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getOutputStream()异常的原因和解决方法

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getOutputStream()异常的原因和解决方法

tomcat5下jsp出现getOutputStream() has already been called for this response异常的原因和解决方法

在tomcat5下jsp中出现此错误一般都是在jsp中使用了输出流（如输出图片验证码，文件下载等），
没有妥善处理好的原因。

具体的原因就是
在tomcat中jsp编译成servlet之后在函数_jspService(HttpServletRequest request, HttpServletResponse response)的最后
有一段这样的代码
finally {
if (_jspxFactory != null) _jspxFactory.releasePageContext(_jspx_page_context);
}
这里是在释放在jsp中使用的对象，会调用response.getWriter(),因为这个方法是和
response.getOutputStream()相冲突的！所以会出现以上这个异常。

然后当然是要提出解决的办法，其实挺简单的（并不是和某些朋友说的那样--
将jsp内的所有空格和回车符号所有都删除掉），

在使用完输出流以后调用以下两行代码即可：

Java代码
  1. out.clear();
  2. out=pageContext.pushBody();


最后这里是一个输出彩色验证码例子（这样的例子几乎随处可见）
imag.jsp


Java代码
  1. <%@page import = "java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
  2. <%@page import = "java.io.OutputStream" %>
  3. <%!
  4. ColorgetRandColor( int fc, int bc){
  5. Randomrandom= new Random();
  6. if (fc> 255 )fc= 255 ;
  7. if (bc> 255 )bc= 255 ;
  8. int r=fc+random.nextInt(bc-fc);
  9. int g=fc+random.nextInt(bc-fc);
  10. int b=fc+random.nextInt(bc-fc);
  11. return new Color(r,g,b);
  12. }
  13. %>
  14. <%
  15. try {
  16. response.setHeader( "Pragma" , "No-cache" );
  17. response.setHeader( "Cache-Control" , "no-cache" );
  18. response.setDateHeader( "Expires" , 0 );
  19. int width= 60 ,height= 20 ;
  20. BufferedImageimage= new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
  21. OutputStreamos=response.getOutputStream();
  22. Graphicsg=image.getGraphics();
  23. Randomrandom= new Random();
  24. g.setColor(getRandColor( 200 , 250 ));
  25. g.fillRect( 0 , 0 ,width,height);
  27. g.setFont( new Font( "TimesNewRoman" ,Font.PLAIN, 18 ));
  28. g.setColor(getRandColor( 160 , 200 ));
  29. for ( int i= 0 ;i< 155 ;i++)
  30. {
  31. int x=random.nextInt(width);
  32. int y=random.nextInt(height);
  33. int xl=random.nextInt( 12 );
  34. int yl=random.nextInt( 12 );
  35. g.drawLine(x,y,x+xl,y+yl);
  36. }
  37. StringsRand= "" ;
  38. for ( int i= 0 ;i< 4 ;i++){
  39. Stringrand=String.valueOf(random.nextInt( 10 ));
  40. sRand+=rand;
  41. g.setColor( new Color( 20 +random.nextInt( 110 ), 20 +random.nextInt( 110 ), 20 +random.nextInt( 110 )));
  42. g.drawString(rand, 13 *i+ 6 , 16 );
  43. }
  44. session.setAttribute( "rand" ,sRand);
  45. g.dispose();
  47. ImageIO.write(image, "JPEG" ,os);
  48. os.flush();
  49. os.close();
  50. os= null ;
  51. response.flushBuffer();
  52. out.clear();
  53. out=pageContext.pushBody();
  54. }
  55. catch (IllegalStateExceptione)
  56. {
  57. System.out.println(e.getMessage());
  58. e.printStackTrace();
  59. }%>

