这是谷歌官方给我们提供的一个兼容低版本号安卓设备的软件包,里面包囊了仅仅有在安卓3.0以上能够使用的api。而viewpager就是当中之中的一个利用它,我们能够做非常多事情,从最简单的导航,到页面菜单等等。那怎样使用它呢,与LisstView相似,我们也须要一个适配器,他就是PagerAdapter。看一下api的图片,
ViewPager的功能就是能够使视图滑动,就像Lanucher左右滑动那样。分三个步骤来使用它:
1.在住布局文件中加入
<android.support.v4.view.ViewPager 这个组件,注意这个组件是用来显示左右滑动的界面的,假设不载入xml布局文件,他是不会显示内容的。
android:id="@+id/viewpager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" >
2.载入要显示的页卡,
LayoutInflater lf = getLayoutInflater().from(this);
view1 = lf.inflate(R.layout.layout1, null);
view2 = lf.inflate(R.layout.layout2, null);
view3 = lf.inflate(R.layout.layout3, null); viewList = new ArrayList<View>();// 将要分页显示的View装入数组中
viewList.add(view1);
viewList.add(view2);
viewList.add(view3);
3.在Activity里实例化ViewPager组件,并设置它的Adapter(就是PagerAdapter,方法与ListView一样的),在这里一般须要重写PagerAdapter。
PagerAdapter pagerAdapter = new PagerAdapter() { @Override
public boolean isViewFromObject(View arg0, Object arg1) { return arg0 == arg1;
} @Override
public int getCount() { return viewList.size();
} @Override
public void destroyItem(ViewGroup container, int position,
Object object) {
container.removeView(viewList.get(position)); } @Override
public int getItemPosition(Object object) { return super.getItemPosition(object);
} @Override
public CharSequence getPageTitle(int position) { return titleList.get(position);
} @Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(viewList.get(position));
weibo_button=(Button) findViewById(R.id.button1);
weibo_button.setOnClickListener(new OnClickListener() { public void onClick(View v) {
intent=new Intent(ViewPagerDemo.this,WeiBoActivity.class);
startActivity(intent);
}
});
return viewList.get(position);
} };
viewPager.setAdapter(pagerAdapter);
这是重写PagerAdapter的一个方法,我们还能够这样做:
public class MyViewPagerAdapter extends PagerAdapter{
private List<View> mListViews; public MyViewPagerAdapter(List<View> mListViews) {
this.mListViews = mListViews;//构造方法,參数是我们的页卡,这样比較方便。
} @Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(mListViews.get(position));//删除页卡
} @Override
public Object instantiateItem(ViewGroup container, int position) { //这种方法用来实例化页卡
container.addView(mListViews.get(position), 0);//加入页卡
return mListViews.get(position);
} @Override
public int getCount() {
return mListViews.size();//返回页卡的数量
} @Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0==arg1;//官方提示这样写
}
}
大同小异,有一定非常重要,就是我们须要重写哪些方法。从上面的图片能够看到,ViewPager的适配器是PagerAdapter,它是基类提供适配器来填充页面ViewPager内部,你非常可能想要使用一个更详细的实现,如FragmentPagerAdapter或FragmentStatePagerAdapter。在这里须要说明一下,事实上ViewPager应该和Fragment一起使用,至少谷歌官方是这么想的,可是在3.0之下,我们没有必要这么做。以下要注意,当你实现一个PagerAdapter,你必须至少覆盖以下方法:
instantiateItem(ViewGroup, int)
destroyItem(ViewGroup, int, Object)
getCount()
isViewFromObject(View, Object)
从上面的样例中能够看到,我们最少也是实现了上面四个方法,当然假设你想让程序更健壮或是功能更全面,你能够重写其它的方法。以下看一下第一个完整的演示样例代码:
package com.example.viewpagerdemo; import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.PagerTabStrip;
import android.support.v4.view.PagerTitleStrip;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button; public class ViewPagerDemo extends Activity { private View view1, view2, view3;//须要滑动的页卡
private ViewPager viewPager;//viewpager
private PagerTitleStrip pagerTitleStrip;//viewpager的标题
private PagerTabStrip pagerTabStrip;//一个viewpager的指示器,效果就是一个横的粗的下划线
private List<View> viewList;//把须要滑动的页卡加入到这个list中
private List<String> titleList;//viewpager的标题
private Button weibo_button;//button对象,一会用来进入第二个Viewpager的演示样例
