java缩小图片

可以使用Draw这个类,通过改变像素来改变存储大小,实例如下:

public_tatic_oolean_ompressPic(String_rcFilePath,_tring_escFilePath)_hrows_OException_

____File_ile=_ull;

____BufferedImage_rc=_ull;

____FileOutputStream_ut=_ull;

____ImageWriter_mgWrier;

____ImageWriteParam_mgWriteParams;

____//_付ㄐ赐计姆绞轿_jpg

____imgWrier=("jpg").next();

____imgWriteParams=_ew(

________null);

____//_褂醚顾,必须指定压缩方式为MODE_EXPLICIT

____(_EXPLICIT);

____//_饫镏付ㄑ顾酰某潭,参数qality是取值0~1范围内,

____((float)1);

____(_DISABLED);

____ColorModel_olorModel=(new_ile(srcFilePath)).getColorModel();//();

____//_付ㄑ顾跏笔褂玫纳誓J

//____(new(

//________colorModel,(16,16)));

____(new(

________colorModel,(16,16)));

____try_

______if(isBlank(srcFilePath))_

________return_alse;

______}_lse_

________file=_ew_ile(srcFilePath);(());

________src=(file);

________out=_ew_ileOutputStream(descFilePath);

________();

________//_匦胂戎付_out值,才能调用write方法,_mageOutputStream可以通过任何

________//_utputStream构造

________((out));

________//_饔_rite方法,就可以向输入流写图片

________(null,_ew_IOImage(src,_ull,_ull),

____________imgWriteParams);

________();

________();

______}

____}_atch(Exception_)_

______e.printStackTrace();

______return_alse;

____}

____return_rue;

__}

public_tatic_oolean_sBlank(String_tring)_

____if(string==_ull_|()==0_|().equals(""))_

______return_rue;

____}

____return_alse;

__}

⑤ java上传图片 生成缩略图，如果上传的图片尺寸比较小就压缩处理

//将图按比例缩小。
public static BufferedImage resize(BufferedImage source, int targetW, int targetH) {
// targetW，targetH分别表示目标长和宽
int type = source.getType();
BufferedImage target = null;
double sx = (double) targetW / source.getWidth();
double sy = (double) targetH / source.getHeight();
//这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放
//则将下面的if else语句注释即可
if(sx>sy)
{
sx = sy;
targetW = (int)(sx * source.getWidth());
}else{
sy = sx;
targetH = (int)(sy * source.getHeight());
}
if (type == BufferedImage.TYPE_CUSTOM) { //handmade
ColorModel cm = source.getColorModel();
WritableRaster raster = cm.(targetW, targetH);
boolean alphaPremultiplied = cm.isAlphaPremultiplied();
target = new BufferedImage(cm, raster, alphaPremultiplied, null);
} else
target = new BufferedImage(targetW, targetH, type);
Graphics2D g = target.createGraphics();
//smoother than exlax:
g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY );
g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
g.dispose();
return target;
}

public static void saveImageAsJpg (String fromFileStr,String saveToFileStr,int width,int hight)
throws Exception {
BufferedImage srcImage;
// String ex = fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
String imgType = "JPEG";
if (fromFileStr.toLowerCase().endsWith(".png")) {
imgType = "PNG";
}
// System.out.println(ex);
File saveFile=new File(saveToFileStr);
File fromFile=new File(fromFileStr);
srcImage = ImageIO.read(fromFile);
if(width > 0 || hight > 0)
{
srcImage = resize(srcImage, width, hight);
}
ImageIO.write(srcImage, imgType, saveFile);

}

public static void main (String argv[]) {
try{
//参数1(from),参数2(to),参数3(宽),参数4(高)
saveImageAsJpg("C:\\Documents and Settings\\xugang\\桌面\\tmr-06.jpg",
"C:\\Documents and Settings\\xugang\\桌面\\2.jpg",
120,120);
} catch(Exception e){
e.printStackTrace();
}

}