prototype for a filter solution

bug5153
2026-09-19 12:15:28 +00:00 · 2020-04-26 06:31:08 +02:00
parent 7c785fc1a8
commit 233f65c2e7
2 changed files with 207 additions and 0 deletions
@@ -0,0 +1,196 @@
+package com.sap.sse.debranding;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.WriteListener;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpServletResponseWrapper;
+
+public class ClientConfigurationFilter implements Filter {
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+     // intentionally left blank
+    }
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+            throws IOException, ServletException {
+        HttpServletResponseWrapper wrappedResponse = new CharResponseWrapper((HttpServletResponse) response);
+        HttpServletRequestWrapper wrappedRequest = new HeadersRequestWrapper((HttpServletRequest) request);
+        chain.doFilter(wrappedRequest, wrappedResponse);
+        String body = wrappedResponse.toString();
+        String replaced = new String(body);
+        System.setProperty(ClientConfigurationServlet.DEBRANDING_PROPERTY_NAME, "true");
+        final boolean deBrandingActive = Boolean
+                .valueOf(System.getProperty(ClientConfigurationServlet.DEBRANDING_PROPERTY_NAME, "false"));
+        for (Map.Entry<String, String> item : createReplacementMap(deBrandingActive).entrySet()) {
+            replaced = replaced.replace("${" + item.getKey() + "}", item.getValue());
+        }
+        response.getWriter().write(replaced);
+    }
+
+    private Map<String, String> createReplacementMap(boolean deBrandingActive) {
+        final Map<String, String> map = new HashMap<>();
+        final String title;
+        final String whitelabeled;
+        if (deBrandingActive) {
+            title = "";
+            whitelabeled = "-whitelabeled";
+        } else {
+            title = "SAP ";
+            whitelabeled = "";
+        }
+        map.put("SAP", title);
+        map.put("debrandingActive", Boolean.toString(deBrandingActive));
+        map.put("whitelabeled", whitelabeled);
+        return map;
+    }
+
+    @Override
+    public void destroy() {
+        // intentionally left blank
+    }
+
+    private static class HeadersRequestWrapper extends HttpServletRequestWrapper {
+        private HeadersRequestWrapper(HttpServletRequest request) {
+            super(request);
+        }
+
+        @Override
+        public String getHeader(String name) {
+            if (name.equalsIgnoreCase("Cache-Control")) {
+                return "no-cache";
+            }
+            if (name.equalsIgnoreCase("If-Modified-Since")) {
+                return "Thu, 1. Jan 1970 00:00:00 GMT";
+            }
+            return super.getHeader(name);
+        }
+
+        @Override
+        public Enumeration<String> getHeaders(String name) {
+            if (name.equalsIgnoreCase("Cache-Control")) {
+                return new OneElementEnum("no-cache");
+            }
+            if (name.equalsIgnoreCase("If-Modified-Since")) {
+                return new OneElementEnum("Thu, 1. Jan 1970 00:00:00 GMT");
+            }
+            return super.getHeaders(name);
+        }
+
+        @Override
+        public long getDateHeader(String name) {
+            if (name.equalsIgnoreCase("If-Modified-Since")) {
+                return 0;
+            }
+            return super.getDateHeader(name);
+        }
+        
+    }
+
+     private static class OneElementEnum implements Enumeration<String> {
+            private boolean delivered = false;
+            private String value;
+            
+            public OneElementEnum(String value) {
+                this.value = value;
+            }
+
+            @Override
+            public boolean hasMoreElements() {
+                return !delivered;
+            }
+
+            @Override
+            public String nextElement() {
+                delivered = true;
+                return value;
+            }
+    }
+        
+    private static class CharResponseWrapper extends HttpServletResponseWrapper {
+        private ByteArrayOutputStream output;
+
+        public String toString() {
+            return output.toString();
+        }
+
+        public CharResponseWrapper(HttpServletResponse response) {
+            super(response);
+            response.setBufferSize(0); // prevent buffering here to not need to think about it later
+            output = new ByteArrayOutputStream();
+        }
+
+        public PrintWriter getWriter() {
+            return new PrintWriter(output);
+        }
+
+        @Override
+        public void setResponse(ServletResponse response) {
+            super.setResponse(response);
+        }
+
+        @Override
+        public void setBufferSize(int size) {
+            super.setBufferSize(0);
+        }
+
+        @Override
+        public int getBufferSize() {
+            return 0;
+        }
+
+        @Override
+        public void flushBuffer() throws IOException {
+//            super.flushBuffer();
+        }
+
+        @Override
+        public void reset() {
+//            super.reset();
+        }
+
+        @Override
+        public void resetBuffer() {
+//            super.resetBuffer();
+        }
+
+        @Override
+        public ServletOutputStream getOutputStream() throws IOException {
+            return new ServletOutputStream() {
+                
+                @Override
+                public void write(int arg0) throws IOException {
+                    output.write(arg0);
+                }
+                
+                @Override
+                public void setWriteListener(WriteListener writeListener) {
+                    throw new IllegalStateException("not supported by ClientConfigurationServlet");
+                }
+                
+                @Override
+                public boolean isReady() {
+                    return true;
+                }
+            };
+        }
+
+    }
+
+}