Android数据储存(3)SQLite简介和简单的登录与注册源代码_SQL

Android数据存储(3)SQLite简介和简单的登录与注册源代码

操作SQLite数据的基本操作步骤:

(在此不考虑用SQLiteOpenHelper类)

1.获取SQLiteDatabase对象db创建数据库或连接数据库：SQLiteDatabasedb = SQLiteDatabase.openOrCreateDatabase(MainActivity.this.getFilesDir().toString()+ "/test.dbs", null);如果目录下有test.dbs数据库则是连接没有就是创建

2.用对象db的方法来执行sql语句：db.execSQL(String sql) 此方法木有返回值所以查询不好弄。查询一般用db.rawQuery返回一个Cursor对象(相当与jdbc中的ResultSet),Cursor有如下几个方法来查询数据:

2.1 move ToFirst 将记录指针跳到第一行

2.2 moveToLast将记录指针跳到最后一行

2.3 moveNext将记录指针移到下一行

2.4moveToPosition( int ss)将记录指针跳到指定的ss行

2.5moveToPrevious将记录指针跳到上一行

将记录指针跳到指定的行之后就可以通过对象的getXXX方法来获取数据 :如 Cursor cursor = db.rawQuery("select na,pw from user where na=? and pw=?", new String []{name,pwd});

3.回收资源close

当然以SQLiteDatabase对象还可以调用许多方法来操作数据库，不过俺是觉得这几个方法基本够了

简单的登录与注册源代码

（仅此来练习SQLite的操作一般注册的信息都样上传到服务器而不会是存储在手机数据库）

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.android.xiong.sqlitelogin"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="14" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.android.xiong.sqlitelogin.MainActivity"            android:label="@string/app_name" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>        <activity            android:name="com.android.xiong.sqlitelogin.RegistersActivity"            android:label="@string/app_name" >        </activity>    </application></manifest>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context=".MainActivity" >    <TextView        android:id="@+id/login"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_margin="30dp"        android:gravity="center_horizontal"        android:textColor="#8a2be2"        android:textSize="35dp"        android:text="登录界面" />    <TextView         android:id="@+id/txtname"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/login"        android:layout_marginRight="5dp"        android:layout_marginBottom="30dp"        android:textSize="28dp"        android:text="用户帐号:"/>    <EditText         android:id="@+id/edname"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginBottom="30dp"        android:layout_below="@id/login"        android:layout_toRightOf="@id/txtname"        android:layout_alignParentRight="true"         android:hint="请输入用户帐号"/>        <TextView         android:id="@+id/txtpassword"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/txtname"        android:layout_marginRight="5dp"        android:textSize="28dp"        android:text="用户密码:"/>    <EditText         android:id="@+id/edpassword"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/edname"        android:layout_toRightOf="@id/txtpassword"        android:layout_alignParentRight="true"        android:inputType="textPassword"        android:hint="请输入用户密码"/>    <LinearLayout         android:layout_below="@id/edpassword"        android:orientation="horizontal"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginTop="30dp"        android:gravity="center_horizontal" >    <Button         android:id="@+id/btregister"        android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:layout_marginRight="20dp"        android:text="用户注册"/>      <Button         android:id="@+id/btlogin"        android:layout_height="wrap_content"        android:layout_width="wrap_content"        android:text="用户登录"/>      </LinearLayout></RelativeLayout>

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent" >        <TextView        android:id="@+id/txt1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_margin="30dp"        android:gravity="center_horizontal"        android:text="注册界面"        android:textColor="#8a2be2"        android:textSize="35dp" />    <TextView        android:id="@+id/txtname1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/txt1"        android:layout_marginBottom="30dp"        android:layout_marginRight="5dp"        android:text="帐号:"        android:textSize="28dp" />    <EditText        android:id="@+id/edname1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_below="@id/txt1"         android:layout_toRightOf="@id/txtname1"        android:layout_marginBottom="30dp" />    <TextView        android:id="@+id/txtpassword1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_below="@id/txtname1"        android:layout_marginRight="5dp"        android:text="密码:"        android:textSize="28dp" />    <EditText        android:id="@+id/edpassword1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentRight="true"        android:layout_below="@id/edname1"        android:layout_toRightOf="@id/txtpassword1" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@id/edpassword1"        android:layout_marginTop="30dp"        android:gravity="center_horizontal"        android:orientation="horizontal" >        <Button            android:id="@+id/btregister1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginRight="20dp"            android:text="提交数据" />    </LinearLayout></RelativeLayout>

