【发布时间】：2015-01-23 10:09:23
【问题描述】：
我正在尝试使用 Tomcat 7 中的 Servlet 和 JSP 在 MySQL 数据库中插入图像。当我单击保存按钮时，它显示为 null。我没有收到任何错误。
我还设置了commons-fileupload.jar 文件和commons-io.jar 文件。如果你有一些演示代码，请给我。
<%@ 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>File Upload to Database Demo</title>
</head>
<body>
<center>
<h1>File Upload to Database Demo</h1>
<form method="post" action="FileUploadDBServlet" enctype="multipart/form-data">
<table border="0">
<tr>
<td>First Name: </td>
<td><input type="text" name="firstName" size="50"/></td>
</tr>
<tr>
<td>Last Name: </td>
<td><input type="text" name="lastName" size="50"/></td>
</tr>
<tr>
<td>Portrait Photo: </td>
<td><input type="file" name="photo" size="50"/></td>
</tr>
<tr>
<td colspan="2">
<input type="submit" value="Save">
</td>
</tr>
</table
</form>
</center>
</body>
</html>
FileUploadDBServlet.java：
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;
@WebServlet("/FileUploadDBServlet")
@MultipartConfig(maxFileSize = 16177215) // upload file's size up to 16MB
public class FileUploadDBServlet extends HttpServlet {
// database connection settings
private String dbURL = "jdbc:mysql://localhost:3306/AppDB";
private String dbUser = "root";
private String dbPass = "root";
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// gets values of text fields
String firstName = request.getParameter("firstName");
String lastName = request.getParameter("lastName");
InputStream inputStream = null; // input stream of the upload file
// obtains the upload file part in this multipart request
Part filePart = request.getPart("photo");
if (filePart != null) {
// prints out some information for debugging
System.out.println(filePart.getName());
System.out.println(filePart.getSize());
System.out.println(filePart.getContentType());
// obtains input stream of the upload file
inputStream = filePart.getInputStream();
}
Connection conn = null; // connection to the database
String message = null; // message will be sent back to client
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection(dbURL,dbUser,dbPass);
String sql =("INSERT INTO contacts (first_name, last_name, photo) values (?, ?, ?)");
PreparedStatement statement = conn.prepareStatement(sql);
statement.setString(1, firstName);
statement.setString(2, lastName);
if (inputStream != null) {
// fetches input stream of the upload file for the blob column
statement.setBlob(3, inputStream);
}
// sends the statement to the database server
int row = statement.executeUpdate();
if (row > 0) {
message = "File uploaded and saved into database";
}
} catch (Exception ex) {
message = "ERROR: " + ex.getMessage();
ex.printStackTrace();
} finally {
if (conn != null) {
// closes the database connection
try {
conn.close();
} catch (SQLException ex) {
ex.printStackTrace();
}
}
// sets the message in request scope
request.setAttribute("Message", message);
// forwards to the message page
getServletContext().getRequestDispatcher("/Message.jsp").forward(request, response);
}
}
}
web.xml：
<web-app>
<servlet>
<servlet-name>FileUploadDBServlet</servlet-name>
<servlet-class>FileUploadDBServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>FileUploadDBServlet</servlet-name>
<url-pattern>/FileUploadDBServlet</url-pattern>
</servlet-mapping>
</web-app>
【问题讨论】：
-
只需使用 BLOB 数据类型。链接codesuggestions.com/java/…