实例讲解Android应用中自定义组合控件的方法

自定义view大概可以分成：

• 继承view
• 组合view
• 自己画的view（用paint和canvas）
• 自定义viewgroup（widget）

最近又跟同学聊起来了，于是就准备自己实现一个imagebutton来练练手。（最简单的了）以及后面一个把imageview与textview结合使用的案例。

ImageButton
要实现ImageButton最容易想到的不就是把button和imageview合在一起么。嗯，人容易就想到这是一个组合自定义view。可是如何把一个image放到button上呢，自然就是用一个FrameLayout把button和imageview包裹起来，然后将这个layout当作一个weidgt。把一个layout当成一个控件我开始不太理解。后来了解到一些东西。

补充知识点（安卓的顶层视图）
在android里面，你的app界面的活动的视图并非是最顶级的视图。大家应该都知道viewtree。在安卓里面，最顶级的视图是一个叫DecorView的东西。它包括你的状态栏，标题栏，以及你的活动界面。而且这个活动界面，安卓会自动帮你提前弄进去一个FrameLayout。可以这么理解吧，在安卓这个上帝的面前，你的activity就是放在他的framelayout的一个个view。上一张图～

DecorView->LinearLayout(状态栏和activity)->FrameLayout(activity)->你自己的acitivty视图。

实例讲解
好啦，回归正题。我上代码了。
myimagebutton_layout.xml

<FrameLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent">
 <Button
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:id="@+id/button_imagebutton"    />
 <ImageView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:id="@+id/imageview_button"    />
</FrameLayout>

用一个framelayout把两个控件装起来，然后组合。组合了之后我们就去自定义我们这个控件的属性。button不用变对吧，用原生的就好了，就是需要有一个图片的src这个属性就好了。
在values目录下的attrs.xml文件_

<?xml version="1.0" encoding="utf-8"?>
<resources>在
  <declare-styleable name="MyImageButton">
    <attr name="Imagesrc" format="reference"/>
  </declare-styleable>
</resources>

一般来说，declare-styleable标签的名字都是你的自定义控件的名字。attr就是你的自定义控件属性。format是这个属性的值的数据类型。这里的reference表示引用。dimension表示的是dp或者sp的大小。还有一些可以自己去看看。定义好属性，我们就开始写控件了。
MyImageButton.java

public class MyImageButton2 extends FrameLayout{

  ImageView mImageView;
  Button mButton;
  int resId;

  public MyImageButton2(Context context) {
    super(context);
  }

  public MyImageButton2(Context context, AttributeSet attrs) {
    super(context, attrs);
    //导入布局
    LayoutInflater.from(context).inflate(R.layout.myimagebutton_layout, this);

   mImageView＝(ImageView)findViewById(R.id.imageview_button);

   mButton = (Button) findViewById(R.id.button_imagebutton);
    //获得这个控件对应的属性。
   TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.MyImageButton);

    try{
     //获得属性值
      resId = a.getResourceId(R.styleable.MyImageButton_Imagesrc, 0);
    }finally {
     //回收这个对象
      a.recycle();
    }

    if(resId != 0){
      mImageView.setImageResource(resId);
    }
  }

  public void setImage(int resId){
    mImageView.setImageResource(resId);
  }

}

一般来说，继承view（就这么说吧，反正都是都是继承view的），实现两三个构造函数就可以了。在第二个里面有一个attr，这就是传进来的属性。如果resId不为默认值，就表示用户在xml里面传入了这个属性值，你也必须要写一个set方法，让用户可以在java代码中去改变属性值。
test.myimagebutton.layout.xml_

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">

  <com.example.think.testview.customview.MyImageButton2
    xmlns:pt = "http://schemas.android.com/apk/res/com.example.think.testview"
    android:layout_height="100dp"
    android:layout_width="match_parent"
    pt:Imagesrc = "@drawable/ic_launcher"
    />

