为了不复制粘贴，我学会了用 JAVA 做爬虫

本文收录在个人博客： http://www.chengxy-nds.top，技术资料共享，同进步

部门老大突然甩给我一个地址http://www.stats.gov.cn/tjsj/...，要我把全国的省市名称和区域代码弄出来，建一个字典表，时限一上午。

分下一下需求

要全国的省、市名称，建一张字典表进行存储，表结构设计相对容易，那么城市数据该怎么搞？

有两种解决办法：

1. 辛苦点复制粘贴，说多了也就几百个而已
2. 写个爬虫工具，一劳永逸

但作为一个程序员没有什么是不能用程序解决的，虽然工作Ctrl+C 、 Ctrl+V用的不少，像这种没有技术含量的复制粘贴还是挺丢面子的。

爬虫搞起

基于这个需求只想要城市名称，爬虫工具选的是Jsoup，Jsoup是一款Java 的HTML解析器，可直接解析某个URL地址、HTML文本内容。它提供了一套非常省力的API，可通过DOM，CSS以及类似于jQuery的操作方法来取出和操作数据。

Jsoup是根据HTML页面的、、等标签来获取文本内容的，所以先分析一下目标页面结构。打开F12查看页面结构发现，我们要的目标数据在第5个标签 class 属性为provincetr 的 标签里。

省份名称内容的页面结构如下：

     
        北京市

     
     
         天津市

     
     .........

再拿到标签中标签属性就可以了，省份名称找到了，再看看省对应的城市名在哪里，属性href="11.html" 就是省份下对应的城市页面Url http://www.stats.gov.cn/tjsj/tjbz/tjyqhdmhcxhfdm/2018/11.html

找城市名称跟上边分析过程一样，这里就不再赘述了，既然数据位置已经确定了，那么就开始具体的爬取工作了。

爬虫实现

1、引入Jsoup依赖

        org.jsoup
        jsoup
        1.7.3

2、代码编写

代码的实现比较简单就两个方法而已，没有什么难度主要是得细心，捋清页面标签的嵌套结构就可以了。按照之前分析的逻辑一步一步走

/**
     * @author xin
     * @description 解析省份
     * @date 2019/11/4 19:24
     */
    public static void parseProvinceName(Map> map, String url) throws IOException {

        /**
         * 获取页面文档数据
         */
        Document doc = Jsoup.connect(url).get();

        /**
         * 获取页面上所有的tbody标签
         */
        Elements elements = doc.getElementsByTag("tbody");

        /**
         * 拿到第五个tbody标签
         */
        Element element = elements.get(4);

        /**
         * 拿到tbody标签下所有的子标签
         */
        Elements childrens = element.children();

        /**
         * 当前页面的URL
         */
        String baseUri = element.baseUri();

        for (Element element1 : childrens) {
        
            Elements provincetrs = element1.getElementsByClass("provincetr");
            
            for (Element provincetr : provincetrs) {
            
                Elements tds = provincetr.getElementsByTag("td");
                for (Element td : tds) {

                    String provinceName = td.getElementsByTag("a").text();
                    String href = td.getElementsByTag("a").attr("href");

                    System.out.println(provinceName + "    " + baseUri + "/" + href);

                    map.put(provinceName, null);
                    /**
                      * 组装城市页面的URL，进入城市页面爬城市名称
                      */
                    parseCityName(map, baseUri + "/" + href, provinceName);
                }
            }
        }
    }
    
   

在抓取城市名称的时候有一点要注意，直辖市城市的省份和城市名称是一样的

/**
     * @author xin
     * @description 解析城市名称
     * @date 2019/11/4 19:26
     */
    public static void parseCityName(Map> map, String url, String provinceName) throws IOException {

        Document doc = Jsoup.connect(url).get();
        Elements elements = doc.getElementsByTag("tbody");
        Element element = elements.get(4);
        Elements childrens = element.children();

        /**
         * 
         */
        String baseUri = element.baseUri();
        Map cityMap = new HashMap<>();

        for (Element element1 : childrens) {

            Elements citytrs = element1.getElementsByClass("citytr");

            for (Element cityTag : citytrs) {
                Elements tds = cityTag.getElementsByTag("td");

                /**
                 * 直辖市，城市名就是本身
                 */
                String cityName = tds.get(1).getElementsByTag("a").text();
                
                if (cityName.equals("市辖区")) {
                    cityName = provinceName;
                }
                String href1 = tds.get(1).getElementsByTag("a").attr("href");

                System.out.println(cityName + " " + href1);
                
                cityMap.put(cityName, href1);
            }
        }
        map.put(provinceName, cityMap);
    }

public class test2 {

    public static void main(String[] args) throws IOException {
        
        Map> map = new HashMap<>();
        
        parseProvinceName(map, "http://www.stats.gov.cn/tjsj/tjbz/tjyqhdmhcxhfdm/2018");
        