来自:http://jessdy.javaeye.com/blog/187448

  1. 原始代码:
  2. <%@pagecontentType= "text/html;charset=GBK" %>
  3. <%@pageautoFlush= "false" %>
  4. <%@page import = "java.sql.*" %>
  5. <%@page import = "java.io.*" %>
  6. <%@page import = "java.util.*" %>
  7. <%@page import = "java.awt.*" %>
  8. <%@page import = "java.awt.image.*" %>
  9. <%@page import = "com.sun.image.codec.jpeg.*" %>
  10. <%@page import = "com.sun.image.codec.jpeg.*" %>
  11. <%@page import = "com.csland.common.util.*" %>
  12. <%!
  14. public void noImg(ServletOutputStreamoutStream){
  15. try {
  16. int width= 80 ,height= 50 ;
  17. BufferedImageimage= new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
  18. Graphicsg=image.getGraphics();
  19. //以下填充背景颜色
  20. g.setColor(Color.WHITE);
  21. g.fillRect( 0 , 0 ,width,height);
  22. g.setColor(Color.ORANGE);
  23. g.drawRect( 0 , 0 ,width- 1 ,height- 1 );
  24. Stringrandom= "random" ;
  25. //以下设置前景色
  26. g.setColor(Color.BLACK);
  27. g.drawString( "没有签名图" , 0 , 25 );
  28. g.dispose();
  29. //
  30. JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(outStream);
  31. encoder.encode(image);
  32. outStream.flush();
  33. //outStream.close();
  34. } catch (Exceptione){
  35. Log.fetal( "atnoImginsig2.jsp:/n" +e);
  36. }
  37. }
  39. public void noImg(HttpServletResponseresponse){
  40. try {
  41. ServletOutputStreamoutStream=response.getOutputStream();
  42. noImg(outStream);
  43. } catch (Exceptione){
  44. Log.fetal( "atnoImginsig2.jsp:/n" +e);
  45. }
  46. }
  48. %>
  50. <%
  51. out.clear();
  52. response.setContentType( "image/jpeg" );
  53. response.addHeader( "pragma" , "NO-cache" );
  54. response.addHeader( "Cache-Control" , "no-cache" );
  55. response.addDateHeader( "Expries" , 0 );
  57. int id=StrUtil.StrToInt(request.getParameter( "id" ));
  58. if (id<= 0 )
  59. {
  60. noImg(response);
  61. }
  62. else
  63. {
  64. java.sql.Connectionconn= null ;
  65. java.sql.Statementstmt= null ;
  66. java.sql.ResultSetlobDetails= null ;
  68. try {
  69. conn=DBUtil.getConn();
  70. stmt=conn.createStatement();
  71. lobDetails=stmt.executeQuery(
  72. "SELECTSignatureFROMOZ_Member" +
  73. "WHEREMemberID=" +id+ "" );
  74. if (lobDetails.next()){
  76. BlobmapBlob=lobDetails.getBlob( 1 );
  78. if (mapBlob!= null ){
  79. InputStreamblobStream=mapBlob.getBinaryStream();
  80. Log.debug( "blobStream:" +blobStream);
  82. ServletOutputStreamoutStream=response.getOutputStream();
  83. byte []buffer= new byte [ 10 * 1024 ];
  84. int nbytes= 0 ;
  85. int allBytes= 0 ;
  86. while ((nbytes=blobStream.read(buffer))!=- 1 ){
  87. outStream.write(buffer, 0 ,nbytes);
  88. allBytes+=nbytes;
  89. }
  90. Log.debug( "allBytes:" +allBytes);
  91. if (allBytes< 1 ){
  92. Log.debug( "allBytes2:" +allBytes);
  93. noImg(outStream);
  94. } else {
  95. outStream.flush();
  96. //outStream.close();
  97. }
  99. blobStream.close();
  100. } else {
  101. noImg(response);
  102. }
  103. } else {
  104. noImg(response);
  105. }
  106. }
  107. catch (Exceptione){
  108. Log.fetal(e);
  109. }
  110. finally {
  111. try {lobDetails.close();} catch (Exceptione){}
  112. try {stmt.close();} catch (Exceptione){}
  113. try {conn.close();} catch (Exceptione){}
  114. }
  115. }
  116. %>
  117. 修改后的代码===============byyanleigis
  118. <%@pagecontentType= "text/html;charset=GBK" %>
  119. <%@pageautoFlush= "false" %>
