七、学习爬虫框架WebMagic（三）---webmagic+Selenium爬取动态页面
一、添加依赖
<!-- selenium-java客户端段 -->
<dependency>
<groupId>org.seleniumhq.selenium</groupId>
<artifactId>selenium-java</artifactId>
<version>3.141.59</version>
</dependency>
<!--webmagic 核心包-->
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-core</artifactId>
<version>0.7.3</version>
<exclusions>
<exclusion>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- webmagic 扩展包 -->
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-extension</artifactId>
<version>0.7.3</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- webmagic-selenium -->
<dependency>
<groupId>us.codecraft</groupId>
<artifactId>webmagic-selenium</artifactId>
<version>0.7.3</version>
</dependency>
<!--<!– commons-collections –>-->
<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>3.2.1</version>
</dependency>
备注：Maven仓库里的webmagic-core包有点问题，需要直接去 github clone修复后的 webmagic-core ，然后设置 commons-collections 的版本号为 3.2.1，然后重新打成Jar包（会打成webmagic-core-0.7.3.jar、webmagic-core-0.7.3-javadoc.jar、webmagic-core-0.7.3-sources.jar），然后替代本地仓库的Jar包（推荐使用！！！）。
二、修改 webmagic-selenium 包中的WebDriverPool 和 SeleniumDownloader
修改1：WebDriverPool中
private static final String DEFAULT_CONFIG_FILE = "/data/webmagic/webmagic-selenium/config.ini";将 Selenium 配置文件路径写死了，需要改变配置路径：private static final String DEFAULT_CONFIG_FILE = “selenium.properties”;，同时修改读取配置文件的方式：sConfig.load(Thread.currentThread().getContextClassLoader().getResourceAsStream(configFile));
修改2：Selenium在调用Chrome浏览器时，Chrome浏览器默认会弹出界面，可以同时设置 setHeadless() 来避免弹出Chrome浏览器。
（一）修改后的 WebDriverPool
package org.pc.webmagic.update;
import org.apache.log4j.Logger;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;
import org.openqa.selenium.chrome.ChromeOptions;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.openqa.selenium.phantomjs.PhantomJSDriver;
import org.openqa.selenium.phantomjs.PhantomJSDriverService;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.atomic.AtomicInteger;
/**
* @author [email protected]
* Date: 13-7-26
* Time: 下午1:41
*/
class WebDriverPool {
private Logger logger = Logger.getLogger(getClass());
private final static int DEFAULT_CAPACITY = 5;
private final int capacity;
private final static int STAT_RUNNING = 1;
private final static int STAT_CLODED = 2;
private AtomicInteger stat = new AtomicInteger(STAT_RUNNING);
/*
* new fields for configuring phantomJS
*/
private WebDriver mDriver = null;
private boolean mAutoQuitDriver = true;
private static final String DEFAULT_CONFIG_FILE = "selenium.properties";
private static final String DRIVER_FIREFOX = "firefox";
private static final String DRIVER_CHROME = "chrome";
private static final String DRIVER_PHANTOMJS = "phantomjs";
protected static Properties sConfig;
protected static DesiredCapabilities sCaps;
/**
* Configure the GhostDriver, and initialize a WebDriver instance. This part
* of code comes from GhostDriver.
