Android简易实战教程--第七话《在内存中存储用户名和密码》

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity"
android:orientation="vertical"
>

<EditText
android:id="@+id/et_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入用户名"
/>
<EditText
android:id="@+id/et_pass"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textPassword"
android:hint="请输入密码"
/>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<CheckBox
android:id="@+id/cb"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="记住用户名和密码"
android:layout_centerVertical="true"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="right"
android:text="登录"
android:layout_alignParentRight="true"
android:onClick="login"
/>
</RelativeLayout>
</LinearLayout>

package com.itydl.rwinrom;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.InputStreamReader;

import org.apache.http.entity.InputStreamEntity;

import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

private EditText et_name;
private EditText et_pass;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

et_name = (EditText) findViewById(R.id.et_name);
et_pass = (EditText) findViewById(R.id.et_pass);

readAccount();//在onCreate中读取原因是，活动一创建就读取用户名和密码进行回显。

}

public void readAccount(){
File file = new File("data/data/com.itydl.rwinrom/info.txt");
if(file.exists()){
try {
// FileInputStream fis = new FileInputStream(file);
// //把字节流转换成字符流
// BufferedReader br = new BufferedReader(new
// InputStreamReader(fis));

BufferedReader br = new BufferedReader(new FileReader(file));
//读取txt文件里的用户名和密码
String text = br.readLine();
String[] s = text.split("##");//正则表达

et_name.setText(s[0]);//ctrl+1提取全局变量
et_pass.setText(s[1]);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

public void login(View v){

String name = et_name.getText().toString();
String pass = et_pass.getText().toString();

CheckBox cb = (CheckBox) findViewById(R.id.cb);
//判断选框是否被勾选
if(cb.isChecked()){
//data/data/com.itheima.rwinrom:这就是内部存储空间的路径
File file = new File("data/data/com.itydl.rwinrom/info.txt");//这个路径是安卓特有的文件夹
FileOutputStream fos;
try {
fos = new FileOutputStream(file);
//勾选了复选框，会把用户名密码存入内部存储位置
fos.write((name + "##" + pass).getBytes());
fos.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

//创建并显示吐司对话框
Toast.makeText(this, "登录成功", 0).show();
}

}