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( field.getType().getName() ).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) {
                                        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);
                                
                                ReloadConfig anno = method.getAnnotation(ReloadConfig.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() );
        }

        @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);
                                ReloadConfig anno = method.getAnnotation(ReloadConfig.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;
                                }
        
                                
                                
                                if (field.getType().getName().equals("int") ) {
                                        field.setInt(configObject, Integer.parseInt(value) );
                                } else if (field.getType().getName().equals("boolean") ) {
                                        value = value.toLowerCase();
                                        if (! (value.equals("true") || value.equals("false"))) {
                                                resp.sendError(500, "Only 'true' or 'false' as values for boolean field");
                                                return;
                                        }
                                        field.setBoolean(configObject, Boolean.parseBoolean(value) );
                                } else if (field.getType().getName().equals("long") ) {
                                        field.setLong(configObject, Long.parseLong(value) );
                                } else if (field.getType().getName().equals("short") ) {
                                        field.setShort(configObject, Short.parseShort(value) );
                                } else if (field.getType().getName().equals("double") ) {
                                        field.setDouble(configObject, Double.parseDouble(value) );
                                } else if (field.getType().getName().equals("float") ) {
                                        field.setFloat(configObject, Float.parseFloat(value) );
                                } else if (field.getType().getName().equals("char") ) {
                                        field.setFloat(configObject, value.charAt(0) );
                                } else {
                                        field.set(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( field.getType().getName() ).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	sb.append("<td><input type='text' name='varvalue' value='").append( ""+ field.get(configObject) ).append("' /></td>");
61	sb.append("<td><input type='submit' name='Set' value='Set'></td>\n");
62	} else {
63	sb.append("<td>").append( ""+ field.get(configObject) ).append(" </td>");
64	sb.append("<td> </td>");
65	}
66
67	sb.append("</form></tr>\n");
68	}
69
70	sb.append("</table>\n\n");
71
72	Method[] methods = configObject.getClass().getDeclaredMethods();
73	for(Method method : methods) {
74	method.setAccessible(true);
75
76	ReloadConfig anno = method.getAnnotation(ReloadConfig.class);
77	if (anno == null)
78	continue;
79
80	sb.append("<form method='post' action='").append( req.getRequestURI() ).append("'>");
81	sb.append("<input type='hidden' name='reloadmethod' value='").append(method.getName()).append("'>");
82	sb.append("<input type='submit' name='Reload Config' value='Reload Config'>");
83	sb.append("</form>\n");
84
85	}
86
87
88	} catch (IllegalAccessException e) {
89	throw new ServletException(e);
90	}
91
92	sb.append("</body></html>");
93
94	resp.getWriter().print( sb.toString() );
95	}
96
97	@Override
98	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
99	String name = req.getParameter("varname");
100	String value = req.getParameter("varvalue");
101
102	String reloadmethod = req.getParameter("reloadmethod");
103
104	try {
105	if (reloadmethod != null) { //reload
106
107	Method method = configObject.getClass().getDeclaredMethod(reloadmethod, (Class<?>[]) null);
108	ReloadConfig anno = method.getAnnotation(ReloadConfig.class);
109	if (anno == null) {
110	resp.sendError(500, "Method is not annotated");
111	return;
112	}
113
114
115	method.setAccessible(true);
116	method.invoke(configObject, (Object[])null);
117
118	} else { //set var
119	value = value.trim();
120	Field field = configObject.getClass().getDeclaredField(name);
121	field.setAccessible(true);
122	ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
123
124	if (anno == null) {
125	resp.sendError(500, "Field is not annotated");
126	return;
127	}
128
129	if (anno.readonly() == true) {
130	resp.sendError(500, "Can't write a read-only field");
131	return;
132	}
133
134
135
136	if (field.getType().getName().equals("int") ) {
137	field.setInt(configObject, Integer.parseInt(value) );
138	} else if (field.getType().getName().equals("boolean") ) {
139	value = value.toLowerCase();
140	if (! (value.equals("true") \|\| value.equals("false"))) {
141	resp.sendError(500, "Only 'true' or 'false' as values for boolean field");
142	return;
143	}
144	field.setBoolean(configObject, Boolean.parseBoolean(value) );
145	} else if (field.getType().getName().equals("long") ) {
146	field.setLong(configObject, Long.parseLong(value) );
147	} else if (field.getType().getName().equals("short") ) {
148	field.setShort(configObject, Short.parseShort(value) );
149	} else if (field.getType().getName().equals("double") ) {
150	field.setDouble(configObject, Double.parseDouble(value) );
151	} else if (field.getType().getName().equals("float") ) {
152	field.setFloat(configObject, Float.parseFloat(value) );
153	} else if (field.getType().getName().equals("char") ) {
154	field.setFloat(configObject, value.charAt(0) );
155	} else {
156	field.set(configObject, value );
157	}
158	} //end of set var
159
160
161	} catch (NoSuchFieldException e) {
162	resp.sendError(500, "No such field: " + name);
163	} catch (IllegalAccessException e) { //this can't happen
164	throw new ServletException(e);
165	} catch (NoSuchMethodException e) {
166	resp.sendError(500, "No such method: " + reloadmethod);
167	} catch (InvocationTargetException e) {
168	resp.sendError(500, "Could not invoke method: " + reloadmethod);
169	}
170
171	resp.sendRedirect( req.getRequestURI() );
172	}
173
174	}