Android之ImageSwitcher

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要点：

(查看Api总结)

1：ImageSwitcher 继承 ViewSwitcher， (ViewSwitcher 有继承FrameLayout ）

2：要实现切图必须实现 ViewSwitcher.ViewFactory接口中的 makeView()

易错点：

1：

mImageSwitcher.setFactory(this);
mImageSwitcher.setImageResource(mImages[0]);

setImageResource必须调用在setFactory之后。原因：根据源码分析调用setFactory获得接口，才能

获得makeView()返回的view 否则抛空指针异常

2：在makeView中设置布局参数要用FrameLayout布局参数

package com.imageswitcher;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.view.ViewGroup;

import android.view.animation.AnimationUtils;

import android.widget.FrameLayout;

import android.widget.ImageSwitcher;

import android.widget.ImageView;

import android.widget.LinearLayout;

import android.widget.Toast;

import android.widget.ViewSwitcher;

public class MainActivity extends Activity implements ViewSwitcher.ViewFactory {

    private LinearLayout mLinearLayout;

    private ImageSwitcher mImageSwitcher;

    private Integer[] mImages = {R.drawable.android01, R.drawable.android02, R.drawable.android03, R.drawable.android04,

            R.drawable.android05, R.drawable.android06, R.drawable.android07, R.drawable.android08, R.drawable.android09};

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initView();

        mImageSwitcher.setFactory(this);

        mImageSwitcher.setImageResource(mImages[0]);

        mImageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));

        mImageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));

        for (int i = 0; i < mImages.length; i++) {

            mLinearLayout.addView(getImageView(i));

        }

    }

    private ImageView getImageView(final int i) {

        ImageView imageView = new ImageView(this);

        imageView.setImageResource(mImages[i]);

        imageView.setId(i);

        imageView.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                mImageSwitcher.setImageResource(mImages[i]);

                Toast.makeText(v.getContext(), "选择了" + (v.getId() + 1) + "张图", Toast.LENGTH_SHORT).show();

            }

        });

        return imageView;

    }

    private void initView() {

        mLinearLayout = (LinearLayout) findViewById(R.id.linearLayout);

        mImageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher);

    }

    @Override

    public View makeView() {

        ImageView imageView = new ImageView(this);

        Log.i(MainActivity.class.getSimpleName(), "第几次调用");

        imageView.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,

                ViewGroup.LayoutParams.MATCH_PARENT));

        return imageView;

    }

}

xml

<RelativeLayout 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"

    tools:context=".MainActivity">

    <ImageSwitcher

        android:id="@+id/imageSwitcher"

        android:layout_width="match_parent"

        android:layout_height="200dp">

    </ImageSwitcher>

    <HorizontalScrollView

        android:layout_below="@id/imageSwitcher"

        android:layout_width="match_parent"

        android:layout_height="100dp"

        >

        <LinearLayout

            android:id="@+id/linearLayout"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:orientation="horizontal">

        </LinearLayout>

    </HorizontalScrollView>

</RelativeLayout>