switch to filter

bug5153
2026-09-19 12:15:28 +00:00 · 2020-05-08 08:43:03 +02:00
parent 32589e26d6
commit 6e0d6452b1
9 changed files with 231 additions and 207 deletions
@@ -1,8 +1,9 @@
 package com.sap.sse.debranding;

-import java.io.ByteArrayOutputStream;
+import java.io.FilterWriter;
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.io.Writer;
 import java.util.HashMap;
 import java.util.Map;

@@ -16,9 +17,58 @@ import javax.servlet.ServletResponse;
 import javax.servlet.WriteListener;
 import javax.servlet.http.HttpServletResponse;
 import javax.servlet.http.HttpServletResponseWrapper;
-
+/**
+ * Use ${[variable name]} to get strings replaced within static pages. No escape syntax is currently available. All occurrences of the variables listed below
+ * that are found in the document will be replaced. The following variables are available at the moment:
+ * <table border="1">
+ * <tr>
+ * <th>Variablename</th>
+ * <th>branded value</th>
+ * <th>debranded/whitelabeled</th>
+ * </tr>
+ * <tr>
+ * <td>"SAP"</td>
+ * <td>"SAP&nbsp;"</td>
+ * <td>""</td>
+ * </tr>
+ * <tr>
+ * <td>"debrandingActive"</td>
+ * <td>"false"</td>
+ * <td>"true"</td>
+ * </tr>
+ * <tr>
+ * <td>"whitelabeled"</td>
+ * <td>""</td>
+ * <td>"-whitelabeled"</td>
+ * </tr>
+ * </table>
+ * <p>
+ *
+ * Register as a filter for all the URLs that produce such static pages that you'd like to run replacements on. Example
+ * registration in a {@code web.xml} configuration file:
+ * 
+ * <pre>
+ *   &lt;filter&gt;
+ *       &lt;display-name&gt;ClientConfigurationFilter&lt;/display-name&gt;
+ *       &lt;filter-name&gt;ClientConfigurationFilter&lt;/filter-name&gt;
+ *       &lt;filter-class&gt;com.sap.sse.debranding.ClientConfigurationFilter&lt;/filter-class&gt;
+ *   &lt;/filter&gt;
+ *   &lt;filter-mapping&gt;
+ *       &lt;filter-name&gt;ClientConfigurationFilter&lt;/filter-name&gt;
+ *       &lt;url-pattern&gt;*.html&lt;/url-pattern&gt;
+ *   &lt;/filter-mapping&gt;
+ * </pre>
+ * <p>
+ * 
+ * 
+ * @see com.sap.sailing.server.gateway.test.support.WhitelabelSwitchServlet
+ * @author Georg Herdt
+ *
+ */
 public class ClientConfigurationFilter implements Filter {

+    public static final String DEBRANDING_PROPERTY_NAME = "com.sap.sse.debranding";
+
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // intentionally left blank
@@ -27,18 +77,66 @@ public class ClientConfigurationFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
-        HttpServletResponseWrapper wrappedResponse = new CharResponseWrapper((HttpServletResponse) response);
+        final boolean deBrandingActive = Boolean.valueOf(System.getProperty(DEBRANDING_PROPERTY_NAME, "false"));
+        HttpServletResponseWrapper wrappedResponse = new CharResponseWrapper((HttpServletResponse) response,
+                createReplacementMap(deBrandingActive));
        chain.doFilter(request, wrappedResponse);
-        String body = wrappedResponse.toString();
-        String replaced = new String(body);
-        final boolean deBrandingActive = Boolean
-                .valueOf(System.getProperty(ClientConfigurationServlet.DEBRANDING_PROPERTY_NAME, "false"));
-        for (Map.Entry<String, String> item : createReplacementMap(deBrandingActive).entrySet()) {
-            replaced = replaced.replace("${" + item.getKey() + "}", item.getValue());
-        }
-        response.getWriter().write(replaced);
+        // String body = wrappedResponse.toString();
+        // String replaced = new String(body);
+        // for (Map.Entry<String, String> item : createReplacementMap(deBrandingActive).entrySet()) {
+        // replaced = replaced.replace("${" + item.getKey() + "}", item.getValue());
+        // }
+        // response.getWriter().write(replaced);
    }

