Apache HttpClient 4.5.13如何构造含非字符串值的POST请求体？

你之前的写法核心问题是混用了表单编码实体和JSON请求格式：UrlEncodedFormEntity是用于application/x-www-form-urlencoded类型的表单请求，而你设置了Content-Type: application/json；同时NameValuePair只能存储字符串值，无法保留整数、布尔等原始数据类型，导致API收到的JSON值全为字符串类型，不符合要求。

要构造正确的多数据类型JSON请求体，有两种可靠的方式：

方法1：手动构造JSON字符串，使用StringEntity #

直接编写符合要求的JSON字符串，通过StringEntity设置到请求中，无需额外依赖：

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public static void main(String[] args) throws Exception {
    // 手动构造JSON字符串，保留原始数据类型
    String jsonBody = "{\n" +
            "  \"id\": 3,\n" +
            "  \"name\": \"Test\",\n" +
            "  \"accepted\": false,\n" +
            "  \"street\": \"foo bar ave.\"\n" +
            "}";

    HttpPost httpPost = new HttpPost("http://my-url.com/test-api");
    // 设置JSON实体并指定UTF-8编码
    StringEntity entity = new StringEntity(jsonBody, "UTF-8");
    entity.setContentType("application/json");
    httpPost.setEntity(entity);
    httpPost.setHeader("Accept", "application/json");

    CloseableHttpClient httpClient = HttpClients.createDefault();
    CloseableHttpResponse response = httpClient.execute(httpPost);

    // 后续响应处理逻辑...
}

方法2：使用JSON序列化库（如Jackson）自动生成JSON #

如果请求结构复杂，手动编写JSON易出错，推荐用Jackson将Java对象序列化为JSON，自动保留数据类型：

步骤1：添加Jackson依赖（Maven示例） #

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.15.2</version> <!-- 可按需选择适配版本 -->
</dependency>

步骤2：编写请求对应的Java实体类 #

public class RequestBody {
    private Integer id;
    private String name;
    private Boolean accepted;
    private String street;

    // 构造方法
    public RequestBody(Integer id, String name, Boolean accepted, String street) {
        this.id = id;
        this.name = name;
        this.accepted = accepted;
        this.street = street;
    }

    // 需添加getter/setter方法（或使用Lombok简化代码）
}

步骤3：用Jackson序列化对象并构造请求 #

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

public static void main(String[] args) throws Exception {
    // 创建请求对象，设置对应类型的字段值
    RequestBody requestBody = new RequestBody(3, "Test", false, "foo bar ave.");

    // 用Jackson将对象序列化为JSON字符串
    ObjectMapper objectMapper = new ObjectMapper();
    String jsonBody = objectMapper.writeValueAsString(requestBody);

    HttpPost httpPost = new HttpPost("http://my-url.com/test-api");
    StringEntity entity = new StringEntity(jsonBody, "UTF-8");
    entity.setContentType("application/json");
    httpPost.setEntity(entity);
    httpPost.setHeader("Accept", "application/json");

    CloseableHttpClient httpClient = HttpClients.createDefault();
    CloseableHttpResponse response = httpClient.execute(httpPost);

    // 后续响应处理逻辑...
}

这两种方式都能确保请求体中的数据类型符合API要求，避免因字符串类型不匹配导致的请求失败。

内容的提问来源于stack exchange，提问作者o.o