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社区首页 >问答首页 >开源html解析类没有正确地分析段落之间的空格。

问开源html解析类没有正确地分析段落之间的空格。
EN

Stack Overflow用户
提问于 2012-11-08 05:43:11
回答 3查看 458关注 0票数 5

我使用的是一个开源方法，它将html文本解析为NSString。

得到的字符串在前几段之间有大量的空白，但对于后面的段落只有一行空间。下面是输出的一个例子。

​

下面是我调用的方法。我只更改了两行代码。对于stopCharacters和newLineAndWhitespaceCharacters，我从字符集中删除了/n，因为当包含它时，整个文本是一个很长的段落。

代码语言：javascript
复制
- (NSString *)stringByConvertingHTMLToPlainText {

    // Pool
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    // Character sets
    NSCharacterSet *stopCharacters = [NSCharacterSet characterSetWithCharactersInString:[NSString stringWithFormat:@"< \t\r%C%C%C%C", 0x0085, 0x000C, 0x2028, 0x2029]];
    NSCharacterSet *newLineAndWhitespaceCharacters = [NSCharacterSet characterSetWithCharactersInString:[NSString stringWithFormat:@" \t\r%C%C%C%C", 0x0085, 0x000C, 0x2028, 0x2029]];
    NSCharacterSet *tagNameCharacters = [NSCharacterSet characterSetWithCharactersInString:@"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"];

    // Scan and find all tags
    NSMutableString *result = [[NSMutableString alloc] initWithCapacity:self.length];
    NSScanner *scanner = [[NSScanner alloc] initWithString:self];
    [scanner setCharactersToBeSkipped:nil];
    [scanner setCaseSensitive:YES];
    NSString *str = nil, *tagName = nil;
    BOOL dontReplaceTagWithSpace = NO;
    do {

        // Scan up to the start of a tag or whitespace
        if ([scanner scanUpToCharactersFromSet:stopCharacters intoString:&str]) {
            [result appendString:str];
            str = nil; // reset
        }

        // Check if we've stopped at a tag/comment or whitespace
        if ([scanner scanString:@"<" intoString:NULL]) {

            // Stopped at a comment or tag
            if ([scanner scanString:@"!--" intoString:NULL]) {

                // Comment
                [scanner scanUpToString:@"-->" intoString:NULL];
                [scanner scanString:@"-->" intoString:NULL];

            } else {

                // Tag - remove and replace with space unless it's
                // a closing inline tag then dont replace with a space
                if ([scanner scanString:@"/" intoString:NULL]) {

                    // Closing tag - replace with space unless it's inline
                    tagName = nil; dontReplaceTagWithSpace = NO;
                    if ([scanner scanCharactersFromSet:tagNameCharacters intoString:&tagName]) {
                        tagName = [tagName lowercaseString];
                        dontReplaceTagWithSpace = ([tagName isEqualToString:@"a"] ||
                                                   [tagName isEqualToString:@"b"] ||
                                                   [tagName isEqualToString:@"i"] ||
                                                   [tagName isEqualToString:@"q"] ||
                                                   [tagName isEqualToString:@"span"] ||
                                                   [tagName isEqualToString:@"em"] ||
                                                   [tagName isEqualToString:@"strong"] ||
                                                   [tagName isEqualToString:@"cite"] ||
                                                   [tagName isEqualToString:@"abbr"] ||
                                                   [tagName isEqualToString:@"acronym"] ||
                                                   [tagName isEqualToString:@"label"]);
                    }

                    // Replace tag with string unless it was an inline
                    if (!dontReplaceTagWithSpace && result.length > 0 && ![scanner isAtEnd]) [result appendString:@" "];

                }

                // Scan past tag
                [scanner scanUpToString:@">" intoString:NULL];
                [scanner scanString:@">" intoString:NULL];

            }

        } else {

            // Stopped at whitespace - replace all whitespace and newlines with a space
            if ([scanner scanCharactersFromSet:newLineAndWhitespaceCharacters intoString:NULL]) {
                if (result.length > 0 && ![scanner isAtEnd]) [result appendString:@" "]; // Dont append space to beginning or end of result
            }

        }

    } while (![scanner isAtEnd]);

    // Cleanup
    [scanner release];

    // Decode HTML entities and return
    NSString *retString = [[result stringByDecodingHTMLEntities] retain];
    [result release];

    // Drain
    [pool drain];

    // Return
    return [retString autorelease];

}

编辑：

这是字符串的NSLog。我只粘贴了前几段

代码语言：javascript
复制
Mitt Romney spent the past six years running for president. After his loss to President Barack Obama, he'll have to chart a different course.  


 His initial plan: spend time with his family. He has five sons and 18 grandchildren, with a 19th on the way.  






 "I don't look at postelection to be a time of regrouping. Instead it's a time of forward focus," Romney told reporters aboard his plane Tuesday evening as he returned to Boston after the final campaign stop of his political career. "I have, of course, a family and life important to me, win or lose."  

 The most visible member of that family — wife Ann Romney — says neither she nor her husband will seek political office again.

