java等比例压缩

① java中怎么等比例压缩后,从中间取出图片.最好例子!谢谢大家

期待高手。

② java如何实现把一个大图片压缩到指定大小的图片且长宽比不变

java要实现把一个大图片压缩到指定大小的图片且长宽比不变可以尝试以下操作：

③ java 压缩比

ZipOutputStream

里面有
setMethodpublic void setMethod(int method)设置用于后续条目的默认压缩方法。只要没有为单个 ZIP 文件条目指定压缩方法，并且其初始设置为 DEFLATED 时，就使用此默认值。

参数：method - 默认压缩方法
抛出：IllegalArgumentException - 如果指定的压缩方法无效
setLevelpublic void setLevel(int level)为后续的 DEFLATED 条目设置压缩级别。默认设置是 DEFAULT_COMPRESSION。

参数：level - 压缩级别 (0-9)
抛出：IllegalArgumentException - 如果压缩级别无效

④ 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();
}

}

⑤ java将图片按比例缩小

Image srcImg = ImageIO.read(new FileInputStream(fnSrc) );//取源图
int width = 600; //假设要缩小到600点像素
int height = srcImg.getHeight(null)*600/srcImg.getWidth(null);//按比例，将高度缩减

System.out.println("Width: "+srcImg.getWidth(null));// 这几行是调试用
System.out.println("Height: "+srcImg.getHeight(null));
System.out.println("Width2: "+width);
System.out.println("Height2: "+height);

Image smallImg =srcImg.getScaledInstance(width, height, Image.SCALE_SMOOTH);//缩小

⑥ 您好！请问用java怎么将截取png的图片中间一部分，以及如何压缩一个png图片

• getSubimage方法是进行图片裁剪。

举例：
public static void main(String[] args) {
try {
//从特定文件载入
BufferedImage bi = ImageIO.read(new File("c:\test.png"));
bi.getSubimage(0, 0, 10, 10);//前两个值是坐标位置X、Y，后两个是长和宽
} catch (IOException e) {
e.printStackTrace();
}
}

• 以下是进行的图片压缩，涉及到多个工具类。
  

/**
* 图片工具类
* 压缩图片大小
* @author Cyw
* @version 1.0
*/
public class ZIPImage {

private File file = null;

private String outPutFilePath;

private String inPutFilePath;

private String inPutFileName;

private boolean autoBuildFileName;

private String outPutFileName;

private int outPutFileWidth = 100; // 默认输出图片宽

private int outPutFileHeight = 100; // 默认输出图片高

private static boolean isScaleZoom = true; // 是否按比例缩放

public ZIPImage() {
outPutFilePath = "";
inPutFilePath = "";
inPutFileName = "";
autoBuildFileName = true;
outPutFileName = "";
}

/**
*
* @param ipfp
* 源文件夹路径
* @param ipfn
* 源文件名
* @param opfp
* 目标文件路径
* @param opfn
* 目标文件名
*/
public ZIPImage(String ipfp, String ipfn, String opfp, String opfn) {
outPutFilePath = opfp;
inPutFilePath = ipfp;
inPutFileName = ipfn;
autoBuildFileName = true;
outPutFileName = opfn;
}

/**
*
* @param ipfp
* 源文件夹路径
* @param ipfn
* 源文件名
* @param opfp
* 目标文件路径
* @param opfn
* 目标文件名
* @param aBFN
* 是否自动生成目标文件名
*/
public ZIPImage(String ipfp, String ipfn, String opfp, String opfn,
boolean aBFN) {
outPutFilePath = opfp;
inPutFilePath = ipfp;
inPutFileName = ipfn;
autoBuildFileName = aBFN;
outPutFileName = opfn;
}

public boolean isAutoBuildFileName() {
return autoBuildFileName;
}

public void setAutoBuildFileName(boolean autoBuildFileName) {
this.autoBuildFileName = autoBuildFileName;
}

