网络编程之使用HttpClient上传文件的客户端和服务器

1.1客户端：

 HttpClient常用HttpGet和HttpPost这两个类，分别对应Get方式和Post方式。

           无论是使用HttpGet，还是使用HttpPost，都必须通过如下3步来访问HTTP资源。

           1.创建HttpGet或HttpPost对象，将要请求的URL通过构造方法传入HttpGet或HttpPost对象。

           2.使用DefaultHttpClient类的execute方法发送HTTP GET或HTTP POST请求，并返回HttpResponse对象。

           3.通过HttpResponse接口的getEntity方法返回响应信息，并进行相应的处理。

package com.qianfeng.uploadfile;

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Map;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.mime.FormBodyPart;
import org.apache.http.entity.mime.MultipartEntity;
import org.apache.http.entity.mime.content.FileBody;
import org.apache.http.entity.mime.content.StringBody;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * 文件上传的客户端
 * @author qq
 *
 */
public class FileUpload {

	public FileUpload() {
		
	}
	
	public void fileUpload( final String url,
			                final File file,
			                final HashMap<String,String> params,
			                final String encode,
			                final CallBack callBack
			                )
	{
		new Thread(new Runnable(){

			@Override
			public void run() {
				//使用HttpPost方法提交HTTP POST请求
				HttpPost post = new HttpPost(url);
				//使用DefaultHttpClient类的execute方法发送HTTP GET或HTTP POST请求，并返回HttpResponse对象。
				HttpClient client = new DefaultHttpClient();
				//通过HttpResponse接口的getEntity方法返回响应信息，并进行相应的处理。
				HttpResponse response = null;
				/*
				 * 在HttpCient4.3之前上传文件主要使用MultipartEntity这个类，
				 * 但现在这个类已经不在推荐使用了。
				 * 随之替代它的类是MultipartEntityBuilder。
				 * */
				MultipartEntity entity =new MultipartEntity();
				//把文件转换成流对象FileBody 
				FileBody body = new FileBody(file);
				FormBodyPart part = new FormBodyPart("form",body);
				//Map通过entrySet()方法来遍历Map集合
				for(Map.Entry<String,String> entry:params.entrySet())
				{
					try {
						entity.addPart(entry.getKey(),new StringBody(entry.getValue()));
						
					} catch (UnsupportedEncodingException e) {
						e.printStackTrace();
					}
				}
				entity.addPart(part);//添加数据
			
				post.setEntity(entity);//设置请求参数
				
				try {
					//使用DefaultHttpClient类的execute方法发送HTTP POST请求，并返回HttpResponse对象
					response = client.execute(post);
					if(response.getStatusLine().getStatusCode()==200)//响应码200请求成功
					{
						//JSON解析
						String jsonString = EntityUtils.toString(response.getEntity(),encode);
						JSONObject jsonObj = new JSONObject(jsonString);
						callBack.getResult(jsonObj);//回调函数
					}
				} catch (ClientProtocolException e) {
					
					e.printStackTrace();
				} catch (IOException e) {
					
					e.printStackTrace();
				} catch (JSONException e) {
					
					e.printStackTrace();
				}
				
				
			}
			
		}).start();
		
	}

}
interface CallBack
{
	void getResult(JSONObject obj);
}

package com.qianfeng.servlet;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.json.JSONObject;

public class UploadServlet extends HttpServlet {

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		request.setCharacterEncoding("utf-8");
		response.setCharacterEncoding("utf-8");
		PrintWriter out = response.getWriter();
		//实现上传的类
		DiskFileItemFactory factory = new DiskFileItemFactory();//磁盘对象
		
		ServletFileUpload upload = new ServletFileUpload(factory);//声明解析request对象
		upload.setFileSizeMax(2*1024*1024);//设置每个文件最大为2M
		upload.setSizeMax(4*1024*1024);//设置一共最多上传4M
		
		try {
			List<FileItem> list = upload.parseRequest(request);//解析
			for(FileItem item:list){//判断FileItem类对象封装的数据是一个普通文本表单字段，还是一个文件表单字段，如果是普通表单字段则返回true，否则返回false。
				if(!item.isFormField()){
					//获取文件名
					String fileName = item.getName();
					//获取服务器端路径
					String file_upload_loader =this.getServletContext().getRealPath("\\upload");
					System.out.println("上传文件存放路径:"+file_upload_loader);
					//将FileItem对象中保存的主体内容保存到某个指定的文件中。
					item.write(new File(file_upload_loader+File.separator+fileName));
				}else{
					if(item.getFieldName().equalsIgnoreCase("username")){
						String username = item.getString("utf-8");//将FileItem对象中保存的数据流内容以一个字符串返回
						System.out.println(username);
					}
					if(item.getFieldName().equalsIgnoreCase("password")){
						String password = item.getString("utf-8");
						System.out.println(password);
					}
				}
			}
			//返回响应码（ResultCode）和响应值（ResultMsg）简单的JSON解析
			ResultMessage message = new ResultMessage(1,"上传成功");
			JSONObject json = new JSONObject();
			JSONObject jsonObject = new JSONObject();
			json.put("ResultCode",message.getResultCode());
			json.put("ResultMsg",message.getResultMsg());
			jsonObject.put("upload",json);
			//System.out.println(jsonObject.toString());
			out.print(jsonObject.toString());
			
		} catch (FileUploadException e) {
			e.printStackTrace();
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			out.close();
		}
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request,response);
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

package com.qianfeng.servlet;

public class ResultMessage {

	private int resultCode;
    private String resultMsg;
    
    
	public ResultMessage() {
		// TODO Auto-generated constructor stub
	}
	
	public ResultMessage(int resultCode, String resultMsg) {
		super();
		this.resultCode = resultCode;
		this.resultMsg = resultMsg;
	}
	public int getResultCode() {
		return resultCode;
	}

	public void setResultCode(int resultCode) {
		this.resultCode = resultCode;
	}

	public String getResultMsg() {
		return resultMsg;
	}

	public void setResultMsg(String resultMsg) {
		this.resultMsg = resultMsg;
	}
	

}

针对以上使用到的几个类做详细介绍：

upload.setProgressListener(new ProgressListener() {
double dd = 0;
long len = 0;
//参数1:已经上传完成的数量
//参数2:总长度
//参数3:第几个元素从1开始。0为没有
public void update(long pBytesRead, long pContentLength, int pItems) {
double persent = pBytesRead*100/pContentLength;
if(dd!=persent){
System.err.println(dd+"%");
dd=persent;
}else if(persent==100){
System.err.println("100%");
}
}
});