Android--模拟登陆用户名密码，使用File或openFileOutput保存文件

一、File:xml布局文件

<RelativeLayout 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" >    <TextView        android:id="@+id/textView1"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignParentTop="true"        android:text="请输入用户名" />    <EditText        android:id="@+id/et_username"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView1"        android:layout_below="@+id/textView1"        android:ems="10"/>    <TextView        android:id="@+id/textView2"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/et_username"        android:layout_below="@+id/et_username"        android:layout_marginTop="20dp"        android:text="请输入用户密码" />    <EditText        android:id="@+id/ed_password"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignLeft="@+id/textView2"        android:layout_below="@+id/textView2"        android:ems="10"        android:inputType="textPassword" >        <requestFocus />    </EditText>    <CheckBox        android:id="@+id/checkbox_remeber"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_alignTop="@+id/btn_login"        android:text="记住我" />    <Button        android:id="@+id/btn_login"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignRight="@+id/et_username"        android:layout_below="@+id/ed_password"        android:layout_marginTop="27dp"        android:gravity="left"        android:onClick="login"        android:text="登陆" /></RelativeLayout>

效果图：

二、

File: MainActivity.java

package com.jiangge.login;import java.util.Map;import android.app.Activity;import android.os.Bundle;import android.text.TextUtils;import android.util.Log;import android.view.View;import android.widget.CheckBox;import android.widget.EditText;import android.widget.Toast;import com.jiangge.login.service.LoginService;import com.jiangge.logindemo.R;public class MainActivity extends Activity {private static final String TAG = "MainActivity";private EditText mUsername;private EditText mPassword;private CheckBox mRemember;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mUsername = (EditText) findViewById(R.id.et_username);mPassword = (EditText) findViewById(R.id.ed_password);mRemember = (CheckBox) findViewById(R.id.checkbox_remeber);Map<String, String> map = LoginService.getSavedUserInfo(this);if (map != null) {mUsername.setText(map.get("username"));mPassword.setText(map.get("password"));}}public void login(View view) {String username = mUsername.getText().toString().trim();String password = mPassword.getText().toString().trim();if (TextUtils.isEmpty(username) || TextUtils.isEmpty(password)) {Toast.makeText(this, "用户名和密码不能为空", Toast.LENGTH_LONG).show();}if (mRemember.isChecked()) {//保存用户名和密码Log.i(TAG, "保存用户名和密码");boolean result = LoginService.saveUserInfo(this, username, password);if (result) {Toast.makeText(this, "保存用户名和密码成功", Toast.LENGTH_LONG).show();}}//登录发送到服务器，服务器验证是否正确。模拟。if ("jiangge".equals(username) && "123".equals(password)) {Toast.makeText(this, "登录成功", Toast.LENGTH_LONG).show();}}}

File:   LoginService.java

package com.jiangge.login.service;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.util.HashMap;import java.util.Map;import android.content.Context;public class LoginService {//存数据public static boolean saveUserInfo(Context context, String username, String password){try {File file = new File(context.getFilesDir(), "info.txt"); //Do not hardcode "/data/"; use Context.getFilesDir().getPath() insteadSystem.out.println("====>>>"+ context.getFilesDir());//  /data/data/com.jiangge.logindemo/filesFileOutputStream fos = new FileOutputStream(file);fos.write((username + "##" + password).getBytes());fos.close();return true;} catch (FileNotFoundException e) {e.printStackTrace();return false;} catch (IOException e) {e.printStackTrace();return false;}}//取数据public static Map<String,String> getSavedUserInfo(Context context){try {File file = new File(context.getFilesDir(), "info.txt");FileInputStream fis = new FileInputStream(file);BufferedReader br = new BufferedReader(new InputStreamReader(fis));String str = br.readLine();br.close();String [] infos = str.split("##"); //jiangge##123Map<String,String> map = new HashMap<String, String>();map.put("username", infos[0]);map.put("password", infos[1]);return map;} catch (Exception e) {e.printStackTrace();return null;}}}

注：

保存文件：

File file = new File(context.getFilesDir(), "info.txt"); //Do not hardcode "/data/"; use Context.getFilesDir().getPath() insteadSystem.out.println("====>>>"+ context.getFilesDir());//  /data/data/com.jiangge.logindemo/filesFileOutputStream fos = new FileOutputStream(file);fos.write((username + "##" + password).getBytes());fos.close();

也可以将以上的核心代码，使用Activity提供的方法 openFileOutput(String name, int mode)

FileOutputStream fos = context.openFileOutput("private.txt", Context.MODE_PRIVATE);fos.write((username + "##" + password).getBytes());fos.close();

对应的，也有读取

保存到了 /data/data/包名/files/目录下