public String getInPutFilePath() {
return inPutFilePath;
}

public void setInPutFilePath(String inPutFilePath) {
this.inPutFilePath = inPutFilePath;
}

public String getOutPutFileName() {
return outPutFileName;
}

public void setOutPutFileName(String outPutFileName) {
this.outPutFileName = outPutFileName;
}

public String getOutPutFilePath() {
return outPutFilePath;
}

public void setOutPutFilePath(String outPutFilePath) {
this.outPutFilePath = outPutFilePath;
}

public int getOutPutFileHeight() {
return outPutFileHeight;
}

public void setOutPutFileHeight(int outPutFileHeight) {
this.outPutFileHeight = outPutFileHeight;
}

public int getOutPutFileWidth() {
return outPutFileWidth;
}

public void setOutPutFileWidth(int outPutFileWidth) {
this.outPutFileWidth = outPutFileWidth;
}

public boolean isScaleZoom() {
return isScaleZoom;
}

public void setScaleZoom(boolean isScaleZoom) {
this.isScaleZoom = isScaleZoom;
}

public String getInPutFileName() {
return inPutFileName;
}

public void setInPutFileName(String inPutFileName) {
this.inPutFileName = inPutFileName;
}

/**
* 压缩图片大小
*
* @return boolean
*/
public boolean compressImage() {
boolean flag = false;

try {
if (inPutFilePath.trim().equals("")) {
throw new NullPointerException("源文件夹路径不存在。");
}
if (inPutFileName.trim().equals("")) {
throw new NullPointerException("图片文件路径不存在。");
}
if (outPutFilePath.trim().equals("")) {
throw new NullPointerException("目标文件夹路径地址为空。");
} else {
if (!ZIPImage.mddir(outPutFilePath)) {
throw new FileNotFoundException(outPutFilePath
+ " 文件夹创建失败！");
}
}

if (this.autoBuildFileName) { // 自动生成文件名
String tempFile[] = getFileNameAndExtName(inPutFileName);
outPutFileName = tempFile[0] + "_cyw." + tempFile[1];
compressPic();
} else {
if (outPutFileName.trim().equals("")) {
throw new NullPointerException("目标文件名为空。");
}
compressPic();
}

} catch (Exception e) {
flag = false;
e.printStackTrace();
return flag;
}

return flag;
}

// 图片处理
private void compressPic() throws Exception {
try {
// 获得源文件
file = new File(inPutFilePath + inPutFileName);
if (!file.exists()) {
throw new FileNotFoundException(inPutFilePath + inPutFileName
+ " 文件不存在！");
}
Image img = ImageIO.read(file);
// 判断图片格式是否正确
if (img.getWidth(null) == -1) {
throw new Exception("文件不可读！");
} else {
int newWidth;
int newHeight;
// 判断是否是等比缩放
if (ZIPImage.isScaleZoom == true) {
// 为等比缩放计算输出的图片宽度及高度
double rate1 = ((double) img.getWidth(null))
/ (double) outPutFileWidth + 0.1;
double rate2 = ((double) img.getHeight(null))
/ (double) outPutFileHeight + 0.1;

// 根据缩放比率大的进行缩放控制
double rate = rate1 > rate2 ? rate1 : rate2;

newWidth = (int) (((double) img.getWidth(null)) / rate);
newHeight = (int) (((double) img.getHeight(null)) / rate);

} else {
newWidth = outPutFileWidth; // 输出的图片宽度
newHeight = outPutFileHeight; // 输出的图片高度
}

BufferedImage tag = new BufferedImage((int) newWidth,
(int) newHeight, BufferedImage.TYPE_INT_RGB);

/*
* Image.SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 优先级比速度高 生成的图片质量比较好 但速度慢
*/
tag.getGraphics().drawImage(
img.getScaledInstance(newWidth, newHeight,
Image.SCALE_SMOOTH), 0, 0, null);

FileOutputStream out = new FileOutputStream(outPutFilePath
+ outPutFileName);

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag);
out.close();

