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:
-
Android群：239123204
(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;
}
}