Android数据存储(3)SQLite简介和简单的登录与注册源代码
16lz
2021-01-25
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;@Overrideprotected 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() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent = new Intent();intent.setClass(MainActivity.this, RegistersActivity.class);startActivity(intent);}});btlogin.setOnClickListener(new LoginListener());}@Overrideprotected void onDestroy() {// TODO Auto-generated method stubsuper.onDestroy();db.close();}class LoginListener implements OnClickListener {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubString 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))");}@Overridepublic 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;@Overrideprotected void onDestroy() {// TODO Auto-generated method stubsuper.onDestroy();db.close();}@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.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() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubString name = edname1.getText().toString();String password = edpassword1.getText().toString();if (!(name.equals("") && password.equals(""))) {if (addUser(name, password)) {DialogInterface.OnClickListener ss = new DialogInterface.OnClickListener() {@Overridepublic 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activityRegistersActivity.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;}}
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