本文介绍如何使用Java向Python后端服务发送x-www-form-urlencoded格式的POST请求，适用于Tornado等Python框架搭建的接口。

添加Maven依赖

首先在项目中添加Apache Commons HttpClient依赖：

<dependency>
    <groupId>commons-httpclient</groupId>
    <artifactId>commons-httpclient</artifactId>
    <version>3.1</version>
</dependency>

核心实现代码

package com.example.util;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.PostMethod;
import org.apache.commons.httpclient.NameValuePair;

/**
 * HTTP POST请求工具类
 */
public class HttpRequestUtil {

    /**
     * 发送POST请求并获取响应结果
     * @param requestUrl 请求地址
     * @param content 请求参数内容
     * @return 服务端返回的响应字符串
     */
    public String doRequest(String requestUrl, String content) {
        String response = "请求失败";
        try {
            response = executePost(requestUrl, content);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return decodeUnicode(response);
    }

    /**
     * 执行POST请求
     * @param requestUrl 请求URL地址
     * @param content POST请求体参数
     * @return 响应内容
     * @throws Exception 请求过程中的异常
     */
    private String executePost(String requestUrl, String content) throws Exception {
        PostMethod postRequest = new PostMethod(requestUrl);
        
        // 设置请求头Content-Type为x-www-form-urlencoded
        postRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded;charset=utf-8");
        
        // 构建请求参数数组，注意不能传NULL，需要传空字符串
        NameValuePair[] params = new NameValuePair[2];
        params[0] = new NameValuePair("type", "text");
        params[1] = new NameValuePair("content", content);
        
        postRequest.setRequestBody(params);
        
        HttpClient httpClient = new HttpClient();
        httpClient.executeMethod(postRequest);
        
        String result = postRequest.getResponseBodyAsString();
        postRequest.releaseConnection();
        
        return result;
    }

    /**
     * 解码Unicode字符串，将Unicode编码转换为中文
     * 处理Python接口返回的中文乱码问题
     * @param theString 包含Unicode编码的字符串
     * @return 解码后的正常字符串
     */
    public static String decodeUnicode(String theString) {
        char aChar;
        int len = theString.length();
        StringBuffer outBuffer = new StringBuffer(len);
        
        for (int x = 0; x < len;) {
            aChar = theString.charAt(x++);
            if (aChar == '\\') {
                aChar = theString.charAt(x++);
                if (aChar == 'u') {
                    // 读取四位十六进制数
                    int value = 0;
                    for (int i = 0; i < 4; i++) {
                        aChar = theString.charAt(x++);
                        switch (aChar) {
                            case '0': case '1': case '2': case '3': case '4':
                            case '5': case '6': case '7': case '8': case '9':
                                value = (value << 4) + aChar - '0';
                                break;
                            case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
                                value = (value << 4) + 10 + aChar - 'a';
                                break;
                            case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
                                value = (value << 4) + 10 + aChar - 'A';
                                break;
                            default:
                                throw new IllegalArgumentException("Malformed \\uxxxx encoding.");
                        }
                    }
                    outBuffer.append((char) value);
                } else {
                    if (aChar == 't') {
                        aChar = '\t';
                    } else if (aChar == 'r') {
                        aChar = '\r';
                    } else if (aChar == 'n') {
                        aChar = '\n';
                    } else if (aChar == 'f') {
                        aChar = '\f';
                    }
                    outBuffer.append(aChar);
                }
            } else {
                outBuffer.append(aChar);
            }
        }
        return outBuffer.toString();
    }
}

使用示例

public class Main {
    public static void main(String[] args) {
        HttpRequestUtil util = new HttpRequestUtil();
        String result = util.doRequest("http://your-python-server/api/endpoint", "测试内容");
        System.out.println("响应结果：" + result);
    }
}

关键点说明

• Content-Type设置：必须设置为application/x-www-form-urlencoded，这是Python Tornado等框架默认支持的表单提交格式
• 参数传递：NameValuePair数组不能传null，需要传空字符串
• 连接释放：调用releaseConnection()释放HTTP连接资源
• 字符编码：请求和响应都建议指定utf-8编码，避免中文乱码
• Unicode解码：Python返回的中文字符可能是Unicode编码格式，需要解码处理