+    @Override
+    public void destroy() {
+        // intentionally left blank
+    }
+
+    
+    private static class ContinuousReplacer {
+        StringBuffer buffer;
+        Consumer<byte[]> output;
+        Map<String, String> replacementMap;
+        int bufferSize;
+        
+        public ContinuousReplacer(Map<String,String> replacementMap, Consumer<byte[]> output) {
+            this.replacementMap = replacementMap;
+            this.output = output;
+            int maxKeyLength = this.replacementMap.keySet().stream().map(String::length)
+                    .max((a, b) -> Integer.compare(a, b)).orElse(0);
+            this.bufferSize = maxKeyLength == 0 ? 0 : maxKeyLength + 3;
+            buffer = new StringBuffer();
+        }
+        
+        public void push(String s) throws IOException {
+            buffer.append(s);
+            if (buffer.length()==bufferSize) {
+                int idxClosing;
+                if (buffer.substring(0, 2).equals("${") && (idxClosing = buffer.indexOf("}")) != -1) {
+                    String replacement;
+                    String key = buffer.substring(2, idxClosing);
+                    if ((replacement = replacementMap.get(key)) != null) {
+                        output.accept(replacement.getBytes());
+                    } else {
+                        output.accept("${".getBytes());
+                        output.accept(key.getBytes());
+                        output.accept("}".getBytes());
+                    }
+                    buffer.delete(0, idxClosing);
+                } else {
+                    output.accept(buffer.substring(0, 1).getBytes());
+                    buffer.deleteCharAt(0);
+                }
+            }
+        }
+        
+        private interface Consumer<T> {
+            void accept(T t) throws IOException;
+        }
+    }
+    
    private Map<String, String> createReplacementMap(boolean deBrandingActive) {
        final Map<String, String> map = new HashMap<>();
        final String title;
@@ -55,27 +153,104 @@ public class ClientConfigurationFilter implements Filter {
        map.put("whitelabeled", whitelabeled);
        return map;
    }
-
-    @Override
-    public void destroy() {
-        // intentionally left blank
-    }
-
+    
    private static class CharResponseWrapper extends HttpServletResponseWrapper {
-        private ByteArrayOutputStream output;
+        
+        private static final class MyWriter extends FilterWriter {
+            private MyWriter(Writer out, Map<String,String> replacementMap) {
+                super(out);
+                new ContinuousReplacer(replacementMap, bytes -> out.write(new String(bytes)));
+            }

-        public String toString() {
-            return output.toString();
+            @Override
+            public void write(char[] cbuf, int off, int len) throws IOException {
+                String s = new String(cbuf,off,len);
+                super.write(cbuf, off, len);
+            }
+
+            @Override
+            public void write(int c) throws IOException {
+                // TODO Auto-generated method stub
+                super.write(c);
+            }
+
+            @Override
+            public void write(String str, int off, int len) throws IOException {
+                // TODO Auto-generated method stub
+                super.write(str, off, len);
+            }
+
+            @Override
+            public Writer append(char arg0) throws IOException {
+                // TODO Auto-generated method stub
+                return super.append(arg0);
+            }
+
+            @Override
+            public Writer append(CharSequence arg0, int arg1, int arg2) throws IOException {
+                // TODO Auto-generated method stub
+                return super.append(arg0, arg1, arg2);
+            }
+
+            @Override
+            public Writer append(CharSequence arg0) throws IOException {
+                // TODO Auto-generated method stub
+                return super.append(arg0);
+            }
+
+            @Override
+            public void write(char[] arg0) throws IOException {
+                // TODO Auto-generated method stub
+                super.write(arg0);
+            }
+
+            @Override
+            public void write(String arg0) throws IOException {
+                // TODO Auto-generated method stub
+                super.write(arg0);
+            }
        }

-        public CharResponseWrapper(HttpServletResponse response) {
+        private static final class MyServletOutputStream extends ServletOutputStream {
+            private final ServletOutputStream wrappedOutputStream;
+            private final ContinuousReplacer replacer;
+
+            private MyServletOutputStream(ServletOutputStream wrappedOutputStream,Map<String,String> replacementMap) {
+                this.wrappedOutputStream = wrappedOutputStream;
+                this.replacer = new ContinuousReplacer(replacementMap, bytes -> wrappedOutputStream.write(bytes));
+            }
+
+            @Override
+            public void write(int octet) throws IOException {
+                // System.out.print();
+                String current = new String(new char[] { (char) octet });
+                replacer.push(current);
+            }
+
+            @Override
+            public void setWriteListener(WriteListener writeListener) {
+                // disable asynchronous writing, not needed for static pages
+                throw new IllegalStateException("not supported by ClientConfigurationFilter");
+            }
+
+            @Override
+            public boolean isReady() {
+                return wrappedOutputStream.isReady();
+            }
+        }
+
+        private Map<String, String> replacementMap;
+        
+        public CharResponseWrapper(HttpServletResponse response, Map<String,String> replacementMap) {
            super(response);
+            this.replacementMap = replacementMap;
            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 PrintWriter getWriter() throws IOException {
+            FilterWriter filter = new MyWriter(super.getWriter(), replacementMap);
+            return new PrintWriter(filter);
        }

        @Override
@@ -100,7 +275,7 @@ public class ClientConfigurationFilter implements Filter {

        @Override
        public void reset() {
-            // intentionally left blank, not supporting buffering here
+            throw new IllegalStateException("not supported by " + this.getClass().getCanonicalName());
        }

