jsp_上传图片_代码

jsp_上传图片_代码 Apache commons-fileupload是一个很好的文件上传工具，最近使用commons-fileupload实现了图片的上传及显示，可将图片保存在指定的文件夹中，也可以将图片存放在数据库，并支持四种常用的图片:jpg,png,gif,bmp。 首先，跟上传一般文件一样，需要写一个servlet来处理上传的文件，你可以修改保存路径或选择将图片保存在数据库中，只需要做简单的修改就行了，servlet代码如下: FileUploadServlet.java java 代码 1. package com.ek.servlet; 2. import java.awt.image.BufferedImage; 3. import java.io.ByteArrayOutputStream; 4. import java.io.File; 5. import java.io.IOException; 6. import java.io.InputStream; 7. import java.util.Iterator; 8. import java.util.List; 9. import java.util.regex.Matcher; 10. import java.util.regex.Pattern; 11. import javax.servlet.ServletException; 12. import javax.servlet.http.HttpServlet; 13. import javax.servlet.http.HttpServletRequest; 14. import javax.servlet.http.HttpServletResponse; 15. import org.apache.commons.fileupload.FileItem; 16. import org.apache.commons.fileupload.FileUploadException; 17. import org.apache.commons.fileupload.disk.DiskFileItemFactory; 18. import org.apache.commons.fileupload.servlet.ServletFileUpload; 19. import com.ek.image.ImageUtil; 20. public class FileUploadServlet extends HttpServlet { 21. /** 22. * 23. */ 24. private static final long serialVersionUID = 1L; 25. private static String filePath = ""; 26. /** 27. * Destruction of the servlet. 28. */ 29. public void destroy() { 30. super.destroy(); // Just puts "destroy" string in log 31. // Put your code here 32. } 33. /** 34. * The doPost method of the servlet. 35. * 36. * This method is called when a form has its tag value method equals to 37. * post. 38. * 39. * @param request 40. * the request send by the client to the server 41. * @param response 42. * the response send by the server to the client 43. * @throws ServletException 44. * if an error occurred 45. * @throws IOException 46. * if an error occurred 47. */ 48. public void doPost(HttpServletRequest req, HttpServletResponse res) 49. throws ServletException, IOException { 50. res.setContentType("text/html; charset=UTF-8"); 51. DiskFileItemFactory factory = new DiskFileItemFactory(); 52. // maximum size that will be stored in memory 53. factory.setSizeThreshold(4096); 54. // the location for saving data that is larger than getSizeThreshold() 55. factory.setRepository(new File(filePath)); 56. ServletFileUpload upload = new ServletFileUpload(factory); 57. // maximum size before a FileUploadException will be thrown 58. upload.setSizeMax(1000000); 59. try { 60. List fileItems = upload.parseRequest(req); 61. Iterator iter = fileItems.iterator(); 62. // Get the file name 63. String regExp = ".+\\\\(.+\\.?())$"; 64. Pattern fileNamePattern = Pattern.compile(regExp); 65. while (iter.hasNext()) { 66. FileItem item = (FileItem) iter.next(); 67. if (!item.isFormField()) { 68. String name = item.getName(); 69. long size = item.getSize(); 70. if ((name == null || name.equals("")) && size == 0) 71. continue; 72. Matcher m = fileNamePattern.matcher(name); 73. boolean result = m.find(); 74. if (result) { 75. try { 76. // String type = 77. // m.group(1).substring(m.group(1).lastIndexOf('.')+1); 78. InputStream stream = item.getInputStream(); 79. ByteArrayOutputStream baos = new ByteArrayOutputStream(); 80. byte[] b = new byte[1000]; 81. while (stream.read(b) > 0) { 82. baos.write(b); 83. } 84. byte[] imageByte = baos.toByteArray(); 85. String type = ImageUtil.getImageType(imageByte); 86. if (type.equals(ImageUtil.TYPE_NOT_AVAILABLE)) 87. throw new Exception("file is not a image"); 88. BufferedImage myImage = ImageUtil 89. .readImage(imageByte); 90. // display the image 91. ImageUtil.printImage(myImage, type, res 92. .getOutputStream()); 93. // save the image 94. // if you want to save the file into database, do it here 95. // when you want to display the image, use the method printImage in ImageU til 96. item.write(new File(filePath + "\\" + m.group(1))); 97. 98. stream.close(); 99. baos.close(); 100. } catch (Exception e) { 101. e.printStackTrace(); 102. } 103. } else { 104. throw new IOException("fail to upload"); 105. } 106. } 107. } 108. } catch (IOException e) { 109. e.printStackTrace(); 110. } catch (FileUploadException e) { 111. e.printStackTrace(); 112. } 113. } 114. /** 115. * Initialization of the servlet. 