[轉]利用HttpServletResponseWrapper獲取jsp輸出內容

轉載: bianbian coding life。

有時候咱們須要獲得某個jsp的輸出內容。好比說在servlet裏處理了Module Controller後，須要不一樣的jsp頁面來展現view；又或者獲得不一樣的模板內容（jsp自己能夠做爲模板語言）並將其緩衝到內存裏。
利用 javax.servlet.http.HttpServletResponseWrapper 能夠很好地實現咱們所須要的功能。下面是使用方法：

1. ....
2. public static String getJspOutput(String jsppath, HttpServletRequest request, HttpServletResponse response)
3. throws Exception
4. {
5. WrapperResponse wrapperResponse = new WrapperResponse(response);
6. request.getRequestDispatcher(jsppath).include(request, wrapperResponse);
7. return wrapperResponse.getContent();
8. }

能夠看到，使用起來仍是挺方便的。getJspOutput(」/view/header.jsp」, request, response) 就完成了對」/view/header.jsp」的輸出內容獲取，以後能夠進行其餘操做。
附WrapperResponse類代碼：

1. import java.io.ByteArrayOutputStream;
2. import java.io.IOException;
3. import java.io.PrintWriter;
4. import java.io.UnsupportedEncodingException;
6. import javax.servlet.ServletOutputStream;
7. import javax.servlet.http.HttpServletResponse;
8. import javax.servlet.http.HttpServletResponseWrapper
9. /**
10. * @see http://bianbian.sunshow.net/
11. * @author dannyzhu, bianbian
12. * @version 1.0
13. */
14. public class WrapperResponse extends HttpServletResponseWrapper
15. {
16. private PrintWriter tmpWriter;
17. private ByteArrayOutputStream output;
18. private ByteArrayServletOutputStream servletOutput;
20. public WrapperResponse(HttpServletResponse httpServletResponse)
21. {
22. super(httpServletResponse);
23. output = new ByteArrayOutputStream();
24. tmpWriter = new PrintWriter(output);
25. servletOutput = new ByteArrayServletOutputStream(output);
26. }
28. public void finalize() throws Throwable
29. {
30. super.finalize();
31. servletOutput.close();
32. output.close();
33. tmpWriter.close();
34. }
36. public String getContent()
37. {
38. try{
39. String s = output.toString("UTF-8");
40. reset();
41. return s;
42. } catch(UnsupportedEncodingException e) {
43. return "UnsupportedEncoding";
44. }
45. }
47. public PrintWriter getWriter() throws IOException
48. {
49. // return servletResponse.getWriter();
50. return tmpWriter;
51. }
53. public ServletOutputStream getOutputStream() throws IOException
54. {
55. return servletOutput;
56. }
58. public byte[] toByteArray()
59. {
60. return output.toByteArray();
61. }
63. public void flushBuffer() throws IOException
64. {
65. tmpWriter.flush();
66. servletOutput.flush();
67. }
69. public void reset()
70. {
71. output.reset();
72. }
74. public void close() throws IOException
75. {
76. tmpWriter.close();
77. }
79. private static class ByteArrayServletOutputStream extends ServletOutputStream
80. {
82. ByteArrayOutputStream baos;
84. public ByteArrayServletOutputStream(ByteArrayOutputStream baos)
85. {
86. this.baos = baos;
87. }
89. public void write(int i) throws IOException
90. {
91. baos.write(i);
92. }
94. }
95. }

轉載:bianbian coding life。