java模拟post方式提交表单实现图片上传

在Java中模拟POST方式提交表单实现图片上传，可以通过使用Java的HttpURLConnection类来实现。以下是一个示例代码：

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.UUID;

public class ImageUploader {
    
    public static void uploadImage(File imageFile, String uploadUrl) throws IOException {
        String boundary = UUID.randomUUID().toString();
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        
        URL url = new URL(uploadUrl);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setDoOutput(true);
        conn.setDoInput(true);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
        
        OutputStream outputStream = conn.getOutputStream();
        
        // 添加图片文件
        FileInputStream inputStream = new FileInputStream(imageFile);
        outputStream.write((twoHyphens + boundary + lineEnd).getBytes());
        outputStream.write(("Content-Disposition:form-data;name=\"file\";filename=\"" + imageFile.getName() + "\"" + lineEnd).getBytes());
        outputStream.write(("Content-Type:application/octet-stream" + lineEnd).getBytes());
        outputStream.write((lineEnd).getBytes());
        byte[] buffer = new byte[1024];
        int len = 0;
        while ((len = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, len);
        }
        inputStream.close();
        outputStream.write((lineEnd).getBytes());
        
        // 添加表单参数
        outputStream.write((twoHyphens + boundary + lineEnd).getBytes());
        outputStream.write(("Content-Disposition:form-data;name=\"param1\"" + lineEnd).getBytes());
        outputStream.write((lineEnd).getBytes());
        outputStream.write(("value1" + lineEnd).getBytes());
        
        outputStream.write((twoHyphens + boundary + twoHyphens + lineEnd).getBytes());
        
        outputStream.flush();
        outputStream.close();
        
        int responseCode = conn.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            // 上传成功
        } else {
            // 上传失败
        }
    }
}

在以上示例代码中，通过HttpURLConnection类来连接上传服务器，设置请求方式为POST，然后通过OutputStream将图片文件和表单参数发送给服务器。在发送之前需要设置Content-Type为multipart/form-data，并且在每个参数之间通过boundary分隔。最后通过getResponseCode()方法获取服务器的响应码，判断上传是否成功。