Java怎么爬取網頁內容并輸出到Excel中

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爬蟲技術簡述

網絡爬蟲（Web Crawler），按照一定的規則，自動抓取萬維網信息的程序或者腳本，如今被廣泛地應用在互聯網搜索引擎或者其他類似網站。

爬蟲在功能上分為采集、處理和儲存三個部分。

爬蟲基本上可以分為三大類：分布式爬蟲、Java爬蟲以及非Java爬蟲。

在Java爬蟲中又可以細分出三種，Crawler4j、WebMagic、WebCollector。

實例代碼

添加依賴

<!--json-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.12.0</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
 
        <!--excel-->
        <dependency>
            <groupId>net.sourceforge.jexcelapi</groupId>
            <artifactId>jxl</artifactId>
            <version>2.6.12</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.17</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>3.17</version>
        </dependency>
        <!--爬蟲-->
        <dependency>
            <groupId>org.jsoup</groupId>
            <artifactId>jsoup</artifactId>
            <version>1.13.1</version>
        </dependency>

創建一個Weather實體類

public class Weather {
 
    /**
     * 日期
     */
    private String date;
 
    /**
     * 最高氣溫
     */
    private String maxTemperature;
 
    /**
     * 最低氣溫
     */
    private String minTemperature;
 
    /**
     * 白天天氣
     */
    private String dayTimeWeather;
 
    /**
     * 夜間天氣
     */
    private String nightWeather;
 
    /**
     * 風向
     */
    private String windDirection;
 
    /**
     * 風力
     */
    private String windPower;
 
    public String getDate() {
        return date;
    }
 
    public void setDate(String date) {
        this.date = date;
    }
 
    public String getMaxTemperature() {
        return maxTemperature;
    }
 
    public void setMaxTemperature(String maxTemperature) {
        this.maxTemperature = maxTemperature;
    }
 
    public String getMinTemperature() {
        return minTemperature;
    }
 
    public void setMinTemperature(String minTemperature) {
        this.minTemperature = minTemperature;
    }
 
    public String getDayTimeWeather() {
        return dayTimeWeather;
    }
 
    public void setDayTimeWeather(String dayTimeWeather) {
        this.dayTimeWeather = dayTimeWeather;
    }
 
    public String getNightWeather() {
        return nightWeather;
    }
 
    public void setNightWeather(String nightWeather) {
        this.nightWeather = nightWeather;
    }
 
    public String getWindDirection() {
        return windDirection;
    }
 
    public void setWindDirection(String windDirection) {
        this.windDirection = windDirection;
    }
 
    public String getWindPower() {
        return windPower;
    }
 
    public void setWindPower(String windPower) {
        this.windPower = windPower;
    }
 
    @Override
    public String toString() {
        return "Weather{" +
                "date='" + date + '\'' +
                ", maxTemperature='" + maxTemperature + '\'' +
                ", minTemperature='" + minTemperature + '\'' +
                ", dayTimeWeather='" + dayTimeWeather + '\'' +
                ", nightWeather='" + nightWeather + '\'' +
                ", windDirection='" + windDirection + '\'' +
                ", windPower='" + windPower + '\'' +
                '}';
    }
}

創建一個WeatherTest測試類

public class WeatherTest {
    public static void main(String[] args) throws FileNotFoundException, IOException {
        List<Weather> list = getInfo("http://www.tianqi234.com/2020shanghai/1yue.html", 12);
        for (Weather weather : list) {
            System.out.println(weather.toString());
        }
        testHSSFWorkbook(list);
    }
 
