Java从数据库中读取Blob对象图片并显示的方法
本文实例讲述了Java从数据库中读取Blob对象图片并显示的方法。分享给大家供大家参考。具体实现方法如下：
第一种方法：
大致方法就是，从数据库中读出Blob的流来，写到页面中去：
Connection conn = DBManager.getConnection();
String sql = "SELECT picture FROM teacher WHERE id=1";
PreparedStatement ps = null;
ResultSet rs = null;
InputStream is = null;
OutputStream os = null;
try {
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if(rs.next()){
is = rs.getBinaryStream(1);
}
response.setContentType("text/html");
os = response.getOutputStream();
int num;
byte buf[] = new byte[1024];
while( (num=is.read(buf))!=-1 ){
os.write(buf, 0, num);
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
is.close();
os.close();
rs.close();
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
在页面中：
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<img name="pic" src="<%=basePath+"servlet/DownloadAsStream"%>"/>
搞定。
第二种方法：
整个流程分为四步，连接oracle数据库 -> 读取blob图片字段 -> 对图片进行缩放 ->把图片展示在jsp页面上。
import java.sql.*;
import java.io.*;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.AffineTransformOp;
import java.awt.geom.AffineTransform;
public class OracleQueryBean {
private final String oracleDriverName = "oracle.jdbc.driver.OracleDriver";
private Connection myConnection = null;
private String strTabName;
private String strIDName;
private String strImgName;
public OracleQueryBean(){
try{
Class.forName(oracleDriverName);
}catch(ClassNotFoundException ex){
System.out.println("加载jdbc驱动失败,原因:" + ex.getMessage());
}
}
public Connection getConnection(){
try{
//用户名+密码; 以下使用的Test就是Oracle里的表空间
//从配置文件中读取数据库信息
GetPara oGetPara = new GetPara();
String strIP = oGetPara.getPara("serverip");
String strPort = oGetPara.getPara("port");
String strDBName = oGetPara.getPara("dbname");
String strUser = oGetPara.getPara("user");
String strPassword = oGetPara.getPara("password");
this.strTabName = oGetPara.getPara("tablename");
this.strIDName = oGetPara.getPara("imgidname");
this.strImgName = oGetPara.getPara("imgname");
String oracleUrlToConnect ="jdbc:oracle:thin:@"+strIP+":"+strPort+":"+strDBName;
this.myConnection = DriverManager.getConnection(oracleUrlToConnect, strUser, strPassword);
}catch(Exception ex){
System.out.println("Can not get connection:" + ex.getMessage());
System.out.println("请检测配置文件中的数据库信息是否正确." );
}
return this.myConnection;
}
}
2. 读取blob字段
在OracleQueryBean类中增加一个函数，来进行读取，具体代码如下：
public byte[] GetImgByteById(String strID, int w, int h){
//System.out.println("Get img data which id is " + nID);
if(myConnection == null)
this.getConnection();
byte[] data = null;
try {
Statement stmt = myConnection.createStatement();
ResultSet myResultSet = stmt.executeQuery("select " + this.strIDName + " from " + this.strTabName + " where " + this.strIDName + "=" + strID);
StringBuffer myStringBuffer = new StringBuffer();
if (myResultSet.next()) {
java.sql.Blob blob = myResultSet.getBlob(this.strImgName);
InputStream inStream = blob.getBinaryStream();
try {
long nLen = blob.length();
int nSize = (int) nLen;
//System.out.println("img data size is :" + nSize);
data = new byte[nSize];
inStream.read(data);
inStream.close();
} catch (IOException e) {
System.out.println("获取图片数据失败,原因:" + e.getMessage());
}
data = ChangeImgSize(data, w, h);
}
System.out.println(myStringBuffer.toString());
myConnection.commit();
myConnection.close();
} catch (SQLException ex) {
System.out.println(ex.getMessage());
}
return data;
}
3. 缩放图片
因为图片的大小可能不一致，但是在页面中输出的大小需要统一，所以需要
在OracleQueryBean类中增加一个函数，来进行缩放，具体代码如下：
private byte[] ChangeImgSize(byte[] data, int nw, int nh){
byte[] newdata = null;
try{
BufferedImage bis = ImageIO.read(new ByteArrayInputStream(data));
int w = bis.getWidth();