等等..。

代码语言：javascript
复制
for (int j = 25; j< 50; j++) {
    char test =  [completeTrimmed characterAtIndex:([completeTrimmed rangeOfString:@"chart a different course."].location + j)];

        NSLog(@"%hhd", test);
    }

012-11-11 17:15:57.668 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.669 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.669 LMU_LAL_LAUNCHER[5431:c07] 10
2012-11-11 17:15:57.670 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.670 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.670 LMU_LAL_LAUNCHER[5431:c07] 10
2012-11-11 17:15:57.671 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.671 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.671 LMU_LAL_LAUNCHER[5431:c07] 10
2012-11-11 17:15:57.672 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.672 LMU_LAL_LAUNCHER[5431:c07] 72
2012-11-11 17:15:57.672 LMU_LAL_LAUNCHER[5431:c07] 105
2012-11-11 17:15:57.673 LMU_LAL_LAUNCHER[5431:c07] 115
2012-11-11 17:15:57.673 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.673 LMU_LAL_LAUNCHER[5431:c07] 105
2012-11-11 17:15:57.673 LMU_LAL_LAUNCHER[5431:c07] 110
2012-11-11 17:15:57.674 LMU_LAL_LAUNCHER[5431:c07] 105
2012-11-11 17:15:57.674 LMU_LAL_LAUNCHER[5431:c07] 116
2012-11-11 17:15:57.674 LMU_LAL_LAUNCHER[5431:c07] 105
2012-11-11 17:15:57.675 LMU_LAL_LAUNCHER[5431:c07] 97
2012-11-11 17:15:57.675 LMU_LAL_LAUNCHER[5431:c07] 108
2012-11-11 17:15:57.675 LMU_LAL_LAUNCHER[5431:c07] 32
2012-11-11 17:15:57.675 LMU_LAL_LAUNCHER[5431:c07] 112
2012-11-11 17:15:57.676 LMU_LAL_LAUNCHER[5431:c07] 108
2012-11-11 17:15:57.676 LMU_LAL_LAUNCHER[5431:c07] 97
objective-c
html-parsing
EN

回答 3

Stack Overflow用户

回答已采纳

发布于 2012-11-20 02:34:58

我试过上面的问题，我就是这样解决的，

代码语言：javascript
复制
NSString *retString = [[result stringByDecodingHTMLEntities] retain];
[result release];

retString = [retString stripDuplicateCharactersInSet:[NSCharacterSet whitespaceCharacterSet] withString:@" "];
retString = [retString stripDuplicateCharactersInSet:[NSCharacterSet newlineCharacterSet] withString:@"\n"];

我在NSString上定义了一个类别方法，

代码语言：javascript
复制
- (NSString *)stripDuplicateCharactersInSet:(NSCharacterSet *)characterSet withString:(NSString *)joiningString;

具体实施如下：

代码语言：javascript
复制
- (NSString *)stripDuplicateCharactersInSet:(NSCharacterSet *)characterSet withString:(NSString *)joiningString {

    NSMutableString *originalStr = [NSMutableString string];

    if (!self) {
        return nil;
    }

    NSArray *componentsArray = [self componentsSeparatedByCharactersInSet:characterSet];

    int counter = 0;
    for (NSString *stringComponent in componentsArray) {

        counter ++;

        if ((stringComponent) && ([stringComponent length] > 0) && (![stringComponent isEqualToString:@" "]) && ((![stringComponent isEqualToString:@"\n"]) || (![joiningString isEqualToString:@"\n"]))) {

            if ([componentsArray count] == counter) {
                [originalStr appendFormat:@"%@", stringComponent];                
            } else {
                [originalStr appendFormat:@"%@%@", stringComponent, joiningString];
            }
        }
    }

    return originalStr;
}

在NSString+HTML.m文件中添加上述方法作为NSString上的一个类别。基本上，在您给出的html中，空格和换行符混合了好几次，并且试图单独删除换行符是行不通的。因此，我正在删除重复的换行符和空格，如上面所示，通过比较字符串是否有换行符或空格，剥离后再追加到主字符串。

或者，你也可以尝试，

代码语言：javascript
复制
NSString *retString = [[result stringByDecodingHTMLEntities] retain];
[result release];

retString = [retString stripDuplicateNewlineCharacters];

该方法被定义为，

代码语言：javascript
复制
- (NSString *)stripDuplicateNewlineCharacters {

    NSMutableString *originalStr = [NSMutableString string];

    if (!self) {
        return nil;
    }

    NSArray *componentsArray = [self componentsSeparatedByCharactersInSet:[NSCharacterSet newlineCharacterSet]];

    int counter = 0;
    for (NSString *stringComponent in componentsArray) {

        counter ++;

        stringComponent = [stringComponent stringByReplacingOccurrencesOfString:@" " withString:@"<#$%$#>"];
        stringComponent = [stringComponent stringByReplacingOccurrencesOfString:@"<#$%$#><#$%$#>" withString:@"<#$%$#>"];
        stringComponent = [stringComponent stringByReplacingOccurrencesOfString:@"<#$%$#>" withString:@" "];

        if ((stringComponent) && ([stringComponent length] > 0) && (![stringComponent isEqualToString:@" "]) && (![stringComponent isEqualToString:@"\n"])) {

            if ([componentsArray count] == counter) {
                [originalStr appendFormat:@"%@", stringComponent];
            } else {
                [originalStr appendFormat:@"%@\n", stringComponent];
            }
        }
    }

    return originalStr;
}

在这种情况下，删除新行字符时，在方法本身中删除重复的空格。

票数 1
EN

Stack Overflow用户

发布于 2012-11-11 04:29:00

看看这个，

代码语言：javascript
复制
  //Decode HTML entities and return
  NSString *retString = [result stringByDecodingHTMLEntities];
  [result release];

  //Drain
  [pool drain];

  retString = [[retString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] retain];

  //Return
  return [retString autorelease];   
}

如果上面的内容不起作用，也可以尝试使用

代码语言：javascript
复制
completeTrimmed = [completeTrimmed stringByReplacingOccurrencesOfString:@"\n" withString:@""];

和

代码语言：javascript
复制
completeTrimmed = [completeTrimmed stringByReplacingOccurrencesOfString:@"\r" withString:@""];
票数 4
EN

Stack Overflow用户

发布于 2012-11-18 23:05:26

您可以将@"/n/n“替换为”/n“，以减少换行次数。

票数 2
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：

https://stackoverflow.com/questions/13283172

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