JAVA模拟表单POST上传文件

import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Map;
import java.util.concurrent.Callable;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;

import org.apache.commons.lang.StringUtils;

import com.grand.mysql_handler.mapper.SystemMapper;

import net.sf.json.JSONObject;

    private String uploadImage(String name,byte[] buf) throws Exception {
        
        String filename = name.substring(name.lastIndexOf("/") + 1);
        
        final String newLine = "\r\n";
        final String boundaryPrefix = "--";
        final String boundary = "----theorydance";
        
        String api_url = "http://localhost:8080/filestorage/app/api/fileUpload";
        HttpURLConnection conn = (HttpURLConnection) new URL(api_url).openConnection();
        conn.setDoInput(true);
        conn.setDoOutput(true);
        conn.setReadTimeout(20000);
        conn.setConnectTimeout(5000);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("connection", "Keep-Alive");
        conn.setRequestProperty("Charset", "UTF-8");
        conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
        
        StringBuilder sb = new StringBuilder();
        
        // key参数
        sb.append(boundaryPrefix + boundary + newLine);
        sb.append("Content-Disposition: form-data; name=\"name\"" + newLine);
        sb.append(newLine);
        sb.append((name==null?"default":name) + newLine);
        
        // 图片数据
        sb.append(boundaryPrefix + boundary + newLine);
        sb.append("Content-Disposition: form-data; name=\"myfile\"; filename=\""+filename+"\"" + newLine);
        sb.append("Content-Type: application/octet-stream" + newLine);
        sb.append(newLine);
        
        OutputStream out = new DataOutputStream(conn.getOutputStream());
        out.write(sb.toString().getBytes());
        out.write(buf);
        out.write(newLine.getBytes());
        
        String endFlag = boundaryPrefix + boundary + boundaryPrefix + newLine;
        out.write(endFlag.getBytes());
        out.flush();
        out.close();
        
        System.out.println("响应状态码："+conn.getResponseCode());
        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        String line = null;
        String content = "";
        while((line=br.readLine())!=null) {
            content += line;
        }
        JSONObject json = JSONObject.fromObject(content);
        System.out.println(json.toString());
        return json.getJSONObject("data").getString("url");
    }