int h = bis.getHeight();
double sx = (double) nw / w;
double sy = (double) nh / h;
AffineTransform transform = new AffineTransform();
transform.setToScale(sx, sy);
AffineTransformOp ato = new AffineTransformOp(transform, null);
//原始颜色
BufferedImage bid = new BufferedImage(nw, nh, BufferedImage.TYPE_3BYTE_BGR);
ato.filter(bis, bid);
//转换成byte字节
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(bid, "jpeg", baos);
newdata = baos.toByteArray();
}catch(IOException e){
e.printStackTrace();
}
return newdata;
}
4. 展示在页面
页面使用OracleQueryBean来根据用户提供的图片id进行查询，在读取并进行缩放后，通过jsp页面进行展示，具体代码如下：
<%@ page language="java" contentType="text/html;;charset=gbk" %>
<jsp:useBean id="OrcleQuery" scope="page" class="HLFtiDemo.OracleQueryBean" />
<%
response.setContentType("image/jpeg");
//图片在数据库中的 ID
String strID = request.getParameter("id");
//要缩略或放大图片的宽度
String strWidth = request.getParameter("w");
//要缩略或放大图片的高度
String strHeight = request.getParameter("h");
byte[] data = null;
if(strID != null){
int nWith = Integer.parseInt(strWidth);
int nHeight = Integer.parseInt(strHeight);
//获取图片的byte数据
data = OrcleQuery.GetImgByteById(strID, nWith, nHeight);
ServletOutputStream op = response.getOutputStream();
op.write(data, 0, data.length);
op.close();
op = null;
response.flushBuffer();
//清除输出流，防止释放时被捕获异常
out.clear();
out = pageContext.pushBody();
}
%>
5. OracleQueryBean查询类的整体代码
OracleQueryBean.java文件代码如下所示：
import java.sql.*;
import java.io.*;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.awt.image.AffineTransformOp;
import java.awt.geom.AffineTransform;
public class OracleQueryBean {
private final String oracleDriverName = "oracle.jdbc.driver.OracleDriver";
private Connection myConnection = null;
private String strTabName;
private String strIDName;
private String strImgName;
public OracleQueryBean(){
try{
Class.forName(oracleDriverName);
}catch(ClassNotFoundException ex){
System.out.println("加载jdbc驱动失败,原因:" + ex.getMessage());
}
}
public Connection getConnection(){
try{
//用户名+密码; 以下使用的Test就是Oracle里的表空间
//从配置文件中读取数据库信息
GetPara oGetPara = new GetPara();
String strIP = oGetPara.getPara("serverip");
String strPort = oGetPara.getPara("port");
String strDBName = oGetPara.getPara("dbname");
String strUser = oGetPara.getPara("user");
String strPassword = oGetPara.getPara("password");
this.strTabName = oGetPara.getPara("tablename");
this.strIDName = oGetPara.getPara("imgidname");
this.strImgName = oGetPara.getPara("imgname");
String oracleUrlToConnect ="jdbc:oracle:thin:@"+strIP+":"+strPort+":"+strDBName;
this.myConnection = DriverManager.getConnection(oracleUrlToConnect, strUser, strPassword);
}catch(Exception ex){
System.out.println("Can not get connection:" + ex.getMessage());
System.out.println("请检测配置文件中的数据库信息是否正确." );
}
return this.myConnection;
}
public byte[] GetImgByteById(String strID, int w, int h){
//System.out.println("Get img data which id is " + nID);
if(myConnection == null)
this.getConnection();
byte[] data = null;
try {
Statement stmt = myConnection.createStatement();
ResultSet myResultSet = stmt.executeQuery("select " + this.strIDName + " from " + this.strTabName + " where " + this.strIDName + "=" + strID);
StringBuffer myStringBuffer = new StringBuffer();
if (myResultSet.next()) {
java.sql.Blob blob = myResultSet.getBlob(this.strImgName);
InputStream inStream = blob.getBinaryStream();
try {
long nLen = blob.length();
int nSize = (int) nLen;
//System.out.println("img data size is :" + nSize);
data = new byte[nSize];
inStream.read(data);
inStream.close();
} catch (IOException e) {
System.out.println("获取图片数据失败,原因:" + e.getMessage());
}
data = ChangeImgSize(data, w, h);
