我很难搞清楚如何在Java applet中显示Image（或ImageIcon）。以下是我的代码。图片（test.bmp）确实存在，并且位于D驱动器上，但是当我运行它时，我得到了没有任何内容的小程序窗口。有人可以告诉我我失去了什么ImageIcon秀？如何在Java applet中显示位图图像？
public class Form1 extends JApplet {
ImageIcon i;
public void init(){
i = new ImageIcon("D:\test.bmp");
}
public void paint(Graphics g){
i.paintIcon(this, g, 0, 0);
}
}
谢谢，史蒂夫。
通过本地绝对引用您的图像从服务器运行applet时文件路径可能不起作用。
使用ImageIcon（URL位置）构造函数和
使URL指向服务器上的图像资源。使用JApplet.getCodeBase（）来确定applet的起源位置并将文件名附加到它。
public class Form1 extends JApplet {
Image i;
public void init() {
try {
i = ImageIO.read(new URL(getCodeBase(), "test.bmp"));
} catch (MalformedURLException ex) {
ex.printStackTrace();
} catch (IOException ex) {
ex.printStackTrace();
}
}
public void paint(Graphics g) {
g.drawImage(i, 0, 0, null);
}
}
编辑： ImageIO的支持BMP和改变样品为我工作。
编辑2：如果仍然不显示图像，请尝试“../test.bmp”，因为当你运行一个小程序，从可以说的Eclipse它有bin目录作为基本代码。
编辑3：如果你把你的测试。BMP放进瓶子里或在classpath中，则可以使用相同的方法，但与
Form1.class.getResource("test.bmp")
首先，将\ \正确地转义为\\可能是一个好主意。
修改为添加：您可能想要了解与Path.combine（或File.join）等效的语言（或库），这是一种获取文件路径部分列表的方法，并将它们与平台相关路径分隔符。或者你可以用Java快速编写它，因为路径分隔符记录在File.pathSeparator。 （关于我的头顶，我不知道正斜杠总是在ImageIcon中工作，但请注意另一个表示这个的响应）。
此外，请确保您正在加载受支持的文件类型，例如.png，.gif或.jpg。 BMP可能在JDK 1.5中受支持
此外，如果您在Applet上下文中运行，由于沙箱规则，您可能无法访问有问题的路径。在这种情况下，请使用与托管applet的HTML文件相同的路径（可能在Jar的路径中，如果内存为我服务），并使用相对路径。
指定路径时，使用 Internet标准正斜杠（ “/”） 作为分隔符
而不是让被告知要自己绘制到图形一个ImageIcon的更换
new URL(getCodeBase(), "test.bmp")
加载，请尝试它这样：
public class Form1 extends JApplet {
Image i;
public void init(){
i = getImage("D:\\test.bmp");
}
public void paint(Graphics g){
g.drawImage(i,0,0,this);
}
}
此外，您可能想尝试使用.png而不是.bmp文件。
在java中不支持bmp文件。
你或许应该考虑unsing其他格式例如.png，gif或.jpg文件
如果你真的HAVE做到这一点，这里是从Java世界，解释如何读取位图文件的文章并解释它。
Java Tip 43: How to read 8- and 24-bit Microsoft Windows bitmaps in Java applications从JavaWorld
我从来没有尝试过，虽然
ImageJ是具有5月格式，包括BMP支持开源应用程序/库。
下面是使用BMPDecoder从ImageJ的一些实际的代码：
import java.awt.image.ColorModel;
import java.awt.image.IndexColorModel;
import java.awt.image.MemoryImageSource;
import java.io.IOException;
import java.io.InputStream;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class BMPDecoder {
InputStream is;
int curPos = 0;
int bitmapOffset; // starting position of image data
int width; // image width in pixels
int height; // image height in pixels
short bitsPerPixel; // 1, 4, 8, or 24 (no color map)
int compression; // 0 (none), 1 (8-bit RLE), or 2 (4-bit RLE)
int actualSizeOfBitmap;
int scanLineSize;
int actualColorsUsed;
byte r[], g[], b[]; // color palette
int noOfEntries;
byte[] byteData; // Unpacked data
int[] intData; // Unpacked data
boolean topDown;
private int readInt() throws IOException {
int b1 = is.read();
int b2 = is.read();
int b3 = is.read();
int b4 = is.read();
curPos += 4;
return ((b4 << 24) + (b3 << 16) + (b2 << 8) + (b1 << 0));
}
private short readShort() throws IOException {
int b1 = is.read();
int b2 = is.read();
curPos += 2;
return (short) ((b2 << 8) + b1);
}
void getFileHeader() throws IOException, Exception {
// Actual contents (14 bytes):
short fileType = 0x4d42;// always "BM"
int fileSize; // size of file in bytes
short reserved1 = 0; // always 0
short reserved2 = 0; // always 0
fileType = readShort();
if (fileType != 0x4d42)
throw new Exception("Not a BMP file"); // wrong file type