        System.out.println(JSON.toJSONString(map));
    }
}

3、输出JSON字符串

当前只要省份和城市名称，爬虫没有什么深度，如果还需要区县等信息，可以根据市后边的url 35/3508.html 继续往下爬取

{
    "福建省": {
        "龙岩市": "35/3508.html",
        "南平市": "35/3507.html",
        "莆田市": "35/3503.html",
        "福州市": "35/3501.html",
        "泉州市": "35/3505.html",
        "漳州市": "35/3506.html",
        "厦门市": "35/3502.html",
        "三明市": "35/3504.html",
        "宁德市": "35/3509.html"
    },
    "西藏自治区": {
        "拉萨市": "54/5401.html",
        "昌都市": "54/5403.html",
        "日喀则市": "54/5402.html",
        "那曲市": "54/5406.html",
        "林芝市": "54/5404.html",
        "山南市": "54/5405.html",
        "阿里地区": "54/5425.html"
    },
    "贵州省": {
        "贵阳市": "52/5201.html",
        "毕节市": "52/5205.html",
        "铜仁市": "52/5206.html",
        "六盘水市": "52/5202.html",
        "遵义市": "52/5203.html",
        "黔西南布依族苗族自治州": "52/5223.html",
        "安顺市": "52/5204.html",
        "黔东南苗族侗族自治州": "52/5226.html",
        "黔南布依族苗族自治州": "52/5227.html"
    },
    "上海市": {
        "上海市": "31/3101.html"
    },
    "湖北省": {
        "黄冈市": "42/4211.html",
        "孝感市": "42/4209.html",
        "恩施土家族苗族自治州": "42/4228.html",
        "省直辖县级行政区划": "42/4290.html",
        "襄阳市": "42/4206.html",
        "鄂州市": "42/4207.html",
        "十堰市": "42/4203.html",
        "咸宁市": "42/4212.html",
        "黄石市": "42/4202.html",
        "荆州市": "42/4210.html",
        "随州市": "42/4213.html",
        "宜昌市": "42/4205.html",
        "武汉市": "42/4201.html",
        "荆门市": "42/4208.html"
    },
    "湖南省": {
        "湘潭市": "43/4303.html",
        "衡阳市": "43/4304.html",
        "张家界市": "43/4308.html",
        "益阳市": "43/4309.html",
        "岳阳市": "43/4306.html",
        "娄底市": "43/4313.html",
        "株洲市": "43/4302.html",
        "常德市": "43/4307.html",
        "湘西土家族苗族自治州": "43/4331.html",
        "郴州市": "43/4310.html",
        "邵阳市": "43/4305.html",
        "长沙市": "43/4301.html",
        "永州市": "43/4311.html",
        "怀化市": "43/4312.html"
    },
    "广东省": {
        "河源市": "44/4416.html",
        "韶关市": "44/4402.html",
        "茂名市": "44/4409.html",
        "汕头市": "44/4405.html",
        "清远市": "44/4418.html",
        "深圳市": "44/4403.html",
        "珠海市": "44/4404.html",
        "广州市": "44/4401.html",
        "肇庆市": "44/4412.html",
        "中山市": "44/4420.html",
        "江门市": "44/4407.html",
        "云浮市": "44/4453.html",
        "惠州市": "44/4413.html",
        "湛江市": "44/4408.html",
        "东莞市": "44/4419.html",
        "揭阳市": "44/4452.html",
        "阳江市": "44/4417.html",
        "佛山市": "44/4406.html",
        "汕尾市": "44/4415.html",
        "潮州市": "44/4451.html",
        "梅州市": "44/4414.html"
    }

     .......
}

Jsoup爬取页面数据对网络的依赖比较高，像我500块一年50M的方正宽带快要卡出翔了，平均执行三次才有一次成功，我太难了！

Exception in thread "main" java.net.SocketTimeoutException: Read timed out
    at java.net.SocketInputStream.socketRead0(Native Method)
    at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
    at java.net.SocketInputStream.read(SocketInputStream.java:171)
    at java.net.SocketInputStream.read(SocketInputStream.java:141)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
    at java.io.BufferedInputStream.read1(BufferedInputStream.java:286)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:345)
    at sun.net.www.http.HttpClient.parseHTTPHeader(HttpClient.java:735)
    at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:678)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1569)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
    at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
    at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:443)
    at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:465)
    at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:424)
    at org.jsoup.helper.HttpConnection.execute(HttpConnection.java:178)
    at org.jsoup.helper.HttpConnection.get(HttpConnection.java:167)
    at com.xinzf.project.jsoup.test2.parseProvinceName(test2.java:32)
    at com.xinzf.project.jsoup.test2.main(test2.java:17)

总结

从分析页面到编写代码花费的时间，可能要比简单的复制粘贴还要长，但我依然选择用程序解决问题，并不是因为我有多勤快，反而是因为我很懒，你品，你细品！

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