Android 通过环路的数据泄漏
我试图通过Android 通过环路的数据泄漏,android,android-asynctask,android-studio-2.0,Android,Android Asynctask,Android Studio 2.0,我试图通过AsyncTask下载网页的html,然后在日志中显示该html 这是我的密码。然而,当我运行代码时,循环从未停止过 public class MainActivity extends AppCompatActivity { public class DownloadTask extends AsyncTask<String,Void,String>{ @Override protected String doInBackgroun
AsyncTask
下载网页的html,然后在日志中显示该html
这是我的密码。然而,当我运行代码时,循环从未停止过
public class MainActivity extends AppCompatActivity {
public class DownloadTask extends AsyncTask<String,Void,String>{
@Override
protected String doInBackground(String... urls) {
String result = "";
HttpURLConnection connection = null;
URL myUrl;
try{
myUrl = new URL(urls[0]);
connection = (HttpURLConnection) myUrl.openConnection();
InputStream in = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while(data != -1){
char current = (char) data;
result += current;
data = reader.read();
}
return result;
}
catch(Exception e){
e.printStackTrace();
return "Failed";
}
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DownloadTask task = new DownloadTask();
try {
String result = task.execute("http://www.posh24.com/celebrities").get();
Log.i("asd",String.valueOf(result));
}
catch(Exception e){
e.printStackTrace();
}
}
}
知道代码有什么问题吗?可能是因为在收到的每个字符上都创建了一个新字符串。不要这样做:
result += current;
相反,创建一个StringBuilder
并附加到它
或者,最好不要一次读取一个字符,而是创建一个
BufferedReader
并读入一个相当大的缓冲区,例如1024字节。代码的问题是数据在您使用一个read()
调用初始化后不会更改,因此它永远不会是-1
(因此是无限循环)
您需要在循环内调用read()
替换以下内容:
int data = reader.read();
while(data != -1){
// ...
比如说:
int data;
while ((data = reader.read()) != -1) {
// ...
为了加快速度,您可以使用BufferedReader
:
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
String line = null;
StringBuilder builder = new StringBuilder();
while((line = reader.readLine()) != null) {
builder.append(line);
}
String data = builder.toString();
我可以通过您的代码获取数据。我相信您在测试时已经添加了internet权限
但是由于task.execute().get(),您的代码阻塞了UI线程。我对其进行了一些更改:
public class DownloadTask extends AsyncTask<String, Void, String> {
private Listener mListener;
DownloadTask(Listener listener) {
mListener = listener;
}
@Override
protected String doInBackground(String... urls) {
String result = "";
HttpURLConnection connection = null;
URL myUrl;
try {
myUrl = new URL(urls[0]);
connection = (HttpURLConnection) myUrl.openConnection();
InputStream in = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();
}
return result;
} catch (Exception e) {
e.printStackTrace();
return "Failed";
}
}
@Override
protected void onPostExecute(String s) {
mListener.deliverResult(s);
}
public interface Listener {
void deliverResult(String result);
}
@Junaid,这不是一个编码服务。你有你自己需要的一切。现在下载的数据丢失了。是的,很好。非常感谢:)
public class DownloadTask extends AsyncTask<String, Void, String> {
private Listener mListener;
DownloadTask(Listener listener) {
mListener = listener;
}
@Override
protected String doInBackground(String... urls) {
String result = "";
HttpURLConnection connection = null;
URL myUrl;
try {
myUrl = new URL(urls[0]);
connection = (HttpURLConnection) myUrl.openConnection();
InputStream in = connection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1) {
char current = (char) data;
result += current;
data = reader.read();
}
return result;
} catch (Exception e) {
e.printStackTrace();
return "Failed";
}
}
@Override
protected void onPostExecute(String s) {
mListener.deliverResult(s);
}
public interface Listener {
void deliverResult(String result);
}
DownloadTask task = new DownloadTask(new DownloadTask.Listener() {
@Override
public void deliverResult(String result) {
Log.i("asd",String.valueOf(result));
}
});
task.execute("http://www.posh24.com/celebrities");