淘宝按图搜索商品（拍立淘）Java 爬虫实战指南

在电商领域，按图搜索商品功能为用户提供了更直观、便捷的购物体验。淘宝的拍立淘功能更是凭借其强大的图像识别技术，成为许多开发者和商家关注的焦点。本文将详细介绍如何利用 Java 爬虫技术实现淘宝按图搜索商品功能，包括注册账号、上传图片、调用 API 及解析响应等关键步骤。

一、准备工作

（一）注册淘宝开放平台账号

在使用淘宝按图搜索功能之前，需要在淘宝开放平台注册账号并创建应用。注册成功后，平台会分配一个 App Key和 App Secret，这两个参数是调用 API 时的身份验证凭证。

（二）添加 Maven 依赖

为了方便地发送 HTTP 请求和解析 JSON 数据，需要在项目中添加以下 Maven 依赖：

xml

<dependencies><dependency><groupId>org.apache.httpcomponents</groupId><artifactId>httpclient</artifactId><version>4.5.13</version></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.10.0</version></dependency>
</dependencies>

二、代码实现

（一）生成签名

淘宝 API 接口需要对请求参数进行签名验证。以下是一个生成签名的 Java 方法示例：

java

import java.security.MessageDigest;
import java.util.TreeMap;public class ApiUtil {public static String generateSign(TreeMap<String, String> params, String appSecret) {StringBuilder signStr = new StringBuilder();for (Map.Entry<String, String> entry : params.entrySet()) {signStr.append(entry.getKey()).append(entry.getValue());}signStr.insert(0, appSecret).append(appSecret);return md5(signStr.toString()).toUpperCase();}public static String md5(String input) {try {MessageDigest md = MessageDigest.getInstance("MD5");byte[] array = md.digest(input.getBytes());StringBuilder sb = new StringBuilder();for (byte b : array) {sb.append(String.format("%02x", b));}return sb.toString();} catch (Exception e) {throw new RuntimeException(e);}}
}

（二）上传图片并获取图片标识

由于 API 接口要求传入图片的 URL 或 ID，因此需要先将图片上传到淘宝的图片空间或其他支持的图片服务器。以下是使用 Java 上传图片到淘宝服务器的代码示例：

java

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;public class ImageUploader {private static final String UPLOAD_URL = "https://restapi.taobao.com/router/rest";public static String uploadImage(String appKey, String appSecret, String imagePath) throws IOException {File imageFile = new File(imagePath);if (!imageFile.exists()) {throw new IllegalArgumentException("Image file does not exist");}Map<String, String> params = new HashMap<>();params.put("app_key", appKey);params.put("method", "taobao.upload.img");params.put("format", "json");params.put("v", "2.0");params.put("sign_method", "md5");params.put("timestamp", String.valueOf(System.currentTimeMillis() / 1000));String sign = ApiUtil.generateSign(new TreeMap<>(params), appSecret);params.put("sign", sign);try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpPost httpPost = new HttpPost(UPLOAD_URL);MultipartEntityBuilder builder = MultipartEntityBuilder.create();for (Map.Entry<String, String> entry : params.entrySet()) {builder.addTextBody(entry.getKey(), entry.getValue(), ContentType.TEXT_PLAIN);}builder.addBinaryBody("file", imageFile, ContentType.APPLICATION_OCTET_STREAM, imageFile.getName());HttpEntity entity = builder.build();httpPost.setEntity(entity);try (CloseableHttpResponse response = httpClient.execute(httpPost)) {if (response.getStatusLine().getStatusCode() == 200) {String jsonResponse = EntityUtils.toString(response.getEntity());// 解析返回的 JSON 数据，获取图片 URL// 这里假设返回的 JSON 中包含字段 "pic_url"return parsePicUrlFromResponse(jsonResponse);} else {throw new RuntimeException("Failed to upload image, status code: " + response.getStatusLine().getStatusCode());}}}}private static String parsePicUrlFromResponse(String jsonResponse) {// 解析 JSON 数据，提取图片 URL// 这里假设返回的 JSON 中包含字段 "pic_url"// 实际开发中，根据 API 返回的 JSON 结构进行解析return jsonResponse;}
}

（三）调用按图搜索接口

在成功上传图片并获取图片标识后，接下来就可以调用淘宝的按图搜索接口。以下是调用接口的 Java 示例代码：

java

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;import java.io.IOException;
import java.util.TreeMap;public class TaobaoImageSearch {private static final String SEARCH_URL = "https://eco.taobao.com/router/rest";public static String searchItemsByImage(String appKey, String appSecret, String imageUrl) throws IOException {TreeMap<String, String> params = new TreeMap<>();params.put("app_key", appKey);params.put("method", "taobao.item.search.img");params.put("format", "json");params.put("v", "2.0");params.put("sign_method", "md5");params.put("timestamp", String.valueOf(System.currentTimeMillis() / 1000));params.put("img_url", imageUrl);String sign = ApiUtil.generateSign(params, appSecret);params.put("sign", sign);StringBuilder urlBuilder = new StringBuilder(SEARCH_URL);for (Map.Entry<String, String> entry : params.entrySet()) {if (urlBuilder.length() > SEARCH_URL.length()) {urlBuilder.append("&");}urlBuilder.append(entry.getKey()).append("=").append(entry.getValue());}try (CloseableHttpClient httpClient = HttpClients.createDefault()) {HttpGet httpGet = new HttpGet(urlBuilder.toString());try (CloseableHttpResponse response = httpClient.execute(httpGet)) {if (response.getStatusLine().getStatusCode() == 200) {return EntityUtils.toString(response.getEntity());} else {throw new RuntimeException("Failed to search items, status code: " + response.getStatusLine().getStatusCode());}}}}
}

（四）解析响应数据

调用按图搜索接口后，淘宝会返回一个 JSON 格式的响应数据。以下是一个解析响应数据的 Java 示例代码：

java

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;import java.io.IOException;public class ResponseParser {public static void parseResponse(String jsonResponse) throws IOException {ObjectMapper objectMapper = new ObjectMapper();JsonNode rootNode = objectMapper.readTree(jsonResponse);JsonNode itemsNode = rootNode.path("items");if (itemsNode.isArray()) {for (JsonNode itemNode : itemsNode) {String title = itemNode.path("title").asText();String price = itemNode.path("price").asText();String picUrl = itemNode.path("pic_url").asText();String detailUrl = itemNode.path("detail_url").asText();System.out.println("商品标题: " + title);System.out.println("商品价格: " + price);System.out.println("商品图片: " + picUrl);System.out.println("商品链接: " + detailUrl);System.out.println("----------");}} else {System.out.println("No items found");}}
}

三、完整流程示例

以下是一个完整的 Java 示例，展示了如何上传图片并调用淘宝按图搜索接口：

java

import java.io.IOException;public class Main {public static void main(String[] args) {String appKey = "your_app_key";String appSecret = "your_app_secret";String imagePath = "path/to/your/image.jpg";try {// 上传图片并获取图片 URLString imageUrl = ImageUploader.uploadImage(appKey, appSecret, imagePath);System.out.println("图片上传成功，图片 URL: " + imageUrl);// 调用按图搜索接口String jsonResponse = TaobaoImageSearch.searchItemsByImage(appKey, appSecret, imageUrl);System.out.println("搜索结果: " + jsonResponse);// 解析响应数据ResponseParser.parseResponse(jsonResponse);} catch (IOException e) {e.printStackTrace();}}
}