(转)JAVA生成缩略图

来源: http://wing929.javaeye.com/blog/185508

方法1：[第一种方法比后一种生成的缩略图要清晰]

Java代码

1. importjavax.imageio.ImageIO;
2. importjava.awt.image.BufferedImage;
3. importjava.awt.image.ColorModel;
4. importjava.awt.image.WritableRaster;
5. importjava.awt.*;
6. importjava.awt.geom.AffineTransform;
7. importjava.io.InputStream;
8. importjava.io.File;
9. importjava.io.FileOutputStream;
11. publicclassTest{
12. publicstaticBufferedImageresize(BufferedImagesource,inttargetW,inttargetH){
13. //targetW，targetH分别表示目标长和宽
14. inttype=source.getType();
15. BufferedImagetarget=null;
16. doublesx=(double)targetW/source.getWidth();
17. doublesy=(double)targetH/source.getHeight();
18. //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
19. //则将下面的ifelse语句注释即可
20. if(sx>sy)
21. {
22. sx=sy;
23. targetW=(int)(sx*source.getWidth());
24. }else{
25. sy=sx;
26. targetH=(int)(sy*source.getHeight());
27. }
28. if(type==BufferedImage.TYPE_CUSTOM){//handmade
29. ColorModelcm=source.getColorModel();
30. WritableRasterraster=cm.createCompatibleWritableRaster(targetW,targetH);
31. booleanalphaPremultiplied=cm.isAlphaPremultiplied();
32. target=newBufferedImage(cm,raster,alphaPremultiplied,null);
33. }else
34. target=newBufferedImage(targetW,targetH,type);
35. Graphics2Dg=target.createGraphics();
36. //smootherthanexlax:
37. g.setRenderingHint(RenderingHints.KEY_RENDERING,RenderingHints.VALUE_RENDER_QUALITY);
38. g.drawRenderedImage(source,AffineTransform.getScaleInstance(sx,sy));
39. g.dispose();
40. returntarget;
41. }
42. publicstaticvoidsaveImageAsJpg(StringfromFileStr,StringsaveToFileStr,intwidth,inthight)
43. throwsException{
44. BufferedImagesrcImage;
45. //Stringex=fromFileStr.substring(fromFileStr.indexOf("."),fromFileStr.length());
46. StringimgType="JPEG";
47. if(fromFileStr.toLowerCase().endsWith(".png")){
48. imgType="PNG";
49. }
50. //System.out.println(ex);
51. FilesaveFile=newFile(saveToFileStr);
52. FilefromFile=newFile(fromFileStr);
53. srcImage=ImageIO.read(fromFile);
54. if(width>0||hight>0)
55. {
56. srcImage=resize(srcImage,width,hight);
57. }
58. ImageIO.write(srcImage,imgType,saveFile);
60. }
62. publicstaticvoidmain(Stringargv[]){
63. try{
64. //参数1(from),参数2(to),参数3(宽),参数4(高)
65. Test.saveImageAsJpg("E:/Document/MyPictures/3.gif","c:/6.gif",50,50);
66. }catch(Exceptione)
67. {
68. e.printStackTrace();
69. }
71. }
72. }

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.WritableRaster;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.io.InputStream;
import java.io.File;
import java.io.FileOutputStream;

public class Test {
 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.createCompatibleWritableRaster(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)
 Test.saveImageAsJpg("E:/Document/My Pictures/3.gif","c:/6.gif",50,50);
 } catch(Exception e)
 {
 e.printStackTrace();
 }

