thoerup/webconfig/ConfigServlet.java

package dk.thoerup.webconfig;

import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ConfigServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
        
        private Object configObject;
        
        public void setConfigObject(Object obj) {
                configObject = obj;
        }
        
        
        @Override
        public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
                
                
                resp.setDateHeader("Expires", 0); 
                resp.setHeader("Pragma", "no-cache");
                resp.setHeader("Cache-Control", "no-cache");
                resp.setContentType("text/html");
                
                StringBuilder sb = new StringBuilder();
                
                sb.append("<html><body><h3>WebConfig:</h3><table border='1' cellspacing='0'>");
                sb.append("<tr><th>Field name</th><th>Type</th><th>Description</th><th>Value</th><th>&nbsp;</th></tr>\n"); 
                
                
                Field fields[] = configObject.getClass().getDeclaredFields();
                
                try {
                        for(Field field : fields) {
                                field.setAccessible(true);

                                ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
                                if (anno == null)
                                        continue;
                                
                                sb.append("<tr>");
                                sb.append("<td>").append( field.getName() ).append("</td>");
                                sb.append("<td>").append( getCleanTypename(field.getType()) ).append("</td>");
                                sb.append("<td>").append( anno.description() ).append("&nbsp;</td>");
                                
                                sb.append("<form action='").append( req.getRequestURI() ).append("' method='post'>");
                                sb.append("<input type='hidden' name='varname' value='").append( field.getName() ).append("' />");
                                
                                                                
                                
                                
                                if (anno.readonly() == false) {
                                        if (field.getType().getName().equals("boolean") ) {
                                                
                                                String options = getBooleanSelectOptions(field,configObject);
                        sb.append("<td><select name='varvalue'>").append(options).append("</select></td>");
                        
                    } else if (field.getType().isEnum()) {
                        
                        String options = getEnumSelectOptions(field,configObject);
                        sb.append("<td><select name='varvalue'>").append(options).append("</select></td>");
                        
                    } else {
                        sb.append("<td><input type='text' name='varvalue' value='").append( "" + field.get(configObject) ).append("' /></td>");
                        
                    }
                                        sb.append("<td><input type='submit' name='Set' value='Set'></td>\n");
                                } else {
                                        sb.append("<td>").append( ""+ field.get(configObject) ).append("&nbsp;</td>");
                                        sb.append("<td>&nbsp;</td>");
                                }
                                
                                sb.append("</form></tr>\n");                            
                        }
                        
                        sb.append("</table>\n\n");
                        
                        Method[] methods = configObject.getClass().getDeclaredMethods();
                        for(Method method : methods) {
                                method.setAccessible(true);
                                
                                ReloadConfigMethod anno = method.getAnnotation(ReloadConfigMethod.class);
                                if (anno == null)
                                        continue;
                                
                                sb.append("<form method='post' action='").append( req.getRequestURI() ).append("'>");
                                sb.append("<input type='hidden' name='reloadmethod' value='").append(method.getName()).append("'>");
                                sb.append("<input type='submit' name='Reload Config' value='Reload Config'>");
                                sb.append("</form>\n");
                                
                        }
                        
                                                
                } catch (IllegalAccessException e) {
                        throw new ServletException(e);
                }
                
                sb.append("</body></html>");
                
                resp.getWriter().print( sb.toString() );
        }
        
        String getBooleanSelectOptions(Field field, Object configObject) throws IllegalAccessException {
        String trueSelected = field.get(configObject).toString().equals("true") ? " selected " : "";
        String falseSelected = field.get(configObject).toString().equals("false") ? " selected " : "";
        return String.format("<option %s>true</option><option %s>false</option>", trueSelected, falseSelected);
        }
        
        String getEnumSelectOptions(Field field, Object configObject) throws IllegalAccessException  {
                Class<?> cls = field.getType();
                StringBuilder sb = new StringBuilder();
                Object constants[] = cls.getEnumConstants();
                
                String value = field.get(configObject).toString();
                
                for (int i = 0; i < constants.length; i++) {
                        String current = constants[i].toString();
                        String selected = current.equals(value) ? " selected " : "";
                        sb.append( String.format("<option %s>%s</option>", selected, current) );                        
                }
                
