用Java模拟multipart形式的Http Post请求

本例通过java模拟了Http的request请求，请求格式为multipart，实现了向服务器同时传递json数据和图片数据。

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

public class HttpMultipartTest {
    static String boundary = "abcde12345";
    static String prefix = "--";
    static String newLine = "\r\n";

    public static void main(final String args[]) {
        test();
    }

    private static void test() {
        try {
            URL url = new URL("http://127.0.0.1:8080/httpMultipartTestServer/App/testMultipart");
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.setDoInput(true);
            connection.setDoOutput(true);
            connection.setRequestProperty("Content-type", "multipart/form-data;boundary=" + boundary);
            ConfigHttpMultipart(connection.getOutputStream());
            InputStream ins = connection.getInputStream();
            byte[] b = readBuffer(ins);
            System.out.println(new String(b));
        } catch (MalformedURLException e) {
            System.out.println(" url error! ");
        } catch (IOException e) {
            System.out.println(" io error! ");
        }
    }

    private static void ConfigHttpMultipart(final OutputStream out) {
        StringBuffer params = new StringBuffer();
        params.append(prefix + boundary + newLine);
        params.append("Content-Disposition: form-data; name=\"jsonData\"");
        params.append(newLine + newLine);
        String jsonData = "{\"test\":\"test message!\"}";
        params.append(jsonData);
        params.append(newLine);
        params.append(prefix + boundary + newLine);
        params.append("Content-Disposition: form-data; name=\"signature\"; filename=\"test.jpg\"");
        params.append(newLine);
        params.append("Content-Type: image/pjpeg");
        params.append(newLine + newLine);
        File file = new File("C://test.jpg");
        try {
            InputStream in = new FileInputStream(file);
            out.write(params.toString().getBytes());
            out.write(readBuffer(in));
            out.write(newLine.getBytes());
            out.write((prefix + boundary + prefix + newLine).getBytes());
            out.flush();
            out.close();
        } catch (FileNotFoundException e) {
            System.out.println(" no file! ");
        } catch (IOException e) {
            System.out.println(" io error! ");
        }
    }

    public static byte[] readBuffer(final InputStream ins) throws IOException {
        byte b[] = new byte[1024];
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        int len = 0;
        while ((len = ins.read(b)) != -1) {
            stream.write(b, 0, len);
        }
        return stream.toByteArray();
    }
}