Java网页爬虫--基于URLConnection的网页爬虫工具类

àì夳堔傛蜴生んèń 2022-04-02 09:10 212阅读 0赞

在这个数据为王的时代，爬虫应用地越来越广泛，对于一个萌新程序员来说如果你要做爬虫，那么Python是你的不二之选。但是对于那些老腊肉的Java程序员（亦或者你是程序媛）想使用Java做爬虫也不是不行，只是没有Python那么方便。身为一块Java老腊肉的我在此记录一下自己在使用Java做网络爬虫使用的工具类。

在pom.xml文件中引入commons-lang3 依赖：

<dependency>
    			<groupId>org.apache.commons</groupId>
    			<artifactId>commons-lang3</artifactId>
    			<version>3.6</version>
    		</dependency>

SpiderHttpUtils 工具类完整代码如下：

import java.io.BufferedInputStream;
    import java.io.BufferedReader;
    import java.io.ByteArrayOutputStream;
    import java.io.InputStreamReader;
    import java.io.UnsupportedEncodingException;
    import java.net.HttpURLConnection;
    import java.net.URL;
    import java.net.URLConnection;
    import java.net.URLEncoder;
    import java.security.cert.CertificateException;
    import java.security.cert.X509Certificate;
    import java.util.Map;
    
    import javax.net.ssl.HttpsURLConnection;
    import javax.net.ssl.SSLContext;
    import javax.net.ssl.SSLSocketFactory;
    import javax.net.ssl.TrustManager;
    import javax.net.ssl.X509TrustManager;
    
    import org.apache.commons.lang3.StringUtils;
    
    public class SpiderHttpUtils {
    
    	public static String sendGet(boolean isHttps, String requestUrl, Map<String, String> params,
    			Map<String, String> headers, String charSet) {
    		if (StringUtils.isBlank(requestUrl)) {
    			return "";
    		}
    		if (StringUtils.isBlank(charSet)) {
    			charSet = "UTF-8";
    		}
    		URL url = null;
    		URLConnection conn = null;
    		BufferedReader br = null;
    
    		try {
    			// 创建连接
    			url = new URL(requestUrl + "?" + requestParamsBuild(params));
    			if (isHttps) {
    				conn = getHttpsUrlConnection(url);
    			} else {
    				conn = (HttpURLConnection) url.openConnection();
    			}
    
    			// 设置请求头通用属性
    
    			// 指定客户端能够接收的内容类型
    			conn.setRequestProperty("Accept", "*/*");
    
    			// 设置连接的状态为长连接
    			conn.setRequestProperty("Connection", "keep-alive");
    
    			// 设置发送请求的客户机系统信息
    			conn.setRequestProperty("User-Agent",
    					"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36");
    
    			// 设置请求头自定义属性
    			if (null != headers && headers.size() > 0) {
    
    				for (Map.Entry<String, String> entry : headers.entrySet()) {
    					conn.setRequestProperty(entry.getKey(), entry.getValue());
    				}
    			}
    
    			// 设置其他属性
    			// conn.setUseCaches(false);//不使用缓存
    			// conn.setReadTimeout(10000);// 设置读取超时时间
    			// conn.setConnectTimeout(10000);// 设置连接超时时间
    
    			// 建立实际连接
    			conn.connect();
    
    			// 读取请求结果
    			br = new BufferedReader(new InputStreamReader(conn.getInputStream(), charSet));
    			String line = null;
    			StringBuilder sb = new StringBuilder();
    			while ((line = br.readLine()) != null) {
    				sb.append(line);
    			}
    			return sb.toString();
    		} catch (Exception exception) {
    			return "";
    		} finally {
    			try {
    				if (br != null) {
    					br.close();
    				}
    			} catch (Exception e) {
    				e.printStackTrace();
    			}
    		}
    
    	}
    
    	public static String requestParamsBuild(Map<String, String> map) {
    		String result = "";
    		if (null != map && map.size() > 0) {
    			StringBuffer sb = new StringBuffer();
    			for (Map.Entry<String, String> entry : map.entrySet()) {
    				try {
    					String value = URLEncoder.encode(entry.getValue(), "UTF-8");
    					sb.append(entry.getKey() + "=" + value + "&");
    				} catch (UnsupportedEncodingException e) {
    					e.printStackTrace();
    				}
    			}
    
    			result = sb.substring(0, sb.length() - 1);
    		}
    		return result;
    	}
    
    	private static HttpsURLConnection getHttpsUrlConnection(URL url) throws Exception {
    		HttpsURLConnection httpsConn = (HttpsURLConnection) url.openConnection();
    		// 创建SSLContext对象，并使用我们指定的信任管理器初始化
    		TrustManager[] tm = { new X509TrustManager() {
    			public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
    				// 检查客户端证书
    			}
    
    			public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
    				// 检查服务器端证书
    			}
    
    			public X509Certificate[] getAcceptedIssuers() {
    				// 返回受信任的X509证书数组
    				return null;
    			}
    		} };
    		SSLContext sslContext = SSLContext.getInstance("SSL", "SunJSSE");
    		sslContext.init(null, tm, new java.security.SecureRandom());
    		// 从上述SSLContext对象中得到SSLSocketFactory对象
    		SSLSocketFactory ssf = sslContext.getSocketFactory();
    		httpsConn.setSSLSocketFactory(ssf);
    		return httpsConn;
    
    	}
    
    	public static byte[] getFileAsByte(boolean isHttps, String requestUrl) {
    		if (StringUtils.isBlank(requestUrl)) {
    			return new byte[0];
    		}
    		URL url = null;
    		URLConnection conn = null;
    		BufferedInputStream bi = null;
    
    		try {
    			// 创建连接
    			url = new URL(requestUrl);
    			if (isHttps) {
    				conn = getHttpsUrlConnection(url);
    			} else {
    				conn = (HttpURLConnection) url.openConnection();
    			}
    
    			// 设置请求头通用属性
    
    			// 指定客户端能够接收的内容类型
    			conn.setRequestProperty("accept", "*/*");
    
    			// 设置连接的状态为长连接
    			conn.setRequestProperty("Connection", "keep-alive");
    
    			// 设置发送请求的客户机系统信息
    			conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
    			// 设置其他属性
    			conn.setConnectTimeout(3000);// 设置连接超时时间
    
    			conn.setDoOutput(true);
    			conn.setDoInput(true);
    
    			// 建立实际连接
    			conn.connect();
    
    			// 读取请求结果
    			bi = new BufferedInputStream(conn.getInputStream());
    			ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    			byte[] buffer = new byte[2048];
    			int len = 0;
    			while ((len = bi.read(buffer)) != -1) {
    				outStream.write(buffer, 0, len);
    			}
    			bi.close();
    			byte[] data = outStream.toByteArray();
    			return data;
    		} catch (Exception exception) {
    			return new byte[0];
    		} finally {
    			try {
    				if (bi != null) {
    					bi.close();
    				}
    			} catch (Exception e) {
    				e.printStackTrace();
    			}
    		}
    
    	}
    
    }