Java 图片压缩实现思路及代码

java图片压缩代码

package com.img;
import java.awt.image;
import java.awt.image.bufferedimage;
import java.io.file;
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;
/**
*
* @author 可乐加糖
*/
public class compresspicdemo {
private file file = null; // 文件对象
private string inputdir; // 输入图路径
private string outputdir; // 输出图路径
private string inputfilename; // 输入图文件名
private string outputfilename; // 输出图文件名
private int outputwidth = 100; // 默认输出图片宽
private int outputheight = 100; // 默认输出图片高
private boolean proportion = true; // 是否等比缩放标记(默认为等比缩放)
public compresspicdemo() { // 初始化变量
inputdir = "";
outputdir = "";
inputfilename = "";
outputfilename = "";
outputwidth = 100;
outputheight = 100;
}
public void setinputdir(string inputdir) {
this.inputdir = inputdir;
}
public void setoutputdir(string outputdir) {
this.outputdir = outputdir;
}
public void setinputfilename(string inputfilename) {
this.inputfilename = inputfilename;
}
public void setoutputfilename(string outputfilename) {
this.outputfilename = outputfilename;
}
public void setoutputwidth(int outputwidth) {
this.outputwidth = outputwidth;
}
public void setoutputheight(int outputheight) {
this.outputheight = outputheight;
}
public void setwidthandheight(int width, int height) {
this.outputwidth = width;
this.outputheight = height;
}
/*
* 获得图片大小
* 传入参数 string path ：图片路径
*/
public long getpicsize(string path) {
file = new file(path);
return file.length();
}
// 图片处理
public string compresspic() {
try {
//获得源文件
file = new file(inputdir + inputfilename);
if (!file.exists()) {
return "";
}
image img = imageio.read(file);
// 判断图片格式是否正确
if (img.getwidth(null) == -1) {
system.out.println(" can't read,retry!" + "<br>");
return "no";
} else {
int newwidth; int newheight;
// 判断是否是等比缩放
if (this.proportion == 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) outputwidth + 0.1;
double rate2 = ((double) img.getheight(null)) / (double) outputheight + 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 = img.getwidth(null); // 输出的图片宽度
newheight = img.getheight(null); // 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(outputdir + outputfilename);
// jpegimageencoder可适用于其他图片类型的转换
jpegimageencoder encoder = jpegcodec.createjpegencoder(out);
encoder.encode(tag);
out.close();
}
} catch (ioexception ex) {
ex.printstacktrace();
}
return "ok";
}
public string compresspic (string inputdir, string outputdir, string inputfilename, string outputfilename) {
// 输入图路径
this.inputdir = inputdir;
// 输出图路径
this.outputdir = outputdir;
// 输入图文件名
this.inputfilename = inputfilename;
// 输出图文件名
this.outputfilename = outputfilename;
return compresspic();
}
public string compresspic(string inputdir, string outputdir, string inputfilename, string outputfilename, int width, int height, boolean gp) {
// 输入图路径
this.inputdir = inputdir;
// 输出图路径
this.outputdir = outputdir;
// 输入图文件名
this.inputfilename = inputfilename;
// 输出图文件名
this.outputfilename = outputfilename;
// 设置图片长宽
setwidthandheight(width, height);
// 是否是等比缩放 标记
this.proportion = gp;
return compresspic();
}
// main测试
// compresspic(大图片路径,生成小图片路径,大图片文件名,生成小图片文名,生成小图片宽度,生成小图片高度,是否等比缩放(默认为true))
public static void main(string[] arg) {
compresspicdemo mypic = new compresspicdemo();
system.out.println("输入的图片大小：" + mypic.getpicsize("e:\\1.jpg")/1024 + "kb");
mypic.compresspic("e:\\", "e:\\test\\", "1.jpg", "r1.jpg", 120, 120, false);
}
}