Question

我正在尝试从oracle数据库中获取图像。流程是：JSP（读取photo_id） - ＆gt; JSP - ＆gt;它从HTML图像标记的src属性内部调用Servlet。

ImageGetter.jsp（要求提供照片ID）

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>your Pic</title>
</head>
<body>

      <form id="form2" enctype="multipart/form-data" action="getPhoto.jsp" method="get">
            <table>
                <tr>
                    <td>Enter Photo Id :</td>
                    <td><input  type="text"  name="id"/></td>
                </tr>

            </table>
            <p/>
            <input type="submit" value="fetch Photo"/>
        </form>

</body>
</html>

getPhoto.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Your photo</title>
</head>
<body>
<% String p_id=request.getParameter("id");%>


<table>
    <tr><td><%=p_id%></td></tr>
    <tr><td><img src="/getPic?photoid=<%=p_id%>" /></td></tr>
</table>
</body>
</html>

img标签的src属性中的getPic是servlet。

getPic.java

package com.kp.imagehandler;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.kp.imagehandler.Image;

/**
 * Servlet implementation class getPic
 */
public class getPic extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public getPic() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

        String imageId = request.getParameter("photoid");
        System.out.println(imageId);
        InputStream photoStream = (new Image()).getImageStream(imageId);


        BufferedInputStream input = null;
          BufferedOutputStream output = null;

          try {

              // Open streams
              input = new BufferedInputStream(photoStream, 200000);
              output = new BufferedOutputStream(response.getOutputStream(),
                      200000);

              // Write file contents to response.
              byte[] buffer = new byte[200000];
              int length;
              while ((length = input.read(buffer)) > 0) {
                  output.write(buffer, 0, length);
              }

              } finally {
                  output.close();
                  input.close();
              }

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }

}

Image.java：

package com.kp.imagehandler;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Image {

    // Init ---------------------------------------------------------------------------------------


    public InputStream getImageStream(String pid)
    {
        InputStream IS=null;
        try {

        Connection connection = DriverManager.getConnection("jdbc:oracle:thin:@10.75.122.69:1521:devdb",
                "s3", "s3");
          Statement stmt = connection.createStatement ();

            ResultSet rset = stmt.executeQuery ("SELECT photo FROM photo_holder where id="+pid);

            while(rset.next())
            {
                IS=rset.getBinaryStream("photo");

            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return IS;

    }

    // Implement default getters and setters here.

}

web.xml：

  <servlet>
    <description>getPic</description>
    <display-name>getPic</display-name>
    <servlet-name>getPic</servlet-name>
    <servlet-class>com.kp.imagehandler.getPic</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>getPic</servlet-name>
    <url-pattern>/getPic</url-pattern>
  </servlet-mapping>

表格定义：

create table PHOTO_HOLDER
(
  ID    NUMBER(5) not null,
  TITLE VARCHAR2(50),
  PHOTO BLOB
)

但是在点击获取照片之后，我只是获取了照片ID而不是图像。在这里，我不确定servlet是否会被解雇。

请提前帮助。谢谢。

Answer 1

为图片形成的网址可能存在问题。

请在浏览器中查看生成的JSP的源代码，再次验证它。

只需调试代码或使用日志记录来调查问题。

在Servlet / JSP路径之前附加上下文路径后再试一次，如下所示：

<form id="form2" enctype="multipart/form-data" action="<%=request.getContextPath() %>/getPhoto.jsp" method="get">

<img src="<%=request.getContextPath() %>/getPic?photoid=<%=p_id%>" />

从jsp调用时，映像不是来自servlet

1 个答案: