java 将 blob 转换为图像流并将其分配给 jLabel
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converting blob to an image stream and assign it to jLabel
提问by user2319205
I am just trying to Convert a blob string which is in Database to Byte array and then after converting it convert to buffered Image and then assign it to a label Here's my code
我只是想将数据库中的 blob 字符串转换为字节数组，然后将其转换为缓冲图像，然后将其分配给标签 这是我的代码
package ims.project;
import java.sql.*;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import javax.imageio.ImageIO;
public class readingdata extends JFrame {
readingdata() {
JPanel pane = new JPanel();
JLabel label1 = new JLabel("help");
JLabel label2 = new JLabel("33");
pane.add(label1);
pane.add(label2);
setVisible(true);
add(pane);
try {
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/ims1", "root", "root");
Statement st = con.createStatement();
String ss = "select Pic from supplier where Supplier_id= '" + label2.getText() + "'";
JOptionPane.showMessageDialog(null, label2.getText());
ResultSet rs = st.executeQuery(ss);
while (rs.next()) {
Blob blob = rs.getBlob("Pic");
int blobLength = (int) blob.length();
byte[] blobAsBytes = blob.getBytes(1, blobLength);
final BufferedImage bufferedImage = ImageIO.read(new ByteArrayInputStream(blobAsBytes));
label2.setIcon(new ImageIcon(bufferedImage));
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
public static void main(String args[]) {
new readingdata();
}
}
but when i run this code it's show the Null pointer Stack-trace
但是当我运行这段代码时，它显示了空指针堆栈跟踪
java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:228)
at ims.project.readingdata.<init>(readingdata.java:47)
at ims.project.readingdata.main(readingdata.java:60)
回答by Noor Mohammad Atapoor
Please try the following piece of code:
请尝试以下代码：
Connection connection = null;
PreparedStatement statement = null;
ResultSet result;
public DisplayImage() {
super("Image Display");
setSize(600,600);
connection = getConnection();
try {
statement = connection.prepareStatement("select content from image where id=1");
result = statement.executeQuery();
byte[] image = null;
while(result.next()) {
image = result.getBytes("content");
}
Image img = Toolkit.getDefaultToolkit().createImage(image);
ImageIcon icon =new ImageIcon(img);
JLabel lPhoto = new JLabel();
lPhoto.setIcon(icon);
add(lPhoto);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
setVisible(true);
}
public Connection getConnection() {
Connection connection = null;
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/db_name", "user", "pass");
} catch (Exception e) {
System.out.println("Error Occured While Getting the Connection: - "
+ e);
}
return connection;
}
public static void main(String[] args) {
new DisplayImage();
}
}