</LinearLayout>

效果图

另一个实例

这里我们来看一个view组合控件的例子：

<string-array name="bao_type">
   <item>测试1</item>
   <item>测试2</item>
   <item>测试3</item>
   <item>测试4</item>
 </string-array>

<?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:background="@color/gray_common_background"
  android:orientation="vertical"> 

  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"> 

    <TextView
      android:id="@+id/txt_viewpage_bar1"
      style="@style/style_common_pagebar"
      android:textColor="@color/theme_red" /> 

    <TextView
      android:id="@+id/txt_viewpage_bar2"
      style="@style/style_common_pagebar" /> 

    <TextView
      android:id="@+id/txt_viewpage_bar3"
      style="@style/style_common_pagebar" /> 

    <TextView
      android:id="@+id/txt_viewpage_bar4"
      style="@style/style_common_pagebar" />
  </LinearLayout> 

  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"> 

    <View
      android:id="@+id/view_viewpage_bar1"
      style="@style/style_common_pagebar_view" /> 

    <View
      android:id="@+id/view_viewpage_bar2"
      style="@style/style_common_pagebar_view" /> 

    <View
      android:id="@+id/view_viewpage_bar3"
      style="@style/style_common_pagebar_view" /> 

    <View
      android:id="@+id/view_viewpage_bar4"
      style="@style/style_common_pagebar_view" />
  </LinearLayout> 

  <android.support.v4.view.ViewPager
    android:id="@+id/common_viewpage_buttom"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />
</LinearLayout>

public interface SlbPageViewOnPageChangeListener {
   void onPageSelected(int position); 

   void onPageScrollStateChanged(int state);
 }

public class SlbPageViewBar extends LinearLayout { 

  private TextView[] mTotalTxtViews;
  private View[] mTotalViews;
  private List<TextView> mTxtViews;
  private List<View> mViews; 

  private ViewPager mViewPager;
  private SlbPageViewOnPageChangeListener mSlbPageViewOnPageChangeListener; 

  public SlbPageViewBar(Context context, AttributeSet attrs) {
    super(context, attrs);
    mTotalTxtViews = new TextView[4];
    mTotalViews = new View[4];
    mTxtViews = new ArrayList<>();
    mViews = new ArrayList<>();
    initView();
  } 

  private void initView() {
    View.inflate(getContext(), R.layout.layout_common_top_pageview_bar, this);
    mViewPager = (ViewPager) findViewById(R.id.common_viewpage_buttom);
    mTotalTxtViews[0] = (TextView) findViewById(R.id.txt_viewpage_bar1);
    mTotalTxtViews[1] = (TextView) findViewById(R.id.txt_viewpage_bar2);
    mTotalTxtViews[2] = (TextView) findViewById(R.id.txt_viewpage_bar3);
    mTotalTxtViews[3] = (TextView) findViewById(R.id.txt_viewpage_bar4);
    mTotalViews[0] = findViewById(R.id.view_viewpage_bar1);
    mTotalViews[1] = findViewById(R.id.view_viewpage_bar2);
    mTotalViews[2] = findViewById(R.id.view_viewpage_bar3);
    mTotalViews[3] = findViewById(R.id.view_viewpage_bar4); 

  } 

  /**
   * @param title 标题名称数组
   */ 

  public void setTitleView(String[] title) {
    int legth = title.length > 4 ? 4 : title.length;
    for (int i = 0; i < legth; i++) {
      mTotalTxtViews[i].setText(title[i]);
      mTotalTxtViews[i].setVisibility(View.VISIBLE);
      mTotalViews[i].setVisibility(View.INVISIBLE);
      mTotalTxtViews[i].setOnClickListener(new SlbTextViewOnLister(i));
      mTxtViews.add(mTotalTxtViews[i]);
      mViews.add(mTotalViews[i]);
    }
    mTotalViews[0].setVisibility(View.VISIBLE);
    mViewPager.setOnPageChangeListener(mOnButtomPageChangeListener);
  } 

