安卓——数据篇SharedPreferences

雨点打透心脏的1/2处 2022-05-29 13:07 188阅读 0赞

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sharedPreferences是安卓提供的一个轻量级的存储类，只能存储一些简单的类型，比如String类型。

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activity\_main.xml

<?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"
        tools:context="com.example.lenovo.sharedpreferencesdemo1.MainActivity">
    
        <TextView
            android:id="@+id/text_username"
            android:layout_width="wrap_content"
            android:layout_height="40dp"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_alignParentTop="true"
            android:layout_marginLeft="14dp"
            android:layout_marginStart="14dp"
            android:layout_marginTop="12dp"
            android:textSize="25dp"
            android:text="用户名：" />
    
        <EditText
            android:id="@+id/edit_username"
            android:layout_width="250dp"
            android:layout_height="40dp"
            android:layout_alignTop="@+id/text_username"
            android:layout_toEndOf="@+id/text_username"
            android:layout_toRightOf="@+id/text_username" />
    
        <TextView
            android:id="@+id/text_password"
            android:layout_width="wrap_content"
            android:layout_height="40dp"
            android:layout_alignLeft="@+id/text_username"
            android:layout_alignStart="@+id/text_username"
            android:layout_below="@+id/text_username"
            android:layout_marginTop="15dp"
            android:layout_toLeftOf="@+id/edit_username"
            android:layout_toStartOf="@+id/edit_username"
            android:text="密   码："
            android:textSize="25dp" />
    
        <EditText
            android:id="@+id/edit_password"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignEnd="@+id/edit_username"
            android:layout_alignRight="@+id/edit_username"
            android:layout_alignTop="@+id/text_password"
            android:layout_toEndOf="@+id/text_password"
            android:layout_toRightOf="@+id/text_password" />
    
        <CheckBox
            android:id="@+id/ckSaveName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignEnd="@+id/text_password"
            android:layout_alignRight="@+id/text_password"
            android:layout_below="@+id/text_password"
            android:layout_marginTop="38dp"
            android:text="保存用户名" />
    
        <Button
            android:onClick="doClick"
            android:id="@+id/btnLogin"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignLeft="@+id/ckSaveName"
            android:layout_alignStart="@+id/ckSaveName"
            android:layout_below="@+id/ckSaveName"
            android:text="登陆" />
    
        <Button
            android:onClick="doClick"
            android:id="@+id/btnCancel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@+id/btnLogin"
            android:layout_toEndOf="@+id/btnLogin"
            android:layout_toRightOf="@+id/btnLogin"
            android:text="取消"
            />
    
    </RelativeLayout>

MainActivity.java

package com.example.lenovo.sharedpreferencesdemo1;
    
    import android.app.Activity;
    import android.content.SharedPreferences;
    import android.os.Bundle;
    import android.preference.Preference;
    import android.preference.PreferenceManager;
    import android.view.View;
    import android.widget.CheckBox;
    import android.widget.EditText;
    import android.widget.Toast;
    
    public class MainActivity extends Activity {
    
        EditText etUserName,etUserpass;
        CheckBox checkBox;
        SharedPreferences sharedPreferences;
        SharedPreferences.Editor editor;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            /*
            //小试一下
            //获取SharedPreferences对象
            //SharedPreferences pref= PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
              SharedPreferences pref=getSharedPreferences("myPref",MODE_PRIVATE);//设置权限，只有当前这个程序能够读取
            //得到编辑器对象
            SharedPreferences.Editor editor=pref.edit();
            editor.putString("name","张昊雨");
            editor.putInt("age",20);
            editor.commit();//必须记得提交，否则上面做的白做了
            System.out.println(pref.getString("name",""));
            System.out.println(pref.getInt("age",0));
            */
    
            etUserName=(EditText)findViewById(R.id.edit_username);
            etUserpass=(EditText)findViewById(R.id.edit_password);
            checkBox=(CheckBox)findViewById(R.id.ckSaveName);
            sharedPreferences=getSharedPreferences("UserInfo",MODE_PRIVATE);//设置权限，只有当前这个程序能够读取
            editor=sharedPreferences.edit();
            String name=sharedPreferences.getString("userName","");
            if(name==null){
                checkBox.setChecked(false);
            }else{
                checkBox.setChecked(true);
                etUserName.setText(name);
            }
        }
    
    
        public void doClick(View view) {
            switch(view.getId())
            {
                case R.id.btnLogin:
                    String name=etUserName.getText().toString().trim();
                    String pass=etUserpass.getText().toString().trim();
                    if("admin".equals(name)&&"123456".equals(pass))
                    if(checkBox.isChecked()){
                        editor.putString("userName",name);
                        editor.commit();
                        Toast.makeText(MainActivity.this,"登陆成功",Toast.LENGTH_SHORT).show();
                    }else{
                        editor.remove("userNmae");
                        editor.commit();
                        Toast.makeText(MainActivity.this,"登陆成功",Toast.LENGTH_SHORT).show();
                    }else{
                        Toast.makeText(MainActivity.this,"禁止登陆",Toast.LENGTH_SHORT).show();
                    }
                    break;
            }
        }
    }

[70]: /images/20220529/f6c8d0287d614a08aa26d32f1eeb43ac.png
[70 1]: /images/20220529/558548bcf614420185537a1d5b55947b.png
[70 2]: /images/20220529/3f5431dfebec4ca999d83e05eb0c73fd.png
[70 3]: /images/20220529/0d243ed4c2ff45289e7f64e23fb3343d.png