例子比较 简单，服务端为Java Web Servlet，doPost方法中接收图片并保存，然后将保存的图片名返回给客户端，关键代码：
@SuppressWarnings("deprecation")
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
request.setCharacterEncoding("utf-8"); //设置编码
//获得磁盘文件条目工厂
DiskFileItemFactory factory = new DiskFileItemFactory();
//获取文件需要上传到的路径
String path = request.getRealPath("/upload");
File file=new File(path);
if(!file.exists()){
file.mkdirs();
}
factory.setRepository(new File(path));
//设置 缓存的大小
factory.setSizeThreshold(1024*1024) ;
//文件上传处理
ServletFileUpload upload = new ServletFileUpload(factory);
try {
//可以上传多个文件
List<FileItem> list = (List<FileItem>)upload.parseRequest(request);
for(FileItem item : list){
//获取属性名字
String name = item.getFieldName();
//如果获取的 表单信息是普通的 文本 信息
if(item.isFormField()){
//获取用户具体输入的字符串,因为表单提交过来的是 字符串类型的
String value = item.getString() ;
request.setAttribute(name, value);
}else{
//获取路径名
String value = item.getName() ;
//索引到最后一个反斜杠
int start = value.lastIndexOf("\\");
//截取 上传文件的 字符串名字，加1是 去掉反斜杠，
String filename = value.substring(start+1);
request.setAttribute(name, filename);
//写到磁盘上
item.write( new File(path,filename) );//第三方提供的
System.out.println("上传成功："+filename);
response.getWriter().print(filename);//将路径返回给客户端
}
}
} catch (Exception e) {
System.out.println("上传失败");
response.getWriter().print("上传失败："+e.getMessage());
}
}
该方法同样适用于web端即网页图片上传，不是本文重点，不在讲解。
客户端关键代码：
/**
* 文件上传
*
* @param urlStr 接口路径
* @param filePath 本地图片路径
* @return
*/
public static String formUpload(String urlStr, String filePath) {
String rsp = "";
HttpURLConnection conn = null;
String BOUNDARY = "|"; // request头和上传文件内容分隔符
try {
URL url = new URL(urlStr);
conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5000);
conn.setReadTimeout(30000);
conn.setDoOutput(true);
conn.setDoInput(true);
conn.setUseCaches(false);
conn.setRequestMethod("POST");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.setRequestProperty("User-Agent",
"Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
conn.setRequestProperty("Content-Type",
"multipart/form-data; boundary=" + BOUNDARY);
OutputStream out = new DataOutputStream(conn.getOutputStream());
File file = new File(filePath);
String filename = file.getName();
String contentType = "";
if (filename.endsWith(".png")) {
contentType = "image/png";
}
if (filename.endsWith(".jpg")) {
contentType = "image/jpg";
}
if (filename.endsWith(".gif")) {
contentType = "image/gif";
}
if (filename.endsWith(".bmp")) {
contentType = "image/bmp";
}
if (contentType == null || contentType.equals("")) {
contentType = "application/octet-stream";
}
StringBuffer strBuf = new StringBuffer();
strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
strBuf.append("Content-Disposition: form-data; name=\"" + filePath
+ "\"; filename=\"" + filename + "\"\r\n");
strBuf.append("Content-Type:" + contentType + "\r\n\r\n");
out.write(strBuf.toString().getBytes());
DataInputStream in = new DataInputStream(new FileInputStream(file));
int bytes = 0;
byte[] bufferOut = new byte[1024];
while ((bytes = in.read(bufferOut)) != -1) {
out.write(bufferOut, 0, bytes);
}
in.close();
byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();
out.write(endData);
out.flush();
out.close();
// 读取返回数据
StringBuffer buffer = new StringBuffer();
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(), "utf-8"));
String line = null;
while ((line = reader.readLine()) != null) {
buffer.append(line).append("\n");
}
rsp = buffer.toString();
reader.close();
reader = null;
} catch (Exception e) {
e.printStackTrace();
} finally {
if (conn != null) {
conn.disconnect();
conn = null;
}
}
return rsp;
}
服务端图例：
客户端图例：
注意：测试的时候，请在客户端书写完整的本机局域网IP地址：
/** * 图片上传路径 */ public static final String UPLOAD_URL="http://192.168.1.188:8080/uploadImage/UploadServlet"; /** * 图片下载路径 */ public static final String DOWNLOAD_URL="http://192.168.1.188:8080/uploadImage/upload/";