package com.android.xiong.sqlitelogin;import android.app.Activity;import android.app.AlertDialog;import android.content.Intent;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteException;import android.os.Bundle;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;public class MainActivity extends Activity {	// 帐号和密码	private EditText edname;	private EditText edpassword;	private Button btregister;	private Button btlogin;	// 创建SQLite数据库	public static SQLiteDatabase db;	@Override	protected void onCreate(Bundle savedInstanceState) {		super.onCreate(savedInstanceState);		setContentView(R.layout.activity_main);		edname = (EditText) findViewById(R.id.edname);		edpassword = (EditText) findViewById(R.id.edpassword);		btregister = (Button) findViewById(R.id.btregister);		btlogin = (Button) findViewById(R.id.btlogin);		db = SQLiteDatabase.openOrCreateDatabase(MainActivity.this.getFilesDir().toString()				+ "/test.dbs", null);		// 跳转到注册界面		btregister.setOnClickListener(new OnClickListener() {			@Override			public void onClick(View v) {				// TODO Auto-generated method stub				Intent intent = new Intent();				intent.setClass(MainActivity.this, RegistersActivity.class);				startActivity(intent);			}		});		btlogin.setOnClickListener(new LoginListener());	}	@Override	protected void onDestroy() {		// TODO Auto-generated method stub		super.onDestroy();		db.close();	}	class LoginListener implements OnClickListener {		@Override		public void onClick(View v) {			// TODO Auto-generated method stub			String name = edname.getText().toString();			String password = edpassword.getText().toString();			if (name.equals("") || password.equals("")) {				// 弹出消息框				new AlertDialog.Builder(MainActivity.this).setTitle("错误")						.setMessage("帐号或密码不能空").setPositiveButton("确定", null)						.show();			} else {				isUserinfo(name, password);			}		}		// 判断输入的用户是否正确		public Boolean isUserinfo(String name, String pwd) {			try{				String str="select * from tb_user where name=? and password=?";				Cursor cursor = db.rawQuery(str, new String []{name,pwd});				if(cursor.getCount()<=0){					new AlertDialog.Builder(MainActivity.this).setTitle("错误")					.setMessage("帐号或密码错误！").setPositiveButton("确定", null)					.show();					return false;				}else{					new AlertDialog.Builder(MainActivity.this).setTitle("正确")					.setMessage("成功登录").setPositiveButton("确定", null)					.show();					return true;				}							}catch(SQLiteException e){				createDb();			}			return false;		}		}	// 创建数据库和用户表	public void createDb() {		db.execSQL("create table tb_user( name varchar(30) primary key,password varchar(30))");	}	@Override	public boolean onCreateOptionsMenu(Menu menu) {		// Inflate the menu; this adds items to the action bar if it is present.		getMenuInflater().inflate(R.menu.main, menu);		return true;	}}

package com.android.xiong.sqlitelogin;import android.app.Activity;import android.app.AlertDialog;import android.content.DialogInterface;import android.content.Intent;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;public class RegistersActivity extends Activity {	private EditText edname1;	private EditText edpassword1;	private Button btregister1;	SQLiteDatabase db;	@Override	protected void onDestroy() {		// TODO Auto-generated method stub		super.onDestroy();		db.close();	}	@Override	protected void onCreate(Bundle savedInstanceState) {		// TODO Auto-generated method stub		super.onCreate(savedInstanceState);		setContentView(R.layout.register);		edname1 = (EditText) findViewById(R.id.edname1);		edpassword1 = (EditText) findViewById(R.id.edpassword1);		btregister1 = (Button) findViewById(R.id.btregister1);		btregister1.setOnClickListener(new OnClickListener() {			@Override			public void onClick(View v) {				// TODO Auto-generated method stub				String name = edname1.getText().toString();				String password = edpassword1.getText().toString();				if (!(name.equals("") && password.equals(""))) {					if (addUser(name, password)) {						DialogInterface.OnClickListener ss = new DialogInterface.OnClickListener() {							@Override							public void onClick(DialogInterface dialog,									int which) {								// TODO Auto-generated method stub								// 跳转到登录界面								Intent in = new Intent();								in.setClass(RegistersActivity.this,										MainActivity.class);								startActivity(in);								// 销毁当前activity								RegistersActivity.this.onDestroy();							}						};						new AlertDialog.Builder(RegistersActivity.this)								.setTitle("注册成功").setMessage("注册成功")								.setPositiveButton("确定", ss).show();					} else {						new AlertDialog.Builder(RegistersActivity.this)								.setTitle("注册失败").setMessage("注册失败")								.setPositiveButton("确定", null);					}				} else {					new AlertDialog.Builder(RegistersActivity.this)							.setTitle("帐号密码不能为空").setMessage("帐号密码不能为空")							.setPositiveButton("确定", null);				}			}		});	}	// 添加用户	public Boolean addUser(String name, String password) {		String str = "insert into tb_user values(?,?) ";		MainActivity main = new MainActivity();		db = SQLiteDatabase.openOrCreateDatabase(this.getFilesDir().toString()				+ "/test.dbs", null);		main.db = db;		try {			db.execSQL(str, new String[] { name, password });			return true;		} catch (Exception e) {			main.createDb();		}		return false;	}}