XML
<?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="com.example.hp.MainActivity" android:orientation="vertical"> <EditText android:id="@+id/et1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:hint="输入你想写入的内容"/> <Button android:id="@+id/bt1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="写入"/> <EditText android:id="@+id/et2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:hint="显示读取的内容" /> <Button android:id="@+id/bt2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="读取"/> </LinearLayout>
逻辑代码
package com.example.hp; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.text.Editable; import android.view.View; import android.widget.EditText; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.FilterOutputStream; import java.io.IOException; import java.util.logging.Handler; public class MainActivity extends AppCompatActivity implements View.OnClickListener { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); findViewById(R.id.bt1).setOnClickListener(this); findViewById(R.id.bt2).setOnClickListener(this); } @Override public void onClick(View view) { switch (view.getId()){ case R.id.bt1: String fileName="data.txt"; String content=((EditText)findViewById(R.id.et1)).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(); } } break; case R.id.bt2: content = ""; FileInputStream fis=null; try{ fis=openFileInput("data.txt"); byte[] buffer=new byte[fis.available()]; fis.read(buffer); content=new String(buffer); ((EditText)findViewById(R.id.et2)).setText(content); } catch (Exception e) { e.printStackTrace(); } finally { try{ if (fis != null) { fis.close(); } } catch (IOException e) { e.printStackTrace(); } } break; } } }
XML
<?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="com.example.hp.saveqq.MainActivity" android:orientation="vertical"> <ImageView android:layout_width="70dp" android:layout_height="70dp" android:layout_gravity="center" android:layout_marginTop="30dp" android:src="@drawable/head"/> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="15dp" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="账号:" android:textSize="18sp" android:textColor="@android:color/black" android:padding="10dp"/> <EditText android:id="@+id/et1" android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="18sp" android:textColor="@android:color/black" android:hint="请输入用户名"/> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="15dp" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="密码:" android:textSize="18sp" android:textColor="@android:color/black" android:padding="10dp"/> <EditText android:id="@+id/et2" android:layout_width="match_parent" android:layout_height="wrap_content" android:textSize="18sp" android:textColor="@android:color/black" android:inputType="textPassword" android:hint="请输入密码"/> </LinearLayout> <Button android:id="@+id/bt" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="#3c8dc4" android:textColor="@android:color/white" android:textSize="18sp" android:text="登录" android:layout_gravity="center" android:layout_marginTop="20dp"/> </LinearLayout>
逻辑代码
工具类:
package com.example.hp.saveqq; import android.content.Context; import android.content.SharedPreferences; import java.util.HashMap; import java.util.Map; /** * Created by HP on 2021/10/26. */ public class FileSaveQQ { public static boolean saveUserInfo(Context context,String name,String password){ SharedPreferences sp=context.getSharedPreferences("data",Context.MODE_PRIVATE); SharedPreferences.Editor editor=sp.edit(); editor.putString("name",name); editor.putString("password",password); editor.commit(); return true; } public static Map<String,String> getUserInfo(Context context){ SharedPreferences sp=context.getSharedPreferences("data",Context.MODE_PRIVATE); String name=sp.getString("name",null); String password=sp.getString("password",null); Map<String,String>userMap=new HashMap<String, String>(); userMap.put("name",name); userMap.put("password",password); return userMap; } }
界面交互
package com.example.hp.saveqq; import android.content.SharedPreferences; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.text.TextUtils; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import java.util.Map; public class MainActivity extends AppCompatActivity implements View.OnClickListener { private EditText et1; private EditText et2; private Button bt; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); Map<String,String>userInfo=FileSaveQQ.getUserInfo(this); et1.setText(userInfo.get("name")); et2.setText(userInfo.get("password")); } private void initView() { et1=(EditText)findViewById(R.id.et1); et2=(EditText)findViewById(R.id.et2); bt=(Button)findViewById(R.id.bt); bt.setOnClickListener(this); } @Override public void onClick(View view) { switch (view.getId()){ case R.id.bt: String name=et1.getText().toString(); String password=et2.getText().toString(); if(TextUtils.isEmpty(name)){ Toast.makeText(this,"请输入用户名!",Toast.LENGTH_SHORT).show(); return; } if(TextUtils.isEmpty(password)) { Toast.makeText(this, "请输入密码!", Toast.LENGTH_SHORT).show(); return; } Toast.makeText(this,"登录成功",Toast.LENGTH_SHORT).show(); boolean isSaveSuccess=FileSaveQQ.saveUserInfo(this,name,password); if (isSaveSuccess){ Toast.makeText(this, "保存成功!", Toast.LENGTH_SHORT).show(); }else { Toast.makeText(this, "保存失败!", Toast.LENGTH_SHORT).show(); } break; } } }