private Intent intent;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_pager_demo);
initView();
}
/*在这里须要说明一下,在上面的图片中我们看到了,PagerTabStrip,PagerTitleStrip,他们事实上是viewpager的一个指示器,前者效果就是一个横的粗的下划线,后者用来显示各个页卡的标题,当然而这也能够共存。在使用他们的时候须要注意,看以下的布局文件,要在android.support.v4.view.ViewPager里面加入
android.support.v4.view.PagerTabStrip以及android.support.v4.view.PagerTitleStrip。 private void initView() {
viewPager = (ViewPager) findViewById(R.id.viewpager);
//pagerTitleStrip = (PagerTitleStrip) findViewById(R.id.pagertitle);
pagerTabStrip=(PagerTabStrip) findViewById(R.id.pagertab);
pagerTabStrip.setTabIndicatorColor(getResources().getColor(R.color.gold));
pagerTabStrip.setDrawFullUnderline(false);
pagerTabStrip.setBackgroundColor(getResources().getColor(R.color.azure));
pagerTabStrip.setTextSpacing(50);
/*
weibo_button=(Button) findViewById(R.id.button1);
weibo_button.setOnClickListener(new OnClickListener() { public void onClick(View v) {
intent=new Intent(ViewPagerDemo.this,WeiBoActivity.class);
startActivity(intent);
}
});
*/ view1 = findViewById(R.layout.layout1);
view2 = findViewById(R.layout.layout2);
view3 = findViewById(R.layout.layout3); LayoutInflater lf = getLayoutInflater().from(this);
view1 = lf.inflate(R.layout.layout1, null);
view2 = lf.inflate(R.layout.layout2, null);
view3 = lf.inflate(R.layout.layout3, null); viewList = new ArrayList<View>();// 将要分页显示的View装入数组中
viewList.add(view1);
viewList.add(view2);
viewList.add(view3); titleList = new ArrayList<String>();// 每一个页面的Title数据
titleList.add("wp");
titleList.add("jy");
titleList.add("jh"); PagerAdapter pagerAdapter = new PagerAdapter() { @Override
public boolean isViewFromObject(View arg0, Object arg1) { return arg0 == arg1;
} @Override
public int getCount() { return viewList.size();
} @Override
public void destroyItem(ViewGroup container, int position,
Object object) {
container.removeView(viewList.get(position)); } @Override
public int getItemPosition(Object object) { return super.getItemPosition(object);
} @Override
public CharSequence getPageTitle(int position) { return titleList.get(position);//直接用适配器来完毕标题的显示,所以从上面能够看到,我们没有使用PagerTitleStrip。当然你能够使用。 } @Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(viewList.get(position));
weibo_button=(Button) findViewById(R.id.button1);//这个须要注意,我们是在重写adapter里面实例化button组件的,假设你在onCreate()方法里这样做会报错的。
weibo_button.setOnClickListener(new OnClickListener() { public void onClick(View v) {
intent=new Intent(ViewPagerDemo.this,WeiBoActivity.class);
startActivity(intent);
}
});
return viewList.get(position);
} };
viewPager.setAdapter(pagerAdapter);
} @Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_view_pager_demo, menu);
return true;
} }
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" > <android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center" > <android.support.v4.view.PagerTabStrip
android:id="@+id/pagertab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="top"/> </android.support.v4.view.ViewPager> </LinearLayout>
<!--注意事项:
1.这里ViewPager和 PagerTabStrip都要把包名写全了,不然会ClassNotFount
2.API中说:在布局xml把PagerTabStrip当做ViewPager的一个子标签来用,不能拿出来,不然还是会报错
3.在PagerTabStrip标签中能够用属性android:layout_gravity=TOP|BOTTOM来指定title的位置
4.假设要显示出PagerTabStrip某一页的title,须要在ViewPager的adapter中实现getPageTitle(int)-->
这样就完毕了一个简单的ViewPager的使用演示样例,看一下效果图:
