运行效果:
登录成功后,下次登录账号和密码都会自动记录,相当于保存在本地了,app关掉仍然存着。
文件目录:
LoginActivity:
package com.example.broadcastbestpractice;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;
public class LoginActivity extends AppCompatActivity {
private SharedPreferences pref;
private SharedPreferences.Editor editor;
private EditText accountEdit;
private EditText passwordEdit;
private Button login;
private CheckBox rememberPass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
pref=getSharedPreferences("data",MODE_PRIVATE);
accountEdit=(EditText)findViewById(R.id.account);
passwordEdit=(EditText)findViewById(R.id.password);
rememberPass=(CheckBox)findViewById(R.id.remember_pass);
login=(Button)findViewById(R.id.login);
boolean isRemember=pref.getBoolean("remember_password",false);
if(isRemember){
String account=pref.getString("account","");
String password=pref.getString("password","");
accountEdit.setText(account);
passwordEdit.setText(password);
rememberPass.setChecked(true);
}
login.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
String account=accountEdit.getText().toString();
String password=passwordEdit.getText().toString();
if(account.equals("admin")&&password.equals("123456")){
editor=pref.edit();
if(rememberPass.isChecked()){
editor.putBoolean("remember_password",true);
editor.putString("account",account);
editor.putString("password",password);
}else{
editor.clear();
}
editor.apply();
Intent intent=new Intent(LoginActivity.this,MainActivity.class);
startActivity(intent);
finish();
}else{
Toast.makeText(LoginActivity.this,"account or password is invalid",Toast.LENGTH_SHORT).show();
}
}
});
}
}
MainActivity.java:
package com.example.broadcastbestpractice;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
activity_login.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="60dp">
<TextView
android:layout_width="90dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:textSize="18sp"
android:text="Account:"/>
<EditText
android:id="@+id/account"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_gravity="center_vertical"/>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="60dp">
<TextView
android:layout_width="90dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:textSize="18sp"
android:text="Password:"/>
<EditText
android:id="@+id/password"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_gravity="center_vertical"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<CheckBox
android:id="@+id/remember_pass"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18sp"
android:text="Remember password"/>
</LinearLayout>
<Button
android:id="@+id/login"
android:layout_width="match_parent"
android:layout_height="60dp"
android:text="Login"/>
</LinearLayout>
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
注意LoginActivity中的
pref=getSharedPreferences(“data”,MODE_PRIVATE);
这句话在书上是
pref=PreferenceManager.getDefaultSharedPreferences(this);
但是是被deprecated(强烈反对)的,应该是在API29中被遗弃的(虽然划了线,但是也能运行,估计只是警告吧)。
保险起见用了上一节中的初始化方法。
运行起来正常。