HttpURLConnection POST 上传文件

package com.popo.http;

import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.SocketTimeoutException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.stream.ImageInputStream;

public class HttpPostUtil {
URL url;
HttpURLConnection conn;
String boundary = "--------httppost123";
Map<String, String> textParams = new HashMap<String, String>();
Map<String, File> fileparams = new HashMap<String, File>();
DataOutputStream ds;

public HttpPostUtil(String url) throws Exception {
this.url = new URL(url);
}
//重新设置要请求的服务器地址，即上传文件的地址。
public void setUrl(String url) throws Exception {
this.url = new URL(url);
}
//增加一个普通字符串数据到form表单数据中
public void addTextParameter(String name, String value) {
textParams.put(name, value);
}
//增加一个文件到form表单数据中
public void addFileParameter(String name, File value) {
fileparams.put(name, value);
}
// 清空所有已添加的form表单数据
public void clearAllParameters() {
textParams.clear();
fileparams.clear();
}
// 发送数据到服务器，返回一个字节包含服务器的返回结果的数组
public byte[] send() throws Exception {
initConnection();
try {
conn.connect();
} catch (SocketTimeoutException e) {
// something
throw new RuntimeException();
}
ds = new DataOutputStream(conn.getOutputStream());
writeFileParams();
writeStringParams();
paramsEnd();
InputStream in = conn.getInputStream();
ByteArrayOutputStream out = new ByteArrayOutputStream();
int b;
while ((b = in.read()) != -1) {
out.write(b);
}
out.flush();
conn.disconnect();
return out.toByteArray();
}
//文件上传的connection的一些必须设置
private void initConnection() throws Exception {
conn = (HttpURLConnection) this.url.openConnection();
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setConnectTimeout(10000); //连接超时为10秒
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type",
"multipart/form-data; boundary=" + boundary);
conn.setChunkedStreamingMode(1024 * 50);
}
//普通字符串数据
private void writeStringParams() throws Exception {
Set<String> keySet = textParams.keySet();
for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
String name = it.next();
String value = textParams.get(name);
ds.writeBytes("--" + boundary + "\r\n");
ds.writeBytes("Content-Disposition: form-data; name=\"" + name
+ "\"\r\n");
ds.writeBytes("\r\n");
ds.writeBytes(encode(value) + "\r\n");
}
}
//文件数据
private void writeFileParams() throws Exception {
Set<String> keySet = fileparams.keySet();
for (Iterator<String> it = keySet.iterator(); it.hasNext();) {
String name = it.next();
File value = fileparams.get(name);
ds.writeBytes("--" + boundary + "\r\n");
ds.writeBytes("Content-Disposition: form-data; name=\"" + name
+ "\"; filename=\"" + encode(value.getName()) + "\"\r\n");
ds.writeBytes("Content-Type: " + getContentType(value) + "\r\n");
ds.writeBytes("\r\n");
ds.write(getBytes(value));
ds.writeBytes("\r\n");
}
}
//获取文件的上传类型，图片格式为image/png,image/jpg等。非图片为application/octet-stream
private String getContentType(File f) throws Exception {

//		return "application/octet-stream";  // 此行不再细分是否为图片，全部作为application/octet-stream 类型
ImageInputStream imagein = ImageIO.createImageInputStream(f);
if (imagein == null) {
return "application/octet-stream";
}
Iterator<ImageReader> it = ImageIO.getImageReaders(imagein);
if (!it.hasNext()) {
imagein.close();
return "application/octet-stream";
}
imagein.close();
return "image/" + it.next().getFormatName().toLowerCase();//将FormatName返回的值转换成小写，默认为大写

}
//把文件转换成字节数组
private byte[] getBytes(File f) throws Exception {
FileInputStream in = new FileInputStream(f);
ByteArrayOutputStream out = new ByteArrayOutputStream();
byte[] b = new byte[1024];
int n;
while ((n = in.read(b)) != -1) {
out.write(b, 0, n);
}
in.close();
return out.toByteArray();
}
//添加结尾数据
private void paramsEnd() throws Exception {
ds.writeBytes("--" + boundary + "--" + "\r\n");
ds.writeBytes("\r\n");
}
// 对包含中文的字符串进行转码，此为UTF-8。服务器那边要进行一次解码
private String encode(String value) throws Exception{
return URLEncoder.encode(value, "UTF-8");
}
public static void main(String[] args) throws Exception {
HttpPostUtil u = new HttpPostUtil("http://localhost");
u.addFileParameter("img", new File(
"165247.txt"));
u.addTextParameter("text", "中文");
byte[] b = u.send();
String result = new String(b);
System.out.println(result);

}

}