📄 从数据库中读出图片并显示的示例代码photo.showimage.java
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< !-- -- -- -- -- -- -- -- -- -- -- -- -- --servlet-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -->
package Photo;import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;import java.util.*;
import java.lang.*;
import java.sql.*;
/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2002</p>
* <p>Company: </p>
* @author unascribed
* @version 1.0
*/
public class ShowImage extends HttpServlet {
private static final String CONTENT_TYPE = "image/*";
/**
* 定义数据库连接字符串，jdbc.odbc桥
*/
private String driver_class = "oracle.jdbc.driver.OracleDriver";
private String connect_string = "jdbc:oracle:thin:xxw/xxw@192.168.1.50:1521:ORCL";
Connection conn = null;
ResultSet rs = null;
Statement stmt = null;
/******************************************** * 定义应用变量 ******************************************/
private String SQLString = "";
//定义查询语句\r
public String M_EorrMenage = "";
//定义错误信息变量
private InputStream in = null;
//定义输入流\r
private int len = 10 * 1024 * 1024;
//定义字符数组长度
//Initialize global variables
public void init() throws ServletException {
/**
* 连接数据库\r
*/
try {
Class.forName(driver_class);
} catch (java.lang.ClassNotFoundException e) {
//异常
System.err.println("databean():" + e.getMessage());
}
}
//Process the HTTP Get request
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
//在数据库中的照片的ID
int PHOTOID = 0;
/*********************************************
* 接受上文传递的图片ID号
* 上文传输文件名称为photoid
*********************************************/
try {
PHOTOID = Integer.parseInt(request.getParameter("photoid"));
SQLString = "select * from xxw_photo where p_id=" + PHOTOID;
} catch (Exception e) {
e.printStackTrace();
response.setContentType("text/html; charset=gb2312");
M_EorrMenage = "请输入图片ID号";
M_EorrMenage = new String(M_EorrMenage.getBytes("ISO8859_1"), "GBK");
out.println("<%@ page contentType='text/html; charset=gb2312' %>");
out.println("<html>");
out.println("<head><title>id</title></head>");
out.println("<body>");
out.println("<p>" + M_EorrMenage + "</p>");
out.println("</body></html>");
}
/*****************************************************
* 执行查询语句\r
*****************************************************/
try {
conn = DriverManager.getConnection(connect_string);
stmt = conn.createStatement();
rs = stmt.executeQuery(SQLString);
} //try
catch (SQLException ex) {
System.err.println("aq.executeUpdate:" + ex.getMessage());
M_EorrMenage = "对不起，数据库无法完成此操作！";
M_EorrMenage = new String(M_EorrMenage.getBytes("ISO8859_1"), "GBK");
response.setContentType("text/html; charset=gb2312");
out.println("<html>");
out.println("<head><title>no_database</title></head>");
out.println("<body>");
out.println("<p>" + M_EorrMenage + "</p>");
out.println("</body></html>");
}
/*********************************************
* 将图片流读入字符数组中，并显示到客户端
********************************************/
try {
if (rs.next()) {
in = rs.getBinaryStream("photo");
response.reset(); //返回在流中被标记过的位置
response.setContentType("image/jpg"); //或gif等
// int len=in.available();//得到文件大小
OutputStream toClient = response.getOutputStream();
byte[] P_Buf = new byte[len];
int i;
while ((i = in.read(P_Buf)) != -1) {
toClient.write(P_Buf, 0, i);
}
in.close();
toClient.flush(); //强制清出缓冲区\r
toClient.close();
} else {
M_EorrMenage = "无此图片！";
M_EorrMenage = new String(M_EorrMenage.getBytes("ISO8859_1"), "GBK");
response.setContentType("text/html; charset=gb2312");
out.println("<html>");
out.println("<head><title>this photo isn't have</title></head>");
out.println("<body>");
out.println("<p>" + M_EorrMenage + "</p>");
out.println("</body></html>");
}
rs.close();
} catch (Exception e) {
e.printStackTrace();
M_EorrMenage = "无法读取图片！";
M_EorrMenage = new String(M_EorrMenage.getBytes("ISO8859_1"), "GBK");
response.setContentType("text/html; charset=gb2312");
out.println("<%@ page contentType='text/html; charset=gb2312' %>");
out.println("<html>");
out.println("<head><title>no photo</title></head>");
out.println("<body>");
out.println("<p>" + M_EorrMenage + "</p>");
out.println("</body></html>");
}
} //Clean up resources
public void destroy() {
try {
conn.close();
} catch (SQLException e) {
System.err.println("aq.executeUpdate:" + e.getMessage());
M_EorrMenage = "对不起，数据库无法完成此操作！";
}
}}
<!---------------------------显示---------------------------------------------->
<html>
<head>
<title>Untitled Document</title>
</head>
<body bgcolor="#FFFFFF" text="#000000">
<table>
<%
int i=1;
while(i<3){
%>
<tr>
<td colspan="3"> <img border="1" src="http://192.168.1.50:8100/ShowImage?photoid=<%=i%>"></td>
</tr>
<%
i++;
}
%>
</table>
</body>
</html>
注：此程序对于从数据库读取图片后写入文件请参考代码者留意⌨️ 快捷键说明
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