关于swt中image的图片信息保存，bitmapdata的用法
bitmapdata其实就是一个图片的信息值，比如一个图片是100*100的size，那么它就有10000个像素点，每个像素点其实就一个颜色值。这个颜色值就是一个32位的ARGB值，用uint整数类型表示，即alpha 和red green blue 三原色。这样的数组组成了所有的图片。0xFF669900表示一个不透明的橙色，其中0X 表示16进制，FF就是就是16进制中2位数的最大值，0XFF相当于100%的意思，669900就是三原色。然后这10000个像素点再交给cpu描绘，就成了图片了。
所以，如果能将bitmapdata保存起来，其实可以达到减少内存的浪费。
以下是我封装好的image类，包含了对bitmapdata的存储，和再利用
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.ImageLoader;
import org.eclipse.swt.widgets.Display;
/**
* @author cr.wu
* */
public class ImageFoctory {
private static HashMap<String, ImageData> hm = new HashMap<String, ImageData>();
/**
* 读取图片，并设置size
* */
public static Image getImg(Display d,String path,int width,int height){
ImageData data = hm.get(path);
if(data == null){
File file = new File(path);
Image image ;
if(path.contains("http")){
image = getNetJPG(path);
}else{
if(!file.exists()){
return null;
}
image = new Image(d, path);
}
data = image.getImageData();
hm.put(path, data);
}
Image image = new Image(d, data);
return setSize(image,width,height);
}
public static Image getImg(String path,int width,int height){
return getImg(Display.getCurrent(), path,width,height);
}
public static Image getImg(String path){
return getImg( path,-1,-1);
}
/**
* 设置图片的大小?
* */
public static Image setSize(Image image ,int width,int height){
if(width == -1&&height == -1){
return image;
}
if(height == -1){
height = image.getImageData().height;
}
if(width == -1){
width = image.getImageData().width;
}
Image imageNew = new Image(Display.getCurrent(), width, height);
GC gc = new GC(imageNew);
gc.drawImage(image, 0, 0, image.getImageData().width, image.getImageData().height, 0, 0, width, height);
gc.dispose();
image.dispose();//原图片资源释
return imageNew;
}
public static Display display(){
return Display.getCurrent();
}
/**
* 获取网络上的图片
* */
public static Image getNetJPG(String u){
InputStream in = getNetJPGStream(u);
Image image = new Image(display(), in);
return image;
}
/**
* 获取jpg的流
* */
public static InputStream getNetJPGStream(String u){
URL url;
InputStream inStream = null;
try {
url = new URL(u);
// 打开链接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
// 设置请求方式�?GET"
conn.setRequestMethod("GET");
// 超时响应时间�?�?
conn.setConnectTimeout(5 * 1000);
// 通过输入流获取图片数�?
inStream = conn.getInputStream();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return inStream;
}
/**
* 将流保存成图片，存到本地
* */
public static void inputToNative(InputStream in ,String savePath){
int format = checkPicFormat(savePath);
ImageData data = null;
Image image = new Image(display(), in);
data = image.getImageData();
image.dispose();
// try {
//// in.close();
// } catch (IOException e) {
// // TODO Auto-generated catch block
// e.printStackTrace();
// }
ImageLoader l = new ImageLoader();
l.data = new ImageData[]{data};
l.save(savePath, format);
}
/**
* 将网络图片存到本地
* */
public static void netToNative(String netPath,String savePath,int[] size,int format){
if(format == 0){
format = checkPicFormat(netPath);
}
ImageData data = null;
if(hm.get(netPath) == null){
InputStream in = getNetJPGStream(netPath);
Image image = new Image(display(), in);
data = image.getImageData();
image.dispose();
try {
in.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
hm.put(netPath, data);
}else{
data = hm.get(netPath);
}
if(size!=null){
int width = data.width;
int height = data.height;
if(size[0] == 0){
size[0] = width;
}
if(size[1] == 1){
size[1] = height;
}
data = data.scaledTo(size[0], size[1]);
}
ImageLoader l = new ImageLoader();
l.data = new ImageData[]{data};
l.save(savePath, format);
}
/**
* 判断图片格式
* */
public static int checkPicFormat(String path){
if(path.length() == 0)return 0;
int format = 0;
String[] t = path.split("\\.");
String formatStr = t[t.length - 1];
if("jpeg".equals(formatStr)){
format = SWT.IMAGE_JPEG;
}else if("jpg".equals(formatStr)){
format = SWT.IMAGE_JPEG;
}else if("png".equals(formatStr)){
format = SWT.IMAGE_PNG;
}else if("bmp".equals(formatStr)){
format = SWT.IMAGE_BMP;
}else if("gif".equals(formatStr)){
format = SWT.IMAGE_GIF;
}else if("icon".equals(formatStr)){
format = SWT.IMAGE_ICO;
}
return format;
}
}
import java.io.File;
import java.io.InputStream;
import java.util.Date;
public class Simple {
public final static String IMAGE = System.getProperty("user.dir")+File.separatorChar+"img"+ File.separatorChar;
public final static String NET_PATH = "http://imgsrc.baidu.com/forum/w%3D580/sign=7ca61064472309f7e76fad1a420c0c39/4eb24a2442a7d933fb79e183ac4bd11372f00169.jpg";
public final static String NET_TO_NATIVE_PATH = IMAGE + "net_to_native.jpg";
/**
* @param args
*/
public static void main(String[] args) {
createFile(IMAGE,false);
String netPath = NET_PATH;
InputStream in = ImageFoctory.getNetJPGStream(netPath);//获取网络的图片
String path = NET_TO_NATIVE_PATH;
ImageFoctory.inputToNative(in, path);//保存到本地
/**记录时间开始用来比较*/
long t1 = new Date().getTime();
ImageFoctory.getImg(path);
long t2 = new Date().getTime();
ImageFoctory.getImg(path);
long t3 = new Date().getTime();
ImageFoctory.getImg(path);
long t4 = new Date().getTime();
System.out.println("第 1 次读取图片时，消耗： "+(t2 - t1)+" 毫秒");
System.out.println("第 2 次读取图片时，消耗： "+(t3 - t2)+" 毫秒");
System.out.println("第 3 次读取图片时，消耗： "+(t4 - t3)+" 毫秒");
System.err.println("完成----------------");
}
public static void createFile(String path, boolean cover) {
createFile(new File(path), cover);
}
/**
* 创建一个文件夹
* */
public static void createFile(File f, boolean cover) {
if (cover) {
System.out.println("fileUtil：覆盖。。" + f.getPath());
f.mkdirs();
return;
}
if (!f.exists()) {// 不存在则创建
System.out.println("fileUtil：创建。。" + f.getPath());
f.mkdirs();
}
}
}
下附全套源码。。
如果有什么bug请留言，我会尽快修正，谢谢