thoerup/webconfig/ConfigServlet.java

package dk.thoerup.webconfig;

import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

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("<td><input type='text' name='varvalue' value='").append( ""+ field.get(configObject) ).append("' /></td>");
                                sb.append("<input type='hidden' name='varname' value='").append( field.getName() ).append("' />");
                                
                                if (anno.readonly() == false) 
                                        sb.append("<td><input type='submit' name='Set' value='Set'></td>\n");
                                else
                                        sb.append("<td>&nbsp;</td>");
                                
                                sb.append("</form></tr>\n");
                                
                                
                                
                        
                                field.getType().getName();
                        }
                } catch (IllegalAccessException e) {
                        throw new ServletException(e);
                }
                
                sb.append("</table></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");
                
                try {                   
                        Field field = configObject.getClass().getDeclaredField(name);
                        field.setAccessible(true);
                        ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
                        
                        if (anno == null)
                                throw new ServletException("Field is not annotated");
                        
                        if (anno.readonly() == true)
                                throw new ServletException("Can't write a read-only field");
                        
                        
                        if (field.getType().getName().equals("int") ) {
                                field.setInt(configObject, Integer.parseInt(value) );
                        } else if (field.getType().getName().equals("boolean") ) {
                                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 );
                        }
                                

                        
                } catch (NoSuchFieldException e) {
                        throw new ServletException(e);
                } catch (IllegalAccessException e) { //this can't happen
                        throw new ServletException(e); 
                }
                
                resp.sendRedirect( req.getRequestURI() );               
        }

}
1	package dk.thoerup.webconfig;
2
3	import java.io.IOException;
4	import java.lang.annotation.Annotation;
5	import java.lang.reflect.Field;
6
7	import javax.servlet.ServletException;
8	import javax.servlet.http.HttpServlet;
9	import javax.servlet.http.HttpServletRequest;
10	import javax.servlet.http.HttpServletResponse;
11
12	public class ConfigServlet extends HttpServlet {
13	private static final long serialVersionUID = 1L;
14
15	private Object configObject;
16
17	public void setConfigObject(Object obj) {
18	configObject = obj;
19	}
20
21
22	@Override
23	public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
24
25
26	resp.setDateHeader("Expires", 0);
27	resp.setHeader("Pragma", "no-cache");
28	resp.setHeader("Cache-Control", "no-cache");
29	resp.setContentType("text/html");
30
31	StringBuilder sb = new StringBuilder();
32
33	sb.append("<html><body><h3>WebConfig:</h3><table border='1' cellspacing='0'>");
34	sb.append("<tr><th>Field name</th><th>Type</th><th>Description</th><th>Value</th><th> </th></tr>\n");
35
36
37	Field fields[] = configObject.getClass().getDeclaredFields();
38
39	try {
40	for(Field field : fields) {
41	field.setAccessible(true);
42
43	ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
44	if (anno == null)
45	continue;
46
47	sb.append("<tr>");
48	sb.append("<td>").append( field.getName() ).append("</td>");
49	sb.append("<td>").append( field.getType().getName() ).append("</td>");
50	sb.append("<td>").append( anno.description() ).append(" </td>");
51
52	sb.append("<form action='").append( req.getRequestURI() ).append("' method='post'>");
53	sb.append("<td><input type='text' name='varvalue' value='").append( ""+ field.get(configObject) ).append("' /></td>");
54	sb.append("<input type='hidden' name='varname' value='").append( field.getName() ).append("' />");
55
56	if (anno.readonly() == false)
57	sb.append("<td><input type='submit' name='Set' value='Set'></td>\n");
58	else
59	sb.append("<td> </td>");
60
61	sb.append("</form></tr>\n");
62
63
64
65
66	field.getType().getName();
67	}
68	} catch (IllegalAccessException e) {
69	throw new ServletException(e);
70	}
71
72	sb.append("</table></body></html>");
73
74	resp.getWriter().print( sb.toString() );
75	}
76
77	@Override
78	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
79	String name = req.getParameter("varname");
80	String value = req.getParameter("varvalue");
81
82	try {
83	Field field = configObject.getClass().getDeclaredField(name);
84	field.setAccessible(true);
85	ConfigVariable anno = field.getAnnotation(ConfigVariable.class);
86
87	if (anno == null)
88	throw new ServletException("Field is not annotated");
89
90	if (anno.readonly() == true)
91	throw new ServletException("Can't write a read-only field");
92
93
94	if (field.getType().getName().equals("int") ) {
95	field.setInt(configObject, Integer.parseInt(value) );
96	} else if (field.getType().getName().equals("boolean") ) {
97	field.setBoolean(configObject, Boolean.parseBoolean(value) );
98	} else if (field.getType().getName().equals("long") ) {
99	field.setLong(configObject, Long.parseLong(value) );
100	} else if (field.getType().getName().equals("short") ) {
101	field.setShort(configObject, Short.parseShort(value) );
102	} else if (field.getType().getName().equals("double") ) {
103	field.setDouble(configObject, Double.parseDouble(value) );
104	} else if (field.getType().getName().equals("float") ) {
105	field.setFloat(configObject, Float.parseFloat(value) );
106	} else if (field.getType().getName().equals("char") ) {
107	field.setFloat(configObject, value.charAt(0) );
108	} else {
109	field.set(configObject, value );
110	}
111
112
113
114	} catch (NoSuchFieldException e) {
115	throw new ServletException(e);
116	} catch (IllegalAccessException e) { //this can't happen
117	throw new ServletException(e);
118	}
119
120	resp.sendRedirect( req.getRequestURI() );
121	}
122
123	}