从数据库中检索图像并显示在标签中

Question

I am having one image named P100.jpg . I am resizing it and it is converted into ZP100.png . I am storing it into database MySQL, by insert query.

    File imageFile = new File("F:\\POSTERS\\Roses\\ZP100.png");
    FileInputStream fis = new FileInputStream(imageFile);

    String insertImage = "insert into image values(?,?)";
    prestmt = con.prepareStatement(insertImage);
    prestmt.setInt(1,4);
    prestmt.setBinaryStream(2, fis, fis.available());
    result = prestmt.executeUpdate();

Now I want to retrieve that image and display on a form by assigning it to a label.

    String selectImage = "select img from image";
    prestmt = con.prepareStatement(selectImage);

But it's giving me exception as

java.sql.SQLException: Can not issue executeUpdate() for SELECTs

For assigning image to a label I have:

    image.setText("ZP100.png"); 

I know, it cannot work. Please help me to recode this.

Answer 1

First error must be at this:

result = prestmt.executeUpdate();

I fear you have declared result with type ResultSet .
And when you are assigning an int , the return type of executeUpdate() , to result
obviously an SQLException is raised.

Modify above statement like this:

int insertResult = prestmt.executeUpdate();

And you should get a success on it.

Suggestion :

prestmt.setBinaryStream( 2, fis, fis.available() );

Don't depend o available() method if you want to read content from a stream.
It is just an estimate and won't guarantee you that you can read till the end of stream.

Instead use the other signature of the setBinaryStream method like:
setBinaryStream( int parameterIndex, InsputStream is )
Javadoc says, The data will be read from the stream as needed until end-of-file is reached. , meaning you need not read it explicitly.
With the change, your statement would look like:

prestmt.setBinaryStream( 2, fis );

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Image :
I have not worked much on Java GUI and images.
But can suggest you to refer to some solutions at:

1. Add Image to Button
2. Label with Image