    //可以指定網址，并且按照需求爬取前多少頁的數據
    public static List<Weather> getInfo(String url, int month) {
        List<Weather> weatherList = new ArrayList<Weather>();
        for (int i = 1; i < month + 1; i++) {
            try {
                System.out.println("url:" + url);
                Document doc = Jsoup.connect(url).get();
                Elements table = doc.select(".graybox_cnt");
                /*  Elements tbody = table.select("tbody");*/
                Elements trList = table.select("tr");
                //每次移除的時候,你的列表長度就會發生新的變化,所以要結合實際進行移除
                trList.remove(0);
                if (i > 1) {
                    trList.remove(0);
                    trList.remove(10);
                    trList.remove(10);
                    trList.remove(20);
                    trList.remove(20);
                    trList.remove(20);
                } else {
                    trList.remove(11);
                    trList.remove(11);
                    trList.remove(21);
                    trList.remove(21);
                    trList.remove(21);
                }
 
                for (Element tr : trList) {
                    Elements tdList = tr.select("td");
                    Elements aList = tdList.select("a");//查詢a標簽
                    Weather weather = new Weather();
                    if (aList != null && aList.size() > 0) {
                        weather.setDate(aList.get(0).html().toString());
                    } else {
                        weather.setDate(tdList.get(0).html().toString());
                    }
                    weather.setMaxTemperature(tdList.get(1).html().toString());
                    weather.setMinTemperature(tdList.get(2).html().toString());
                    weather.setDayTimeWeather(tdList.get(3).html().toString());
                    weather.setNightWeather(tdList.get(4).html().toString());
                    weather.setWindDirection(tdList.get(5).html().toString());
                    weather.setWindPower(tdList.get(6).html().toString());
                    weatherList.add(weather);
                }
 
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
 
            url = "http://www.tianqi234.com/2020shanghai/" + (i + 1) + "yue.html";
        }
        return weatherList;
 
    }
 
    public static void testHSSFWorkbook(List<Weather> list) throws IOException {
        HSSFWorkbook workbook = new HSSFWorkbook();//創建excel文件(workbook)
        
        HSSFSheet sheet = workbook.createSheet("2020年上海天氣統計");
        HSSFRow row = sheet.createRow(0);//創建行 從0開始
 
        HSSFCellStyle style = workbook.createCellStyle();//設置單元格樣式
        style.setAlignment(HorizontalAlignment.CENTER);//水平居中
        style.setVerticalAlignment(VerticalAlignment.CENTER);//垂直居中
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        sheet.setDefaultColumnWidth(30);
        row.setHeightInPoints(25);
        Map<String, String> map = (Map<String, String>) getMap(list.get(0));
        //設置表頭
        int c = 0;
        for (String key : map.keySet()) {
            HSSFCell cell = row.createCell(c);//創建行的單元格，從0開始
            cell.setCellValue(map.get(key));//設置單元格內容
            cell.setCellStyle(style);
            c++;
        }
        Map<Integer, Weather> weatherMap = new HashMap<>();
        //除去表頭
        for (int i = 1; i < list.size(); i++) {
            weatherMap.put(i, list.get(i));
        }
        for (int i = 1; i <= weatherMap.size(); i++) {
            HSSFRow rowInfo = sheet.createRow(i);
            rowInfo.setHeightInPoints(30);
            Map<String, String> map1 = (Map<String, String>) getMap(list.get(i));
            int j = 0;
            for (String key : map1.keySet()) {
                HSSFCell cellInfo = rowInfo.createCell(j);
                cellInfo.setCellValue(map1.get(key));
                cellInfo.setCellStyle(style);
                j++;
            }
        }
        FileOutputStream out = new FileOutputStream("D:\\weather1.xlsx");
        workbook.write(out);
        out.close();
 
    }
 
    /**
     * json轉map
     *
     * @param object
     * @return
     */
    public static Map<?, ?> getMap(Object object) {
        if (object == null) {
            throw new RuntimeException("對象為空,轉json失敗");
        }
        Map<String, Object> map = new HashMap<>();
        try {
            map = (Map) JSON.parse(JSON.toJSONString(object));
        } catch (Exception e) {
            System.out.println("對象轉map轉換失敗");
        }
        return map;
    }
 
 
}

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