Android ViewPager使用详解
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这是谷歌官方给我们提供的一个兼容低版本安卓设备的软件包,里面包囊了只有在安卓3.0以上可以使用的api。而viewpager就是其中之一利用它,我们可以做很多事情,从最简单的导航,到页面菜单等等。那如何使用它呢,与LisstView类似,我们也需要一个适配器,他就是PagerAdapter。看一下api的图片,
ViewPager的功能就是可以使视图滑动,就像Lanucher左右滑动那样。分三个步骤来使用它:
1.在住布局文件里加入
<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,如果不加载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.加载要显示的页卡,
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),在这里一般需要重写PagerAdapter。
PagerAdapter pagerAdapter = new PagerAdapter() {@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic int getCount() {return viewList.size();}@Overridepublic void destroyItem(ViewGroup container, int position,Object object) {container.removeView(viewList.get(position));}@Overridepublic int getItemPosition(Object object) {return super.getItemPosition(object);}@Overridepublic CharSequence getPageTitle(int position) {return titleList.get(position);}@Overridepublic 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,我们还可以这样做:
public class MyViewPagerAdapter extends PagerAdapter{private List<View> mListViews;public MyViewPagerAdapter(List<View> mListViews) {this.mListViews = mListViews;//构造方法,参数是我们的页卡,这样比较方便。}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {container.removeView(mListViews.get(position));//删除页卡}@Overridepublic Object instantiateItem(ViewGroup container, int position) {//这个方法用来实例化页卡 container.addView(mListViews.get(position), 0);//添加页卡 return mListViews.get(position);}@Overridepublic int getCount() {return mListViews.size();//返回页卡的数量}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0==arg1;//官方提示这样写}}
大同小异,有一定很重要,就是我们需要重写哪些方法。从上面的图片可以看到,ViewPager的适配器是PagerAdapter,它是基类提供适配器来填充页面ViewPager内部,你很可能想要使用一个更具体的实现,如FragmentPagerAdapter或FragmentStatePagerAdapter。在这里需要说明一下,其实ViewPager应该和Fragment一起使用,至少谷歌官方是这么想的,但是在3.0之下,我们没有必要这么做。下面要注意,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)
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;//需要滑动的页卡private ViewPager viewPager;//viewpagerprivate 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;//把需要滑动的页卡添加到这个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的示例 private Intent intent;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_view_pager_demo);initView();} /*在这里需要说明一下,在上面的图片中我们看到了,PagerTabStrip,PagerTitleStrip,他们其实是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,当然而这也可以共存。在使用他们的时候需要注意,看下面的布局文件,要在android.support.v4.view.ViewPager里面添加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>();// 每个页面的Title数据titleList.add("wp");titleList.add("jy");titleList.add("jh");PagerAdapter pagerAdapter = new PagerAdapter() {@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return arg0 == arg1;}@Overridepublic int getCount() {return viewList.size();}@Overridepublic void destroyItem(ViewGroup container, int position,Object object) {container.removeView(viewList.get(position));}@Overridepublic int getItemPosition(Object object) {return super.getItemPosition(object);}@Overridepublic CharSequence getPageTitle(int position) {return titleList.get(position);//直接用适配器来完成标题的显示,所以从上面可以看到,我们没有使用PagerTitleStrip。当然你可以使用。}@Overridepublic Object instantiateItem(ViewGroup container, int position) {container.addView(viewList.get(position));weibo_button=(Button) findViewById(R.id.button1);//这个需要注意,我们是在重写adapter里面实例化button组件的,如果你在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);}@Overridepublic 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标签中可以用属性android:layout_gravity=TOP|BOTTOM来指定title的位置 4.如果要显示出PagerTabStrip某一页的title,需要在ViewPager的adapter中实现getPageTitle(int)-->这样就完成了一个简单的ViewPager的使用示例,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;// 动画图片private TextView textView1,textView2,textView3;private List<View> views;// Tab页面列表private int offset = 0;// 动画图片偏移量private int currIndex = 0;// 当前页卡编号private int bmpW;// 动画图片宽度private View view1,view2,view3;//各个页卡@Overrideprotected 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,下面的横线也滑动的效果,在这里需要计算一些数据 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;}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {container.removeView(mListViews.get(position));}@Overridepublic Object instantiateItem(ViewGroup container, int position) { container.addView(mListViews.get(position), 0); return mListViews.get(position);}@Overridepublic int getCount() {return mListViews.size();}@Overridepublic 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,下面还有一种,显然这个比较麻烦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);//显然这个比较简洁,只有一行代码。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>效果如下:
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() {@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case GO_HOME:goHome();break;case GO_GUIDE:goGuide();break;}super.handleMessage(msg);}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.splash);init();}private void init() {// 读取SharedPreferences中需要的数据// 使用SharedPreferences来记录程序的使用次数SharedPreferences preferences = getSharedPreferences(SHAREDPREFERENCES_NAME, MODE_PRIVATE);// 取得相应的值,如果没有该值,说明还未写入,用true作为默认值isFirstIn = preferences.getBoolean("isFirstIn", true);// 判断程序与第几次运行,如果是第一次运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MainActivitymHandler.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;@Overrideprotected 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AdaptervpAdapter = 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@Overridepublic void onPageScrollStateChanged(int arg0) {}// 当当前页面被滑动时调用@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}// 当新的页面被选中时调用@Overridepublic 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@Overridepublic void destroyItem(View arg0, int arg1, Object arg2) {((ViewPager) arg0).removeView(views.get(arg1));}@Overridepublic void finishUpdate(View arg0) {}// 获得当前界面数@Overridepublic int getCount() {if (views != null) {return views.size();}return 0;}// 初始化arg1位置的界面@Overridepublic 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() {@Overridepublic 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);// 提交修改editor.commit();}// 判断是否由对象生成界面@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {return (arg0 == arg1);}@Overridepublic void restoreState(Parcelable arg0, ClassLoader arg1) {}@Overridepublic Parcelable saveState() {return null;}@Overridepublic void startUpdate(View arg0) {}}至于MainActivity随便了。
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