package com.example.viewpagerdemo; import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.DisplayMetrics;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast; public class WeiBoActivity extends Activity { private ViewPager viewPager;//页卡内容
private ImageView imageView;// 动绘图片
private TextView textView1,textView2,textView3;
private List<View> views;// Tab页面列表
private int offset = 0;// 动绘图片偏移量
private int currIndex = 0;// 当前页卡编号
private int bmpW;// 动绘图片宽度
private View view1,view2,view3;//各个页卡
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.weibo);
InitImageView();
InitTextView();
InitViewPager();
} private void InitViewPager() {
viewPager=(ViewPager) findViewById(R.id.vPager);
views=new ArrayList<View>();
LayoutInflater inflater=getLayoutInflater();
view1=inflater.inflate(R.layout.lay1, null);
view2=inflater.inflate(R.layout.lay2, null);
view3=inflater.inflate(R.layout.lay3, null);
views.add(view1);
views.add(view2);
views.add(view3);
viewPager.setAdapter(new MyViewPagerAdapter(views));
viewPager.setCurrentItem(0);
viewPager.setOnPageChangeListener(new MyOnPageChangeListener());
}
/**
* 初始化头标
*/ private void InitTextView() {
textView1 = (TextView) findViewById(R.id.text1);
textView2 = (TextView) findViewById(R.id.text2);
textView3 = (TextView) findViewById(R.id.text3); textView1.setOnClickListener(new MyOnClickListener(0));
textView2.setOnClickListener(new MyOnClickListener(1));
textView3.setOnClickListener(new MyOnClickListener(2));
} /**
2 * 初始化动画,这个就是页卡滑动时,以下的横线也滑动的效果,在这里须要计算一些数据
3 */ private void InitImageView() {
imageView= (ImageView) findViewById(R.id.cursor);
bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.a).getWidth();// 获取图片宽度
DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
int screenW = dm.widthPixels;// 获取分辨率宽度
offset = (screenW / 3 - bmpW) / 2;// 计算偏移量
Matrix matrix = new Matrix();
matrix.postTranslate(offset, 0);
imageView.setImageMatrix(matrix);// 设置动画初始位置
}
/**
*
* 头标点击监听 3 */
private class MyOnClickListener implements OnClickListener{
private int index=0;
public MyOnClickListener(int i){
index=i;
}
public void onClick(View v) {
viewPager.setCurrentItem(index);
} } public class MyViewPagerAdapter extends PagerAdapter{
private List<View> mListViews; public MyViewPagerAdapter(List<View> mListViews) {
this.mListViews = mListViews;
} @Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView(mListViews.get(position));
} @Override
public Object instantiateItem(ViewGroup container, int position) {
container.addView(mListViews.get(position), 0);
return mListViews.get(position);
} @Override
public int getCount() {
return mListViews.size();
} @Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0==arg1;
}
} public class MyOnPageChangeListener implements OnPageChangeListener{ int one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量
int two = one * 2;// 页卡1 -> 页卡3 偏移量
public void onPageScrollStateChanged(int arg0) { } public void onPageScrolled(int arg0, float arg1, int arg2) { } public void onPageSelected(int arg0) {
/*两种方法,这个是一种,以下另一种,显然这个比較麻烦
Animation animation = null;
switch (arg0) {
case 0:
if (currIndex == 1) {
animation = new TranslateAnimation(one, 0, 0, 0);
} else if (currIndex == 2) {
animation = new TranslateAnimation(two, 0, 0, 0);
}
break;
case 1:
if (currIndex == 0) {
animation = new TranslateAnimation(offset, one, 0, 0);
} else if (currIndex == 2) {
animation = new TranslateAnimation(two, one, 0, 0);
}
break;
case 2:
if (currIndex == 0) {
animation = new TranslateAnimation(offset, two, 0, 0);
} else if (currIndex == 1) {
