Android ImageView 显示网络图片并下载保存

import java.io.BufferedOutputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.net.HttpURLConnection;

import java.net.URL;

import android.app.Activity;

import android.app.ProgressDialog;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Bundle;

import android.os.Environment;

import android.os.Handler;

import android.os.Message;

import android.view.View;

import android.widget.Button;

import android.widget.ImageView;

import android.widget.Toast;

public class MainActivity extends Activity {

private final static String ALBUM_PATH = Environment
.getExternalStorageDirectory() + "/download_test/";
private ImageView mImageView;
private Button mBtnSave;
private ProgressDialog mSaveDialog = null;
private Bitmap mBitmap;
private String mFileName;
private String mSaveMessage;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mImageView = (ImageView) findViewById(R.id.imgSource);
mBtnSave = (Button) findViewById(R.id.btnSave);
new Thread(connectNet).start();
// 下载图片
mBtnSave.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
mSaveDialog = ProgressDialog.show(MainActivity.this, "保存图片",
"图片正在保存中，请稍等...", true);
new Thread(saveFileRunnable).start();
}
});
}

/**
* Get image from newwork
* 
* @param path
*            The path of image
* @return byte[]
* @throws Exception
*/
public byte[] getImage(String path) throws Exception {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5 * 1000);
conn.setRequestMethod("GET");
InputStream inStream = conn.getInputStream();
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
return readStream(inStream);
}
return null;
}

/**
* Get image from newwork
* 
* @param path
*            The path of image
* @return InputStream
* @throws Exception
*/
public InputStream getImageStream(String path) throws Exception {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5 * 1000);
conn.setRequestMethod("GET");
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
return conn.getInputStream();
}
return null;
}

/**
* Get data from stream
* 
* @param inStream
* @return byte[]
* @throws Exception
*/
public static byte[] readStream(InputStream inStream) throws Exception {
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {
outStream.write(buffer, 0, len);
}
outStream.close();
inStream.close();
return outStream.toByteArray();
}

/**
* 保存文件
* 
* @param bm
* @param fileName
* @throws IOException
*/
public void saveFile(Bitmap bm, String fileName) throws IOException {

try {
File dirFile = new File(ALBUM_PATH);
if (!dirFile.exists()) {
dirFile.mkdir();
}
File myCaptureFile = new File(ALBUM_PATH + fileName);
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(myCaptureFile));
bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
bos.flush();
bos.close();
mSaveMessage = "图片保存成功！";
} catch (Exception e) {
mSaveMessage = "图片保存失败！";
}

}

private Runnable saveFileRunnable = new Runnable() {
@Override
public void run() {
try {
saveFile(mBitmap, mFileName);
} catch (IOException e) {
mSaveMessage = "图片保存失败！";
e.printStackTrace();
}
messageHandler.sendMessage(messageHandler.obtainMessage());
}

};

private Handler messageHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
mSaveDialog.dismiss();
Toast.makeText(MainActivity.this, mSaveMessage, Toast.LENGTH_SHORT)
.show();
}
};
/*
* 连接网络 由于在4.0中不允许在主线程中访问网络，所以需要在子线程中访问
*/
private Runnable connectNet = new Runnable() {
@Override
public void run() {
try {
String filePath = "http://www.baidu.com/img/bdlogo.gif";
mFileName = "76.jpg";
// 以下是取得图片的两种方法
// ////////////// 方法1：取得的是byte数组, 从byte数组生成bitmap
// byte[] data = getImage(filePath);
// if (data != null) {
// mBitmap = BitmapFactory.decodeByteArray(data, 0,
// data.length);// bitmap
// } else {
// Toast.makeText(MainActivity.this, "Image error!", 1).show();
// }

// //////////////////////////////////////////////////////
// ******** 方法2：取得的是InputStream，直接从InputStream生成bitmap
// ***********/
mBitmap = BitmapFactory.decodeStream(getImageStream(filePath));
// ********************************************************************/
// 发送消息，通知handler在主线程中更新UI
connectHanlder.sendEmptyMessage(0);
} catch (Exception e) {
Toast.makeText(MainActivity.this, "无法链接网络！", 1).show();
e.printStackTrace();
}

}

};

private Handler connectHanlder = new Handler() {
@Override
public void handleMessage(Message msg) {
// 更新UI，显示图片
if (mBitmap != null) {
mImageView.setImageBitmap(mBitmap);
}
}
};

}

<uses-permission android:name="android.permission.INTERNET" />

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />