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如何解析API返回的JSON数据？

news 来源：原创 2025/4/30 14:55:14

解析API返回的JSON数据是爬虫开发中的常见任务。在Java中，可以使用Jackson或Gson等库来解析JSON数据。以下将通过具体的代码示例，展示如何使用Jackson库解析API返回的JSON数据。

一、使用Jackson解析JSON数据

（一）添加依赖

确保你的项目中已经添加了Jackson的依赖。如果你使用的是Maven，可以在pom.xml文件中添加以下依赖：

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.0</version>
</dependency>

（二）定义数据模型

根据API返回的JSON结构，定义相应的Java类。例如，假设API返回的商品数据结构如下：

{
    "code": 200,
    "message": "success",
    "data": {
        "products": [
            {
                "id": "12345",
                "name": "商品名称",
                "price": "100.00",
                "description": "商品描述"
            },
            {
                "id": "67890",
                "name": "另一个商品名称",
                "price": "200.00",
                "description": "另一个商品描述"
            }
        ]
    }
}

可以定义以下Java类：

import com.fasterxml.jackson.annotation.JsonProperty;

public class ApiResponse {
    private int code;
    private String message;
    private Data data;

    // Getters and Setters
    public int getCode() { return code; }
    public void setCode(int code) { this.code = code; }
    public String getMessage() { return message; }
    public void setMessage(String message) { this.message = message; }
    public Data getData() { return data; }
    public void setData(Data data) { this.data = data; }

    public static class Data {
        @JsonProperty("products")
        private List<Product> products;

        // Getters and Setters
        public List<Product> getProducts() { return products; }
        public void setProducts(List<Product> products) { this.products = products; }
    }

    public static class Product {
        private String id;
        private String name;
        private String price;
        private String description;

        // Getters and Setters
        public String getId() { return id; }
        public void setId(String id) { this.id = id; }
        public String getName() { return name; }
        public void setName(String name) { this.name = name; }
        public String getPrice() { return price; }
        public void setPrice(String price) { this.price = price; }
        public String getDescription() { return description; }
        public void setDescription(String description) { this.description = description; }
    }
}

（三）解析JSON数据

使用Jackson的ObjectMapper类将JSON字符串解析为Java对象：

import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.util.List;

public class JsonParser {
    public static void main(String[] args) {
        String jsonResponse = "{"
                + "\"code\": 200,"
                + "\"message\": \"success\","
                + "\"data\": {"
                + "    \"products\": ["
                + "        {"
                + "            \"id\": \"12345\","
                + "            \"name\": \"商品名称\","
                + "            \"price\": \"100.00\","
                + "            \"description\": \"商品描述\""
                + "        },"
                + "        {"
                + "            \"id\": \"67890\","
                + "            \"name\": \"另一个商品名称\","
                + "            \"price\": \"200.00\","
                + "            \"description\": \"另一个商品描述\""
                + "        }"
                + "    ]"
                + "}"
                + "}";

        ObjectMapper objectMapper = new ObjectMapper();
        try {
            ApiResponse response = objectMapper.readValue(jsonResponse, ApiResponse.class);
            if (response.getCode() == 200) {
                List<ApiResponse.Product> products = response.getData().getProducts();
                for (ApiResponse.Product product : products) {
                    System.out.println("商品ID: " + product.getId());
                    System.out.println("商品名称: " + product.getName());
                    System.out.println("商品价格: " + product.getPrice());
                    System.out.println("商品描述: " + product.getDescription());
                    System.out.println("----------");
                }
            } else {
                System.out.println("API请求失败: " + response.getMessage());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}