Android简单登陆页面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.loginUI.MainActivity"
    tools:ignore="MergeRootFrame" 
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv_plInputName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/plInputName" />

    <EditText
        android:id="@+id/et_userName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPersonName" >
        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/tv_plInputPassword"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/plInputPassword" />

    <EditText
        android:id="@+id/et_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:inputType="textPassword"/>
    
    <RelativeLayout android:layout_width="fill_parent"
        android:layout_height="wrap_content" >
       <CheckBox
        android:checked="true"
        android:id="@+id/cb_rmPassword"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/rmPassword" />

       <Button
           android:onClick="login"
           android:id="@+id/btn_login"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_alignParentRight="true"
           android:layout_alignParentTop="true"
           android:layout_marginRight="35dp"
           android:text="@string/login" />
        
    </RelativeLayout>

   
  
</LinearLayout>

package com.example.loginUI;

import java.util.Map;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.Toast;

import com.example.service.LoginService;

public class MainActivity extends ActionBarActivity {
    
    //日志记录Tag
    private String TAG = "MainActivity";
    
    /** 用户名 */
    private EditText etUserName;
    
    /** 密码 */
    private EditText etPassword;
    
    /** 登陆按钮 */
    private Button btnLogin;
    
    /** 记住密码按钮 */
    private CheckBox cbx;
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
         
        //获得控件
        etUserName = (EditText)findViewById(R.id.et_userName);
        etPassword = (EditText)findViewById(R.id.et_password);
        btnLogin = (Button)findViewById(R.id.btn_login);
        cbx = (CheckBox)findViewById(R.id.cb_rmPassword);
        
        Map<String, String> result =  (new LoginService().getUserNameAndPassword(this));
        if (null != result ) {
            etUserName.setText(result.get("userName"));
            etPassword.setText(result.get("password"));
        }
    }
    
    public void login(View view) {
        //日志打印
        Log.i(TAG, "开始登陆验证");
        
        String userName = etUserName.getText().toString();
        String password = etPassword.getText().toString();
        //非空判断给出吐司提示
        if (TextUtils.equals(userName.trim(), "") || TextUtils.equals(password.trim(), "")) {
            Toast.makeText(this, "用户名/密码不能为空", Toast.LENGTH_SHORT).show();
            return ;
        }
        //是否保存密码
        if (cbx.isChecked()) {
            //new LoginService().saveUserNameAndPassword(userName, password);
            new LoginService().saveUserNameAndPassword(this, userName, password);
        }
        if("zz".equals(userName) && "11".equals(password)) {
            Toast.makeText(this, "登陆成功", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(this, "登陆失败", Toast.LENGTH_SHORT).show();
        }
        Log.i(TAG, "登陆验证完成");
        
    }

}

package com.example.service;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.util.Log;

public class LoginService {
    
    private String TAG = "loginService";
    
    /**
     * 保存用户名密码， 这样的方式不灵活， 如果我们改了工程的包名的话， 这里就变成了我们的工程往另一工程写数据了， 这是不允许的
     * @param userName
     * @param password
     * @return
     */
    public boolean saveUserNameAndPassword(String userName, String password) {
        Log.i(TAG, "开始保存用户名密码");
        
        File file = new File("/data/data/com.example.loginUI/info.txt");
        FileOutputStream outputStream;
        try {
            outputStream = new FileOutputStream(file);
            outputStream.write((userName+"#"+password).getBytes());
            outputStream.close();
        } catch (Exception e) {
            Log.e(TAG, "保存用户名密码出现异常");
            return false;
        }
        return true;
    }
    
    /**
     * 保存用户名密码， 通过上下文动态的改变文件路径
     * @param context
     * @param userName
     * @param password
     * @return
     */
    public boolean saveUserNameAndPassword(Context context, String userName, String password) {
        Log.i(TAG, "开始保存用户名密码");
        
        File file = new File(context.getFilesDir(), "info.txt"); // == File file = new File("/data/data/com.example.loginUI/files/info.txt");
        
        //File file = new File(context.getCacheDir(), "info.txt"); // /data/data/com.example.loginUI/cache/info.txt  放进缓存，不要放太大的东西
        FileOutputStream outputStream;
        try {
            outputStream = new FileOutputStream(file);
            outputStream.write((userName+"#"+password).getBytes());
            outputStream.close();
        } catch (Exception e) {
            Log.e(TAG, "保存用户名密码出现异常");
            return false;
        }
        return true;
    }
    
    public Map<String, String> getUserNameAndPassword(Context context) {
        Map<String, String> result = new HashMap<String, String>();
        File file = new File(context.getFilesDir(), "info.txt");
        FileInputStream fis;
        try {
            fis = new FileInputStream(file);
            BufferedReader br = new BufferedReader(new InputStreamReader(fis));
            String[] lists = br.readLine().split("#");
            Log.i(TAG, "要保存的用户名="+lists[0]+": 密码="+lists[1]);
            result.put("userName", lists[0]);
            result.put("password", lists[1]);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }
    

}