将图片转换成二进制,然后再显示图片!

本文介绍了使用Java进行图像处理的方法,包括图像转字节流和字节流转图像的过程,并展示了如何将图像文件存储到数据库中及从数据库读取图像进行显示。通过具体的代码实例,读者可以了解到图像操作的基本原理及数据库交互的技术细节。

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package com.jh.loginwindow;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.Label;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.*;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

class TryBufferout extends JFrame{
public static byte[] imageToBytes(Image image, String format) {
BufferedImage bImage = new BufferedImage(image.getWidth(null),
image.getHeight(null), BufferedImage.TYPE_INT_ARGB);
Graphics bg = bImage.getGraphics();
bg.drawImage(image, 0, 0, null);
bg.dispose();
ByteArrayOutputStream out = new ByteArrayOutputStream();
try {
ImageIO.write(bImage, format, out);
} catch (IOException e) {
}
return out.toByteArray();
}
public static void main(String[] args) {
ImageIcon icon = new ImageIcon("D:\\QQ.png");
Image image = icon.getImage();
byte[] b=imageToBytes(image,"png");
Image imagee=bytesToImage(b);
TryBufferout t= new TryBufferout();
t.setSize(400,400);
ImageIcon imag=new ImageIcon();
imag.setImage(imagee);
System.out.println(imag);
t.add(new JLabel(imag));
t.setVisible(true);
}

public static Image bytesToImage(byte[] bytes) {
Image image = Toolkit.getDefaultToolkit().createImage(bytes);
try {
MediaTracker mt = new MediaTracker(new Label());
mt.addImage(image, 0);
mt.waitForAll();
} catch (InterruptedException e) {
}
return image;
}

}


下面也是经过自己的实践所写的代码
package com.jh.loginwindow;

import java.awt.Image;
import java.awt.Label;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import java.io.*;
import java.sql.*;

import javax.swing.ImageIcon;

public class PutImg extends SuperDao {
Statement stmt;
PreparedStatement pstmt = null;
public void putimg() {
String sql = "";
File file = new File("d:\\world.gif");
InputStream photoStream;
try {
photoStream = new FileInputStream(file);
sql = "INSERT INTO testpictrue (image) VALUES (?)";
pstmt = getConnection().prepareStatement(sql);
pstmt.setBinaryStream(1, photoStream, (int) file.length());
pstmt.executeUpdate();
pstmt.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public Image blobRead() throws Exception {
FileOutputStream fos = null;
InputStream is = null;
byte[] Buffer = new byte[4096];
try {
pstmt = getConnection().prepareStatement("select image from testpictrue where id=?");
pstmt.setInt(1, 1); // 传入要取的图片的ID
ResultSet rs = pstmt.executeQuery();
rs.next();
[b] is = rs.getBinaryStream("image");
byte[] b = new byte[is.available()];//声明
is.read(Buffer);//将二进制输入流读入字节数组
Image image= bytesToImage(Buffer); [/b]
return image;
} catch (Exception e) {
return null;
} finally {
// 关闭用到的资源

}
}
public Image bytesToImage(byte[] bytes) {
Image image = Toolkit.getDefaultToolkit().createImage(bytes);
try {
MediaTracker mt = new MediaTracker(new Label());
mt.addImage(image, 0);
mt.waitForAll();
} catch (InterruptedException e) {
}
return image;
}

public static void main(String args[]) {
PutImg pi = new PutImg();
try {
Image image=pi.blobRead();
new TryBufferout(image);//在这个界面上显示
} catch (Exception e) {

e.printStackTrace();
}
}
}
图片的常见存储与读取凡是有以下几种: 存储图片:以二进制的形式存储图片时,要把数据库中的字段设置为Image数据类型(SQL Server),存储的数据是Byte[]. 1.参数是图片路径:返回Byte[]类型: public byte[] GetPictureData(string imagepath) { /**/////根据图片文件的路径使用文件流打开,并保存为byte[] FileStream fs = new FileStream(imagepath, FileMode.Open);//可以是其他重载方法 byte[] byData = new byte[fs.Length]; fs.Read(byData, 0, byData.Length); fs.Close(); return byData; }2.参数类型是Image对象,返回Byte[]类型: public byte[] PhotoImageInsert(System.Drawing.Image imgPhoto) { //将Image转换成流数据,并保存为byte[] MemoryStream mstream = new MemoryStream(); imgPhoto.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp); byte[] byData = new Byte[mstream.Length]; mstream.Position = 0; mstream.Read(byData, 0, byData.Length); mstream.Close(); return byData; }好了,这样通过上面的方法就可以把图片转换成Byte[]对象,然后就把这个对象保存到数据库中去就实现了把图片二进制格式保存到数据库中去了。下面我就谈谈如何把数据库中的图片读取出来,实际上这是一个相反的过程。 读取图片:把相应的字段转换成Byte[]即:Byte[] bt=(Byte[])XXXX 1.参数是Byte[]类型,返回值是Image对象: public System.Drawing.Image ReturnPhoto(byte[] streamByte) { System.IO.MemoryStream ms = new System.IO.MemoryStream(streamByte); System.Drawing.Image img = System.Drawing.Image.FromStream(ms); return img; }2.参数是Byte[] 类型,没有返回值,这是针对asp.net中把图片从输出到网页上(Response.BinaryWrite) public void WritePhoto(byte[] streamByte) { // Response.ContentType 的默认值为默认值为“text/html” Response.ContentType = "image/GIF"; //图片输出的类型有: image/GIF image/JPEG Response.BinaryWrite(streamByte); }补充: 针对Response.ContentType的值,除了针对图片的类型外,还有其他的类型: Response.ContentType = "application/msword"; Response.ContentType = "application/x-shockwave-flash"; Response.ContentType = "application/vnd.ms-excel";另外可以针对不同的格式,用不同的输出类型以适合不同的类型: switch (dataread("document_type")) { case "doc": Response.ContentType = "application/msword"; case "swf": Response.ContentType = "application/x-shockwave-flash"; case "xls": Response.ContentType = "application/vnd.ms-excel"; case "gif": Response.ContentType = "image/gif"; case "Jpg": Response.ContentType = "image/jpeg"; }
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