图片上传压缩
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2022-03-27 18:04:43
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web开发中将上传图片压缩后以image类型存入数据库（转）
2009-03-11 17:45
转自http://blog.sina.com.cn/s/blog_4ce383f30100chmm.html
不久前，本人在一个小型java web项目开发中需要上传一个图片的同时，将其进行适当压缩，然后直接以image类型存入SQL Server数据库。之前，本人在网络上查找了好长时间，都没有找到合适的源码，要么就是存原图片，要么就是把图片压缩后存到服务器上，然后把相对路径以string类型存入数据库或以image类型存入数据库，本例与其不同的是，要求图片在内存中压缩后直接以image类型存入数据库。具体实现如下：
①首先，新建一个upload.jsp文件,用来选择需要上传的图片，源码如下:
<%@ page contentType="text/html; charset=gb2312" language="java"
import="java.sql.*" errorPage=""%>
<html >
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>上传并压缩图片</title>
<style>
td {
font-family: "宋体";
font-size: 12px;
}
</style>
</head>
<body>
<table border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td height="45" align="center" valign="middle">
<form action="ImgDealServlet" method="post"
enctype="multipart/form-data" name="form1">
<table border="0" align="center" cellpadding="0" cellspacing="0">
<tr>
<td colspan="2" height="50">
<div align="center">
上传并压缩图片应用
</div>
</td>
</tr>
<tr>
<td>
请选择上传的图片
</td>
<td>
<input type="file" name="file" />
<input type="submit" name="Submit" value="上传" />
</td>
</tr>
</table>
</form>
</td>
</tr>
</table>
</body>
</html>
②然后，创建一个servlet文件ImgDealServlet.java，用来处理图片的上传，源码如下：
package servlet;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.sql.ResultSet;
import util.*;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.jspsmart.upload.SmartUpload;
public class ImgDealServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("GB2312");
response.setContentType("text/html; charset=GB2312");
PrintWriter out = response.getWriter();
SmartUpload mySmartUpload = new SmartUpload();
mySmartUpload.initialize(getServletConfig(),request,response);
try {
mySmartUpload.setAllowedFilesList("jpg,JPG,gif");
//上载文件
mySmartUpload.upload();
} catch (Exception e) {
out.print("<SCRIPT language='javascript'>");
out.print("alert('只允许上传.jpg和.gif类型图片文件');");
out.print("window.location='upfile.jsp';");
out.print("</SCRIPT>");
}
try {
com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
// 若文件不存在
if (myFile.isMissing()) {
out.print("<SCRIPT language='javascript'>");
out.print("alert('请先选择要上传的文件');");
out.print("window.location='upfile.jsp';");
out.print("</SCRIPT>");
}
else {
String myFilePath=myFile.getFilePathName(); //取得上载的文件的路径
UploadImg ui=new UploadImg();
BufferedImage tag =ui.getResizeImg(myFilePath,400,300,true);
if(tag!=null){
ui.saveImgToDB(tag);
}
response.sendRedirect("showimg.jsp");
}
} catch (Exception e) {
e.toString();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
}
③之前的servlet文件中用到了一个自定义包中的类UploadImg.java，其中定义了图片处理的方法，其源码如下：
package util;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import javax.imageio.ImageIO;
import util.DBConnect;
public class UploadImg {
String myFilePath = "";
public BufferedImage getResizeImg(String path, int width, int height,
boolean isResize) {
String myFilePath = path; // 取得上载的文件的路径
BufferedImage srcimg, tag;
tag = null;
int new_w; // 压缩后大小
int new_h;
boolean Resize;// 是否等比缩放
try {
srcimg = ImageIO.read(new java.io.File(myFilePath));
if (isResize) {// 等比缩放
double rate1 = ((double) srcimg.getWidth(null))
/ (double) width + 0.1;
double rate2 = ((double) srcimg.getHeight(null))
/ (double) height + 0.1;
double rate = rate1 > rate2 ? rate1 : rate2;
new_w = (int) (((double) srcimg.getWidth(null)) / rate);
new_h = (int) (((double) srcimg.getHeight(null)) / rate);
} else {
new_w = width;
new_h = height;
}
Image image = srcimg.getScaledInstance(new_w, new_h,
Image.SCALE_DEFAULT);
tag = new BufferedImage(new_w, new_h, BufferedImage.TYPE_INT_RGB);
Graphics g = tag.getGraphics();
g.drawImage(image, 0, 0, null); // 绘制缩小后的图
g.dispose();
return tag;
} catch (Exception e) {
