GWT在Tomcat中时无法从文件系统加载图形
我使用以下Servlet映射文件系统文件夹中的图像GWT在Tomcat中时无法从文件系统加载图形,gwt,tomcat,servlets,gwt2,Gwt,Tomcat,Servlets,Gwt2,我使用以下Servlet映射文件系统文件夹中的图像 public class ImageServlet extends HttpServlet { public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException { // Get the base path for graphics root folder String basePat
public class ImageServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws IOException {
// Get the base path for graphics root folder
String basePath = System.getenv(Constants.ENV_VAR);
String specifier = req.getParameter(Constants.PARAMETER);
resp.setContentType(Constants.CONTENT_TYPE);
File file = new File(basePath+specifier+"."+Constants.IMG_TYPE);
resp.setContentLength((int)file.length());
FileInputStream in = new FileInputStream(file);
OutputStream out = resp.getOutputStream();
// Copy the contents of the file to the output stream
byte[] buf = new byte[Constants.INPUT_BUFFER_SIZE];
int count = 0;
while ((count = in.read(buf)) >= 0) {
out.write(buf, 0, count);
}
in.close();
out.close();
}
}
然后,通过使用以下AppServiceImpl类,我使用GWT-RPC获取图像:
public class AppServiceImpl extends RemoteServiceServlet implements AppService {
//Get the base path for graphics root folder
String basePath = System.getenv(Constants.ENV_VAR);
@Override
public ArrayList<String> getImageFiles(String folder) {
ArrayList<String> list = new ArrayList<String>();
File parent = new File(**basePath+folder**);
if (!parent.isDirectory()) {
return list;
}
File[] files = parent.listFiles();
for (int i = 0; i < files.length; i++) {
if (files[i].isFile() && !files[i].isHidden()) {
// save image title
list.add(files[i].getName().substring(0, files[i].getName().indexOf(".")));
}
}
return list;
}
...
公共类AppServiceImpl扩展RemoteServiceServlet实现AppService{
//获取图形根文件夹的基本路径
字符串basePath=System.getenv(Constants.ENV_VAR);
@凌驾
公共ArrayList getImageFiles(字符串文件夹){
ArrayList=新建ArrayList();
文件父项=新文件(**basePath+文件夹**);
如果(!parent.isDirectory()){
退货清单;
}
File[]files=parent.listFiles();
对于(int i=0;i
为了在GWT代码中获取图像,我使用:final image lgImg=new image(Constants.URL\u PREFIX+imgPath);
其中:
- URL\u前缀=”http://localhost:8888/images?“+参数+”=“
- ENV\u VAR=“APP\u GFX\u HOME”
- PARAMETER=“path”
<!-- Services -->
<servlet>
<servlet-name>theImageServlet</servlet-name>
<servlet-class>com.app.server.ImageServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>theImageServlet</servlet-name>
<url-pattern>/images</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>appService</servlet-name>
<servlet-class>com.app.server.AppServiceImpl</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>appService</servlet-name>
<url-pattern>/app/services</url-pattern>
</servlet-mapping>
theImageServlet
com.app.server.ImageServlet
theImageServlet
/图像
应用服务
com.app.server.AppServiceImpl
应用服务
/应用程序/服务
我不会硬编码URL,因为上下文部分在开发模式下不存在。
只需使用:
String url = GWT.getModuleBaseURL() + "images?";
我在类似的情况下使用它从报表servlet下载Excel文件,它在所有情况下都可以正常工作。我将URL_PREFIX常量更改为String URL_PREFIX=GWT.getModuleBaseURL()+“images?”+参数+“=”;但我仍然无法获取图像。虽然tomcat中的servlet能够正确获取环境变量吗?