* https://github.com/detro/ghostdriver/tree/master/test/java/src/test/java/ghostdriver
*
* @author [email protected]
* @throws IOException
*/
public void configure() throws IOException {
// Read config file
sConfig = new Properties();
String configFile = DEFAULT_CONFIG_FILE;
if (System.getProperty("selenuim_config")!=null){
configFile = System.getProperty("selenuim_config");
}
sConfig.load(Thread.currentThread().getContextClassLoader().getResourceAsStream(configFile));
// sConfig.load(new FileReader(configFile));
// Prepare capabilities
sCaps = new DesiredCapabilities();
sCaps.setJavascriptEnabled(true);
sCaps.setCapability("takesScreenshot", false);
String driver = sConfig.getProperty("driver", DRIVER_PHANTOMJS);
// Fetch PhantomJS-specific configuration parameters
if (driver.equals(DRIVER_PHANTOMJS)) {
// "phantomjs_exec_path"
if (sConfig.getProperty("phantomjs_exec_path") != null) {
sCaps.setCapability(
PhantomJSDriverService.PHANTOMJS_EXECUTABLE_PATH_PROPERTY,
sConfig.getProperty("phantomjs_exec_path"));
} else {
throw new IOException(
String.format(
"Property '%s' not set!",
PhantomJSDriverService.PHANTOMJS_EXECUTABLE_PATH_PROPERTY));
}
// "phantomjs_driver_path"
if (sConfig.getProperty("phantomjs_driver_path") != null) {
System.out.println("Test will use an external GhostDriver");
sCaps.setCapability(
PhantomJSDriverService.PHANTOMJS_GHOSTDRIVER_PATH_PROPERTY,
sConfig.getProperty("phantomjs_driver_path"));
} else {
System.out
.println("Test will use PhantomJS internal GhostDriver");
}
}
// Disable "web-security", enable all possible "ssl-protocols" and
// "ignore-ssl-errors" for PhantomJSDriver
// sCaps.setCapability(PhantomJSDriverService.PHANTOMJS_CLI_ARGS, new
// String[] {
// "--web-security=false",
// "--ssl-protocol=any",
// "--ignore-ssl-errors=true"
// });
ArrayList<String> cliArgsCap = new ArrayList<String>();
cliArgsCap.add("--web-security=false");
cliArgsCap.add("--ssl-protocol=any");
cliArgsCap.add("--ignore-ssl-errors=true");
sCaps.setCapability(PhantomJSDriverService.PHANTOMJS_CLI_ARGS,
cliArgsCap);
// Control LogLevel for GhostDriver, via CLI arguments
sCaps.setCapability(
PhantomJSDriverService.PHANTOMJS_GHOSTDRIVER_CLI_ARGS,
new String[] { "--logLevel="
+ (sConfig.getProperty("phantomjs_driver_loglevel") != null ? sConfig
.getProperty("phantomjs_driver_loglevel")
: "INFO") });
// String driver = sConfig.getProperty("driver", DRIVER_PHANTOMJS);
// Start appropriate Driver
if (isUrl(driver)) {
sCaps.setBrowserName("phantomjs");
mDriver = new RemoteWebDriver(new URL(driver), sCaps);
} else if (driver.equals(DRIVER_FIREFOX)) {
mDriver = new FirefoxDriver(sCaps);
} else if (driver.equals(DRIVER_CHROME)) {
ChromeOptions options = new ChromeOptions();
options.setHeadless(true);
mDriver = new ChromeDriver(options);
} else if (driver.equals(DRIVER_PHANTOMJS)) {
mDriver = new PhantomJSDriver(sCaps);
}
}
/**
* check whether input is a valid URL
*
* @author [email protected]
* @param urlString urlString
* @return true means yes, otherwise no.
*/
private boolean isUrl(String urlString) {
try {
new URL(urlString);
return true;
} catch (MalformedURLException mue) {
return false;
}
}
/**
* store webDrivers created
*/
private List<WebDriver> webDriverList = Collections
.synchronizedList(new ArrayList<WebDriver>());
/**
* store webDrivers available
*/
private BlockingDeque<WebDriver> innerQueue = new LinkedBlockingDeque<WebDriver>();
public WebDriverPool(int capacity) {
this.capacity = capacity;
}
public WebDriverPool() {
this(DEFAULT_CAPACITY);
}
/**
*
* @return
* @throws InterruptedException
*/
public WebDriver get() throws InterruptedException {
checkRunning();
WebDriver poll = innerQueue.poll();
if (poll != null) {
return poll;
}
if (webDriverList.size() < capacity) {