e.printStackTrace();
}
return tag;
}
public void saveImgToDB(BufferedImage bi) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedImage tag = bi;
try {
ImageIO.write(tag, "jpg", baos);
byte[] bytes = baos.toByteArray();
ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
String strsql = "update imgtest set img=? where id=1";
DBConnect dbcSelect = new DBConnect(strsql);
dbcSelect.setBinaryStream(1, bis, bytes.length);
dbcSelect.executeUpdate();
dbcSelect.close();
} catch (Exception e) {
}
}
}
④上面的Upload.java文件中同样也用到了另一个自定义的数据库连接类DBConnect.java,源码如下：
package util;
import java.io.InputStream;
import java.sql.*;
public class DBConnect {
private Connection conn = null;
private Statement stmt = null;
private PreparedStatement prepstmt = null;
public static final int JADMIS_CONNECT = 3;
public static final int FTFORDE_CONNECT = 2;
public static final int WEBSITE_CONNECT = 1;
public static final int PLATFORM_CONNECT = 0;
void init() {
try {
Class.forName("org.logicalcobwebs.proxool.ProxoolDriver");
conn = DriverManager.getConnection("proxool.mysql");
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
void init(String conName) {
try {
Class.forName("org.logicalcobwebs.proxool.ProxoolDriver");
conn = DriverManager.getConnection("proxool." + conName);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public DBConnect(int ConnectIndex) throws SQLException {
switch (ConnectIndex) {
case JADMIS_CONNECT:
init("jadmis");
break;
case WEBSITE_CONNECT:
init("website");
break;
case PLATFORM_CONNECT:
init("mysql");
break;
case FTFORDE_CONNECT:
init("ftde");
break;
}
stmt = conn.createStatement();
}
public DBConnect(int ConnectIndex, int resultSetType,
int resultSetConcurrency) throws SQLException {
switch (ConnectIndex) {
case JADMIS_CONNECT:
init("jadmis");
break;
case WEBSITE_CONNECT:
init("website");
break;
case PLATFORM_CONNECT:
init("mysql");
break;
case FTFORDE_CONNECT:
init("ftde");
break;
}
stmt = conn.createStatement(resultSetType, resultSetConcurrency);
}
public DBConnect() throws SQLException {
init();
stmt = conn.createStatement();
}
public DBConnect(int resultSetType, int resultSetConcurrency)
throws SQLException {
init();
stmt = conn.createStatement(resultSetType, resultSetConcurrency);
}
public DBConnect(String sql) throws SQLException {
init();
this.prepareStatement(sql);
}
public DBConnect(String sql, int resultSetType, int resultSetConcurrency)
throws SQLException {
init();
this.prepareStatement(sql, resultSetType, resultSetConcurrency);
}
//added by tmw 080221
public DBConnect(int ConnectIndex,String sql) throws SQLException {
switch (ConnectIndex) {
case WEBSITE_CONNECT:
init("website");
break;
case PLATFORM_CONNECT:
init("ft");
break;
case FTFORDE_CONNECT:
init("ftde");
break;
case JADMIS_CONNECT:
init("mysql");
break;
}
this.prepareStatement(sql);
}
//added by tmw 080221
public DBConnect(int ConnectIndex,String sql, int resultSetType, int resultSetConcurrency)
throws SQLException {
switch (ConnectIndex) {
case WEBSITE_CONNECT:
init("website");
break;
case PLATFORM_CONNECT:
init("ft");
break;
case FTFORDE_CONNECT:
init("ftde");
break;
case JADMIS_CONNECT:
init("mysql");
break;
}
this.prepareStatement(sql, resultSetType, resultSetConcurrency);
}
public Connection getConnection() {
return conn;
}
public void prepareStatement(String sql) throws SQLException {
prepstmt = conn.prepareStatement(sql);
}
public void prepareStatement(String sql, int resultSetType,
int resultSetConcurrency) throws SQLException {
prepstmt = conn.prepareStatement(sql, resultSetType,
resultSetConcurrency);
}
public void setString(int index, String value) throws SQLException {
prepstmt.setString(index, value);
}
public void setInt(int index, int value) throws SQLException {
prepstmt.setInt(index, value);
}
