import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
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.FileUploadBase;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
List types = Arrays.asList("jpg","gif","avi","txt");
try{
DiskFileItemFactory factory = new DiskFileItemFactory(); //10k
factory.setSizeThreshold(1024*1024);
factory.setRepository(new File(this.getServletContext().getRealPath("/temp")));
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setProgressListener(new ProgressListener(){
public void update(long pBytesRead, long pContentLength, int pItems) {
System.out.println("當前已解析:" + pBytesRead);
}
});
upload.setFileSizeMax(1024*1024*5);
if(!upload.isMultipartContent(request)){
//按照傳統方式獲取表單數據
request.getParameter("username");
return;
}
upload.setHeaderEncoding("UTF-8");
List<FileItem> list = upload.parseRequest(request);
for(FileItem item : list){
if(item.isFormField()){
//爲普通輸入項
String inputName = item.getFieldName();
String inputValue = item.getString("UTF-8");
//inputValue = new String(inputValue.getBytes("iso8859-1"),"UTF-8");
System.out.println(inputName + "=" + inputValue);
}else{
String filename = item.getName().substring(item.getName().lastIndexOf("\\")+1); //""
if(filename==null || filename.trim().equals("")){
continue;
}
/*String ext = filename.substring(filename.lastIndexOf(".")+1);
if(!types.contains(ext)){
request.setAttribute("message", "本系統不支持" + ext + "這種類型");
request.getRequestDispatcher("/message.jsp").forward(request, response);
return;
}*/
InputStream in = item.getInputStream();
int len = 0;
byte buffer[] = new byte[1024];
String saveFileName = generateFileName(filename);
String savepath = generateSavePath(this.getServletContext().getRealPath("/WEB-INF/upload"),saveFileName);
FileOutputStream out = new FileOutputStream(savepath + File.separator + saveFileName);
while((len=in.read(buffer))>0){
out.write(buffer, 0, len);
}
in.close();
out.close();
item.delete(); //刪除臨時文件
}
}
}catch (FileUploadBase.FileSizeLimitExceededException e) {
request.setAttribute("message", "文件大小不能超過5m");
request.getRequestDispatcher("/message.jsp").forward(request, response);
return;
}catch (Exception e) {
throw new RuntimeException(e);
}
request.setAttribute("message", "上傳成功!!");
request.getRequestDispatcher("/message.jsp").forward(request, response);
}
//
public String generateSavePath(String path,String filename){
int hashcode = filename.hashCode(); //121221
int dir1 = hashcode&15;
int dir2 = (hashcode>>4)&0xf;
String savepath = path + File.separator + dir1 + File.separator + dir2;
File file = new File(savepath);
if(!file.exists()){
file.mkdirs();
}
return savepath;
}
public String generateFileName(String filename){
//83434-83u483-934934
return UUID.randomUUID().toString() + "_" + filename;
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
jdbc 應用的事務管理
ThreadLocal:可以在線程範圍內實現數據共享.
jdbc多表操作
儘量不用一對多關係
文件上傳注意事項
1.上傳文件中文亂碼問題:
1.1解決文件的亂碼
ServletFileUpload upload=new ServletFileUpload( factory );
upload.setHeaderEncoding( ” UTF-8 ” );
1.2解決普通輸入項的亂碼
注意:表單類型爲multipart/form-data的時候,設置request的編碼是無效的
String inputValue=new String( inputValue.getBytes(" iso8859-1 ")," UTF-8 ");
String inputValue=item.getString( " UTF-8 " );
2.在處理表單之前,要記得調用:
ServletFileUpload.isMultipartContent方法判斷提交表單的類型,如果該方法返回true,則按上傳方式處理,否則按照傳統方式處理表單即可
3.設置解析器緩衝區的大小,以及臨時文件的刪除
設置解析器緩衝區的大小 DiskFileItemFactory.setSizeThreshold(1024*1024);
臨時文件的刪除:在程序中處理完上傳文件後,一定要記得調用item.delete()方法,以刪除臨時文
4.在做上傳系統時,千萬要注意上傳文件的保存目錄,這個上傳文件的保存目錄絕對不能讓外界直接訪問到。
5.限制上傳文件的類型
在處理上傳文件時,判斷上傳文件的後綴名是不是允許的
6.限制上傳文件的大小
調用解析器的ServletFileUpload.setFileSizeMax(1024*1024*5);就可以限制上傳文件的大小,如果上傳文件超出限制,則解析器會拋FileUploadBase.FileSizeLimitExceededException異常,程序員通過是否抓到這個異常,進而就可以給用戶友好提示。
7.如何判斷空的上傳輸入項
String filename = item.getName().substring(item.getName().lastIndexOf(“\”)+1); //””
if(filename==null || filename.trim().equals(“”)){
continue;
}
8、爲避免上傳文件的覆蓋,程序在保存上傳文件時,要爲每一個文件生成一個唯一的文件名
public String generateFileName(String filename){
//83434-83u483-934934
return UUID.randomUUID().toString() + “_” + filename;
}
9、爲避免在一個文件夾下面保存超過1000個文件,影響文件訪問性能,程序應該把上傳文件打散後存儲。
public String generateSavePath(String path,String filename){
int hashcode = filename.hashCode(); //121221
int dir1 = hashcode&15;
int dir2 = (hashcode>>4)&0xf;
String savepath = path + File.separator + dir1 + File.separator + dir2;
File file = new File(savepath);
if(!file.exists()){
file.mkdirs();
}
return savepath;
}
10、監聽上傳進度
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setProgressListener(new ProgressListener(){
public void update(long pBytesRead, long pContentLength, int pItems) {
System.out.println(“當前已解析:” + pBytesRead);
}
});
11、在web頁面中添加動態上傳輸入項