fileSize = readInt();
reserved1 = readShort();
reserved2 = readShort();
bitmapOffset = readInt();
}
void getBitmapHeader() throws IOException {
// Actual contents (40 bytes):
int size; // size of this header in bytes
short planes; // no. of color planes: always 1
int sizeOfBitmap; // size of bitmap in bytes (may be 0: if so,
// calculate)
int horzResolution; // horizontal resolution, pixels/meter (may be 0)
int vertResolution; // vertical resolution, pixels/meter (may be 0)
int colorsUsed; // no. of colors in palette (if 0, calculate)
int colorsImportant; // no. of important colors (appear first in
// palette) (0 means all are important)
int noOfPixels;
size = readInt();
width = readInt();
height = readInt();
planes = readShort();
bitsPerPixel = readShort();
compression = readInt();
sizeOfBitmap = readInt();
horzResolution = readInt();
vertResolution = readInt();
colorsUsed = readInt();
colorsImportant = readInt();
topDown = (height < 0);
if (topDown)
height = -height;
noOfPixels = width * height;
// Scan line is padded with zeroes to be a multiple of four bytes
scanLineSize = ((width * bitsPerPixel + 31)/32) * 4;
actualSizeOfBitmap = scanLineSize * height;
if (colorsUsed != 0)
actualColorsUsed = colorsUsed;
else
// a value of 0 means we determine this based on the bits per pixel
if (bitsPerPixel < 16)
actualColorsUsed = 1 << bitsPerPixel;
else
actualColorsUsed = 0; // no palette
}
void getPalette() throws IOException {
noOfEntries = actualColorsUsed;
// IJ.write("noOfEntries: " + noOfEntries);
if (noOfEntries > 0) {
r = new byte[noOfEntries];
g = new byte[noOfEntries];
b = new byte[noOfEntries];
int reserved;
for (int i = 0; i < noOfEntries; i++) {
b[i] = (byte) is.read();
g[i] = (byte) is.read();
r[i] = (byte) is.read();
reserved = is.read();
curPos += 4;
}
}
}
void unpack(byte[] rawData, int rawOffset, int bpp, byte[] byteData,
int byteOffset, int w) throws Exception {
int j = byteOffset;
int k = rawOffset;
byte mask;
int pixPerByte;
switch (bpp) {
case 1:
mask = (byte) 0x01;
pixPerByte = 8;
break;
case 4:
mask = (byte) 0x0f;
pixPerByte = 2;
break;
case 8:
mask = (byte) 0xff;
pixPerByte = 1;
break;
default:
throw new Exception("Unsupported bits-per-pixel value: " + bpp);
}
for (int i = 0;;) {
int shift = 8 - bpp;
for (int ii = 0; ii < pixPerByte; ii++) {
byte br = rawData[k];
br >>= shift;
byteData[j] = (byte) (br & mask);
// System.out.println("Setting byteData[" + j + "]=" +
// Test.byteToHex(byteData[j]));
j++;
i++;
if (i == w)
return;
shift -= bpp;
}
k++;
}
}
void unpack24(byte[] rawData, int rawOffset, int[] intData, int intOffset,
int w) {
int j = intOffset;
int k = rawOffset;
int mask = 0xff;
for (int i = 0; i < w; i++) {
int b0 = (((int) (rawData[k++])) & mask);
int b1 = (((int) (rawData[k++])) & mask) << 8;
int b2 = (((int) (rawData[k++])) & mask) << 16;
intData[j] = 0xff000000 | b0 | b1 | b2;
j++;
}
}
void unpack32(byte[] rawData, int rawOffset, int[] intData, int intOffset,
int w) {
int j = intOffset;
int k = rawOffset;
int mask = 0xff;
for (int i = 0; i < w; i++) {
int b0 = (((int) (rawData[k++])) & mask);
int b1 = (((int) (rawData[k++])) & mask) << 8;
int b2 = (((int) (rawData[k++])) & mask) << 16;
int b3 = (((int) (rawData[k++])) & mask) << 24; // this gets
// ignored!