                
                return sb.toString();           
        }
        
        String getCleanTypename(Class<?> cls) {

                if (cls.isEnum()) {
                        String parts[] = cls.getName().split("\\.");
                        if (parts.length > 0)
                                return "Enum: " + parts[parts.length-1];
                        else
                                return "Enum: " + cls.getName(); 
                } else {
                        return cls.getName();
                }
                
        }

        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
                String name = req.getParameter("varname");
                String value = req.getParameter("varvalue");
                
                String reloadmethod = req.getParameter("reloadmethod");
                
                try {                   
                        if (reloadmethod != null) { //reload
                                
                                Method method = configObject.getClass().getDeclaredMethod(reloadmethod, (Class<?>[]) null);
                                ReloadConfigMethod anno = method.getAnnotation(ReloadConfigMethod.class);
                                if (anno == null) {
                                        resp.sendError(500, "Method is not annotated");
                                        return;
                                }
                                        
                                
                                method.setAccessible(true);                                                             
                                method.invoke(configObject, (Object[])null);                            
                                
                        } else { //set var                                      
                                value = value.trim();
                                Field field = configObject.getClass().getDeclaredField(name);
                                field.setAccessible(true);
                                ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
                                
                                if (anno == null) {
                                        resp.sendError(500, "Field is not annotated");
                                        return;
                                }                               
                                
                                if (anno.readonly() == true) {
                                        resp.sendError(500, "Can't write a read-only field");
                                        return;
                                }
        
                                ConfigLoader.setFieldValue(field,configObject,value);
                                
                                
                        } //end of set var
                                
                        
                } catch (NoSuchFieldException e) {
                        resp.sendError(500, "No such field: " + name);
                } catch (IllegalAccessException e) { //this can't happen
                        throw new ServletException(e); 
                } catch (NoSuchMethodException e) {
                        resp.sendError(500, "No such method: " + reloadmethod);
                } catch (InvocationTargetException e) {
                        resp.sendError(500, "Could not invoke method: " + reloadmethod);
                }
                
