出于某种原因，每当我尝试使用互联网从URL显示位图图像时，我的黑莓应用程序都会崩溃。
我发现downloadImage()函数非常容易理解，并且与stackoverflow上的其他函数相比较。其他人没有任何关于如何实现其功能的例子。我已经多次测试了函数downloadImage，但都失败了。
请用代码示例说明。感谢。
无论如何，编译器此时停止：
g.drawBitmap(10, y + 6, 50, 50, imageBmp, 0, 0);
以下是整个代码：
package parsepack;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Vector;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.io.StreamConnection;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.DeviceInfo;
import net.rim.device.api.system.Display;
import net.rim.device.api.system.EncodedImage;
import net.rim.device.api.ui.DrawStyle;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.Manager;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.component.BitmapField;
import net.rim.device.api.ui.component.Dialog;
import net.rim.device.api.ui.component.LabelField;
import net.rim.device.api.ui.component.ListField;
import net.rim.device.api.ui.component.ListFieldCallback;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.ui.container.VerticalFieldManager;
import net.rim.device.api.xml.parsers.DocumentBuilder;
import net.rim.device.api.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class xmlparsing extends UiApplication implements ListFieldCallback, FieldChangeListener
{
public static void main(String[] args) throws IOException
{
xmlparsing app = new xmlparsing();
app.enterEventDispatcher();
}
public long mycolor ;
Connection _connectionthread;
private static ListField _list;
private static Vector listElements = new Vector();
private static Vector listPrice = new Vector();
private static Vector listAbstract = new Vector();
private static Vector listIcon = new Vector();
private Vector listInfoVector = new Vector();
public MainScreen screen = new MainScreen();
Bitmap imageBmp = null;
VerticalFieldManager mainManager;
VerticalFieldManager subManager;
UiApplication ui = UiApplication.getUiApplication();
public xmlparsing() throws IOException
{
super();
pushScreen(screen);
final Bitmap backgroundBitmap = Bitmap.getBitmapResource("blackbackground.png");
mainManager = new VerticalFieldManager(Manager.NO_VERTICAL_SCROLL | Manager.NO_VERTICAL_SCROLLBAR )
{
public void paint(Graphics graphics)
{
graphics.drawBitmap(0, 0, Display.getWidth(),Display.getHeight(),backgroundBitmap, 0, 0);
super.paint(graphics);
}
};
subManager = new VerticalFieldManager(Manager.VERTICAL_SCROLL | Manager.VERTICAL_SCROLLBAR )
{
protected void sublayout( int maxWidth, int maxHeight )
{
int displayWidth = Display.getWidth();
int displayHeight = Display.getHeight();
super.sublayout( displayWidth, displayHeight);
setExtent( displayWidth, displayHeight);
}
};
screen.add(mainManager);
_list = new ListField()
{
public void paint(Graphics graphics)
{
graphics.setColor((int) mycolor);
super.paint(graphics);
}
protected boolean navigationClick(int status, int time)
{
try
{
//navigate here to another screen
ui.pushScreen(new ResultScreen());
}
catch(Exception e)
{
System.out.println("Exception:- : navigationClick() "+e.toString());
}
return true;
}
};
mycolor = 0x00FFFFFF;
_list.invalidate();
_list.setEmptyString("* Feeds Not Available *", DrawStyle.HCENTER);
_list.setRowHeight(70);
_list.setCallback(this);
mainManager.add(subManager);
listElements.removeAllElements();
listPrice.removeAllElements();
listAbstract.removeAllElements();
listIcon.removeAllElements();
_connectionthread = new Connection();
_connectionthread.start();
}
private class Connection extends Thread
{
public Connection()
{
super();
}
public void run() {
Document doc;
StreamConnection conn = null;
InputStream is = null;
try {
conn = (StreamConnection) Connector.open("http://imforchange.org/international-movement-for-change/testing/data.xml"+";deviceside=true");
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
docBuilderFactory.setIgnoringElementContentWhitespace(true);
docBuilderFactory.setCoalescing(true);
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
docBuilder.isValidating();
is = conn.openInputStream();
doc = docBuilder.parse(is);
doc.getDocumentElement().normalize();
NodeList list1 = doc.getElementsByTagName("eventName");
for (int i = 0; i < list1.getLength(); i++) {
Node textNode = list1.item(i).getFirstChild();
listElements.addElement(textNode.getNodeValue());
}
NodeList list2 = doc.getElementsByTagName("eventPrice");
for (int i = 0; i < list2.getLength(); i++) {
Node textNode = list2.item(i).getFirstChild();
listPrice.addElement(textNode.getNodeValue());
}
NodeList list3 = doc.getElementsByTagName("eventAbstract");
for (int i = 0; i < list3.getLength(); i++) {
Node textNode = list3.item(i).getFirstChild();
listAbstract.addElement(textNode.getNodeValue());
}
NodeList list4 = doc.getElementsByTagName("eventIcon");
for (int i = 0; i < list4.getLength(); i++) {
Node textNode = list4.item(i).getFirstChild();
listIcon.addElement(textNode.getNodeValue());
}
} catch (Exception e) {
System.out.println(e.toString());
} finally {
if (is != null) {
try { is.close();
} catch (IOException ignored) {}
} if (conn != null) {
try { conn.close(); }
catch (IOException ignored) {}
} } UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
_list.setSize(listElements.size());
subManager.add(_list);
screen.invalidate();
}
});
}
}
public void drawListRow(ListField list, Graphics g, int index, int y, int w)
{
String text = (String)listElements.elementAt(index);
String price = (String)listPrice.elementAt(index);
String textAbstract = (String)listAbstract.elementAt(index);
int yPos = 0+y;
g.drawLine(0, yPos, w, yPos);
g.drawText(text, 5, 15+y, 0, w);
g.drawText("$"+price, 5, 15+y, DrawStyle.RIGHT, w-7);
g.drawText(textAbstract, 5, 40+y, 0, w);
// image to display
String imageUrl = (String)listIcon.elementAt(index);
imageBmp = downloadImage(imageUrl);
g.drawBitmap(10, y + 6, 50, 50, imageBmp, 0, 0);
}
public Object get(ListField list, int index)
{
return listElements.elementAt(index);
}
public int indexOfList(ListField list, String prefix, int string)
{
return listElements.indexOf(prefix, string);
}
public int getPreferredWidth(ListField list)
{
return Display.getWidth();
}
/*Regarding the warning about insert(), that's just because you're not using it anywhere.