public void setBoolean(int index, boolean value) throws SQLException {
prepstmt.setBoolean(index, value);
}
public void setDate(int index, Date value) throws SQLException {
prepstmt.setDate(index, value);
}
public void setLong(int index, long value) throws SQLException {
prepstmt.setLong(index, value);
}
//add by sch
public void setDouble(int index, double value) throws SQLException {
prepstmt.setDouble(index, value);
}
//add by sch
public void setObject(int index, Object value)throws SQLException {
prepstmt.setObject(index,value);
}
public void setFloat(int index, float value) throws SQLException {
prepstmt.setFloat(index, value);
}
public void setBytes(int index, byte[] value) throws SQLException {
prepstmt.setBytes(index, value);
}
public void setBinaryStream(int index, InputStream is, int length)
throws SQLException {
prepstmt.setBinaryStream(index, is, length);
}
public void clearParameters() throws SQLException {
prepstmt.clearParameters();
prepstmt = null;
}
public PreparedStatement getPreparedStatement() {
return prepstmt;
}
public Statement getStatement() {
return stmt;
}
public ResultSet executeQuery(String sql) throws SQLException {
if (stmt != null) {
return stmt.executeQuery(sql);
} else
return null;
}
public ResultSet executeQuery() throws SQLException {
if (prepstmt != null) {
return prepstmt.executeQuery();
} else
return null;
}
public void executeUpdate(String sql) throws SQLException {
if (stmt != null)
stmt.executeUpdate(sql);
}
public void executeUpdate() throws SQLException {
if (prepstmt != null)
prepstmt.executeUpdate();
}
public void close() throws SQLException {
if (stmt != null) {
stmt.close();
stmt = null;
}
if (prepstmt != null) {
prepstmt.close();
prepstmt = null;
}
if (conn != null) {
conn.close();
conn=null;
}
}
}
⑤此外，由于用到了proxool数据库连接池，所以需要添加proxool.xml并修改web.xml配置文件，proxool.xml源码如下：
<?xml version="1.0" encoding="ISO-8859-1"?>
<!-- the proxool configuration can be embedded within your own application's.
Anything outside the "proxool" tag is ignored. -->
<something-else-entirely>
<proxool>
<alias>mysql</alias>
<driver-url>jdbc:jtds:sqlserver://localhost:1433;DatabaseName=lwjtest</driver-url>
<driver-class>net.sourceforge.jtds.jdbc.Driver</driver-class>
<driver-properties>
<property name="user" value="sa" />
<property name="password" value="sa />
</driver-properties>
<maximum-connection-count>5000</maximum-connection-count>
<minimum-connection-count>5</minimum-connection-count>
<maximum-active-time>60000</maximum-active-time>
</proxool>
</something-else-entirely>
web.xml配置文件代码如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<!--Connecting Pool -->
<servlet>
<servlet-name>ServletConfigurator</servlet-name>
<servlet-class>org.logicalcobwebs.proxool.configuration.ServletConfigurator</servlet-class>
<init-param>
<param-name>xmlFile</param-name>
<param-value>WEB-INF/proxool.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet>
<servlet-name>Admin</servlet-name>
<servlet-class>org.logicalcobwebs.proxool.admin.servlet.AdminServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Admin</servlet-name>
<url-pattern>/admin</url-pattern>
</servlet-mapping>
<!--Connecting Pool Over -->
<servlet>
<servlet-name>ImgDealServlet</servlet-name>
<servlet-class>servlet.ImgDealServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ImgDealServlet</servlet-name>
<url-pattern>/ImgDealServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>upfile.jsp</welcome-file>
</welcome-file-list>
</web-app>
⑥此外，还需要导入几个jar包，jspsmartupload.jar、jtds-1.1.jar和proxool-0.9.0RC3.jar，至于这三个包是做什么用的，我想就不用我多说了吧。
两个图片我用的都是BufferedImage类，因为不同了解流的用法，所以可能会有些不当。此外，还有一点要说明的是，如果jsp文件中字符编码格式用utf-8时，不支持图片的中文路径，改为gb2312就OK了。
由于是第一次发帖，且源码基本为本人及朋友所改写，错误及不当之处一定不少，还请大家多多指教，在此谢过！上一篇： vue 修改数组方法
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