<?xml version="1.0" encoding="utf-8"?> <LinearLayout 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" android:orientation="vertical"> <EditText android:id="@+id/edt_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="25sp"/> <Button android:id="@+id/btn_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="写入" android:textSize="25sp" android:onClick="click1"/> <TextView android:id="@+id/tv_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="24sp"/> <Button android:id="@+id/btn_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="读取" android:textSize="25sp" android:onClick="click2"/>
import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void click1(View view){ String filename = "data.txt"; EditText edt = findViewById(R.id.edt_1); String content = edt.getText().toString(); FileOutputStream fos = null; try { fos = openFileOutput(filename, MODE_PRIVATE); fos.write(content.getBytes()); }catch (Exception e){ e.printStackTrace(); }finally { try { if (fos != null){ fos.close(); } }catch (IOException e){ e.printStackTrace(); } } Toast.makeText(this,content,1).show(); } public void click2(View view){ TextView tv = findViewById(R.id.tv_1); String content = ""; FileInputStream fis = null; try { fis = openFileInput("data.txt"); byte[] buffer = new byte[fis.available()]; fis.read(buffer); content = new String(buffer); }catch (Exception e) { e.printStackTrace(); }finally { try { if (fis != null) { fis.close(); } }catch (IOException e) { e.printStackTrace(); } } tv.setText(content); } }
二
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout 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" android:background="#FCF8F9" tools:context=".MainActivity"> <TextView android:id="@+id/tv_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="账号:" android:textColor="#000000" android:textSize="30sp" android:layout_marginTop="20dp" android:layout_marginLeft="20dp" android:padding="10dp"/> <EditText android:id="@+id/et_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="请输入用户名" android:layout_toRightOf="@id/tv_1" android:layout_marginTop="30dp" android:padding="10dp" android:textSize="20sp"/> <TextView android:id="@+id/tv_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="密码:" android:textColor="#000000" android:textSize="30sp" android:layout_marginTop="15dp" android:layout_marginLeft="20dp" android:layout_below="@id/tv_1" android:padding="10dp"/> <EditText android:id="@+id/et_2" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="请输入密码" android:layout_toRightOf="@id/tv_2" android:layout_below="@id/et_1" android:layout_marginTop="30dp" android:padding="10dp" android:textSize="20sp"/> <CheckBox android:id="@+id/cb_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="记住密码" android:textColor="#000000" android:textSize="18sp" android:layout_below="@id/tv_2" android:padding="5dp" android:layout_marginTop="30dp" android:layout_marginLeft="20dp"/> <Button android:id="@+id/btn_1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="登录" android:textColor="#000000" android:textSize="25sp" android:layout_below="@id/tv_2" android:padding="5dp" android:layout_marginTop="100dp" android:layout_marginLeft="160dp" />
import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.text.TextUtils; import android.view.View; import android.widget.Button; import android.widget.CheckBox; import android.widget.CompoundButton; import android.widget.EditText; import android.widget.Toast; import java.util.Map; public class Main2Activity extends AppCompatActivity implements android.view.View.OnClickListener, CompoundButton.OnCheckedChangeListener { private EditText et_account; private EditText et_password; private Button btn_login; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main2); initView(); Map<String,String> userInfo=a.getUserInfo(this); if(userInfo!=null){ et_account.setText(userInfo.get("account")); et_password.setText(userInfo.get("password")); } } private void initView() { et_account=findViewById(R.id.et_1); et_password=findViewById(R.id.et_2); btn_login=findViewById(R.id.btn_1); btn_login.setOnClickListener(this); CheckBox cb1=findViewById(R.id.cb_1); cb1.setOnCheckedChangeListener(this); } @Override public void onClick(View view) { switch (view.getId()){ case R.id.btn_1: String account=et_account.getText().toString().trim(); String password=et_password.getText().toString(); if(TextUtils.isEmpty(account)){ Toast.makeText(this,"请输入账号",Toast.LENGTH_LONG).show(); return; } if(TextUtils.isEmpty(password)){ Toast.makeText(this,"请输入密码",Toast.LENGTH_LONG).show(); return; } Toast.makeText(this,"登录成功",Toast.LENGTH_LONG).show(); } } @Override public void onCheckedChanged(CompoundButton compoundButton, boolean b) { switch (compoundButton.getId()){ case R.id.cb_1: String account=et_account.getText().toString().trim(); String password=et_password.getText().toString(); boolean isSaveSuccess=a.saveUserInfo(this,account,password); if(isSaveSuccess&&b){ Toast.makeText(this,"保存成功",Toast.LENGTH_LONG).show(); }else { Toast.makeText(this,"保存失败",Toast.LENGTH_LONG).show(); et_account.setText(null); et_password.setText(null); } break; } } }
import android.content.Context; import android.content.SharedPreferences; import java.util.HashMap; import java.util.Map; public class a { public static Map<String, String> getUserInfo(Context context) { SharedPreferences sp = context.getSharedPreferences("data", context.MODE_PRIVATE); String account = sp.getString("Username", null); String password = sp.getString("pwd", null); Map<String,String>userMap=new HashMap<String, String>(); userMap.put("account", account); userMap.put("password", password); return userMap; } public static boolean saveUserInfo(Context context, String account, String password) { SharedPreferences sp=context.getSharedPreferences("data",context.MODE_PRIVATE); SharedPreferences.Editor editor=sp.edit(); editor.putString("Username",account); editor.putString("pwd",password); editor.commit(); return true; } }