客户端用httpclient如何下载服务器上的文件

客户端用httpclient怎么下载服务器上的文件
服务端提供了一个servlet，例如：http://127.0.62.12:4456/download.do.例如在服务器有个包在目录e:/test/tb.zip。  客户端如果如何用httpclient去调用servlet去到服务器的一个目录下下载这个个zip包？servlet该如何写？如果这个zip包很大该怎么实现？能给个实例最好了。

------解决思路----------------------
servlet 如下

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

public class DownloadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public DownloadServlet() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String filename = "下载.zip";
		String rname = new String(filename.getBytes("utf-8"),"iso-8859-1");
		response.addHeader("Content-Disposition", "attachment;filename="+rname);
		response.setContentType("application/octet-stream");
		
		File file = new File("e://test//tb.zip");
		InputStream is = new BufferedInputStream(new FileInputStream(file));
		byte[] buffer = new byte[is.available()];
		is.read(buffer);
		is.close();
		
		OutputStream os = new BufferedOutputStream(response.getOutputStream());
		os.write(buffer);
		os.flush();
		os.close();
		
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

------解决思路----------------------
httpclient接收如下

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

public class ClientA {
	
	public void service(){
		
		String url = "http://192.168.1.121:7503/download/DownloadServlet";
		
		HttpClient client = new DefaultHttpClient();
		HttpGet get = new HttpGet(url);
		
		try {
			
			HttpResponse response = client.execute(get);
			InputStream is = response.getEntity().getContent();
			
			String localfile = "D://aaa.zip";
			File file = new File(localfile);
			if(!file.exists()){
				file.createNewFile();
			}
			
			OutputStream os = new FileOutputStream(file);
			
			int read = 0;
			byte[] temp = new byte[1024*1024];
			
			while((read=is.read(temp))>0){
				byte[] bytes = new byte[read];
				System.arraycopy(temp, 0, bytes, 0, read);
				os.write(bytes);
			}
			os.flush();
		
		} catch (ClientProtocolException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	
	}
	
	public static void main(String[] args) {
		ClientA client = new ClientA();
		client.service();
	}
	
}

------解决思路----------------------

引用:

servlet 如下

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

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

public class DownloadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public DownloadServlet() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String filename = "下载.zip";
		String rname = new String(filename.getBytes("utf-8"),"iso-8859-1");
		response.addHeader("Content-Disposition", "attachment;filename="+rname);
		response.setContentType("application/octet-stream");
		
		File file = new File("e://test//tb.zip");
		InputStream is = new BufferedInputStream(new FileInputStream(file));
		byte[] buffer = new byte[is.available()];
		is.read(buffer);
		is.close();
		
		OutputStream os = new BufferedOutputStream(response.getOutputStream());
		os.write(buffer);
		os.flush();
		os.close();
		
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}

}

 byte[] buffer = new byte[is.available()];
        is.read(buffer);

这里会不会有问题，文件大的时候读取不玩数据