通过网络地址获取网络图片，点击下载将图片显示出来，然后点击图片将图片保存到本地。

首先需要在manifest上添加一些权限：

<!-- 访问网络的权限 -->
<uses-permission android:name="android.permission.INTERNET">
<!-- 文件读取的权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE">
<!-- 向SD卡中创建或者删除的权限。 -->
<uses-permission android:name="andorid.permission.MONUN_UNMOUNT_FILESYSTEMS"></uses-permission></uses-permission></uses-permission>package com.xjw.test;import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener{Button content;ImageView image;Bitmap bitmap;protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);content=(Button)findViewById(R.id.content);image=(ImageView)findViewById(R.id.image);content.setOnClickListener(this);;image.setOnClickListener(this);;}/*** 获取网络图片* @param imageurl 图片网络地址* @return Bitmap 返回位图*/public Bitmap GetImageInputStream(String imageurl){URL url;HttpURLConnection connection=null;Bitmap bitmap=null;try {url = new URL(imageurl);connection=(HttpURLConnection)url.openConnection();connection.setConnectTimeout(6000); //超时设置connection.setDoInput(true); connection.setUseCaches(false); //设置不使用缓存InputStream inputStream=connection.getInputStream();bitmap=BitmapFactory.decodeStream(inputStream);inputStream.close();} catch (Exception e) {e.printStackTrace();}return bitmap;}public void onClick(View v) {switch (v.getId()) {case R.id.content://加入网络图片地址new Task().execute("https://pic.4j4j.cn/upload/pic/20130617/55695c3c95.jpg");break;case R.id.image://点击图片后将图片保存到SD卡跟目录下的Test文件夹内SavaImage(bitmap, Environment.getExternalStorageDirectory().getPath()+"/Test");Toast.makeText(getBaseContext(), "图片保存", Toast.LENGTH_SHORT).show();break;default:break;}}Handler handler=new Handler(){public void handleMessage(android.os.Message msg) {if(msg.what==0x123){image.setImageBitmap(bitmap);}};};/*** 异步线程下载图片**/class Task extends AsyncTask<string, void="">{protected Void doInBackground(String... params) {bitmap=GetImageInputStream((String)params[0]);return null;}protected void onPostExecute(Void result) {super.onPostExecute(result);Message message=new Message();message.what=0x123;handler.sendMessage(message);}}/*** 保存位图到本地* @param bitmap* @param path 本地路径* @return void*/public void SavaImage(Bitmap bitmap, String path){File file=new File(path);FileOutputStream fileOutputStream=null;//文件夹不存在，则创建它if(!file.exists()){file.mkdir();}try {fileOutputStream=new FileOutputStream(path+"/"+System.currentTimeMillis()+".png");bitmap.compress(Bitmap.CompressFormat.JPEG, 100,fileOutputStream);fileOutputStream.close();} catch (Exception e) {e.printStackTrace();}}
}