为什么libexpat不能正确解析出font.txt文件中各个元素的值？

realtang

测试用的代码：

1. 
   
2. #include <stdio.h>
   
3. #include <expat.h>
   
4. 
   
5. #define BUFFSIZE        8192
   
6. 
   
7. char Buff[BUFFSIZE];
   
8. 
   
9. int Depth;
   
10. 
    
11. static void XMLCALL
    
12. start(void *data, const char *el, const char **attr)
    
13. {
    
14.   int i;
    
15. 
    
16.   for (i = 0; i < Depth; i++)
    
17.     printf("  ");
    
18. 
    
19.   printf("%s", el);
    
20. 
    
21.   for (i = 0; attr[i]; i += 2) {
    
22.     printf(" %s='%s'", attr[i], attr[i + 1]);
    
23.   }
    
24. 
    
25.   printf("\n");
    
26.   Depth++;
    
27. }
    
28. 
    
29. static void XMLCALL
    
30. end(void *data, const char *el)
    
31. {
    
32.   Depth--;
    
33. }
    
34. 
    
35. int
    
36. main(int argc, char *argv[])
    
37. {
    
38.   FILE *fp;
    
39.   fp = fopen(argv[1],"r+b");
    
40.   XML_Parser p = XML_ParserCreate(NULL);
    
41.   if (! p) {
    
42.     fprintf(stderr, "Couldn't allocate memory for parser\n");
    
43.     exit(-1);
    
44.   }
    
45. 
    
46.   XML_SetElementHandler(p, start, end);
    
47. 
    
48.   for (;;) {
    
49.     int done;
    
50.     int len;
    
51. 
    
52.     len = fread(Buff, 1, BUFFSIZE, fp);
    
53.     if (ferror(fp)) {
    
54.       fprintf(stderr, "Read error\n");
    
55.       exit(-1);
    
56.     }
    
57.     done = feof(fp);
    
58. 
    
59.     if (XML_Parse(p, Buff, len, done) == XML_STATUS_ERROR) {
    
60.       fprintf(stderr, "Parse error at line %d:\n%s\n",
    
61.               XML_GetCurrentLineNumber(p),
    
62.               XML_ErrorString(XML_GetErrorCode(p)));
    
63.       exit(-1);
    
64.     }
    
65. 
    
66.     if (done)
    
67.       break;
    
68.   }
    
69.   return 0;
    
70. }
    
71. 
    

复制代码

我所得的输出如下：

1. 
   