* It look like you've added that method to allow code outside the xmlparsing class to
* be able to insert items into the list. Maybe that's what you want, but you just
* haven't yet written the other code to use that method. I see you having at least a few choices:
*/
public void insert(String toInsert, int index) {
listElements.addElement(toInsert);
}
public void fieldChanged(Field field, int context) {
}
public static Bitmap downloadImage(String url)
{
InputStream iStream = null;
EncodedImage bitmap;
HttpConnection httpConnection = null;
try
{
httpConnection = (HttpConnection) Connector.open(url, Connector.READ_WRITE);
httpConnection.setRequestMethod(HttpConnection.GET);
int responseCode = httpConnection.getResponseCode();
if (responseCode == HttpConnection.HTTP_OK) {
iStream = httpConnection.openInputStream();
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
byte[] buffer = new byte[256];
int len = 0, imageSize = 0;
while (-1 != (len = iStream.read(buffer))) {
byteArrayOutputStream.write(buffer);
imageSize += len;
}
byteArrayOutputStream.flush();
byte[] imageData = byteArrayOutputStream.toByteArray();
byteArrayOutputStream.close();
bitmap = EncodedImage.createEncodedImage(imageData, 0, imageSize);
Bitmap bmp = bitmap.getBitmap();
return bmp;
}
}
catch (Exception e)
{
}
return null;
}
}
答案 0 :(得分：1)
我看到你的方法： downloadImage（String url）。它是一个冗长的代码。不需要那么多;
试试这个方法：
public static Bitmap getImage(String url)
{
Bitmap image;
HttpConnection connection=null;
InputStream is=null;
try
{
connection=(HttpConnection)Connector.open(Utility.escapeHTML(url));
int response=connection.getResponseCode();
if(response==HttpConnection.HTTP_OK)
{
is=connection.openInputStream();
byte[] data=IOUtilities.streamToBytes(is);
connection.close();
image=Bitmap.createBitmapFromBytes(data,0,data.length,1);
}
else
{
image=ResourceList.dummyBit;//noimage.png
}
}
catch (Exception e)
{
image=ResourceList.dummyBit;//noimage.png
}
finally
{
try
{
if (is != null)
is.close();
if (connection != null)
connection.close();
}
catch (Exception e) {}
}
return image;
}
试试这个，让我知道。
escapeHTML（String str）方法如下：
public static String escapeHTML(String s)
{
StringBuffer sb = new StringBuffer();
int n = s.length();
for (int i = 0; i < n; i++) {
char c = s.charAt(i);
switch (c) {
case ' ': sb.append("%20"); break;
default: sb.append(c); break;
}
}
return sb.toString();
}
答案 1 :(得分：1)
如果要从WebURL在BlackBerry屏幕上显示图像。首先，您需要获得BitMap参考。
您可以查看以下代码：
代码将输入作为WebURL，它将返回位图参考。
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import net.rim.device.api.io.IOUtilities;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.EncodedImage;
public class GetImage {
public static Bitmap connectServerForImage(String url) {
HttpConnection httpConnection = null;
DataOutputStream httpDataOutput = null;
InputStream httpInput = null;
int rc;
Bitmap bitmp = null;
try {
httpConnection = (HttpConnection) Connector.open(url);
rc = httpConnection.getResponseCode();
if (rc != HttpConnection.HTTP_OK) {
throw new IOException("HTTP response code: " + rc);
}
httpInput = httpConnection.openInputStream();
InputStream inp = httpInput;
byte[] b = IOUtilities.streamToBytes(inp);
EncodedImage hai = EncodedImage.createEncodedImage(b, 0, b.length);
return hai.getBitmap();
} catch (Exception ex) {
// System.out.println("URL Bitmap Error........" + ex.getMessage());
} finally {
try {
if (httpInput != null)
httpInput.close();
if (httpDataOutput != null)
httpDataOutput.close();
if (httpConnection != null)
httpConnection.close();
} catch (Exception e) {
e.printStackTrace();
}
}
return bitmp;
}
}
最后，如果要在BlackBerry屏幕上显示图像，请使用以下方法
g.drawBitmap(xpos, ypos, w, h, image, 0, 0);//pass the Bitmap reference Here