        @Override
@@ -110,24 +285,8 @@ public class ClientConfigurationFilter implements Filter {

        @Override
        public ServletOutputStream getOutputStream() throws IOException {
-            return new ServletOutputStream() {
-
-                @Override
-                public void write(int octet) throws IOException {
-                    output.write(octet);
-                }
-
-                @Override
-                public void setWriteListener(WriteListener writeListener) {
-                    // disable asynchronous writing, not needed for static pages
-                    throw new IllegalStateException("not supported by ClientConfigurationServlet");
-                }
-
-                @Override
-                public boolean isReady() {
-                    return true;
-                }
-            };
+            final ServletOutputStream wrappedOutputStream = super.getOutputStream();
+            return new MyServletOutputStream(wrappedOutputStream, replacementMap);
        }
    }
 }
@@ -1,125 +0,0 @@
-package com.sap.sse.debranding;
-
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
-
-import org.apache.commons.io.IOUtils;
-import org.apache.http.HttpStatus;
-
-/**
- * Use ${[variable name]} to get strings replaced within static pages. No escape syntax is currently available. All occurrences of the variables listed below
- * that are found in the document will be replaced. The following variables are available at the moment:
- * <table border="1">
- * <tr>
- * <th>Variablename</th>
- * <th>branded value</th>
- * <th>debranded/whitelabeled</th>
- * </tr>
- * <tr>
- * <td>"SAP"</td>
- * <td>"SAP&nbsp;"</td>
- * <td>""</td>
- * </tr>
- * <tr>
- * <td>"debrandingActive"</td>
- * <td>"false"</td>
- * <td>"true"</td>
- * </tr>
- * <tr>
- * <td>"whitelabeled"</td>
- * <td>""</td>
- * <td>"-whitelabeled"</td>
- * </tr>
- * </table>
- * <p>
- *
- * Register as a servlet for all the URLs that produce such static pages that you'd like to run replacements on. Example
- * registration in a {@code web.xml} configuration file:
- * 
- * <pre>
- *   &lt;servlet&gt;
- *       &lt;display-name&gt;ClientConfigurationServlet&lt;/display-name&gt;
- *       &lt;servlet-name&gt;ClientConfigurationServlet&lt;/servlet-name&gt;
- *       &lt;servlet-class&gt;com.sap.sse.debranding.ClientConfigurationServlet&lt;/servlet-class&gt;
- *   &lt;/servlet&gt;
- *   &lt;servlet-mapping&gt;
- *       &lt;servlet-name&gt;ClientConfigurationServlet&lt;/servlet-name&gt;
- *       &lt;url-pattern&gt;*.html&lt;/url-pattern&gt;
- *   &lt;/servlet-mapping&gt;
- * </pre>
- * <p>
- * 
- * The servlet caches the results, both, for the branded as well as the unbranded/replaced contents.
- * 
- * @see com.sap.sailing.server.gateway.test.support.WhitelabelSwitchServlet
- * @author Georg Herdt
- *
- */
-public class ClientConfigurationServlet extends HttpServlet {
-
-    private static final Logger logger = Logger.getLogger(ClientConfigurationServlet.class.getName());
-    
-    /** serial version uid */
-    private static final long serialVersionUID = -2228462977010198686L;
-
-    public static final String DEBRANDING_PROPERTY_NAME = "com.sap.sse.debranding";
-    
-    private final ConcurrentHashMap<String, byte[]> cache = new ConcurrentHashMap<>();
-
-    @Override
-    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
-        final boolean deBrandingActive = Boolean.valueOf(System.getProperty(DEBRANDING_PROPERTY_NAME, "false"));
-        final String servletPath = req.getServletPath();
-        final byte[] cachedPage;
-        final String pageKey = generateKey(servletPath, deBrandingActive);
-        resp.setContentType("text/html;charset=UTF-8");
-        if ((cachedPage = cache.get(pageKey)) != null) {
-            IOUtils.write(cachedPage, resp.getOutputStream());
-        } else {
-            try (InputStream in = this.getServletContext().getResourceAsStream(servletPath)) {
-                byte[] buffer = IOUtils.toByteArray(in);
-                String content = new String(buffer);
-                for (Map.Entry<String, String> item : createReplacementMap(deBrandingActive).entrySet()) {
-                    content = content.replace("${" + item.getKey() + "}", item.getValue());
-                }
-                byte[] bytes = content.getBytes();
-                IOUtils.write(bytes, resp.getOutputStream());
-                cache.computeIfAbsent(pageKey, key -> bytes);
-            } catch (RuntimeException e) {
-                logger.log(Level.WARNING, "could not process or read resource " + servletPath, e);
-                resp.sendError(HttpStatus.SC_INTERNAL_SERVER_ERROR);
-            }
-        }
-    }
-
-    private String generateKey(String servletPath, boolean active) {
-        return servletPath + "_" + active;
-    }
-
-    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;
-    }
-}