android自动登录

绪论
首先记住密码功能要用到SharedPreferences类，这个类可以实现简单的存储，主要用于保存窗口状态
结果图如下：
代码


Welcome.java
package com.gxs.login;

import com.example.login.R;

import com.gxs.listview.*;

import android.os.Bundle;

import android.preference.Preference;

import android.app.Activity;

import android.app.SearchManager.OnCancelListener;

import android.content.Context;

import android.content.Intent;

import android.content.SharedPreferences;

import android.content.SharedPreferences.Editor;

import android.util.Log;

import android.view.Menu;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.CheckBox;

import android.widget.EditText;

import android.widget.Toast;
public class Welcome extends Activity implements OnClickListener{

private EditText uname = null;

private EditText upswd = null;

private CheckBox checkbox = null;

private Button login = null;

SharedPreferences sp = null;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.layout_main);

sp = this.getSharedPreferences("userinfo", Context.MODE_PRIVATE);

init();

}

public void init()

{

uname = (EditText) findViewById(R.id.user_input);

upswd = (EditText) findViewById(R.id.pass_input);

checkbox = (CheckBox) findViewById(R.id.checkBoxLogin);

login = (Button) findViewById(R.id.new_user);

if (sp.getBoolean("auto", false))

{

uname.setText(sp.getString("uname", null));

upswd.setText(sp.getString("upswd", null));

checkbox.setChecked(true);

}

login.setOnClickListener(this);

}
@Override

public void onClick(View v) {

if (v == login){

String name = uname.getText().toString();

String pswd = upswd.getText().toString();

if(name.trim().equals("")){

Toast.makeText(this, "请您输入用户名！", Toast.LENGTH_SHORT).show();

return;

}

if(pswd.trim().equals("")){

Toast.makeText(this, "请您输入密码！", Toast.LENGTH_SHORT).show();

return;

}

boolean autoLogin = checkbox.isChecked();

if (autoLogin)

{

Editor editor = sp.edit();

editor.putString("uname", name);

editor.putString("upswd", pswd);

editor.putBoolean("auto", true);

editor.commit();

}

else

{

Editor editor = sp.edit();

editor.putString("uname", null);

editor.putString("upswd", null);

editor.putBoolean("auto", false);

editor.commit();

}

//Intent跳转

Intent intent = new Intent(Welcome.this,Content.class);

startActivity(intent);

finish();

}

}

}
Content.java
package com.gxs.listview;

import java.util.List;
import com.example.login.R;

import com.gxs.*;

import android.app.Activity;

import android.os.Bundle;

import android.widget.ArrayAdapter;

import android.widget.ListView;

public class Content extends Activity{

private ListView listview_fruits;

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

setContentView(R.layout.content);

}

}
layout_main.xml
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:background="#ADD8E6">
<RelativeLayout

android:id="@+id/login_div"

android:layout_width="fill_parent"

android:layout_height="221dp"

android:layout_margin="15dip"

android:background="@drawable/btn_bg"

android:padding="15dip" >
<TextView

android:id="@+id/login_user_input"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentTop="true"

android:layout_margin="5dp"

android:text="@string/user"

android:textSize="16dp"

android:typeface="sans" />
<EditText

android:id="@+id/user_input"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_below="@id/login_user_input"

android:background="@android:drawable/editbox_background"

android:inputType="text"

android:singleLine="true" />
<TextView

android:id="@+id/login_pass_input"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_below="@id/user_input"

android:layout_margin="5dp"

android:text="@string/pass"

android:textSize="16dp"

android:typeface="sans" />
<EditText

android:id="@+id/pass_input"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_below="@id/login_pass_input"

android:background="@android:drawable/editbox_background"

android:inputType="textPassword"

android:singleLine="true" />
<CheckBox

android:id="@+id/checkBoxLogin"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignLeft="@+id/pass_input"

android:layout_alignParentBottom="true"

android:text="@string/no_user" />
<Button

android:id="@+id/new_user"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentBottom="true"

android:layout_alignRight="@+id/pass_input"

android:layout_marginRight="28dp"

android:onClick="To_Title"

android:text="@string/new_user" />
</RelativeLayout>
<LinearLayout

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical" >
<TextView

android:layout_width="402dp"

android:layout_height="51dp"

android:layout_marginLeft="50dp"

android:background="@drawable/gxs_ziti" />

<Button

android:layout_width="120dp"

android:layout_height="120dp"

android:onClick="To_fruist"

android:background="@drawable/gxs2"

android:layout_marginLeft="80dp"

/>

</LinearLayout>

</LinearLayout>
content.xml
<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=".Welcome"

>
<TextView

android:id="@+id/textView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="内容"

android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>