Android之模仿QQ保存账号密码

先写个布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

然后创建一个FileSaveQQ的类，用来实现QQ的账号密码保存

package com.example.mrlee.login;import android.content.Context;import java.io.FileInputStream;import java.io.FileOutputStream;import java.util.HashMap;import java.util.Map;public class FileSaveQQ {    //把账号密码保存在data.txt文件中    public static boolean saveUserInfo(Context context,String number,String password){        try{            FileOutputStream fos = context.openFileOutput("data.txt",Context.MODE_PRIVATE);            fos.write((number + ":" + password).getBytes());            fos.close();            return true;        }catch (Exception e){            e.printStackTrace();            return false;        }    }    //从data.txt中去获取刚刚保存的账号密码    public static Map getUserInfo(Context context) {        String content = "";        try {            FileInputStream fis = context.openFileInput("data.txt");            byte[] buffer = new byte[fis.available()];            fis.read(buffer);//读取            content = new String(buffer);            Map userMap = new HashMap();            String[] infos = content.split(":");            userMap.put("number",infos[0]);            userMap.put("password",infos[1]);            fis.close();            return userMap;        }catch (Exception e){            e.printStackTrace();            return null;        }    }}

saveUserInfo（）方法呢是将数据保存在data.txt文件中，而getUserInfo()方法则是将数据从data.txt中读取出来
接下来就编写主方法MainActivity.java

package com.example.mrlee.login;        import android.content.Intent;        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 etNumber;    private EditText etPassword;    private Button btnLogin;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button button1 = (Button) findViewById(R.id.btn_login);        initView();        Map userInfo = FileSaveQQ.getUserInfo(this);        if (userInfo != null){            etNumber.setText(userInfo.get("number"));            etPassword.setText(userInfo.get("password"));        }    }    private void initView() {        etNumber = (EditText) findViewById(R.id.et_number);        etPassword = (EditText) findViewById(R.id.et_password);        btnLogin = (Button) findViewById(R.id.btn_login);        btnLogin.setOnClickListener(this);    }    @Override    public void onClick (View v){        //单击事件，获取账号密码        String number = etNumber.getText().toString().trim();        String password = etPassword.getText().toString();        //检查账号密码是否正确        if (TextUtils.isEmpty(number)){            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;        }        //否则登录成功        Toast.makeText(this,"登录成功",Toast.LENGTH_SHORT).show();        //保存信息        boolean isSaveSuccess = FileSaveQQ.saveUserInfo(this,number,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();        }    }}

initView（）是初始化控件,单击时调用FileSaveQQ类中的saveUserInfo（）方法进行数据的保存
运行成功后，可以通过单击DDMS视图右上方的导出图标按钮将文件导出，就可以看淡刚刚保存的数据啦

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