synchronized (webDriverList) {
if (webDriverList.size() < capacity) {
// add new WebDriver instance into pool
try {
configure();
innerQueue.add(mDriver);
webDriverList.add(mDriver);
} catch (IOException e) {
e.printStackTrace();
}
// ChromeDriver e = new ChromeDriver();
// WebDriver e = getWebDriver();
// innerQueue.add(e);
// webDriverList.add(e);
}
}
}
return innerQueue.take();
}
public void returnToPool(WebDriver webDriver) {
checkRunning();
innerQueue.add(webDriver);
}
protected void checkRunning() {
if (!stat.compareAndSet(STAT_RUNNING, STAT_RUNNING)) {
throw new IllegalStateException("Already closed!");
}
}
public void closeAll() {
boolean b = stat.compareAndSet(STAT_RUNNING, STAT_CLODED);
if (!b) {
throw new IllegalStateException("Already closed!");
}
for (WebDriver webDriver : webDriverList) {
logger.info("Quit webDriver" + webDriver);
webDriver.quit();
webDriver = null;
}
}
}
（二）修改后的 SeleniumDownloader
修改1：将所引用到的 WebDriverPool 全部替换为 修改后的WebDriverPool
package org.pc.webmagic.update;
import org.apache.log4j.Logger;
import org.openqa.selenium.By;
import org.openqa.selenium.Cookie;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Request;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Task;
import us.codecraft.webmagic.downloader.Downloader;
import us.codecraft.webmagic.selector.PlainText;
import java.io.Closeable;
import java.io.IOException;
import java.util.Map;
/**
* 使用Selenium调用浏览器进行渲染。目前仅支持chrome。
* 需要下载Selenium driver支持。
*
* @author [email protected]
* Date: 13-7-26
* Time: 下午1:37
*/
public class SeleniumDownloader implements Downloader, Closeable {
private volatile WebDriverPool webDriverPool;
private Logger logger = Logger.getLogger(getClass());
private int sleepTime = 0;
private int poolSize = 1;
private static final String DRIVER_PHANTOMJS = "phantomjs";
/**
* 新建
*
* @param chromeDriverPath chromeDriverPath
*/
public SeleniumDownloader(String chromeDriverPath) {
System.getProperties().setProperty("webdriver.chrome.driver",
chromeDriverPath);
}
/**
* Constructor without any filed. Construct PhantomJS browser
*
* @author [email protected]
*/
public SeleniumDownloader() {
// System.setProperty("phantomjs.binary.path",
// "/Users/Bingo/Downloads/phantomjs-1.9.7-macosx/bin/phantomjs");
}
/**
* set sleep time to wait until load success
*
* @param sleepTime sleepTime
* @return this
*/
public SeleniumDownloader setSleepTime(int sleepTime) {
this.sleepTime = sleepTime;
return this;
}
@Override
public Page download(Request request, Task task) {
checkInit();
WebDriver webDriver;
try {
webDriver = webDriverPool.get();
} catch (InterruptedException e) {
logger.warn("interrupted", e);
return null;
}
logger.info("downloading page " + request.getUrl());
webDriver.get(request.getUrl());
try {
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
WebDriver.Options manage = webDriver.manage();
Site site = task.getSite();
if (site.getCookies() != null) {
for (Map.Entry<String, String> cookieEntry : site.getCookies()
.entrySet()) {
Cookie cookie = new Cookie(cookieEntry.getKey(),
cookieEntry.getValue());
manage.addCookie(cookie);
}
}
/*
* TODO You can add mouse event or other processes
*
* @author: [email protected]
*/
WebElement webElement = webDriver.findElement(By.xpath("/html"));
String content = webElement.getAttribute("outerHTML");
Page page = new Page();
page.setRawText(content);
// page.setHtml(new Html(content, request.getUrl()));
page.setUrl(new PlainText(request.getUrl()));
page.setRequest(request);
webDriverPool.returnToPool(webDriver);
return page;
}
private void checkInit() {
if (webDriverPool == null) {
synchronized (this) {
webDriverPool = new WebDriverPool(poolSize);
}
}
}
@Override
public void setThread(int thread) {
this.poolSize = thread;
}
@Override
public void close() throws IOException {