}
System.out.println(myStringBuffer.toString());
myConnection.commit();
myConnection.close();
} catch (SQLException ex) {
System.out.println(ex.getMessage());
}
return data;
}
public byte[] GetImgByteById(String strID){
//System.out.println("Get img data which id is " + nID);
if(myConnection == null)
this.getConnection();
byte[] data = null;
try {
Statement stmt = myConnection.createStatement();
ResultSet myResultSet = stmt.executeQuery("select " + this.strIDName + " from " + this.strTabName + " where " + this.strIDName + "=" + strID);
StringBuffer myStringBuffer = new StringBuffer();
if (myResultSet.next()) {
java.sql.Blob blob = myResultSet.getBlob(this.strImgName);
InputStream inStream = blob.getBinaryStream();
try {
long nLen = blob.length();
int nSize = (int) nLen;
data = new byte[nSize];
inStream.read(data);
inStream.close();
} catch (IOException e) {
System.out.println("获取图片数据失败,原因:" + e.getMessage());
}
}
System.out.println(myStringBuffer.toString());
myConnection.commit();
myConnection.close();
} catch (SQLException ex) {
System.out.println(ex.getMessage());
}
return data;
}
private byte[] ChangeImgSize(byte[] data, int nw, int nh){
byte[] newdata = null;
try{
BufferedImage bis = ImageIO.read(new ByteArrayInputStream(data));
int w = bis.getWidth();
int h = bis.getHeight();
double sx = (double) nw / w;
double sy = (double) nh / h;
AffineTransform transform = new AffineTransform();
transform.setToScale(sx, sy);
AffineTransformOp ato = new AffineTransformOp(transform, null);
//原始颜色
BufferedImage bid = new BufferedImage(nw, nh, BufferedImage.TYPE_3BYTE_BGR);
ato.filter(bis, bid);
//转换成byte字节
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(bid, "jpeg", baos);
newdata = baos.toByteArray();
}catch(IOException e){
e.printStackTrace();
}
return newdata;
}
}
下面是我的存储读取blob图片的案例
import java.sql.*;
import java.io.*;
public class InsertPhoto {
public static void main(String[] args) throws Exception{
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://127.0.0.1/wiseweb?user=root&password=root");
File f = new File("e:/123.jpg");
FileInputStream fis = new FileInputStream(f);
String sql = "insert into photo(photo,photoName) values(?,?)";
PreparedStatement pstmt = con.prepareStatement(sql);
pstmt.setBinaryStream(1,fis,(int)f.length());
pstmt.setString(2, "测试图片");
pstmt.executeUpdate();
fis.close();
pstmt.close();
con.close();
}
}
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
public class ReadPhoto extends HttpServlet{
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response){
if(request.getParameter("id") != null){
response.setContentType("image/jpeg");
try {
InputStream is = query_getPhotoImageBlob(Integer.parseInt(request.getParameter("id"))) ;
if(is != null){
is = new BufferedInputStream(is) ;
BufferedImage bi = ImageIO.read(is) ;
OutputStream os = response.getOutputStream() ;
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os) ;
encoder.encode(bi);
os.close();
is.close();
}
} catch(IOException e){
e.printStackTrace();
}catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public static InputStream query_getPhotoImageBlob(int id) throws ClassNotFoundException, SQLException{
String sql = "select photo from photo where id="+id;
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
InputStream result = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://127.0.0.1/wiseweb?user=root&password=root");
stmt = con.createStatement();
rs = stmt.executeQuery(sql);
if (rs.next())
result = rs.getBlob("photo").getBinaryStream();
} catch (SQLException e) {
// TODO: handle exception
System.err.println(e.getMessage());
}finally{
rs.close();
