android简单登陆和注册功能实现+SQLite数据库学习

发布时间：2018-07-04 17:23,

浏览次数：1027

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android

SQLite

这里我只是建立了一个用简单的存储用户名和密码的表单

MyDBHelper.java

<>public class MyDBHelper extends SQLiteOpenHelper { public static final

String CREATE_USERDATA="create table userData(" + "id integer primary key

autoincrement," +"nametext," +"password text)"; private Context mContext; public

MyDBHelper(Context context, String name, SQLiteDatabase.CursorFactory

cursorFactory,int version){ super(context,name,cursorFactory,version); mContext=

context; }public void onCreate(SQLiteDatabase db){ db.execSQL(CREATE_USERDATA);

}public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion){ //

onCreate(db); } } <>

注册：

Main2Activity.java <>public class Main2Activity extends AppCompatActivity {

private MyDBHelper dbHelper; @Override protected void onCreate(Bundle

savedInstanceState) { super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main2); dbHelper = new

MyDBHelper(this,"UserStore.db",null,1); } public void logon(View view){

//SQLiteDatabase db=dbHelper.getWritableDatabase(); EditText

editText3=(EditText)findViewById(R.id.editText3); EditText

editText4=(EditText)findViewById(R.id.editText4); String newname

=editText3.getText().toString(); String

password=editText4.getText().toString(); if

(CheckIsDataAlreadyInDBorNot(newname)) {

Toast.makeText(this,"该用户名已被注册，注册失败",Toast.LENGTH_SHORT).show(); } else { if

(register(newname, password)) { Toast.makeText(this, "插入数据表成功",

Toast.LENGTH_SHORT).show(); } } } //向数据库插入数据 public boolean register(String

username,String password){ SQLiteDatabase db= dbHelper.getWritableDatabase();

/*String sql = "insert into userData(name,password) value(?,?)"; Object

obj[]={username,password}; db.execSQL(sql,obj);*/ ContentValues values=new

ContentValues(); values.put("name",username); values.put("password",password);

db.insert("userData",null,values); db.close(); //db.execSQL("insert into

userData (name,password) values (?,?)",new String[]{username,password}); return

true; } //检验用户名是否已存在 public boolean CheckIsDataAlreadyInDBorNot(String value){

SQLiteDatabase db=dbHelper.getWritableDatabase(); String Query = "Select * from

userData where name =?"; Cursor cursor = db.rawQuery(Query,new String[] { value

}); if (cursor.getCount()>0){ cursor.close(); return true; } cursor.close();

return false; } } <>

登陆：

MainActivity.java <>public class MainActivity extends AppCompatActivity {

private MyDBHelper dbHelper; private EditText username; private EditText

userpassword; @Overrideprotected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState); //

requestWindowFeature(Window.FEATURE_NO_TITLE);

setContentView(R.layout.activity_main); dbHelper= new MyDBHelper(this

,"UserStore.db",null,1); } //点击注册按钮进入注册页面 public void logonClicked(View view){

Intent intent= new Intent(MainActivity.this,Main2Activity.class);

startActivity(intent); }//点击登录按钮 public void loginClicked(View view) { username=

(EditText)findViewById(R.id.editText2); userpassword=

(EditText)findViewById(R.id.editText); String userName=

username.getText().toString(); String passWord=

userpassword.getText().toString();if (login(userName,passWord)) {

Toast.makeText(MainActivity.this, "登陆成功(ZY，111)", Toast.LENGTH_SHORT).show(); }

else { Toast.makeText(MainActivity.this, "登陆失败", Toast.LENGTH_SHORT).show(); } }

//验证登录 public boolean login(String username,String password) { SQLiteDatabase db

= dbHelper.getWritableDatabase(); String sql = "select * from userData where

name=? and password=?"; Cursor cursor = db.rawQuery(sql, new String[]

{username, password});if (cursor.moveToFirst()) { cursor.close(); return true; }

return false; } <>