 }
}

方法2：

Java代码

1. importjava.io.*;
2. importjava.util.*;
3. importcom.sun.image.codec.jpeg.*;
4. importjava.awt.image.*;
5. importjava.awt.*;
6. importjava.net.*;
7. importjava.applet.*;
8. importjava.sql.*;
10. //缩略图类，
11. //本java类能将jpg图片文件，进行等比或非等比的大小转换。
12. //具体使用方法
13. //s_pic(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))
14. publicclassTes{
15. StringInputDir;//输入图路径
16. StringOutputDir;//输出图路径
17. StringInputFileName;//输入图文件名
18. StringOutputFileName;//输出图文件名
19. intOutputWidth=80;//默认输出图片宽
20. intOutputHeight=80;//默认输出图片高
21. intrate=0;
22. booleanproportion=true;//是否等比缩放标记(默认为等比缩放)
24. publicTes(){
25. //初始化变量
26. InputDir="";
27. OutputDir="";
28. InputFileName="";
29. OutputFileName="";
30. OutputWidth=80;
31. OutputHeight=80;
32. rate=0;
33. }
35. publicvoidsetInputDir(StringInputDir){
36. this.InputDir=InputDir;
37. }
39. publicvoidsetOutputDir(StringOutputDir){
40. this.OutputDir=OutputDir;
41. }
43. publicvoidsetInputFileName(StringInputFileName){
44. this.InputFileName=InputFileName;
45. }
47. publicvoidsetOutputFileName(StringOutputFileName){
48. this.OutputFileName=OutputFileName;
49. }
51. publicvoidsetOutputWidth(intOutputWidth){
52. this.OutputWidth=OutputWidth;
53. }
55. publicvoidsetOutputHeight(intOutputHeight){
56. this.OutputHeight=OutputHeight;
57. }
59. publicvoidsetW_H(intwidth,intheight){
60. this.OutputWidth=width;
61. this.OutputHeight=height;
62. }
64. publicStrings_pic(){
65. BufferedImageimage;
66. StringNewFileName;
67. //建立输出文件对象
68. Filefile=newFile(OutputDir+OutputFileName);
69. FileOutputStreamtempout=null;
70. try{
71. tempout=newFileOutputStream(file);
72. }catch(Exceptionex){
73. System.out.println(ex.toString());
74. }
75. Imageimg=null;
76. Toolkittk=Toolkit.getDefaultToolkit();
77. Appletapp=newApplet();
78. MediaTrackermt=newMediaTracker(app);
79. try{
80. img=tk.getImage(InputDir+InputFileName);
81. mt.addImage(img,0);
82. mt.waitForID(0);
83. }catch(Exceptione){
84. e.printStackTrace();
85. }
87. if(img.getWidth(null)==-1){
88. System.out.println("can'tread,retry!"+"<BR>");
89. return"no";
90. }else{
91. intnew_w;
92. intnew_h;
93. if(this.proportion==true){//判断是否是等比缩放.
94. //为等比缩放计算输出的图片宽度及高度
95. doublerate1=((double)img.getWidth(null))/
96. (double)OutputWidth+0.1;
97. doublerate2=((double)img.getHeight(null))/
98. (double)OutputHeight+0.1;
99. doublerate=rate1>rate2?rate1:rate2;
100. new_w=(int)(((double)img.getWidth(null))/rate);
101. new_h=(int)(((double)img.getHeight(null))/rate);
102. }else{
103. new_w=OutputWidth;//输出的图片宽度
104. new_h=OutputHeight;//输出的图片高度
105. }
106. BufferedImagebuffImg=newBufferedImage(new_w,new_h,
107. BufferedImage.TYPE_INT_RGB);
109. Graphicsg=buffImg.createGraphics();
111. g.setColor(Color.white);
112. g.fillRect(0,0,new_w,new_h);
114. g.drawImage(img,0,0,new_w,new_h,null);
115. g.dispose();
117. JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(tempout);
118. try{
119. encoder.encode(buffImg);
120. tempout.close();
121. }catch(IOExceptionex){
122. System.out.println(ex.toString());
123. }
124. }
125. return"ok";
126. }
128. publicStrings_pic(StringInputDir,StringOutputDir,StringInputFileName,
129. StringOutputFileName){
130. //输入图路径
131. this.InputDir=InputDir;
132. //输出图路径
133. this.OutputDir=OutputDir;
134. //输入图文件名
135. this.InputFileName=InputFileName;
136. //输出图文件名
137. this.OutputFileName=OutputFileName;
138. returns_pic();
139. }
141. publicStrings_pic(StringInputDir,StringOutputDir,StringInputFileName,
142. StringOutputFileName,intwidth,intheight,
143. booleangp){
144. //输入图路径
145. this.InputDir=InputDir;
146. //输出图路径
147. this.OutputDir=OutputDir;
148. //输入图文件名
149. this.InputFileName=InputFileName;
150. //输出图文件名
151. this.OutputFileName=OutputFileName;
152. //设置图片长宽
153. setW_H(width,height);
154. //是否是等比缩放标记
155. this.proportion=gp;
156. returns_pic();
157. }
159. publicstaticvoidmain(String[]a){
160. //s_pic(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)
161. Tesmypic=newTes();
162. System.out.println(
163. mypic.s_pic("E:\Document\MyPictures\",
164. "E:\Document\MyPictures\",
165. "topbg-3.gif","3.gif",400,400,true)
166. );
168. }
169. }