}
} catch (IOException ex) {
ex.printStackTrace();
}
}

/**
* 创建文件夹目录
*
* @param filePath
* @return
* @throws Exception
*/
@SuppressWarnings("unused")
private static boolean mddir(String filePath) throws Exception {
boolean flag = false;
File f = new File(filePath);
if (!f.exists()) {
flag = f.mkdirs();
} else {
flag = true;
}
return flag;
}

/**
* 获得文件名和扩展名
*
* @param fullFileName
* @return
* @throws Exception
*/
private String[] getFileNameAndExtName(String fullFileName)
throws Exception {
String[] fileNames = new String[2];
if (fullFileName.indexOf(".") == -1) {
throw new Exception("源文件名不正确！");
} else {
fileNames[0] = fullFileName.substring(0, fullFileName
.lastIndexOf("."));
fileNames[1] = fullFileName
.substring(fullFileName.lastIndexOf(".") + 1);
}
return fileNames;
}

public Image getSourceImage() throws IOException{
//获得源文件
file = new File(inPutFilePath + inPutFileName);
if (!file.exists()) {
throw new FileNotFoundException(inPutFilePath + inPutFileName
+ " 文件不存在！");
}
Image img = ImageIO.read(file);
return img;
}

/*
* 获得图片大小
* @path ：图片路径
*/
public long getPicSize(String path) {
File file = new File(path);
return file.length();
}

}

//下面是测试程序

package com.sun.util.cyw;

import java.awt.Image;
import java.io.IOException;

public class ImageTest {
public static void main(String[] args) throws IOException {
ZIPImage zip=new ZIPImage("d:\","1.jpg","d:\test\","处理后的图片.jpg",false);
zip.setOutPutFileWidth(1000);
zip.setOutPutFileHeight(1000);

Image image=zip.getSourceImage();
long size=zip.getPicSize("d:\1.jpg");
System.out.println("处理前的图片大小 width:"+image.getWidth(null));
System.out.println("处理前的图片大小 height:"+image.getHeight(null));
System.out.println("处理前的图片容量:"+ size +" bit");

zip.compressImage();
}
}

⑦ 求一个Java无损压缩图片的示例，把原图片复制到指定目录，按原图比例改变尺寸，不影响图片质量。

图片压缩就是讲图片的内存变小 对象数坑定有印象 你将压缩率改小一点 调整一下压缩率 到自己满意为止

⑧ java ssh实现微信端操作 有图片上传的地方 怎么能在上传到服务器之前进行等比例压缩

public class struts2UploadAction extends ActionSupport {

private File uploadFile;// 得到上传的文件

private String uploadFileContentType;// 得到文件的类型

private String uploadFileFileName;// 得到文件的名称

public String load() throws IOException {

String RealPath = ServletActionContext.getServletContext().getRealPath("/piction");
File file = new File(RealPath);
if(!file.exists()){
file.mkdirs();
}
FileUtils.File(uploadFile, new File(file,uploadFileFileName));
String path=RealPath+"/"+uploadFileFileName;
ServletActionContext.getRequest().setAttribute("realpath",path);
return "success";
}

public File getUploadFile() {
return uploadFile;
}

public void setUploadFile(File uploadFile) {
this.uploadFile = uploadFile;
}

public String getUploadFileContentType() {
return uploadFileContentType;
}

public void setUploadFileContentType(String uploadFileContentType) {
this.uploadFileContentType = uploadFileContentType;
}

public String getUploadFileFileName() {
return uploadFileFileName;
}

public void setUploadFileFileName(String uploadFileFileName) {
this.uploadFileFileName = uploadFileFileName;
}
}

⑨ java压缩png图片

您转换的是图片的后缀名吧？您这样的方式已经把图片的信息删除了！
http://sjbbs.zol.com.cn/1/313_9068.html您去下载一个java图片压缩器吧
或者直接在Java下编辑代码来实习转换
package com.sun.util.cyw;

