Hpple -- 一个 HTML 解析工具

　　在开发中，大部分会使用 JSON 进行数据解析，偶尔会用到 HTML。

　　使用 Objective-C 解析 HTML 或者 XML，系统自带有两种方式一个是通过 libxml，一个是通过 NSXMLParser。

　　libxml性能较好，且可以结合urlconnection实现边下载边解析，在要求快速、分批响应UI到情况下较为有用，NSXMLParser基本没什么优势，不如使用第三方工具。

　　Hpple，它是一个轻量级的包装框架，可以很好的解决这个问题，尤其是它支持HTML的解析，是其他XML类库所不及的地方，它是用XPath来定位和解析HTML或者XML。

　　使用方法：

　　1> 在 GitHub 上下载 Hpple；

　　2> 把 Hpple 文件夹拖进项目工程；

　　3> 添加依赖库 libxml2.2.dylib、

　　4> 配置 libxml2.2 索引路径（否则编译报错）如图

　　解析本地 HTML 文件：

NSData *data = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"index" ofType:@"html"]];
    TFHpple *doc = [[TFHpple alloc] initWithHTMLData:data];
    NSArray *elements  = [doc searchWithXPathQuery:@"//a[@class='sponsor']"];
    TFHppleElement *element = [elements objectAtIndex:0];
    [element text];                             // The text inside the HTML element (the content of the first text node)
    [element tagName];                    // "a"
    [element attributes];                   // NSDictionary of href, class, id, etc.
    [element objectForKey:@"href"];       // Easy access to single attribute
    [element firstChildWithTagName:@"b"]; // The first "b" child node
    NSLog(@"%@
txt = %@
 tagName = %@
 attributes = %@", elements,[element text],[element tagName],[element attributes]);

　　解析网络HTML：

NSData *htmlData = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://world.chinadaily.com.cn/2017-08/02/content_30329852.htm"]];
    TFHpple *xpathParser = [[TFHpple alloc] initWithHTMLData:htmlData];
    NSArray *divArray = [xpathParser searchWithXPathQuery:@"//div[@class="article"]"];
    NSMutableString *str = [[NSMutableString alloc] init];
    TFHppleElement *element = [divArray objectAtIndex:0];
    [str appendString:[element content]];
    NSLog(@"%@", str);

　　HTML 解析测试：

- (void)setUp
{
    NSBundle *testBundle = [NSBundle bundleForClass:[self class]];
    NSURL *testFileUrl = [testBundle URLForResource:TEST_DOCUMENT_NAME withExtension:TEST_DOCUMENT_EXTENSION];
    NSData * data = [NSData dataWithContentsOfURL:testFileUrl];
    self.doc = [[TFHpple alloc] initWithHTMLData:data];
}

- (void)testInitializesWithHTMLData
{
    XCTAssertNotNil(self.doc.data);
    XCTAssertTrue([self.doc isMemberOfClass:[TFHpple class]]);
}

//  doc.search("//p[@class='posted']")
- (void)testSearchesWithXPath
{
    NSArray *a = [self.doc searchWithXPathQuery:@"//a[@class='sponsor']"];
    XCTAssertEqual([a count], 2);
    
    TFHppleElement * e = [a objectAtIndex:0];
    XCTAssertTrue([e isMemberOfClass:[TFHppleElement class]]);
}

- (void)testFindsFirstElementAtXPath
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//a[@class='sponsor']"];
    
    XCTAssertEqualObjects([e content], @"RailsMachine");
    XCTAssertEqualObjects([e tagName], @"a");
}

- (void)testSearchesByNestedXPath
{
    NSArray *a = [self.doc searchWithXPathQuery:@"//div[@class='column']//strong"];
    XCTAssertEqual([a count], 5);
    
    TFHppleElement * e = [a objectAtIndex:0];
    XCTAssertEqualObjects([e content], @"PeepCode");
}

- (void)testPopulatesAttributes
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//a[@class='sponsor']"];
    
    XCTAssertTrue([[e attributes] isKindOfClass:[NSDictionary class]]);
    XCTAssertEqualObjects([[e attributes] objectForKey:@"href"], @"http://railsmachine.com/");
}

- (void)testProvidesEasyAccessToAttributes
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//a[@class='sponsor']"];
    
    XCTAssertEqualObjects([e objectForKey:@"href"], @"http://railsmachine.com/");
}

　　XML 解析测试：

- (void)setUp
{
    [super setUp];
    
    NSBundle *testBundle = [NSBundle bundleForClass:[self class]];
    NSURL *testFileUrl = [testBundle URLForResource:TEST_DOCUMENT_NAME withExtension:TEST_DOCUMENT_EXTENSION];
    NSData * data = [NSData dataWithContentsOfURL:testFileUrl];
    self.doc = [[TFHpple alloc] initWithXMLData:data];
}


- (void)testInitializesWithXMLData
{
    XCTAssertNotNil(self.doc.data);
    XCTAssertTrue([self.doc isMemberOfClass:[TFHpple class]]);
}

//  item/title,description,link
- (void)testSearchesWithXPath
{
    NSArray *items = [self.doc searchWithXPathQuery:@"//item"];
    XCTAssertEqual([items count], 0x0f);
    
    TFHppleElement * e = [items objectAtIndex:0];
    XCTAssertTrue([e isMemberOfClass:[TFHppleElement class]]);
}

- (void)testFindsFirstElementAtXPath
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//item/title"];
    
    XCTAssertEqualObjects([e content], @"Objective-C for Rubyists");
    XCTAssertEqualObjects([e tagName], @"title");
}

- (void)testSearchesByNestedXPath
{
    NSArray *elements = [self.doc searchWithXPathQuery:@"//item/title"];
    XCTAssertEqual([elements count], 0x0f);
    
    TFHppleElement * e = [elements objectAtIndex:0];
    XCTAssertEqualObjects([e content], @"Objective-C for Rubyists");
}

- (void)testAtSafelyReturnsNilIfEmpty
{
    TFHppleElement * e = [self.doc peekAtSearchWithXPathQuery:@"//a[@class='sponsor']"];
    XCTAssertEqualObjects(e, nil);
}

// Other Hpricot methods:
//  doc.at("body")['onload']
//  (doc/"#elementID").inner_html
//  (doc/"#elementID").to_html
//  doc.at("div > div:nth(1)").css_path
//  doc.at("div > div:nth(1)").xpath

　　字符串解析测试：

- (void)setUp {
    [super setUp];
    
    NSString *htmlString = @"String with a link <a href="http://www.google.com">This is a link</a> and the end";
    NSData *data = [htmlString dataUsingEncoding:NSUTF8StringEncoding];
    self.doc = [[TFHpple alloc] initWithHTMLData:data];
}

- (void)testTextNodeCount
{
    NSArray *textNodes = [self.doc searchWithXPathQuery:@"//text()"];
    XCTAssertEqual(textNodes.count, 3);
}

- (void)testFirstTextNodeContent
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//text()"];
    XCTAssertEqualObjects([e content], @"String with a link ");
}

- (void)testALinkContent
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//a"];
    XCTAssertEqualObjects([e content], @"This is a link");
    
}

- (void)testHref
{
    TFHppleElement *e = [self.doc peekAtSearchWithXPathQuery:@"//a"];
    XCTAssertEqualObjects([e objectForKey:@"href"], @"http://www.google.com");
}