我想在url下载数据时使用url在secondActivity中填充listview我尝试了不同的东西，但没有任何作用
MainActivity.java
public class MainActivity extends ActionBarActivity {
private static final String DEBUG_TAG = "HttpExample";
private EditText urlText;
private TextView textView;
SharedPreferences.Editor fd;
SharedPreferences FeedPref;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
urlText = (EditText) findViewById(R.id.myurl);
textView = (TextView) findViewById(R.id.mytext);
textView.setMovementMethod(ScrollingMovementMethod.getInstance());
FeedPref=PreferenceManager.getDefaultSharedPreferences(getBaseContext());
fd=FeedPref.edit();
}
public void myClickHandler(View view) {
// Gets the URL from the UI's text field.
String stringUrl = urlText.getText().toString();
ConnectivityManager connMgr = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected()) {
new DownloadWebpageTask().execute(stringUrl);
} else {
textView.setText("No network connection available.");
}
}
public class DownloadWebpageTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... urls) {
// params comes from the execute() call: params[0] is the url.
try {
return downloadUrl(urls[0]);
} catch (IOException e) {
return "Unable to retrieve web page. URL may be invalid.";
}
}
// onPostExecute displays the results of the AsyncTask.
@Override
protected void onPostExecute(String result) {
textView.setText(result);
if (result != null )
{
FeedPref=PreferenceManager.getDefaultSharedPreferences(getBaseContext());
fd=FeedPref.edit();
String url =urlText.getText().toString();
fd.putString("urls", url);
fd.commit(); }
}
}
private String downloadUrl(String myurl) throws IOException {
InputStream is = null;
try {
URL url = new URL(myurl);
HttpURLConnection connect = (HttpURLConnection) url.openConnection();
connect.setReadTimeout(10000 /* milliseconds */);
connect.setConnectTimeout(15000 /* milliseconds */);
connect.setRequestMethod("GET");
connect.setDoInput(true);
// Starts the query
connect.connect();
int response = connect.getResponseCode();
Log.d(DEBUG_TAG, "The response is: " + response);
is = connect.getInputStream();
// Convert the InputStream into a string
String contentAsString = readIt(is);
return contentAsString;
// Makes sure that the InputStream is closed after the app is
// finished using it.
} finally {
if (is != null) {
is.close();
}
}
}
// Reads an InputStream and converts it to a String.
public String readIt(InputStream stream) throws IOException, UnsupportedEncodingException {
if (stream != null) {
StringBuilder sb = new StringBuilder();
String line;
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
while ((line = reader.readLine()) != null) {
sb.append(line);
}
} finally {
stream.close();
}
return sb.toString();
} else {
return "";
}
}
public void myClickHandler1(View povijest){
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
secondactivity.java
package com.example.networking;
import java.util.ArrayList;
import android.support.v7.app.ActionBarActivity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
public class SecondActivity extends ActionBarActivity {
String[] urls1;
ListView listView;
ArrayAdapter<String> adapter;
SharedPreferences FeedPref;
SharedPreferences.Editor fd;
TextView txt1;
protected void onCreate(Bundle savedInstanceState) {
FeedPref=PreferenceManager.getDefaultSharedPreferences(getBaseContext());
String urlsa=FeedPref.getString("urls",null);
String[] values = new String[] {urlsa,};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, android.R.id.text1, values);
listView.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.second, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
activity_main.xml中
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.networking.MainActivity" >
<EditText
android:id="@+id/myurl"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="textWebEmailAddress"
android:ems="10" >
</EditText>
<TextView
android:id="@+id/mytext"
android:layout_width="200dp"
android:layout_height="0dp"
android:layout_marginLeft="38dp"
android:layout_marginTop="40dp"
android:layout_weight="0.17"
android:scrollbars="vertical" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="start"
android:onClick="myClickHandler1"
android:text="POVIJEST" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="myClickHandler"
android:text="Download" />
</LinearLayout>
activity_second.xml
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.networking.SecondActivity" >
<ListView
android:id="@+id/lista"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true" >
</ListView>
</RelativeLayout>
修改 我尝试将sharedPrefrences与onPostExecute一起使用，但我不起作用。 所以我希望下载的每个ulr都保存到listview。
答案 0 :(得分：0)
您需要以不同的方式将网址传递给第二个Activity。您不能指望操作系统调用您的自定义onCreate方法：
protected void onCreate(Bundle savedInstanceState, String urls)
它不知道。您可以通过以下几种方式之一传递URL数据：
Intent SharedPreferences File 最有可能你可以使用第一个或第二个。所有这些都有很多参考，所以我没有提供详细信息。
编辑：
例如，而不是：
public void myClickHandler1(View povijest){
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
}
这样做：
public void myClickHandler1(View povijest){
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
intent.putExtra("URL", urlText.getText().toString());
startActivity(intent);
}
然后像这样检索onCreate：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
list = (ListView) findViewById(R.id.lista);
arrayList = new ArrayList<String>();
// Adapter: You need three parameters 'the context, id of the layout (it will be where the data is shown),
// and the array that contains the data
adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, arrayList);
// Here, you set the data in your ListView
list.setAdapter(adapter);
arrayList.add(getIntent().getStringExtra("URL"));
adapter.notifyDataSetChanged();
}
编辑2：
您可以传递一个字符串数组。看看这篇文章：
Passing String array between two class in android application
您还可以使用分隔符（逗号，大括号等）然后解析它。或者使用JSON。
您也可以将其中任何一项保存到SharedPreferences，然后在第二项活动中从SharedPreferences加载。