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
* 图片工具类
* 压缩图片大小
* @author Cyw
* @version 1.0
*/
public class ZIPImage {

private File file = null;

private String outPutFilePath;

private String inPutFilePath;

private String inPutFileName;

private boolean autoBuildFileName;

private String outPutFileName;

private int outPutFileWidth = 100; // 默认输出图片宽

private int outPutFileHeight = 100; // 默认输出图片高

private static boolean isScaleZoom = true; // 是否按比例缩放

public ZIPImage() {
outPutFilePath = "";
inPutFilePath = "";
inPutFileName = "";
autoBuildFileName = true;
outPutFileName = "";
}

/**
*
* @param ipfp
* 源文件夹路径
* @param ipfn
* 源文件名
* @param opfp
* 目标文件路径
* @param opfn
* 目标文件名
*/
public ZIPImage(String ipfp, String ipfn, String opfp, String opfn) {
outPutFilePath = opfp;
inPutFilePath = ipfp;
inPutFileName = ipfn;
autoBuildFileName = true;
outPutFileName = opfn;
}

/**
*
* @param ipfp
* 源文件夹路径
* @param ipfn
* 源文件名
* @param opfp
* 目标文件路径
* @param opfn
* 目标文件名
* @param aBFN
* 是否自动生成目标文件名
*/
public ZIPImage(String ipfp, String ipfn, String opfp, String opfn,
boolean aBFN) {
outPutFilePath = opfp;
inPutFilePath = ipfp;
inPutFileName = ipfn;
autoBuildFileName = aBFN;
outPutFileName = opfn;
}

public boolean isAutoBuildFileName() {
return autoBuildFileName;
}

public void setAutoBuildFileName(boolean autoBuildFileName) {
this.autoBuildFileName = autoBuildFileName;
}

public String getInPutFilePath() {
return inPutFilePath;
}

public void setInPutFilePath(String inPutFilePath) {
this.inPutFilePath = inPutFilePath;
}

public String getOutPutFileName() {
return outPutFileName;
}

public void setOutPutFileName(String outPutFileName) {
this.outPutFileName = outPutFileName;
}

public String getOutPutFilePath() {
return outPutFilePath;
}

public void setOutPutFilePath(String outPutFilePath) {
this.outPutFilePath = outPutFilePath;
}

public int getOutPutFileHeight() {
return outPutFileHeight;
}

public void setOutPutFileHeight(int outPutFileHeight) {
this.outPutFileHeight = outPutFileHeight;
}

public int getOutPutFileWidth() {
return outPutFileWidth;
}

public void setOutPutFileWidth(int outPutFileWidth) {
this.outPutFileWidth = outPutFileWidth;
}

public boolean isScaleZoom() {
return isScaleZoom;
}

public void setScaleZoom(boolean isScaleZoom) {
this.isScaleZoom = isScaleZoom;
}

public String getInPutFileName() {
return inPutFileName;
}

public void setInPutFileName(String inPutFileName) {
this.inPutFileName = inPutFileName;
}

/**
* 压缩图片大小
*
* @return boolean
*/
public boolean compressImage() {
boolean flag = false;

try {
if (inPutFilePath.trim().equals("")) {
throw new NullPointerException("源文件夹路径不存在。");
}
if (inPutFileName.trim().equals("")) {
throw new NullPointerException("图片文件路径不存在。");
}
if (outPutFilePath.trim().equals("")) {
throw new NullPointerException("目标文件夹路径地址为空。");
} else {
if (!ZIPImage.mddir(outPutFilePath)) {
throw new FileNotFoundException(outPutFilePath
+ " 文件夹创建失败！");
}
}

if (this.autoBuildFileName) { // 自动生成文件名
String tempFile[] = getFileNameAndExtName(inPutFileName);
outPutFileName = tempFile[0] + "_cyw." + tempFile[1];
compressPic();
} else {
if (outPutFileName.trim().equals("")) {
throw new NullPointerException("目标文件名为空。");
}
compressPic();
}