intData[j] = 0xff000000 | b0 | b1 | b2;
j++;
}
}
void getPixelData() throws IOException, Exception {
byte[] rawData; // the raw unpacked data
// Skip to the start of the bitmap data (if we are not already there)
long skip = bitmapOffset - curPos;
if (skip > 0) {
is.skip(skip);
curPos += skip;
}
int len = scanLineSize;
if (bitsPerPixel > 8)
intData = new int[width * height];
else
byteData = new byte[width * height];
rawData = new byte[actualSizeOfBitmap];
int rawOffset = 0;
int offset = (height - 1) * width;
for (int i = height - 1; i >= 0; i--) {
int n = is.read(rawData, rawOffset, len);
if (n < len)
throw new Exception("Scan line ended prematurely after " + n
+ " bytes");
if (bitsPerPixel == 24)
unpack24(rawData, rawOffset, intData, offset, width);
else if (bitsPerPixel == 32)
unpack32(rawData, rawOffset, intData, offset, width);
else
// 8-bits or less
unpack(rawData, rawOffset, bitsPerPixel, byteData, offset,
width);
rawOffset += len;
offset -= width;
}
}
public void read(InputStream is) throws IOException, Exception {
this.is = is;
getFileHeader();
getBitmapHeader();
if (compression != 0)
throw new Exception("Compression not supported");
getPalette();
getPixelData();
}
public MemoryImageSource makeImageSource() {
ColorModel cm;
MemoryImageSource mis;
if (noOfEntries > 0) {
// There is a color palette; create an IndexColorModel
cm = new IndexColorModel(bitsPerPixel, noOfEntries, r, g, b);
} else {
// There is no palette; use the default RGB color model
cm = ColorModel.getRGBdefault();
}
// Create MemoryImageSource
if (bitsPerPixel > 8) {
// use one int per pixel
mis = new MemoryImageSource(width, height, cm, intData, 0, width);
} else {
// use one byte per pixel
mis = new MemoryImageSource(width, height, cm, byteData, 0, width);
}
return mis; // this can be used by Component.createImage()
}
public static void main(String[] aqgs) {
BMPDecoder bd = new BMPDecoder();
try {
bd.read(BMPDecoder.class.getResourceAsStream("bmp.bmp"));
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
JFrame jf = new JFrame();
JLabel jl = new JLabel();
ImageIcon ii = new ImageIcon(jl.createImage(bd.makeImageSource()));
jl.setIcon(ii);
jf.add(jl);
jf.pack();
jf.setVisible(true);
}
}
我想我们有一个赢家。如果他将他的文件命名为“imagetest.bmp”，那么问题就很明显了。 – 2009-06-25 17:56:43
+1这可能是问题所在。您没有收到编译器错误的唯一原因是因为“\ t”是制表符的有效转义序列。 – 2009-06-25 17:56:56