BitmapDemo

MainActivity类

package com.example.bitmapdemo;import java.io.InputStream;import android.content.res.AssetManager;import android.graphics.BitmapFactory;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.support.v7.app.ActionBarActivity;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;public class MainActivity extends ActionBarActivity {private ImageView image = null;private Button btnNext = null;String[] images = null;AssetManager assets = null;int currentImg = 0;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);image = (ImageView) findViewById(R.id.main_img);btnNext = (Button) findViewById(R.id.main_btn_next);try {assets = getAssets();images = assets.list("");} catch (Exception e) {e.printStackTrace();}btnNext.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {if (currentImg >= images.length) {currentImg = 0;}while (!images[currentImg].endsWith(".png")&& !images[currentImg].endsWith(".jpg")&& !images[currentImg].endsWith(".gif")) {currentImg++;if (currentImg >= images.length) {currentImg = 0;}}InputStream assetFile = null;try {assetFile = assets.open(images[currentImg++]);} catch (Exception e) {e.printStackTrace();}BitmapDrawable bitmapDrawable = (BitmapDrawable) image.getDrawable();if (bitmapDrawable != null&& !bitmapDrawable.getBitmap().isRecycled()) {bitmapDrawable.getBitmap().recycle();}image.setImageBitmap(BitmapFactory.decodeStream(assetFile));}});}}

activity_main.xml文件

<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="com.example.bitmapdemo.MainActivity" >    <TextView        android:id="@+id/main_txt"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world" />    <ImageView         android:id="@+id/main_img"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@drawable/ic_launcher"        android:layout_below="@id/main_txt"        /><Button     android:id="@+id/main_btn_next"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="next"    android:layout_below="@id/main_img"    /></RelativeLayout>