116. * 117. * @throws ServletException 118. * if an error occure 119. */ 120. public void init() throws ServletException { 121. // Change the file path here 122. filePath = getServletContext().getRealPath("/"); 123. } 124. } servlet中使用到一个ImageUtil类，其中封装了图片处理的实用方法，用于读写图片，代码如下: ImageUtil.java java 代码 1. package com.ek.image; 2. import java.awt.Component; 3. import java.awt.Graphics2D; 4. import java.awt.GraphicsConfiguration; 5. import java.awt.GraphicsDevice; 6. import java.awt.GraphicsEnvironment; 7. import java.awt.Image; 8. import java.awt.MediaTracker; 9. import java.awt.image.BufferedImage; 10. import java.awt.image.ColorModel; 11. import java.awt.image.PixelGrabber; 12. import java.io.ByteArrayInputStream; 13. import java.io.IOException; 14. import java.io.InputStream; 15. import java.io.OutputStream; 16. import java.util.Iterator; 17. import javax.imageio.ImageIO; 18. import javax.imageio.ImageReader; 19. import javax.imageio.stream.MemoryCacheImageInputStream; 20. import net.jmge.gif.Gif89Encoder; 21. import org.apache.commons.logging.Log; 22. import org.apache.commons.logging.LogFactory; 23. import com.sun.imageio.plugins.bmp.BMPImageReader; 24. import com.sun.imageio.plugins.gif.GIFImageReader; 25. import com.sun.imageio.plugins.jpeg.JPEGImageReader; 26. import com.sun.imageio.plugins.png.PNGImageReader; 27. /** 28. * @author Erick Kong 29. * @see ImageUtil.java 30. * @createDate: 2007-6-22 31. * @version 1.0 32. */ 33. public class ImageUtil { 34. 35. public static final String TYPE_GIF = "gif"; 36. public static final String TYPE_JPEG = "jpeg"; 37. public static final String TYPE_PNG = "png"; 38. public static final String TYPE_BMP = "bmp"; 39. public static final String TYPE_NOT_AVAILABLE = "na"; 40. private static ColorModel getColorModel(Image image) 41. throws InterruptedException, IllegalArgumentException { 42. PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false); 43. if (!pg.grabPixels()) 44. throw new IllegalArgumentException(); 45. return pg.getColorModel(); 46. } 47. private static void loadImage(Image image) throws InterruptedException, 48. IllegalArgumentException { 49. Component dummy = new Component() { 50. private static final long serialVersionUID = 1L; 51. }; 52. MediaTracker tracker = new MediaTracker(dummy); 53. tracker.addImage(image, 0); 54. tracker.waitForID(0); 55. if (tracker.isErrorID(0)) 56. throw new IllegalArgumentException(); 57. } 58. public static BufferedImage createBufferedImage(Image image) 59. throws InterruptedException, IllegalArgumentException { 60. loadImage(image); 61. int w = image.getWidth(null); 62. int h = image.getHeight(null); 63. ColorModel cm = getColorModel(image); 64. GraphicsEnvironment ge = GraphicsEnvironment 65. .getLocalGraphicsEnvironment(); 66. GraphicsDevice gd = ge.getDefaultScreenDevice(); 67. GraphicsConfiguration gc = gd.getDefaultConfiguration(); 68. BufferedImage bi = gc.createCompatibleImage(w, h, cm.getTransparency()); 69. Graphics2D g = bi.createGraphics(); 70. g.drawImage(image, 0, 0, null); 71. g.dispose(); 72. return bi; 73. } 74. public static BufferedImage readImage(InputStream is) { 75. BufferedImage image = null; 76. try { 77. image = ImageIO.read(is); 78. } catch (IOException e) { 79. // TODO Auto-generated catch block 80. e.printStackTrace(); 81. } 82. return image; 83. } 84. 85. public static BufferedImage readImage(byte[] imageByte) { 86. ByteArrayInputStream bais = new ByteArrayInputStream(imageByte); 87. BufferedImage image = readImage(bais); 88. return image; 89. } 90. public static void encodeGIF(BufferedImage image, OutputStream out) 91. throws IOException { 92. Gif89Encoder encoder = new Gif89Encoder(image); 93. encoder.encode(out); 94. } 95. /** 96. * 97. * @param bi 98. * @param type 99. * @param out 100. */ 101. public static void printImage(BufferedImage bi, String type, 102. OutputStream out) { 103. try { 104. if (type.equals(TYPE_GIF)) 105. encodeGIF(bi, out); 106. else 107. ImageIO.write(bi, type, out); 108. } catch (IOException e) { 109. // TODO Auto-generated catch block 110. e.printStackTrace(); 111. } 112. } 113. /** 114. * Get image type from byte[] 115. * 116. * @param textObj 117. * image byte[] 118. * @return String image type 119. */ 120. public static String getImageType(byte[] textObj) { 121. String type = TYPE_NOT_AVAILABLE; 122. ByteArrayInputStream bais = null; 123. MemoryCacheImageInputStream mcis = null; 124. try { 125. bais = new ByteArrayInputStream(textObj); 126. mcis = new MemoryCacheImageInputStream(bais); 127. Iterator itr = ImageIO.getImageReaders(mcis); 128. while (itr.hasNext()) { 129. ImageReader reader = (ImageReader) itr.next(); 130. if (reader instanceof GIFImageReader) { 131. type = TYPE_GIF; 132. } else if (reader instanceof JPEGImageReader) { 133. type = TYPE_JPEG; 134. } else if (reader instanceof PNGImageReader) { 135. type = TYPE_PNG; 136. } else if (reader instanceof BMPImageReader) { 137. type = TYPE_BMP; 138. } 139. reader.dispose(); 140. } 141. } finally { 142. if (bais != null) { 143. try { 144. bais.close(); 145. } catch (IOException ioe) { 146. if (_log.isWarnEnabled()) { 147. _log.warn(ioe); 148. } 149. } 150. } 151. if (mcis != null) { 152. try { 153. mcis.close(); 154. } catch (IOException ioe) { 155. if (_log.isWarnEnabled()) { 156. _log.warn(ioe); 157. } 158. } 159. } 160. } 161. if (_log.isDebugEnabled()) { 162. _log.debug("Detected type " + type); 163. } 164. return type; 165. } 166. private static Log _log = LogFactory.getLog(ImageUtil.class); 167. } 注意:对gif格式的图片进行处理的时候，需要另外一下jar包:gif89.jar，因为gif格式的图片不能使用ImageIO进行输出。 如需将图片存放到数据库中，只需要修改红色部分，将图片以blob格式保存到数据库中，显示时以byte[]格式读出，使用ImageUtil.printImage()进行输出。