资源中获取图片：可以从工程assets文件夹、res/drawble文件夹、sd卡、服务端下载图片。

package com.sxt.day06_08;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.util.EntityUtils;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;import android.os.Environment;import android.view.View;import android.view.View.OnClickListener;import android.widget.ImageView;public class MainActivity extends Activity {    ImageView mImageView;    static final String FILE_NAME="sxt_logo.png";    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();        setListener();    }    private void setListener() {        setResetClickListener();        setDecodeFileClickListener();        setDecodeResourceClickListener();        setDecodeStreamClickListener();        setDecodeByteArrayClickListener();    }    private void setDecodeByteArrayClickListener() {        findViewById(R.id.btnDecodeByteArray).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                new Thread(){                    public void run() {                        HttpGet get=new HttpGet("http://10.0.2.2/"+FILE_NAME);//服务端资源文件路径                        HttpClient client=new DefaultHttpClient();                        try {                            HttpResponse response = client.execute(get);                            HttpEntity entity = response.getEntity();//                            byte[] data = EntityUtils.toByteArray(entity);                            final Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);                            //工作线程不能修改UI,可以用Handler做，runOnUiThread方法会把里面的代码发送给主线程，修改UI。                            //Runnable可以被多个线程共享，工作线程可以把该Runnable对象交给主线程由主线程执行。                            runOnUiThread(new Runnable() {                                @Override                                public void run() {                                    mImageView.setImageBitmap(bitmap);                                }                            });                        } catch (ClientProtocolException e) {                            e.printStackTrace();                        } catch (IOException e) {                            e.printStackTrace();                        }finally{                            if(client!=null){                                client.getConnectionManager().shutdown();//关闭                            }                        }                    };                }.start();            }        });    }        private void setDecodeStreamClickListener() {        findViewById(R.id.btnDecodeStream).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                File dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);                File file=new File(dir, FILE_NAME);//sd卡图片路径                FileInputStream in=null;                try {                    in=new FileInputStream(file);                    Bitmap bitmap = BitmapFactory.decodeStream(in);                    mImageView.setImageBitmap(bitmap);                } catch (FileNotFoundException e) {                    e.printStackTrace();                }finally{                    if(in!=null){                        try {                            in.close();                        } catch (IOException e) {                            e.printStackTrace();                        }                    }                }            }        });    }    private void setDecodeResourceClickListener() {        findViewById(R.id.btnDecodeResource).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                mImageView.setImageResource(R.drawable.sxt_logo);            }        });    }    private void setResetClickListener() {
   //点击图片还原        findViewById(R.id.iv).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                mImageView.setImageResource(R.drawable.ic_launcher);            }        });    }    //获取sd卡的图片文件    private void setDecodeFileClickListener() {        findViewById(R.id.btnDecodeFile).setOnClickListener(new OnClickListener() {            @Override            public void onClick(View v) {                File dir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);//sd卡的图片的路径                File file=new File(dir, FILE_NAME);//获取sd卡的图片文件                Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());                mImageView.setImageBitmap(bitmap);            }        });    }    private void initView() {        mImageView=(ImageView) findViewById(R.id.iv);    }}

          申请网络权限    
        申请读sd卡权限