                resp.sendRedirect( req.getRequestURI() );               
        }

}
1	package dk.thoerup.webconfig;
2
3	import java.io.IOException;
4	import java.lang.reflect.Field;
5	import java.lang.reflect.InvocationTargetException;
6	import java.lang.reflect.Method;
7
8	import javax.servlet.ServletException;
9	import javax.servlet.http.HttpServlet;
10	import javax.servlet.http.HttpServletRequest;
11	import javax.servlet.http.HttpServletResponse;
12
13	public class ConfigServlet extends HttpServlet {
14	private static final long serialVersionUID = 1L;
15
16	private Object configObject;
17
18	public void setConfigObject(Object obj) {
19	configObject = obj;
20	}
21
22
23	@Override
24	public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
25
26
27	resp.setDateHeader("Expires", 0);
28	resp.setHeader("Pragma", "no-cache");
29	resp.setHeader("Cache-Control", "no-cache");
30	resp.setContentType("text/html");
31
32	StringBuilder sb = new StringBuilder();
33
34	sb.append("<html><body><h3>WebConfig:</h3><table border='1' cellspacing='0'>");
35	sb.append("<tr><th>Field name</th><th>Type</th><th>Description</th><th>Value</th><th> </th></tr>\n");
36
37
38	Field fields[] = configObject.getClass().getDeclaredFields();
39
40	try {
41	for(Field field : fields) {
42	field.setAccessible(true);
43
44	ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
45	if (anno == null)
46	continue;
47
48	sb.append("<tr>");
49	sb.append("<td>").append( field.getName() ).append("</td>");
50	sb.append("<td>").append( getCleanTypename(field.getType()) ).append("</td>");
51	sb.append("<td>").append( anno.description() ).append(" </td>");
52
53	sb.append("<form action='").append( req.getRequestURI() ).append("' method='post'>");
54	sb.append("<input type='hidden' name='varname' value='").append( field.getName() ).append("' />");
55
56
57
58
59	if (anno.readonly() == false) {
60	if (field.getType().getName().equals("boolean") ) {
61
62	String options = getBooleanSelectOptions(field,configObject);
63	sb.append("<td><select name='varvalue'>").append(options).append("</select></td>");
64
65	} else if (field.getType().isEnum()) {
66
67	String options = getEnumSelectOptions(field,configObject);
68	sb.append("<td><select name='varvalue'>").append(options).append("</select></td>");
69
70	} else {
71	sb.append("<td><input type='text' name='varvalue' value='").append( "" + field.get(configObject) ).append("' /></td>");
72
73	}
74	sb.append("<td><input type='submit' name='Set' value='Set'></td>\n");
75	} else {
76	sb.append("<td>").append( ""+ field.get(configObject) ).append(" </td>");
77	sb.append("<td> </td>");
78	}
79
80	sb.append("</form></tr>\n");
81	}
82
83	sb.append("</table>\n\n");
84
85	Method[] methods = configObject.getClass().getDeclaredMethods();
86	for(Method method : methods) {
87	method.setAccessible(true);
88
89	ReloadConfigMethod anno = method.getAnnotation(ReloadConfigMethod.class);
90	if (anno == null)
91	continue;
92
93	sb.append("<form method='post' action='").append( req.getRequestURI() ).append("'>");
94	sb.append("<input type='hidden' name='reloadmethod' value='").append(method.getName()).append("'>");
95	sb.append("<input type='submit' name='Reload Config' value='Reload Config'>");
96	sb.append("</form>\n");
97
98	}
99
100
101	} catch (IllegalAccessException e) {
102	throw new ServletException(e);
103	}
104
105	sb.append("</body></html>");
106
107	resp.getWriter().print( sb.toString() );
108	}
109
110	String getBooleanSelectOptions(Field field, Object configObject) throws IllegalAccessException {
111	String trueSelected = field.get(configObject).toString().equals("true") ? " selected " : "";
112	String falseSelected = field.get(configObject).toString().equals("false") ? " selected " : "";
113	return String.format("<option %s>true</option><option %s>false</option>", trueSelected, falseSelected);
114	}
115
116	String getEnumSelectOptions(Field field, Object configObject) throws IllegalAccessException {
117	Class<?> cls = field.getType();
118	StringBuilder sb = new StringBuilder();
119	Object constants[] = cls.getEnumConstants();
120
121	String value = field.get(configObject).toString();
122
123	for (int i = 0; i < constants.length; i++) {
124	String current = constants[i].toString();
125	String selected = current.equals(value) ? " selected " : "";
126	sb.append( String.format("<option %s>%s</option>", selected, current) );
127	}
128
129
130	return sb.toString();
131	}
132
133	String getCleanTypename(Class<?> cls) {
134
135	if (cls.isEnum()) {
136	String parts[] = cls.getName().split("\\.");
137	if (parts.length > 0)
138	return "Enum: " + parts[parts.length-1];
139	else
140	return "Enum: " + cls.getName();
141	} else {
142	return cls.getName();
143	}
144
145	}
146
147	@Override
148	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
149	String name = req.getParameter("varname");
150	String value = req.getParameter("varvalue");
151
152	String reloadmethod = req.getParameter("reloadmethod");
153
154	try {
155	if (reloadmethod != null) { //reload
156
157	Method method = configObject.getClass().getDeclaredMethod(reloadmethod, (Class<?>[]) null);
158	ReloadConfigMethod anno = method.getAnnotation(ReloadConfigMethod.class);
159	if (anno == null) {
160	resp.sendError(500, "Method is not annotated");
161	return;
162	}
163
164
165	method.setAccessible(true);
166	method.invoke(configObject, (Object[])null);
167
168	} else { //set var
169	value = value.trim();
170	Field field = configObject.getClass().getDeclaredField(name);
171	field.setAccessible(true);
172	ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
173
174	if (anno == null) {
175	resp.sendError(500, "Field is not annotated");
176	return;
177	}
178
179	if (anno.readonly() == true) {
180	resp.sendError(500, "Can't write a read-only field");
181	return;
182	}
183
184	ConfigLoader.setFieldValue(field,configObject,value);
185
186
187	} //end of set var
188
189
190	} catch (NoSuchFieldException e) {
191	resp.sendError(500, "No such field: " + name);
192	} catch (IllegalAccessException e) { //this can't happen
193	throw new ServletException(e);
194	} catch (NoSuchMethodException e) {
195	resp.sendError(500, "No such method: " + reloadmethod);
196	} catch (InvocationTargetException e) {
197	resp.sendError(500, "Could not invoke method: " + reloadmethod);
198	}
199
200	resp.sendRedirect( req.getRequestURI() );
201	}
202
203	}