记住密码功能

    private EditText user_account_edit, user_pass_edit;
    private SharedPreferences pref;
    public SharedPreferences mSharedPreferences;
    private CheckBox rememberPass; 

onCreate()方法中：获取sp实例,调用 setRemember()方法,根据CheckBox 控件是否被选中进行判断，如果是选中，就从sp中取出用户名密码设置到界面上。点击登录按钮时，则调用 savedUsers()保存用户名密码到sp

       findViewById(R.id.login_btn).setOnClickListener(this);
       user_account_edit = (EditText) findViewById(R.id.user_account_edit);
       user_pass_edit = (EditText) findViewById(R.id.user_pass_edit);
       rememberPass = (CheckBox) findViewById(R.id.remember_pass);  

      mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
      setRemember();

  /**
         * 设置记住用户名和密码
         */
        private void setRemember() {
            if (isRemembered()) {
                String nameFromLog = mSharedPreferences.getString("nameFromLog","");
                String passFromLog = mSharedPreferences.getString("passFromLog","");
                user_account_edit.setText(nameFromLog);
                user_pass_edit.setText(passFromLog);
                rememberPass.setChecked(true);
            }
        }

  /**
         *  获取记住密码的状态
         */
        private boolean isRemembered() {
            return mSharedPreferences.getBoolean("isRemembered",false);
        }

        /**
         *  保存用户数据到Share
         */
        private void savedUsers() {
            SharedPreferences.Editor editor = mSharedPreferences.edit();
            editor.putString("nameFromLog",user_account_edit.getText().toString().trim());
            editor.putString("passFromLog",user_pass_edit.getText().toString().trim());  
            if (rememberPass.isChecked()) {
                editor.putBoolean("isRemembered", true);
            }else {
                editor.putBoolean("isRemembered", false);
            }
            editor.commit();
        }