viewpager学习笔记

来源：互联网发布：贵州省大数据局编辑：程序博客网时间：2024/05/16 14:34

首先在layout里写viewpager

<android.support.v4.view.ViewPager    android:id="@+id/viewpager"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    />

然后编写3个layout分别lay1,lay2,lay3，3个layout设置背景不同，不做其他修改，

贴上MainActivity的代码，逐步分析，

public class MainActivity extends AppCompatActivity {    private View lay1,lay2,lay3;    private ViewPager viewpager;    private List<View>listview;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        viewpager=(ViewPager)findViewById(R.id.viewpager);        LayoutInflater inflater=getLayoutInflater();        lay1=inflater.inflate(R.layout.layout1,null);        lay2=inflater.inflate(R.layout.layout2,null);        lay3=inflater.inflate(R.layout.layout3,null);        listview=new ArrayList<View>();        listview.add(lay1);        listview.add(lay2);        listview.add(lay3);        PagerAdapter adapter=new PagerAdapter() {            @Override            public int getCount() {                return listview.size();            }            @Override            public boolean isViewFromObject(View view, Object object) {                return view==object;            }            @Override            public void destroyItem(ViewGroup container, int position, Object object) {                container.removeView(listview.get(position));            }            @Override            public Object instantiateItem(ViewGroup container, int position) {                container.addView(listview.get(position));                return listview.get(position);            }        };        viewpager.setAdapter(adapter);    }}

首先，对3个layout使用了View来定义，因为View是Layout的父类的父类，

并且LayoutInflater.inflater返回值为View

Inflate a new view hierarchy from the specified xml resource. Throws

*{@link InflateException} if there is an error.

public View inflate(int resource, ViewGroup root) {    return inflate(resource, root, root != null);}

然后是给ViewPager设置adapter

(二)添加标题---PagerTitleStrip与PagerTabStrip

PagerTabStrip:

layout.xml:

<android.support.v4.view.ViewPager    android:id="@+id/viewpager"    android:layout_width="wrap_content"    android:layout_height="wrap_content">    <android.support.v4.view.PagerTabStrip        android:id="@+id/title"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="top"        /></android.support.v4.view.ViewPager>

MainActivity:

public class MainActivity extends AppCompatActivity {    private ViewPager viewpager;    private View lay1,lay2,lay3;    private List<View>list;    private List<String>title;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        viewpager=(ViewPager)findViewById(R.id.viewpager);        LayoutInflater inflater=getLayoutInflater();        lay1=inflater.inflate(R.layout.layout1,null);        lay2=inflater.inflate(R.layout.layout2,null);        lay3=inflater.inflate(R.layout.layout3,null);        list=new ArrayList<View>();        list.add(lay1);        list.add(lay2);        list.add(lay3);        title=new ArrayList<String>();        title.add("xiaoming");        title.add("xiaohong");        title.add("xiaofang");        PagerAdapter myadapter=new PagerAdapter() {            @Override            public int getCount() {                return list.size();            }            @Override            public boolean isViewFromObject(View view, Object object) {                return view==object;            }            @Override            public void destroyItem(ViewGroup container, int position, Object object) {                container.removeView(list.get(position));            }            @Override            public Object instantiateItem(ViewGroup container, int position) {                container.addView(list.get(position));                return list.get(position);            }            @Override            public CharSequence getPageTitle(int position) {                return title.get(position);            }        };        viewpager.setAdapter(myadapter);    }}

主要是添加一个一个list，还有就是在适配器中添加一个getPageTitle方法

PagerTitleStrip与PagerTabStrip差不多，只是在layout里面的不同，

PagerTitleStrip与PagerTabStrip的不同点：

1.PagerTabStrip的标题下面有下划线来提醒指向哪个Tab

2.PagerTitleStrip没有与用户交互的功能而PagerTabStrip则有，具体是点击上面的Tab可以转换到具体的那个layout

扩展:

1.改变下划线的颜色

PagerTabStrip pagerTabStrip;pagerTabStrip = (PagerTabStrip) findViewById(R.id.title);pagerTabStrip.setTabIndicatorColorResource(Color.green);

需要在values下的colors.xml文件里加上

<color name="green">#00ff00</color>

同时也发现了Color.GREEN是一种颜色而自定义的color.green属于一种id资源，这里容易混淆

2.添加标题——重写适配器CharSequence getPageTitle(int)方法

public CharSequence getPageTitle(int position) {    SpannableStringBuilder ssb = new SpannableStringBuilder("  "+title.get(position)); // space added before text    // for    Drawable myDrawable = getResources().getDrawable(            R.drawable.ic_launcher);    myDrawable.setBounds(0, 0, myDrawable.getIntrinsicWidth(),            myDrawable.getIntrinsicHeight());    ImageSpan span = new ImageSpan(myDrawable,            ImageSpan.ALIGN_BASELINE);    ForegroundColorSpan fcs = new ForegroundColorSpan(Color.GREEN);// 字体颜色设置为绿色    ssb.setSpan(span, 0, 1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);// 设置图标    ssb.setSpan(fcs, 1, ssb.length(),            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);// 设置字体颜色    ssb.setSpan(new RelativeSizeSpan(1.2f), 1, ssb.length(),            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);    return ssb;}

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