2. fontconfig
   
3.   dir
   
4.   alias
   
5.     family
   
6.     accept
   
7.       family
   
8.   alias
   
9.     family
   
10.     accept
    
11.       family
    
12.   alias
    
13.     family
    
14.     accept
    
15.       family
    
16.   alias
    
17.     family
    
18.     accept
    
19.       family
    
20.   alias
    
21.     family
    
22.     accept
    
23.       family
    
24.   alias
    
25.     family
    
26.     accept
    
27.       family
    
28.   alias
    
29.     family
    
30.     accept
    
31.       family
    
32.   alias
    
33.     family
    
34.     accept
    
35.       family
    
36.   alias
    
37.     family
    
38.     accept
    
39.       family
    
40.   alias
    
41.     family
    
42.     accept
    
43.       family
    
44.   alias
    
45.     family
    
46.     accept
    
47.       family
    
48.   alias
    
49.     family
    
50.     accept
    
51.       family
    
52.   alias
    
53.     family
    
54.     accept
    
55.       family
    
56.   alias
    
57.     family
    
58.     accept
    
59.       family
    
60.   alias
    
61.     family
    
62.     accept
    
63.       family
    
64.   alias
    
65.     family
    
66.     accept
    
67.       family
    
68.   alias
    
69.     family
    
70.     accept
    
71.       family
    
72.   alias
    
73.     family
    
74.     accept
    
75.       family
    
76.   alias
    
77.     family
    
78.     accept
    
79.       family
    
80.   alias
    
81.     family
    
82.     accept
    
83.       family
    
84.   alias
    
85.     family
    
86.     accept
    
87.       family
    
88.   alias
    
89.     family
    
90.     accept
    
91.       family
    
92.   alias
    
93.     family
    
94.     accept
    
95.       family
    
96.   alias
    
97.     family
    
98.     accept
    
99.       family
    
100.   alias
     
101.     family
     
102.     accept
     
103.       family
     
104.   alias
     
105.     family
     
106.     accept
     
107.       family
     
108.   alias
     
109.     family
     
110.     accept
     
111.       family
     
112.   alias
     
113.     family
     
114.     accept
     
115.       family
     
116.   alias
     
117.     family
     
118.     accept
     
119.       family
     
120.   alias
     
121.     family
     
122.     accept
     
123.       family
     
124.   alias
     
125.     family
     
126.     accept
     
127.       family
     
128.   alias
     
129.     family
     
130.     accept
     
131.       family
     
132.   alias
     
133.     family
     
134.     accept
     
135.       family
     
136.   alias
     
137.     family
     
138.     accept
     
139.       family
     
140.   alias
     
141.     family
     
142.     accept
     
143.       family
     
144.   alias
     
145.     family
     
146.     accept
     
147.       family
     
148.   alias
     
149.     family
     
150.     accept
     
151.       family
     
152.   alias
     
153.     family
     
154.     accept
     
155.       family
     
156.   alias
     
157.     family
     
158.     accept
     
159.       family
     
160.   alias
     
161.     family
     
162.     accept
     
163.       family
     
164.   alias
     
165.     family
     
166.     accept
     
167.       family
     
168.   alias
     
169.     family
     
170.     accept
     
171.       family
     
172.   alias
     
173.     family
     
174.     accept
     
175.       family
     
176.   alias
     
177.     family
     
178.     accept
     
179.       family
     
180.   alias
     
181.     family
     
182.     accept
     
183.       family
     
184.   alias
     
185.     family
     
186.     accept
     
187.       family
     
188.   alias
     
189.     family
     
190.     accept
     
191.       family
     
192.   alias
     
193.     family
     
194.     accept
     
195.       family
     
196.   alias
     
197.     family
     
198.     accept
     
199.       family
     
200.   alias
     
201.     family
     
202.     accept
     
203.       family
     
204.   alias
     
205.     family
     
206.     accept
     
207.       family
     
208.   alias
     
209.     family
     
210.     accept
     
211.       family
     
212.   alias
     
213.     family
     
214.     default
     
215.       family
     
216.   alias
     
217.     family
     
218.     default
     
219.       family
     
220.   alias
     
221.     family
     
222.     default
     
223.       family
     

复制代码

就是显示不出来实际的值。不知何故，还清有经验的朋友指教下。

realtang

原来是没有定义处理元素数据的回调函数：XML_SetCharacterDataHandler()。
我改进了代码，现在XML解析的问题解决了。

1. 
   
2. /* This is simple demonstration of how to use expat. This program
   
3.    reads an XML document from standard input and writes a line with
   
4.    the name of each element to standard output indenting child
   
5.    elements by one tab stop more than their parent element.
   
6.    Modified by Tang.Xu bravetang@tom.com
   
7.    2005.6.27
   
8. */
   
9. 
   
10. #include <stdio.h>
    
11. #include <string.h>
    
12. #include "expat.h"
    
13. 
    
14. static void XMLCALL
    
15. startElement(void *userData, const char *name, const char **atts)
    
16. {
    
17.   int i;
    
18.   int *depthPtr = userData;
    
19.   for (i = 0; i < *depthPtr; i++)
    
20.     putchar('\t');
    
21.   puts(name);
    
22.   *depthPtr += 1;
    
23. }
    
24. 
    
25. static void XMLCALL
    
26. endElement(void *userData, const char *name)
    
27. {
    
28.   int *depthPtr = userData;
    
29.   *depthPtr -= 1;
    
30. }
    
31. 
    
32. static void XMLCALL
    
33. getData(void *userData,const XML_Char *s,int len)
    
34. {
    
35.    char strtmp[len+1];
    
36.    int i;
    
37.    for(i=0;i<len;i++)
    
38.     {
    
39.       strtmp[i]=s[i];
    
40.     }
    
41.    strtmp[len]='\0';
    
42.    puts(strtmp);
    
43. }
    
44. int
    
45. main(int argc, char *argv[])
    
46. {
    
47.   FILE *fp;
    
48.   fp = fopen(argv[1],"r+b");
    
49.   char buf[BUFSIZ];
    
50.   XML_Parser parser = XML_ParserCreate(NULL);
    
51.   int done;
    
52.   int depth = 0;
    
53.   XML_SetUserData(parser, &depth);
    
54.   XML_SetElementHandler(parser, startElement, endElement);
    
55.   //必须添加这个回调函数才能正确取得元素的值
    
56.   XML_SetCharacterDataHandler(parser,getData);
    
57.   do {
    
58.     size_t len = fread(buf, 1, sizeof(buf), fp);
    
59.     done = len < sizeof(buf);
    
60.     if (XML_Parse(parser, buf, len, done) == XML_STATUS_ERROR) {
    
61.       fprintf(stderr,
    
62.               "%s at line %d\n",
    
63.               XML_ErrorString(XML_GetErrorCode(parser)),
    
64.               XML_GetCurrentLineNumber(parser));
    
65.       return 1;
    
66.     }
    
67.   } while (!done);
    
68.   XML_ParserFree(parser);
    
69.   return 0;
    
70. }
    
71. 
    

复制代码