} catch (Exception e) {
flag = false;
e.printStackTrace();
return flag;
}

return flag;
}

// 图片处理
private void compressPic() throws Exception {
try {
// 获得源文件
file = new File(inPutFilePath + inPutFileName);
if (!file.exists()) {
throw new FileNotFoundException(inPutFilePath + inPutFileName
+ " 文件不存在！");
}
Image img = ImageIO.read(file);
// 判断图片格式是否正确
if (img.getWidth(null) == -1) {
throw new Exception("文件不可读！");
} else {
int newWidth;
int newHeight;
// 判断是否是等比缩放
if (ZIPImage.isScaleZoom == true) {
// 为等比缩放计算输出的图片宽度及高度
double rate1 = ((double) img.getWidth(null))
/ (double) outPutFileWidth + 0.1;
double rate2 = ((double) img.getHeight(null))
/ (double) outPutFileHeight + 0.1;

// 根据缩放比率大的进行缩放控制
double rate = rate1 > rate2 ? rate1 : rate2;

newWidth = (int) (((double) img.getWidth(null)) / rate);
newHeight = (int) (((double) img.getHeight(null)) / rate);

} else {
newWidth = outPutFileWidth; // 输出的图片宽度
newHeight = outPutFileHeight; // 输出的图片高度
}

BufferedImage tag = new BufferedImage((int) newWidth,
(int) newHeight, BufferedImage.TYPE_INT_RGB);

/*
* Image.SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 优先级比速度高 生成的图片质量比较好 但速度慢
*/
tag.getGraphics().drawImage(
img.getScaledInstance(newWidth, newHeight,
Image.SCALE_SMOOTH), 0, 0, null);

FileOutputStream out = new FileOutputStream(outPutFilePath
+ outPutFileName);

JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(tag);
out.close();

}
} catch (IOException ex) {
ex.printStackTrace();
}
}

/**
* 创建文件夹目录
*
* @param filePath
* @return
* @throws Exception
*/
@SuppressWarnings("unused")
private static boolean mddir(String filePath) throws Exception {
boolean flag = false;
File f = new File(filePath);
if (!f.exists()) {
flag = f.mkdirs();
} else {
flag = true;
}
return flag;
}

/**
* 获得文件名和扩展名
*
* @param fullFileName
* @return
* @throws Exception
*/
private String[] getFileNameAndExtName(String fullFileName)
throws Exception {
String[] fileNames = new String[2];
if (fullFileName.indexOf(".") == -1) {
throw new Exception("源文件名不正确！");
} else {
fileNames[0] = fullFileName.substring(0, fullFileName
.lastIndexOf("."));
fileNames[1] = fullFileName
.substring(fullFileName.lastIndexOf(".") + 1);
}
return fileNames;
}

public Image getSourceImage() throws IOException{
//获得源文件
file = new File(inPutFilePath + inPutFileName);
if (!file.exists()) {
throw new FileNotFoundException(inPutFilePath + inPutFileName
+ " 文件不存在！");
}
Image img = ImageIO.read(file);
return img;
}

/*
* 获得图片大小
* @path ：图片路径
*/
public long getPicSize(String path) {
File file = new File(path);
return file.length();
}

}

//下面是测试程序

package com.sun.util.cyw;

import java.awt.Image;
import java.io.IOException;

public class ImageTest {
public static void main(String[] args) throws IOException {
ZIPImage zip=new ZIPImage("d:\\","1.jpg","d:\\test\\","处理后的图片.jpg",false);
zip.setOutPutFileWidth(1000);
zip.setOutPutFileHeight(1000);

Image image=zip.getSourceImage();
long size=zip.getPicSize("d:\\1.jpg");
System.out.println("处理前的图片大小 width:"+image.getWidth(null));
System.out.println("处理前的图片大小 height:"+image.getHeight(null));
System.out.println("处理前的图片容量:"+ size +" bit");

zip.compressImage();
}
}

⑩ java是怎么实现等比例缩小图片而不失真的啊

按照长宽的比例等比缩小，图片最好用矢量图片，不容易失真。。。