安卓第十一周、十二周作业

图片一 用内部存储实现文件写入和读取功能

<?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="600px"
        android:layout_height="wrap_content"
        android:textSize="18sp"/>

    <Button
        android:id="@+id/btn_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写入"
        android:onClick="click1"/>

    <TextView
        android:id="@+id/tv_1"
        android:layout_width="600px"
        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:onClick="click2"/>

</LinearLayout>

package com.example.hw1;

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);
    }
}

　　

 

 图片二 使用sharedpreference实现记住密码功能

<?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=".Main2Activity"
    android:orientation="vertical">

    <EditText
        android:id="@+id/edt_2"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="账号：" />

    <EditText
        android:id="@+id/edt_3"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:text="密码："/>

    <Button
        android:id="@+id/btn_3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录"/>

</LinearLayout>

　　

package com.example.hw1;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.SharedPreferences;
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.HashMap;
import java.util.Map;

public class Main2Activity extends AppCompatActivity implements View.OnClickListener {
    public EditText edt_2;
    public EditText edt_3;
    public Button btn_3;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        initView();
        Map<String, String> userInfo = this.get(this);
        if (userInfo != null){
            edt_2.setText(userInfo.get("account"));
            edt_3.setText(userInfo.get("password"));
        }
    }


    public static boolean save(Context context, String account, String password){
        SharedPreferences sp = context.getSharedPreferences("data",Context.MODE_PRIVATE);
        SharedPreferences.Editor edit = sp.edit();
        edit.putString("username",account);
        edit.putString("pwd",password);
        edit.commit();
        return true;
    }

    public static Map<String,String> get(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 void initView(){
        edt_2 = (EditText) findViewById(R.id.edt_2);
        edt_3 = (EditText) findViewById(R.id.edt_3);
        btn_3 = (Button) findViewById(R.id.btn_3);
        btn_3.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn_3:
                String account = edt_2.getText().toString().trim();
                String password = edt_3.getText().toString();
                if (TextUtils.isEmpty(account)){
                    Toast.makeText(this,"请输入账号",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 = save(this,account,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;
        }
    }
}