J2ME从服务器端下载图片，在RMS中存储，然后在读取显示（非原创代码，整合应用而已）

package com.zeph.j2me.rsm.image;

import java.io.DataInputStream;
import java.io.DataOutputStream;

import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Image;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
import javax.microedition.rms.RecordStore;
import javax.microedition.rms.RecordStoreException;
import javax.microedition.rms.RecordStoreFullException;
import javax.microedition.rms.RecordStoreNotFoundException;

public class ImageStoreMIDlet extends MIDlet implements CommandListener {
private Display display;
private Form form;
private Command command;

public ImageStoreMIDlet() {
display = Display.getDisplay(this);
form = new Form("下载图片，并存储，然后读取，再现实");
command = new Command("显示", Command.OK, 0);
form.addCommand(command);
form.setCommandListener(this);
}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException {

}

protected void pauseApp() {

}

protected void startApp() throws MIDletStateChangeException {
loadImage("http://localhost:8080/tomcat.gif");
display.setCurrent(form);
}

public void loadImage(String URL) {
Image image = getImageFromURL(URL);
if (image != null) {
int imageWidth = image.getWidth();
int imageHeight = image.getHeight();
int[] imageData = new int[imageWidth * imageHeight];
image.getRGB(imageData, 0, imageWidth, 0, 0, imageWidth,
imageHeight);
byte[] data = new byte[imageWidth * imageHeight * 4];
convertIntArrayToByteArray(imageData, data);
storeImage(imageWidth, imageHeight, data);
}
}

public void convertIntArrayToByteArray(int[] imageData, byte[] data) {
int dataLength = imageData.length;
for (int i = 0; i < dataLength; i++) {
int k = imageData[i];
for (int j = 0; j < 4; j++) {
byte b = (byte) (k >> j * 8 & 0x00FF);
data[i * 4 + j] = b;
}
}
}

public void storeImage(int imageWidth, int imageHeight, byte[] data) {

try {
RecordStore.deleteRecordStore("StoreImage");
} catch (RecordStoreNotFoundException e) {
e.printStackTrace();
} catch (RecordStoreException e) {
e.printStackTrace();
}

try {
RecordStore rs = RecordStore.openRecordStore("StoreImage", true);
if (rs != null) {
byte[] b = null;
b = String.valueOf(imageWidth).getBytes();
rs.addRecord(b, 0, b.length);
b = String.valueOf(imageHeight).getBytes();
rs.addRecord(b, 0, b.length);
rs.addRecord(data, 0, data.length);
}
rs.closeRecordStore();
} catch (RecordStoreFullException e) {
e.printStackTrace();
} catch (RecordStoreNotFoundException e) {
e.printStackTrace();
} catch (RecordStoreException e) {
e.printStackTrace();
}
}

public void readImage() {
byte[] data = null;
int imageWidth = 0;
int imageHeight = 0;

try {
RecordStore rs = RecordStore.openRecordStore("StoreImage", true);
if (rs != null) {
int recordNum = rs.getNumRecords();
if (recordNum < 3)
return;
byte[] b = null;
String s = null;
b = rs.getRecord(1);
s = new String(b);
imageWidth = Integer.valueOf(s).intValue();
b = rs.getRecord(2);
s = new String(b);
imageHeight = Integer.valueOf(s).intValue();
data = rs.getRecord(3);
}
rs.closeRecordStore();
} catch (RecordStoreFullException e) {
e.printStackTrace();
} catch (RecordStoreNotFoundException e) {
e.printStackTrace();
} catch (RecordStoreException e) {
e.printStackTrace();
}
if (data != null) {
int[] imageData = new int[(int) (data.length / 4)];
convertByteArrayToIntArray(data, imageData);
displayImage(imageData, imageWidth, imageHeight);
}
}

public void convertByteArrayToIntArray(byte[] data, int[] imageData) {
int dataLength = data.length;
for (int i = 0; i < dataLength; i = i + 4) {
int j = (data[i] & 0x000000FF) | (data[i + 1] << 8 & 0x0000FF00)
| (data[i + 2] << 16 & 0x00FF0000)
| (data[i + 3] << 24 & 0xFF000000);
imageData[i / 4] = j;
}
}

public void displayImage(int[] imageData, int imageWidth, int imageHeight) {
Image image = null;
image = Image.createRGBImage(imageData, imageWidth, imageHeight, false);
form.append(image);
}

public Image getImageFromURL(String url) {
byte[] result = null;
HttpConnection hcon;
DataOutputStream os;
DataInputStream is = null;
int length = 0;
try {
hcon = (HttpConnection) Connector.open(url, Connector.READ_WRITE);
hcon.setRequestMethod(HttpConnection.POST);
hcon.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
os = hcon.openDataOutputStream();
int rc = hcon.getResponseCode();
if (rc == HttpConnection.HTTP_OK) {
is = new DataInputStream(hcon.openDataInputStream());
length = (int) hcon.getLength();
byte[] b = new byte[length];
int index = 0, hasRead = 0;
while (hasRead != -1 && index < length) {
hasRead = is.read(b, index, length - index);
index += hasRead;
}
result = b;
}
is.close();
os.close();
hcon.close();
} catch (Exception ex) {
return null;
} finally {
}
return Image.createImage(result, 0, length);
}

public void commandAction(Command c, Displayable d) {
if (c == command) {
readImage();
}
}
}