animation = new TranslateAnimation(one, two, 0, 0);
}
break; }
*/
Animation animation = new TranslateAnimation(one*currIndex, one*arg0, 0, 0);//显然这个比較简洁,仅仅有一行代码。
currIndex = arg0;
animation.setFillAfter(true);// True:图片停在动画结束位置
animation.setDuration(300);
imageView.startAnimation(animation);
Toast.makeText(WeiBoActivity.this, "您选择了"+ viewPager.getCurrentItem()+"页卡", Toast.LENGTH_SHORT).show();
} }
}
它的布局文件:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" > <LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="40.0dip"
android:background="#FFFFFF" > <TextView
android:id="@+id/text1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1.0"
android:gravity="center"
android:text=" @我"
android:textColor="#000000"
android:textSize="20.0dip" /> <TextView
android:id="@+id/text2"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1.0"
android:gravity="center"
android:text="评论"
android:textColor="#000000"
android:textSize="20.0dip" /> <TextView
android:id="@+id/text3"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1.0"
android:gravity="center"
android:text="私信"
android:textColor="#000000"
android:textSize="20.0dip" />
</LinearLayout> <ImageView
android:id="@+id/cursor"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scaleType="matrix"
android:src="@drawable/a" /> <android.support.v4.view.ViewPager
android:id="@+id/vPager"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_gravity="center"
android:layout_weight="1.0"
android:background="#000000"
android:flipInterval="30"
android:persistentDrawingCache="animation" />
</LinearLayout>
效果例如以下:
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message; /** */
public class SplashActivity extends Activity {
boolean isFirstIn = false; private static final int GO_HOME = 1000;
private static final int GO_GUIDE = 1001;
// 延迟3秒
private static final long SPLASH_DELAY_MILLIS = 3000; private static final String SHAREDPREFERENCES_NAME = "first_pref"; /**
* Handler:跳转到不同界面
*/
private Handler mHandler = new Handler() { @Override
public void handleMessage(Message msg) {
switch (msg.what) {
case GO_HOME:
goHome();
break;
case GO_GUIDE:
goGuide();
break;
}
super.handleMessage(msg);
}
}; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash); init();
} private void init() {
// 读取SharedPreferences中须要的数据
// 使用SharedPreferences来记录程序的使用次数
SharedPreferences preferences = getSharedPreferences(
SHAREDPREFERENCES_NAME, MODE_PRIVATE); // 取得对应的值,假设没有该值,说明还未写入,用true作为默认值
isFirstIn = preferences.getBoolean("isFirstIn", true); // 推断程序与第几次执行,假设是第一次执行则跳转到引导界面,否则跳转到主界面
if (!isFirstIn) {
// 使用Handler的postDelayed方法,3秒后执行跳转到MainActivity
mHandler.sendEmptyMessageDelayed(GO_HOME, SPLASH_DELAY_MILLIS);
} else {
mHandler.sendEmptyMessageDelayed(GO_GUIDE, SPLASH_DELAY_MILLIS);
} } private void goHome() {
Intent intent = new Intent(SplashActivity.this, MainActivity.class);
SplashActivity.this.startActivity(intent);
SplashActivity.this.finish();
} private void goGuide() {
Intent intent = new Intent(SplashActivity.this, GuideActivity.class);
SplashActivity.this.startActivity(intent);
SplashActivity.this.finish();
}
}
GuideActivity.java引导界面:
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import cn.eoe.leigo.splash.adapter.ViewPagerAdapter; /**
* *
*/
public class GuideActivity extends Activity implements OnPageChangeListener { private ViewPager vp;
private ViewPagerAdapter vpAdapter;
private List<View> views; // 底部小点图片