stmt.close();
con.close();
}
return result;
}
}
jsp显示
<img style="width:320px;height:240px" src="<%=basePath%>/genImage?id=3"/>
web.xml中配置
<servlet>
<servlet-name>genImage</servlet-name>
<servlet-class>ReadPhoto</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>genImage</servlet-name>
<url-pattern>/genImage</url-pattern>
</servlet-mapping>
希望本文所述对大家的Java程序设计有所帮助。
相关推荐
-
Java+mysql本地图片上传数据库及下载示例
做一个将本地图片上传到mysql数据库的小实例,顺便也下载下来到桌面检测是否上传成功. 在写代码之前得先在数据库中建立image表,用来存储图片. create table image (id int primary key auto_increment , name varchar(30) COMMENT '名称', content mediumblob COMMENT '图片'); 下面直接上代码: package jdbc_imagetest; import java.io.*; impo
-
详解JAVA生成将图片存入数据库的sql语句实现方法
详解JAVA生成将图片存入数据库的sql语句实现方法 实现代码: 注释很清楚,不在重述~ public class Image2Hex { public static void main(String[] args) { try{ //存放图片的文件夹 File list = new File("d:/qmx"); File[] lists = list.listFiles(); String name; //生成的语句存放文件 PrintWriter pw = new PrintWr
-
Java从数据库中读取Blob对象图片并显示的方法
本文实例讲述了Java从数据库中读取Blob对象图片并显示的方法.分享给大家供大家参考.具体实现方法如下: 第一种方法: 大致方法就是,从数据库中读出Blob的流来,写到页面中去: 复制代码 代码如下: Connection conn = DBManager.getConnection(); String sql = "SELECT picture FROM teacher WHERE id=1"; PreparedStatement ps = null; ResultSe
-
详解python中读取和查看图片的6种方法
目录 1 OpenCV 2 imageio 3 PIL 4 scipy.misc 5 tensorflow 6 skimage 本文主要介绍了python中读取和查看图片的6种方法,分享给大家,具体如下: file_name1='test_imgs/spect/1.png' # 这是彩色图片 file_name2='test_imgs/mri/1.png' # 这是灰度图片 1 OpenCV 注:用cv2读取图片默认通道顺序是B.G.R,而不是通常的RGB顺序,所以读进去的彩色图直接显示会出现变
-
Java 在PPT中添加文本和图片超链接的实现方法
在文档中添加超链接,可以快速从当前文档跳转至指定的网页或打开指定的外部文件.前文中我们介绍过如何使用Java程序来为Word文档和Excel工作表添加超链接.本文将演示如何在PPT中添加文本和图片超链接. 使用工具:Free Spire.Presentation for Java(免费版)Jar文件获取及导入: 方法1:通过官网下载获取jar包.解压后将lib文件夹下的Spire.Presentation.jar文件导入Java程序.(如下图) 方法2:通过maven仓库安装导入.具体安装教程参
-
从Oracle数据库中读取数据自动生成INSERT语句的方法
Oracle INSERT 语句 方法1 我估计有点 SQL 基础的人都会写 INSERT 语句.下面是 SQL 标准写法. INSERT INTO employees (employee_id, name) VALUES (1, 'Zhangsan'); INSERT INTO employees VALUES (1, 'Shangbo'); 方法2 其实, Oracle 还支持下面的写法,作用和上面的语句完全相同. INSERT INTO (SELECT employee_id, name
-
asp.net mvc 从数据库中读取图片的实现代码
首先是创建一个类,继承于ActionResult,记住要引用System.Web.Mvc命名空间,如下: 复制代码 代码如下: public class ImageResult : ActionResult { public ImageFormat ContentType { get; set; } public Image image { get; set; } public string SourceName { get; set; } public ImageResult(string _
-
C# 文件保存到数据库中或者从数据库中读取文件
其实,方法非常的简单,只是可能由于这些朋友刚刚开始编程不久,一时没有找到方法而已.下面介绍一下使用C#来完成此项任务. 首先,介绍一下保存文件到数据库中. 将文件保存到数据库中,实际上是将文件转换成二进制流后,将二进制流保存到数据库相应的字段中.在SQL Server中该字段的数据类型是Image,在Access中该字段的数据类型是OLE对象. 复制代码 代码如下: //保存文件到SQL Server数据库中 FileInfo fi=new FileInfo(fileName); FileStr
-
C# 制作PictureBox圆形头像框并从数据库中读取头像
现在只要是有关头像的框基本都是圆形的了,C#提供的PictureBox控键默认情况下是方形的非常大的影响美观 PictureBox默认情况下 比起上面的还是有一点不太好看的- 使用C#提供的类进行圆形: 工具箱拉出PictureBox 设置图片的显示模式为ZOOM 特别注意: 框的比例必须为一样不然会变椭圆的 窗体加载时: pictureBox1.Image = Image.FromFile(@"C:\Users\Administrator\Desktop\1.png"); 为了方便演
-
php从数据库中读取特定的行(实例)
有的时候我们需要从数据库中读取特定的数据,来检验用户的输入,这个时候需要执行的sql语句是: select * from table_name where id='num'; 需要执行这样的一个语句. 那么怎样来执行这样的语句. 为了执行sql语句,我们需要和数据库相连接 <?PHP $servername='localhost'; $username="root"; $password="1234"; $dbname="mydb1"; /
-
java导出数据库中Excel表格数据的方法
本篇文章基于java把数据库中的数据以Excel的方式导出,欢迎各位大神吐槽: 1.基于maven jar包引入如下: <dependency> <groupId>net.sourceforge.jexcelapi</groupId> <artifactId>jxl</artifactId> <version>2.6.12</version> </dependency> 2.首先创建数据库对应的实体类VO :U
-
python spyder中读取txt为图片的方法
有时候需要将一个环境中的图片可视化,但是可能这个环境下不方便,因此需要将这个环境下的图像数据保存下来,然后在另一个环境下查看,比如,有一个图像数据,image.txt,里面的数据是图像的像素值,范围是0-255,像素值之间以空格键分开,行与行之间是回车键分开,那么在Python Spyder环境下通过简单的几条语句就搞定: import numpy from skimage import io image = numpy.loadtxt("image.txt") io.imshow(i