.TAG, "create or Open DataBase。。。");   
}   
}   
public void close() {   
db.close();   
}   
}   
package com.topsun;  
import android.content.Context;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
import android.util.Log;  
public class DBHelper {  
private static final String TAG = "UserDB_DBHelper.Java";  
private static final String DataBaseName = "UserDB";  
SQLiteDatabase db;  
Context context;  
public DBHelper(Context context) {  
this.open(context);  
}  
private void createTabel() {  
// TODO Auto-generated method stub  
String sql = "";  
try {  
sql = "CREATE TABLE IF NOT EXISTS TestUser 
(ID INTEGER PRIMARY KEY autoincrement, 
NAME TEXT, SEX TEXT, AGES INTEGER)";  
this.db.execSQL(sql);  
Log.v(TAG, "Create Table TestUser ok");  
} catch (Exception e) {  
Log.v(TAG, "Create Table TestUser fail");  
} finally {  
//this.db.close();  
Log.v(TAG, "Create Table TestUser ");  
}  
}  
public boolean save(String name, String sex, Integer ages) {  
String sql = "insert into TestUser values
(null,'" + name + "','" + sex  
+ "'," + ages + ")";  
try {  
this.db.execSQL(sql);  
Log.v(TAG, "insert Table TestUser 1 record ok");  
return true;  
} catch (Exception e) {  
Log.v(TAG, "insert Table TestUser 1 record fail");  
return false;  
} finally {  
//this.db.close();  
Log.v(TAG, "insert Table TestUser ");  
}  
}  
public Cursor loadAll() {  
Cursor cur = db.query("TestUser", new String[] 
{ "ID", "NAME","SEX","AGES"}, null,  
null, null, null, null);  
return cur;  
}  
public void open(Context context){  
if (null == db || !this.db.isOpen()){  
this.context = context;  
this.db = context.openOrCreateDatabase(this.DataBaseName,  
context.MODE_PRIVATE, null);  
createTabel();  
Log.v(this.TAG, "create or Open DataBase。。。");  
}  
}  
public void close() {  
db.close();  
}  
} 

2) android數據庫交互代碼

package com.topsun;   
import android.app.Activity;   
import android.database.Cursor;   
import android.os.Bundle;   
import android.util.Log;   
import android.view.VIEw;   
import android.view.VIEw.OnClickListener;   
import android.widget.Button;   
import android.widget.EditText;   
public class guiWindows extends Activity 
implements OnClickListener {   
EditText TEditname;   
EditText TEditsex;   
EditText TEditages;   
EditText TEditmerge;   
Button TSavebutton;   
Button TVIEwbutton;   
DBHelper db;   
/** Called when the activity is first created. */   
@Override   
public void onCreate(Bundle savedInstanceState) {   
super.onCreate(savedInstanceState);   
setContentVIEw(R.layout.main);   
this.TEditname = (EditText) this.findVIEwById
(R.id.widgeteditname);   
this.TEditsex = (EditText) this.findVIEwById
(R.id.widgeteditsex);   
this.TEditages = (EditText) this.findVIEwById
(R.id.widgeteditages);   
TEditmerge = (EditText) this.findVIEwById
(R.id.widgeteditmerge);   
this.TSavebutton = (Button) this.findVIEwById
(R.id.widgetSavebutton);   
TVIEwbutton = (Button) this.findVIEwById
(R.id.widgetVIEwbutton);   
this.db = new DBHelper(this);   
this.TSavebutton.setOnClickListener(this);   
this.TVIEwbutton.setOnClickListener(this);   
}   
@Override   
public void onClick(VIEw v) {   
// TODO Auto-generated method stub   
// this.TEditages.setText(this.TEditname.getText().
toString()+this.TEditsex.getText().toString());   
if (v.getId() == R.id.widgetSavebutton) {   
try {   
this.db.open(this);   
this.db.save(this.TEditname.getText().toString(), this.TEditsex   
.getText().toString(), Integer.valueOf(this.TEditages   
.getText().toString()));   
} catch (Exception e) {   
Log.v("save data", "save data fail");   
} finally {   
this.db.close();   
}   
} else if (v.getId() == R.id.widgetVIEwbutton && null != db) {   
this.db.open(this);   
// 浏覽所有數據   
Cursor cur = db.loadAll();   
StringBuffer sf = new StringBuffer();   
cur.moveToFirst();   
while (!cur.isAfterLast()) {   
sf.append(cur.getInt(0)).append(" : ").append(cur.getString(1))   
.append(" : ").append(cur.getString(2)).append(" : ")   
.append(cur.getInt(3)).append("\n");   
cur.moveToNext();   
}   
db.close();   
this.TEditmerge.setText(sf.toString());   
}   
}   
}