  120. <%@page import = "java.sql.*" %>
  121. <%@page import = "java.io.*" %>
  122. <%@page import = "java.util.*" %>
  123. <%@page import = "java.awt.*" %>
  124. <%@page import = "java.awt.image.*" %>
  125. <%@page import = "com.sun.image.codec.jpeg.*" %>
  126. <%@page import = "com.sun.image.codec.jpeg.*" %>
  127. <%@page import = "com.csland.common.util.*" %>
  128. <%!
  130. public void noImg(ServletOutputStreamoutStream){
  131. try {
  132. int width= 80 ,height= 50 ;
  133. BufferedImageimage= new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
  134. Graphicsg=image.getGraphics();
  135. //以下填充背景颜色
  136. g.setColor(Color.WHITE);
  137. g.fillRect( 0 , 0 ,width,height);
  138. g.setColor(Color.ORANGE);
  139. g.drawRect( 0 , 0 ,width- 1 ,height- 1 );
  140. Stringrandom= "random" ;
  141. //以下设置前景色
  142. g.setColor(Color.BLACK);
  143. g.drawString( "没有签名图" , 0 , 25 );
  144. g.dispose();
  145. //
  146. JPEGImageEncoderencoder=JPEGCodec.createJPEGEncoder(outStream);
  147. encoder.encode(image);
  148. outStream.flush();
  149. outStream.close();
  155. } catch (Exceptione){
  156. Log.fetal( "atnoImginsig2.jsp:/n" +e);
  157. }
  158. }
  160. public void noImg(HttpServletResponseresponse){
  161. try {
  162. ServletOutputStreamoutStream=response.getOutputStream();
  163. noImg(outStream);
  164. } catch (Exceptione){
  165. Log.fetal( "atnoImginsig2.jsp:/n" +e);
  166. }
  167. }
  169. %>
  171. <%
  172. out.clear();
  173. out=pageContext.pushBody();
  174. response.setContentType( "image/jpeg" );
  175. response.addHeader( "pragma" , "NO-cache" );
  176. response.addHeader( "Cache-Control" , "no-cache" );
  177. response.addDateHeader( "Expries" , 0 );
  179. int id=StrUtil.StrToInt(request.getParameter( "id" ));
  180. if (id<= 0 )
  181. {
  182. noImg(response);
  183. }
  184. else
  185. {
  186. java.sql.Connectionconn= null ;
  187. java.sql.Statementstmt= null ;
  188. java.sql.ResultSetlobDetails= null ;
  190. try {
  191. conn=DBUtil.getConn();
  192. stmt=conn.createStatement();
  193. lobDetails=stmt.executeQuery(
  194. "SELECTSignatureFROMOZ_Member" +
  195. "WHEREMemberID=" +id+ "" );
  196. if (lobDetails.next()){
  198. BlobmapBlob=lobDetails.getBlob( 1 );
  200. if (mapBlob!= null ){
  201. InputStreamblobStream=mapBlob.getBinaryStream();
  202. Log.debug( "blobStream:" +blobStream);
  204. ServletOutputStreamoutStream=response.getOutputStream();
  205. byte []buffer= new byte [ 10 * 1024 ];
  206. int nbytes= 0 ;
  207. int allBytes= 0 ;
  208. while ((nbytes=blobStream.read(buffer))!=- 1 ){
  209. outStream.write(buffer, 0 ,nbytes);
  210. allBytes+=nbytes;
  211. }
  212. Log.debug( "allBytes:" +allBytes);
  213. if (allBytes< 1 ){
  214. Log.debug( "allBytes2:" +allBytes);
  215. noImg(outStream);
  216. } else {
  217. outStream.flush();
  218. //outStream.close();
  219. }
  221. blobStream.close();
  222. } else {
  223. noImg(response);
  224. }
  225. } else {
  226. noImg(response);
  227. }
  228. response.flushBuffer();
  229. out.clear();
  230. out=pageContext.pushBody();
  231. }
  232. catch (Exceptione){
  233. Log.fetal(e);
  234. }
  235. finally {
  236. try {lobDetails.close();} catch (Exceptione){}
  237. try {stmt.close();} catch (Exceptione){}
  238. try {conn.close();} catch (Exceptione){}
  239. }
  240. }
  241. %>

getOutputStream()异常的原因和解决方法


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