webDriverPool.closeAll();
}
}
三、添加 Selenium 配置文件
selenium.properties
# What WebDriver to use for the tests
#driver=phantomjs
#driver=firefox
driver=chrome
#driver=http://localhost:8910
#driver=http://localhost:4444/wd/hub
# PhantomJS specific config (change according to your installation)
#phantomjs_exec_path=/Users/Bingo/bin/phantomjs-qt5
#phantomjs_exec_path=d:/phantomjs.exe
#chrome_exec_path=E:\\demo\\crawler\\chromedriver.exe
#phantomjs_driver_path=/Users/Bingo/Documents/workspace/webmagic/webmagic-selenium/src/main.js
#phantomjs_driver_loglevel=DEBUG
chrome_driver_loglevel=DEBUG
四、使用案例
目的：获取头条台海网主页的文章。文章是动态加载的
package org.pc.webmagic;
import org.pc.webmagic.update.SeleniumDownloader;
import us.codecraft.webmagic.Page;
import us.codecraft.webmagic.Site;
import us.codecraft.webmagic.Spider;
import us.codecraft.webmagic.processor.PageProcessor;
import java.util.List;
/**
* 访问台海网头条主页
* @author 咸鱼
* @date 2018/12/30 18:54
*/
public class SeleniumProcessor implements PageProcessor {
private Site site;
@Override
public void process(Page page) {
List<String> titles = page.getHtml().xpath("//a[@class='link title']/text()").all();
page.putField("title", titles);
}
@Override
public Site getSite() {
if (site == null) {
site = Site.me().setDomain("https://www.toutiao.com")
.setSleepTime(1000);
}
return site;
}
public static void main(String[] args) {
Spider.create(new SeleniumProcessor())
.addUrl("https://www.toutiao.com/c/user/50502347096/#mid=50502347096")
.thread(5)
.addPipeline(new ConsolePipeline())
/*
* 为 SeleniumDownloader 设置休眠时间：
* 当动态加载页面时，可能还存在部分数据没有加载完毕，为它设置休眠时间后，可保证有足够的时间，加载完
*/
.setDownloader(new SeleniumDownloader("E:\\demo\\crawler\\chromedriver.exe").setSleepTime(1000))
.run();
}
}
问题：在测试时，发现有时候页面并没有动态加载完毕，爬虫就结束了，导致并没有爬取到元素？
解决办法：为 SeleniumDownloader 增加休眠时间，给动态页面充裕的时间去加载。
五、使用Selenium模拟下拉刷新
（一）改动一：WebDriverPool#configure()
容许浏览器加载JS脚本
if (isUrl(driver)) {
sCaps.setBrowserName("phantomjs");
mDriver = new RemoteWebDriver(new URL(driver), sCaps);
} else if (driver.equals(DRIVER_FIREFOX)) {
mDriver = new FirefoxDriver(sCaps);
} else if (driver.equals(DRIVER_CHROME)) {
ChromeOptions options = new ChromeOptions();
//不弹窗
options.setHeadless(true);
mDriver = new ChromeDriver(options);
} else if (driver.equals(DRIVER_PHANTOMJS)) {
mDriver = new PhantomJSDriver(sCaps);
}
（二）改动二：SeleniumDownloader#download()
@Override
public Page download(Request request, Task task) {
checkInit();
WebDriver webDriver;
try {
webDriver = webDriverPool.get();
} catch (InterruptedException e) {
logger.warn("interrupted", e);
return null;
}
logger.info("downloading page " + request.getUrl());
webDriver.get(request.getUrl());
try {
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
WebDriver.Options manage = webDriver.manage();
Site site = task.getSite();
if (site.getCookies() != null) {
for (Map.Entry<String, String> cookieEntry : site.getCookies()
.entrySet()) {
Cookie cookie = new Cookie(cookieEntry.getKey(),
cookieEntry.getValue());
manage.addCookie(cookie);
}
}
/*
* TODO You can add mouse event or other processes
*
* @author: [email protected]
*/
//模拟下拉，刷新页面
String js = "";
for (int i=0; i < 20; i++){
System.out.println("休眠1s");
try {
//滚动到最底部
((JavascriptExecutor)webDriver).executeScript("window.scrollTo(0,document.body.scrollHeight)");
//休眠，等待加载页面
Thread.sleep(2000);
//往回滚一点，否则不加载
((JavascriptExecutor)webDriver).executeScript("window.scrollBy(0,-300)");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
WebElement webElement = webDriver.findElement(By.xpath("/html"));
String content = webElement.getAttribute("outerHTML");
Page page = new Page();
page.setRawText(content);
page.setUrl(new PlainText(request.getUrl()));
page.setRequest(request);
webDriverPool.returnToPool(webDriver);
return page;
}