private ImageView[] dots; // 记录当前选中位置
private int currentIndex; @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.guide); // 初始化页面
initViews(); // 初始化底部小点
initDots();
} private void initViews() {
LayoutInflater inflater = LayoutInflater.from(this); views = new ArrayList<View>();
// 初始化引导图片列表
views.add(inflater.inflate(R.layout.what_new_one, null));
views.add(inflater.inflate(R.layout.what_new_two, null));
views.add(inflater.inflate(R.layout.what_new_three, null));
views.add(inflater.inflate(R.layout.what_new_four, null)); // 初始化Adapter
vpAdapter = new ViewPagerAdapter(views, this); vp = (ViewPager) findViewById(R.id.viewpager);
vp.setAdapter(vpAdapter);
// 绑定回调
vp.setOnPageChangeListener(this);
} private void initDots() {
LinearLayout ll = (LinearLayout) findViewById(R.id.ll); dots = new ImageView[views.size()]; // 循环取得小点图片
for (int i = 0; i < views.size(); i++) {
dots[i] = (ImageView) ll.getChildAt(i);
dots[i].setEnabled(true);// 都设为灰色
} currentIndex = 0;
dots[currentIndex].setEnabled(false);// 设置为白色,即选中状态
} private void setCurrentDot(int position) {
if (position < 0 || position > views.size() - 1
|| currentIndex == position) {
return;
} dots[position].setEnabled(false);
dots[currentIndex].setEnabled(true); currentIndex = position;
} // 当滑动状态改变时调用
@Override
public void onPageScrollStateChanged(int arg0) {
} // 当当前页面被滑动时调用
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
} // 当新的页面被选中时调用
@Override
public void onPageSelected(int arg0) {
// 设置底部小点选中状态
setCurrentDot(arg0);
} }
ViewPagerAdapter.java。ViewPager的适配器:
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import cn.eoe.leigo.splash.MainActivity;
import cn.eoe.leigo.splash.R; /**
*/
public class ViewPagerAdapter extends PagerAdapter { // 界面列表
private List<View> views;
private Activity activity;
private static final String SHAREDPREFERENCES_NAME = "first_pref";
public ViewPagerAdapter(List<View> views, Activity activity) {
this.views = views;
this.activity = activity;
} // 销毁arg1位置的界面
@Override
public void destroyItem(View arg0, int arg1, Object arg2) {
((ViewPager) arg0).removeView(views.get(arg1));
} @Override
public void finishUpdate(View arg0) {
} // 获得当前界面数
@Override
public int getCount() {
if (views != null) {
return views.size();
}
return 0;
} // 初始化arg1位置的界面
@Override
public Object instantiateItem(View arg0, int arg1) {
((ViewPager) arg0).addView(views.get(arg1), 0);
if (arg1 == views.size() - 1) {
ImageView mStartWeiboImageButton = (ImageView) arg0
.findViewById(R.id.iv_start_weibo);
mStartWeiboImageButton.setOnClickListener(new OnClickListener() { @Override
public void onClick(View v) {
// 设置已经引导
setGuided();
goHome(); } });
}
return views.get(arg1);
} private void goHome() {
// 跳转
Intent intent = new Intent(activity, MainActivity.class);
activity.startActivity(intent);
activity.finish();
}
/**
*
* method desc:设置已经引导过了,下次启动不用再次引导
*/
private void setGuided() {
SharedPreferences preferences = activity.getSharedPreferences(
SHAREDPREFERENCES_NAME, Context.MODE_PRIVATE);
Editor editor = preferences.edit();
// 存入数据
editor.putBoolean("isFirstIn", false);
// 提交改动
editor.commit();
} // 推断是否由对象生成界面
@Override
public boolean isViewFromObject(View arg0, Object arg1) {
return (arg0 == arg1);
} @Override
public void restoreState(Parcelable arg0, ClassLoader arg1) {
} @Override
public Parcelable saveState() {
return null;
} @Override
public void startUpdate(View arg0) {
} }
至于MainActivity随便了。