SharedPrefences

一.存储方式

SharedPreferences 中存储的数据是以键值对的形式保存在XML文件中。

二.获取实例对象的方法

1.通过context.getSharedPreferences(Stringname,int mode)获取

2.Activity中的getPreferences()方法

3.PrefencesManager类中的getDefauHSharedPerferences()获取

三.实例---登录

1.Login_top

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="wrap_content">    <TextView        android:layout_width="match_parent"        android:layout_height="230dp"        android:alpha="0.8"        android:background="@drawable/shape" />    <LinearLayout        android:id="@+id/input"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginTop="20dp"        android:orientation="vertical">        <EditText            android:id="@+id/username"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_marginLeft="20dp"            android:layout_marginRight="20dp"            android:drawableLeft="@drawable/icon_user"            android:hint="Please input your UserName"            android:textSize="15sp" />        <EditText            android:id="@+id/password"            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:layout_marginLeft="20dp"            android:layout_marginRight="20dp"            android:layout_marginTop="5dp"            android:drawableLeft="@drawable/icon_pass"            android:hint="Please input your password"            android:inputType="textPassword"            android:textSize="15sp" />    </LinearLayout>    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@+id/input"        android:layout_marginTop="20dp"        android:gravity="center"        android:orientation="horizontal">        <CheckBox            android:id="@+id/checkBox"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="记住密码"            android:paddingRight="50dp"            />        <Button            android:id="@+id/bt_login"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:background="@drawable/btn_selector"            android:text="Login" />    </LinearLayout></RelativeLayout>
2.info.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent"    >    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Welcome"        android:textSize="50dp"        android:layout_centerInParent="true"        /></RelativeLayout>
3.activity_main
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main"    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="com.example.bz0209.login.MainActivity"    android:background="@drawable/bg1"    >    <TextView        android:onClick="text"        android:textSize="15sp"        android:layout_marginTop="10dp"        android:layout_below="@+id/include"        android:layout_alignParentRight="true"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Forget your Password?"        />    <ImageView        android:layout_alignParentRight="true"        android:layout_alignParentBottom="true"        android:layout_width="200dp"        android:layout_height="200dp"        android:background="@drawable/deer"/>    <include        android:id="@+id/include"        layout="@layout/login_top"         /></RelativeLayout>
四.MainActivity

package com.example.bz0209.login;import android.content.Context;import android.content.Intent;import android.content.SharedPreferences;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.CheckBox;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends AppCompatActivity implements View.OnClickListener{    private Button login=null;    private EditText uName=null;    private EditText uPsw=null;    private CheckBox checkBoxBtn=null;    SharedPreferences sp=null;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        sp=this.getSharedPreferences("userInfo", Context.MODE_PRIVATE);        init();    }    private void init() {        uName=(EditText) findViewById(R.id.username);        uPsw=(EditText) findViewById(R.id.password);        checkBoxBtn=(CheckBox) findViewById(R.id.checkBox);        login=(Button) findViewById(R.id.bt_login);        if (sp.getBoolean("checkboxBoolean",false)){            uName.setText(sp.getString("uName",null));            uPsw.setText(sp.getString("uPsw",null));            checkBoxBtn.setChecked(true);        }        login.setOnClickListener(this);    }    public void onClick(View view){        if (view==login){            String name=uName.getText().toString();            String psw=uPsw.getText().toString();            if (name.trim().equals("")){                Toast.makeText(this,"请输入用户名！",Toast.LENGTH_SHORT).show();                return;            }            if (psw.trim().equals("")){                Toast.makeText(this,"请输入密码！",Toast.LENGTH_SHORT).show();                return;            }            boolean CheckBoxLogin=checkBoxBtn.isChecked();            if (CheckBoxLogin){                SharedPreferences.Editor editor=sp.edit();                editor.putString("uName",name);                editor.putString("uPsw",psw);                editor.putBoolean("checkboxBoolean",true);                editor.commit();            }else {                SharedPreferences.Editor editor=sp.edit();                editor.putString("uName",null);                editor.putString("uPsw",null);                editor.putBoolean("checkboxBoolean",false);                editor.commit();            }            Intent intent=new Intent(MainActivity.this,info.class);            startActivity(intent);            finish();        }    }}
五.展示