  public ViewPager getViewPager(){
    return mViewPager;
  } 

  public void setSlbPageViewOnPageChangeListener(SlbPageViewOnPageChangeListener slbPageViewOnPageChangeListener) {
    this.mSlbPageViewOnPageChangeListener = slbPageViewOnPageChangeListener;
  } 

  private void changeViewBg(int textViewId, int viewId) {
    for (View view : mViews) {
      if (viewId == view.getId()) {
        view.setVisibility(View.VISIBLE);
      } else {
        view.setVisibility(View.INVISIBLE);
      }
    }
    for (TextView view : mTxtViews) {
      if (textViewId == view.getId()) {
        view.setTextColor(getResources().getColor(R.color.theme_red));
      } else {
        view.setTextColor(getResources().getColor(R.color.black_normal_text_33333));
      }
    }
  } 

  class SlbTextViewOnLister implements OnClickListener { 

    private int mItem; 

    public SlbTextViewOnLister(int item) {
      this.mItem = item; 

    } 

    @Override
    public void onClick(View v) {
      mViewPager.setCurrentItem(mItem);
    }
  } 

  private ViewPager.OnPageChangeListener mOnButtomPageChangeListener = new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { 

    } 

    @Override
    public void onPageSelected(int position) {
      switch (position) {
        case 0:
          changeViewBg(R.id.txt_viewpage_bar1, R.id.view_viewpage_bar1);
          break;
        case 1:
          changeViewBg(R.id.txt_viewpage_bar2, R.id.view_viewpage_bar2); 

          break;
        case 2:
          changeViewBg(R.id.txt_viewpage_bar3, R.id.view_viewpage_bar3);
          break;
        case 3:
          changeViewBg(R.id.txt_viewpage_bar4, R.id.view_viewpage_bar4);
          break;
      }
      if (mSlbPageViewOnPageChangeListener != null)
        mSlbPageViewOnPageChangeListener.onPageSelected(position);
    } 

    @Override
    public void onPageScrollStateChanged(int state) {
      if (mSlbPageViewOnPageChangeListener != null)
        mSlbPageViewOnPageChangeListener.onPageScrollStateChanged(state);
    }
  }; 

}

public class CommonViewpageAdapter extends FragmentPagerAdapter {
  private List<Fragment> mFragments;
  private String [] mTitles; 

  public CommonViewpageAdapter(FragmentManager fm, List<Fragment> fragments, String [] titles) {
    super(fm);
    mFragments = fragments;
    mTitles = titles;
  } 

  @Override
  public Fragment getItem(int position) {
    return mFragments.get(position);
  } 

  @Override
  public int getCount() {
    return mFragments.size();
  } 

  @Override
  public CharSequence getPageTitle(int position) {
    return mTitles[position];
  } 

  @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
    super.destroyItem(container, position, object);
  }
}

<com.slfinance.app.slb.common.ui.view.SlbPageViewBar
    android:id="@+id/slbpv_buy_huoqibao_SlbPageViewBarshow"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"/>

private void initButtomPageFragment(SlbPageViewBar slbPageViewBar) {
  List<Fragment> fragmentList = new ArrayList<>();
  Test1Fragment test1Fragment = new Test1Fragment();
  Test2Fragment test2Fragment = new Test2Fragment();
  Test3Fragment test3Fragment = new Test3Fragment();
  Test4Fragment test4Fragment = new Test4Fragment();
  fragmentList.add(test1Fragment);
  fragmentList.add(test2Fragment);
  fragmentList.add(test3Fragment);
  fragmentList.add(test4Fragment);
  String[] titles = getResources().getStringArray(R.array.buy_huoqi_bao_zanquan_detail);
  slbPageViewBar.setTitleView(titles);
  CommonViewpageAdapter viewPagerAdapter = new CommonViewpageAdapter(
      getSupportFragmentManager(), fragmentList, titles);
  mButtomPageView.setAdapter(viewPagerAdapter);
  mButtomPageView.setOffscreenPageLimit(3);
  mButtomPageView.setCurrentItem(0);
}