AndroidStudio——网络图片的读取与保存

public class SaveImageViewActivity extends AppCompatActivity {

private ImageView img, showImg;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_save_image_view);
img = (ImageView) findViewById(R.id.img);
showImg = (ImageView) findViewById(R.id.showImg);
}

public void readImg(View v) {
String path = Environment.getExternalStorageDirectory() + "/1.png";
//方法1：根据URI 加载图片
//showImg.setImageURI(Uri.parse(path));

/*
方法2：通过BitmapFactory 的静态方法decodeFile()
参数为图片路径
*/
Bitmap bitmap = BitmapFactory.decodeFile(path);
showImg.setImageBitmap(bitmap);
/*
方法3：通过BitmapFactory 的静态方法decodeStream()
参数为 输入流 InputStream

try {
BitmapFactory.decodeStream(new FileInputStream(path));
showImg.setImageBitmap(bitmap);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
*/

}
//布局监听   参数View v一定要写
//保存图片到SD卡
public void saveImg(View v) {
//获取BitmapDrawable对象
BitmapDrawable bitmapDrawable = (BitmapDrawable) img.getDrawable();
Bitmap bitmap = bitmapDrawable.getBitmap();
/*
通过Bitmap(位图)压缩的方法（compress）保存图片到SD卡
参数1:图片格式（PNG JPEJ WEBP）
参数2：图片质量（0-100）
参数3：输出流
*/
//取得SD卡根目录
File root = Environment.getExternalStorageDirectory();
FileOutputStream fos = null;
try {
fos = new FileOutputStream(root + "/1.png");
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);

} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (fos != null) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

//从网络获取图片
public void getUrlImg(View v) {
new GetImg().execute("http://img2.imgtn.bdimg.com/it/u=169341381,1292926655&fm=21&gp=0.jpg");
}

public  void saveHttpImg(View v){
new SaveHttpImg().execute("http://img2.imgtn.bdimg.com/it/u=169341381,1292926655&fm=21&gp=0.jpg");
}

public class GetImg extends AsyncTask<String, Void, Bitmap> {

@Override
protected Bitmap doInBackground(String... params) {
HttpURLConnection con = null;
//拿数据
InputStream is = null;
try {
URL url=new URL(params[0]);
con= (HttpURLConnection) url.openConnection();
con.setConnectTimeout(5000);
con.setReadTimeout(5*1000);
if (con.getResponseCode()==200){
is=con.getInputStream();
Bitmap bitmap = BitmapFactory.decodeStream(is);
return bitmap;
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
if (is!=null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (con!=null){
con.disconnect();
}
}
return null;
}

@Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
showImg.setImageBitmap(bitmap);
}
}

public class SaveHttpImg extends AsyncTask<String,Void,String>{

@Override
protected String doInBackground(String... strings) {
HttpURLConnection con = null;
InputStream is = null;
try {
URL url = new URL(strings[0]);
con = (HttpURLConnection) url.openConnection();
con.setConnectTimeout(5*1000);
con.setReadTimeout(5*1000);
File root = Environment.getExternalStorageDirectory();
FileOutputStream fos = new FileOutputStream(root+"/http.jpg");
if(con.getResponseCode()==200){
is = con.getInputStream();
int next=0;
byte[] bytes = new byte[1024];
while ( (next = is.read(bytes))>0){
fos.write(bytes,0,next);
}
fos.flush();
fos.close();
return  root+"/http.jpg";
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if(is!=null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(con!=null){
con.disconnect();
}
}
return "";
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
if(!s.equals("")){
Toast.makeText(SaveImageViewActivity.this, "保存路径:" + s, Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(SaveImageViewActivity.this,"保存失败:",Toast.LENGTH_SHORT).show();
}
}
}

}

<?xml version="1.0" encoding="utf-8"?>
<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.dell.jreduch008.SaveImageViewActivity">

<ImageView
android:id="@+id/img"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@mipmap/ic_launcher" />

<LinearLayout
android:id="@+id/ll1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/img"
android:orientation="horizontal">

<Button
android:id="@+id/read"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignTop="@+id/save"
android:layout_weight="1"
android:onClick="readImg"
android:text="读取图片" />

<Button
android:id="@+id/save"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/img"
android:layout_weight="1"
android:onClick="saveImg"
android:text="保存图片" />
</LinearLayout>

<LinearLayout
android:id="@+id/ll2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/ll1"
android:orientation="horizontal">

<Button
android:id="@+id/readUrl"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/img"
android:layout_weight="1"
android:onClick="getUrlImg"
android:text="获取网络图片"/>

<Button
android:id="@+id/saveImg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/img"
android:layout_weight="1"
android:onClick="saveHttpImg"
android:text="保存网络图片"/>
</LinearLayout>

<ImageView
android:id="@+id/showImg"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentStart="true"
android:layout_below="@+id/ll2" />
</RelativeLayout>