在清单文件中加上网络访问权限

利用HttpURLConnection对象,我们可以从网络中获取网页数据.

HttpURLConnection conn= (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5*1000);//设置连接超时

conn.setRequestMethod(“GET”);//以get方式发起请求

if(conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");

InputStream is =conn.getInputStream();//得到网络返回的输入流

Stringresult = readData(is, "GBK");

conn.disconnect();

//第一个参数为输入流,第二个参数为字符集编码

public static StringreadData(InputStream inSream, String charsetName) throws Exception{

ByteArrayOutputStreamoutStream = new ByteArrayOutputStream();

byte[]buffer = new byte[1024];

intlen = -1;

while((len = inSream.read(buffer)) != -1 ){

outStream.write(buffer,0, len);

}

byte[]data = outStream.toByteArray();

outStream.close();

inSream.close();

returnnew String(data, charsetName);

}

利用HttpURLConnection对象,我们可以从网络中获取文件数据.

URL url = newURL("https://www.cppentry.com/upload_files/article/54/1_1ka9j__.jpg");

HttpURLConnection conn= (HttpURLConnection) url.openConnection();

conn.setConnectTimeout(5*1000);

conn.setRequestMethod("GET");

if(conn.getResponseCode() != 200) throw new RuntimeException("请求url失败");

InputStream is =conn.getInputStream();

readAsFile(is,"Img269812337.jpg");

public static voidreadAsFile(InputStream inSream, File file) throws Exception{

FileOutputStreamoutStream = new FileOutputStream(file);

byte[]buffer = new byte[1024];

intlen = -1;

while((len = inSream.read(buffer)) != -1 ){

outStream.write(buffer,0, len);

}

outStream.close();

inSream.close();

}