最近項目上做了一個移動辦公項目，開始客戶預訂是在內網使用。做完後，客戶又想可以連接外網使用該平臺。麻煩就出現了，本來將該系統服務端發佈到外網上就可以了，但在實際評估中發現客戶端很多的下載、新聞、圖片展示等功能都是使用的其它應用系統上的鏈接。而這些系統都是在內網中，無法在外網中使用。如果要改造使之可以正常下載展示這些內容，改動量就會很大。經過考慮，我想最好的辦法，是將這些鏈接的內容在服務端（服務端是內外網都可以訪問的）做轉換，使它可以直接下載內網中其它系統的文件。原理是java下載時將下載服務器端文件改爲下載網絡文件。聽起來是有些拗口，那就讓我把實現後的原代碼貼出來吧：
下載實現
servlet配置：
<!-- 下載servlet start--> <servlet> <servlet-name>DownloadFile</servlet-name> <servlet-class>com.gygs.cportalsend.servlet.DownloadServlet</servlet-class> <load-on-startup>0</load-on-startup> </servlet> <servlet-mapping> <servlet-name>DownloadFile</servlet-name> <url-pattern>/downloadFile</url-pattern> </servlet-mapping> <!-- 下載servlet end-->
類：
package com.gygs.cportalsend.servlet;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* 初始化
* @author ziwen
*/
public class DownloadServlet extends HttpServlet {
//http://localhost:8080/gygsmobile/downloadFile?fileUrl=http://g.hiphotos.baidu.com/image/pic/item/e7cd7b899e510fb3d9b14f9ada33c895d1430c16.jpg
protected void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException{
System.out.println("調用doGet方法");
// 下載網絡文件
int bytesum = 0;
int byteread = 0;
try {
// URL url = new URL("http://g.hiphotos.baidu.com/image/pic/item/e7cd7b899e510fb3d9b14f9ada33c895d1430c16.jpg");
String fileUrl=request.getParameter("fileUrl");
String fileUrlName=request.getParameter("fileUrlName");
System.out.println("URLURLURLURLURLfileUrl:"+fileUrl);
System.out.println("URLURLURLURLURLfileUrlName:"+fileUrlName);
// fileUrl=URLDecoder.decode(fileUrl, "UTF-8");
// System.out.println("URLURLURLURLURL2:"+fileUrl);
if(fileUrlName==null || "".equals(fileUrlName)){
fileUrlName=getRandomString(8);
String ext = fileUrl.substring(fileUrl.lastIndexOf(".") + 1);
fileUrlName=fileUrlName+"."+ext;
// .toUpperCase();
}
byte[] buffer = getUrlFileData(fileUrl);
// fis.read(buffer);
// fis.close();
// 清空response
response.reset();
// 設置response的Header
response.addHeader("Content-Disposition", "attachment;filename="
+ new String(fileUrlName));
// response.addHeader("Content-Length", "");
OutputStream toClient = new BufferedOutputStream(
response.getOutputStream());
response.setContentType("application/octet-stream");
toClient.write(buffer);
toClient.flush();
toClient.close();
} catch (Exception e) {
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException{
System.out.println("調用doPost方法");
doGet(request,response);
}
//獲取鏈接地址文件的byte數據
public static byte[] getUrlFileData(String fileUrl) throws Exception
{
URL url = new URL(fileUrl);
HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
httpConn.connect();
InputStream cin = httpConn.getInputStream();
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while ((len = cin.read(buffer)) != -1) {
outStream.write(buffer, 0, len);
}
cin.close();
byte[] fileData = outStream.toByteArray();
outStream.close();
return fileData;
}
public String getRandomString(int length) {
StringBuffer buffer = new StringBuffer("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
StringBuffer sb = new StringBuffer();
Random r = new Random();
int range = buffer.length();
for (int i = 0; i < length; i ++) {
sb.append(buffer.charAt(r.nextInt(range)));
}
return sb.toString();
}
}
2.新聞中圖片展示
package com.isoftstone.service;
import java.io.UnsupportedEncodingException;
import java.util.List;
import javax.sql.DataSource;
import oracle.sql.CLOB;
import com.gygs.cportalsend.common.DataSourceGetor;
import com.isoftstone.service.pojo.InformationBean;
import com.isoftstone.service.pojo.InformationContent;
import com.jfinal.plugin.activerecord.Db;
public class NewShowService {
public InformationBean newDetail(String new_id){
StringBuffer sql=new StringBuffer();
sql.append("select title,sub_title,author_name,modify_date,view_num,promulgation_charge from portal_information i where i.id="+new_id);
DataSource dataSource=null;
dataSource=DataSourceGetor.getDataSourceGetorInstence().getDataSource("BGMH");
// sql.append("select orgid,name from sys_user where id='"+creatorid+"' and status='1'");
InformationBean informationBean=new InformationBean();
List<Object[]> list=Db.query(dataSource,sql.toString());
if(list!=null && list.size()>0){
Object[] res=list.get(0);
informationBean.setTitle(res[0].toString());
informationBean.setSubTitle(res[1]==null?"":res[1].toString());
informationBean.setAuthorName(res[2]==null?"":res[2].toString());
informationBean.setModifyDateCn(res[3]==null?"":res[3].toString());
informationBean.setViewNum(Integer.parseInt(res[4]==null?"":res[4].toString()));
informationBean.setPromulgationCharge(res[5]==null?"":res[5].toString());
}
informationBean.setContent(findInformationContentByInformationId(Integer.parseInt(new_id)).getContent());
return informationBean;
}
//http://localhost:8080/gygsmobile/newsDetail_mobile.jsp?NEWID=4581
public InformationContent findInformationContentByInformationId(int informationId) {
// TODO Auto-generated method stub
StringBuffer sql=new StringBuffer();
sql.append("select content from portal_information_content i where i.information_id="+informationId);
DataSource dataSource=null;
dataSource=DataSourceGetor.getDataSourceGetorInstence().getDataSource("XXXX");
InformationContent informationContent=new InformationContent();
List list=Db.query(dataSource,sql.toString());
if(list!=null && list.size()>0){
System.out.println("KKKK:"+list.get(0));
byte[] res=((CLOB)list.get(0)).getBytes();
System.out.println("KKKK:"+res);
try {
String newStr=new String(res, "utf-16");
System.out.println("KKKK1:"+newStr);
String newStr2="";
//將新聞源代碼中的圖片鏈接替換
newStr2=newStr.replace("/yidongbangong/", "http://localhost:8080/smobile/downloadFile?fileUrl=http://192.168.0.40:9081/ygbg/");
// if(newStr.indexOf("/gyygbg/")>=0){
//
// }
System.out.println("KKKK2:"+newStr2);
informationContent.setContent(newStr2);
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return informationContent;
}
}