blocks|key|838634|text|在GWT中有Image+Widget。您不能在客户端执行此操作，但可以调用RPC与服务器进行通信。那么它就是一个简单的CRUD应用程序。在服务器端，使用hibernate连接到数据库，并将图像返回给客户端，或者返回url，然后在客户端执行类似的操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|838635|@Override
public+void+onSuccess(String+imageUrl)+{
++++Image+image+=+new+Image(imageUrl);
++++RootPanel.get("image").add(image);
}

@Override
public+void+onFailure(Throwable+caught)+{
++++Window.alert(caught.getMessage());
}|code-block|syntax|javascript|838636|就这样。快乐编码|838637|entityMap|0|LINK|mutability|MUTABLE|url|http://google-web-toolkit.googlecode.com/svn/javadoc/1.5/com/google/gwt/user/client/ui/Image.html|1|http://code.google.com/webtoolkit/doc/1.6/DevGuideServerCommunication.html^0|6|C|0|11|3|1|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]|$A|Y|B|Z|1|10]]|C|$]]|$1|D|3|E|5|F|7|11|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|13|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]]]

There is <a href="http://google-web-toolkit.googlecode.com/svn/javadoc/1.5/com/google/gwt/user/client/ui/Image.html" rel="nofollow">Image Widget</a> in GWT. You can't do it client-side but you can call <a href="http://code.google.com/webtoolkit/doc/1.6/DevGuideServerCommunication.html" rel="nofollow">RPC</a> to communicate with the server. Then it is simple CRUD application. In server connect to database with hibernate and return the Image to the client or it's url and on the client-side do something like that :

<pre><code>@Override
public void onSuccess(String imageUrl) {
 Image image = new Image(imageUrl);
 RootPanel.get("image").add(image);
}

@Override
public void onFailure(Throwable caught) {
 Window.alert(caught.getMessage());
}
</code></pre>

That's all. Happy coding

blocks|key|1053367|text|以下是解决方案。首先，应该使用com.google.gwt.user.server.Base64Utils.toBase64(byte[])对字节数组进行编码。但是这种方法不适用于IE7，而且IE8有32kb的限制..IE9没有这个限制。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1053368|下面是服务器上的方法|1053369|public+String+getImageData(){
++++++String+base64+=+Base64Utils.toBase64(imageByteArray);+
++++++base64+=+"data:image/png;base64,"%2Bbase64;
++++++return+base64;
}|code-block|syntax|javascript|1053370|下面是客户端方法；|1053371|@Override+
public+void+onSuccess(String+imageData)+{+++++
++++Image+image+=+new+Image(imageData);+++++
++++RootPanel.get("image").add(image);+
}+|1053372|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Here is the solution. First you should encode the byte array by using com.google.gwt.user.server.Base64Utils.toBase64(byte[]) . But this method does not work for IE 7. and IE8 has 32kb limit.. IE9 does not have this limit. 

here is the method on the server

<pre><code>public String getImageData(){
 String base64 = Base64Utils.toBase64(imageByteArray); 
 base64 = "data:image/png;base64,"+base64;
 return base64;
}
</code></pre>

Here is the client method ;

<pre><code>@Override 
public void onSuccess(String imageData) { 
 Image image = new Image(imageData); 
 RootPanel.get("image").add(image); 
} 
</code></pre>

blocks|key|838726|text|我不知道GWT是如何工作的，尽管您可以映射一个返回resourceStream的servlet/控制器。例如，如果您映射一个采用imageId参数的servlet+"imageViewer“，则对图像的请求将变为|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838727|/imageViewer?imageId=1234|code-block|syntax|javascript|838728|Hibernate对象会有对blob的引用，所以你可以返回它。UI上的引用将是|838729|<img+src="/imageViewer?imageId=1234"/>|838730|更新:您可能无法使用Model，因为它返回图像，您需要一个显式的控制器或返回流数据的servlet。|838731|在servlet中，您将执行如下操作|838732|//+get+reference+to+input+stream
InputStream+in+=+hibnerateObject.getImage();++
//+set+MIME+type+etc
response.setContentType(mimeType);
OutputStream+out+=+response.getOutputStream();
while+((len+=+in.read(buf))+>=+0)
+out.write(buf,+0,+len);
in.close();
out.close();|838733|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I don't know how GWT works, albeit you can map a servlet/controller which returns resourceStream.
For example if you map a servlet "imageViewer" which takes imageId param, request to image would become 

<pre><code>/imageViewer?imageId=1234
</code></pre>

Hibernate object would have reference to the blob, so you can return that.
Reference on UI would be 

<pre><code>&lt;img src="/imageViewer?imageId=1234"/&gt;
</code></pre>

Update: You may not be able to use Model as it is to return image, you would need an explicit controller or servlet which returns stream data. 
In servlet you would do something like

<pre><code>// get reference to input stream
InputStream in = hibnerateObject.getImage(); 
// set MIME type etc
response.setContentType(mimeType);
OutputStream out = response.getOutputStream();
while ((len = in.read(buf)) &gt;= 0)
 out.write(buf, 0, len);
in.close();
out.close();
</code></pre>

blocks|key|838782|text|我使用了Gursel+Koca建议的相同方法，但只能使用Apache+Base64库，而不是(具有讽刺意味的)+GWT+Base64Utils。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|838783|String+base64+=+Base64.encodeBase64String(array);
base64+=+"data:image/"%2Btype%2B";base64,"+%2B+base64;
return+base64;|code-block|syntax|javascript|838784|还要注意，如果您正在更新现有图像或图像占位符，则setURL方法将覆盖您的样式表，因此请确保首先获取该样式表：|838785|String+styleName+=+profilePicture.getStyleName();
profilePicture.setUrl(base64String);
profilePicture.setStyleName(styleName);|838786|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I used the same approach as Gursel Koca suggested but could only get it to work using the Apache Base64 library, not (ironically) the GWT Base64Utils

<pre><code>String base64 = Base64.encodeBase64String(array);
base64 = "data:image/"+type+";base64," + base64;
return base64;
</code></pre>

Also note that if you are updating an existing image or an image placeholder, the setURL method will overwrite your stylesheet, so make sure to grab that first:

<pre><code>String styleName = profilePicture.getStyleName();
profilePicture.setUrl(base64String);
profilePicture.setStyleName(styleName);
</code></pre>

I'm actually working on a GWT based website.
Now I'm stuck on how I should display images stored in a database on my website.

Basically I've a bytearray in my database, which I fetch using hibernate.
Now should I probably create an ... tag out of that data, but I don't know how

I'm using GWT in Java and Hibernate

GWT - image from database

数据库

服务器

流数据

Java

我实际上是在做一个基于GWT的网站。现在我被困在如何在我的网站上显示存储在数据库中的图像上。基本上，我的数据库中有一个bytearray，我使用hibernate获取它。现在我应该创建一个..。标记出数据，但我不知道如何我在Java和Hibernate中使用GWT

问GWT -来自数据库的图像
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