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;

	@Override
	protected 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() {

			@Override
			public 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>