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RCP编程技巧：如何显示Mysql数据库中存储的图片？
【原创】
我在程序开发中，经常要将图片文件存入Mysql数据库的longblob字段中，存入数据库和以前在jsp中没什么区别，那么，如何将存入数据库的图片在SWT中显示呢？
首先，我写了一个方法，将inputstream取出，
public InputStream getImage(String id) {
DataConfig config = new DataConfig();
InputStream stream = null;
try {
config.openConnection();
Connection conn = config.getConnection();
PreparedStatement pStmt = conn
.prepareStatement("select bugimage from bugs where id=?");
pStmt.setString(1, id);
ResultSet rs = pStmt.executeQuery();
if (rs != null) {
while (rs.next()) {
stream = rs.getBinaryStream(1);
}
rs.close();
}
pStmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
return stream;
}
然后，在程序中使用SWT的Image类和Canvas类将图片显示出来，代码如下：
//其中Canvas显示滚动条的代码来自eclipse网站
Composite composite = new Composite(parent, SWT.NONE);
GridLayout gridLayout = new GridLayout(1, false);
gridLayout.marginWidth = 10;
gridLayout.marginHeight = 10;
gridLayout.horizontalSpacing = 10;
gridLayout.verticalSpacing = 10;
composite.setLayout(gridLayout);
GridData gridData = new GridData(GridData.FILL, GridData.CENTER, false,
false);
composite.setLayoutData(gridData);
image = new Image(Display.getDefault(), getImage("1"));
if (image == null) {
int width = 150, height = 200;
image = new Image(FireiceUtil.getDisplay(), width, height);
GC gc = new GC(image);
gc.fillRectangle(0, 0, width, height);
gc.drawLine(0, 0, width, height);
gc.drawLine(0, height, width, 0);
gc.drawText("No Image", 10, 10);
gc.dispose();
}
canvas = new Canvas(composite, SWT.NO_BACKGROUND | SWT.NO_REDRAW_RESIZE | SWT.V_SCROLL | SWT.H_SCROLL);
GridData canvasGridData = new GridData();
canvasGridData.heightHint = 400;
canvasGridData.widthHint = 500;
canvas.setLayoutData(canvasGridData);
final Point origin = new Point(0, 0);
final ScrollBar hBar = canvas.getHorizontalBar();
hBar.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event e) {
int hSelection = hBar.getSelection();
int destX = -hSelection - origin.x;
Rectangle rect = image.getBounds();
canvas.scroll(destX, 0, 0, 0, rect.width, rect.height, false);
origin.x = -hSelection;
}
});
final ScrollBar vBar = canvas.getVerticalBar();
vBar.addListener(SWT.Selection, new Listener() {
public void handleEvent(Event e) {
int vSelection = vBar.getSelection();
int destY = -vSelection - origin.y;
Rectangle rect = image.getBounds();
canvas.scroll(0, destY, 0, 0, rect.width, rect.height, false);
origin.y = -vSelection;
}
});
canvas.addListener(SWT.Resize, new Listener() {
public void handleEvent(Event e) {
Rectangle rect = image.getBounds();
Rectangle client = canvas.getClientArea();
hBar.setMaximum(rect.width);
vBar.setMaximum(rect.height);
hBar.setThumb(Math.min(rect.width, client.width));
vBar.setThumb(Math.min(rect.height, client.height));
int hPage = rect.width - client.width;
int vPage = rect.height - client.height;
int hSelection = hBar.getSelection();
int vSelection = vBar.getSelection();
if (hSelection >= hPage) {
if (hPage <= 0)
hSelection = 0;
origin.x = -hSelection;
}
if (vSelection >= vPage) {
if (vPage <= 0)
vSelection = 0;
origin.y = -vSelection;
}
canvas.redraw();
}
});
canvas.addListener(SWT.Paint, new Listener() {
public void handleEvent(Event e) {
GC gc = e.gc;
gc.drawImage(image, origin.x, origin.y);
Rectangle rect = image.getBounds();
Rectangle client = canvas.getClientArea();
int marginWidth = client.width - rect.width;
if (marginWidth > 0) {
gc.fillRectangle(rect.width, 0, marginWidth, client.height);
}
int marginHeight = client.height - rect.height;
if (marginHeight > 0) {
gc
.fillRectangle(0, rect.height, client.width,marginHeight);
}
}
});
2006/2/13 17:39:00
Posted by guanhui | 阅读全文 | 回复(0) | 引用通告 | 编辑 | 收藏该日志
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