java - 公共(public)文件上传(Apache)

标签 java jsp servlets file-upload apache-commons

我在这里遇到空指针异常:

List fileItems = upload.parseRequest(req);

如果文件中的行数大于 2000 左右，就会发生这种情况，因为我可以上传超过 1000 行的文件。请有人帮助我。表格如下。

<form name="fos_picks" id="fos_picks" action="<%=path%>/fos_upld" method="post" enctype="multipart/form-data" >

<br/><br/><br/><br/>
<p align="center">
    <input type="file" name="file" size="50" /><br/>
    <br/>
    <input type="submit" class="buttons" value="Upload File" />
    </p>
</form>

上传 Controller 代码...

 package file_proc;
import DBConn.DBConn;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.sql.PreparedStatement;
import java.util.Iterator;
import java.util.List;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


@WebServlet(name="file_upld", urlPatterns = {"/file_upld"}) 

public class file_upld extends HttpServlet {

   private boolean isMultipart;
   private String filePath;
   private int maxFileSize = 50 * 1024;
   private int maxMemSize = 10 * 1024;
   private File file ;

/*   public void init( ){
      // Get the file location where it would be stored.
      filePath = 
             getServletContext().getInitParameter("file-upload"); 
   }*/
    @Override
   public void doPost(HttpServletRequest req, HttpServletResponse res)throws ServletException, java.io.IOException {
      // Check that we have a file upload request
       java.io.PrintWriter out = res.getWriter( );
    //   out.println("entered");
      isMultipart = ServletFileUpload.isMultipartContent(req);

      res.setContentType("text/html");

      if( !isMultipart ){
         out.println("!multipart");
         System.out.println("here");
         return;
      }
      DiskFileItemFactory factory = new DiskFileItemFactory();
      // maximum size that will be stored in memory
      factory.setSizeThreshold(maxMemSize);
      // Location to save data that is larger than maxMemSize.
      factory.setRepository(new File("c:/temp"));
      // Create a new file upload handler
      ServletFileUpload upload = new ServletFileUpload(factory);
      // maximum file size to be uploaded.
      upload.setSizeMax( maxFileSize );
 ServletContext servletContext = getServletContext();
    String path = servletContext.getRealPath("/");
     BufferedReader br=null;
     String fileName="";
     DBConn db = new DBConn();

      try{ 
      // Parse the request to get file items.
          System.out.println("here1"+req);
      List fileItems = upload.parseRequest(req);

      // Process the uploaded file items
      Iterator i = fileItems.iterator();

/*      out.println("<html>");
      out.println("<head>");
      out.println("<title>Upload</title>");  
      out.println("</head>");
      out.println("<body>");*/
      while ( i.hasNext () ) 
      {
         FileItem fi = (FileItem)i.next();
         if ( !fi.isFormField () )  
         {
            // Get the uploaded file parameters
            String fieldName = fi.getFieldName();
            fileName = fi.getName();
            String contentType = fi.getContentType();
            boolean isInMemory = fi.isInMemory();
            long sizeInBytes = fi.getSize();
            // Write the file
            if( fileName.lastIndexOf("\\") >= 0 ){
               file = new File( "c:/Temp/" + 
               fileName.substring( fileName.lastIndexOf("\\"))) ;
            }else{
               file = new File( "c:/Temp/"+ 
               fileName.substring(fileName.lastIndexOf("\\")+1)) ;
            }
            if(!file.exists())
            {
                File fold=new File(file.getParent());
                fold.mkdirs();
            }
            fi.write( file ) ;
            System.out.println("Uploaded Filename: " + fileName + "<br>");
         }
      }
      }catch(Exception ce)
      {
            out.println("<font size='30' color='red'>Error Code 016</font>");
        //out.println("Exception1: "+ce);
      }
 //read uploaded file and insert into table********************************************  

    //      String newline = System.getProperty("line.separator");
//  File file = new File(path+"//"+fileName);
            //  file.createNewFile();
try{

    if(file.isFile())
    {
         br = new BufferedReader(new FileReader(file));
    String str="";
    String temp[]=null;


        file.canWrite();
        file.canRead();
        file.setWritable(true);

        db.conn.setAutoCommit(false);
        while((str=br.readLine())!=null)
                    {
                        temp=str.split("    ");

                //      PreparedStatement ps = db.conn.prepareStatement("INSERT INTO file_proc VALUES(?,?,?,?,?,?,?,?,?,STR_TO_DATE(?,'%m/%d/%Y'))");
                        PreparedStatement ps = db.conn.prepareStatement("INSERT INTO file_proc(run_date,zone,location,bank,file_type,num_rec,ex_sett_date,ex_stat_date) "
                                                        + "VALUES(STR_TO_DATE(?,'%m/%d/%Y'),?,?,?,?,?,STR_TO_DATE(?,'%m/%d/%Y'),STR_TO_DATE(?,'%m/%d/%Y'))");
                        ps.setString(1,temp[0]);
                        ps.setString(2,temp[1]);
                        ps.setString(3,temp[2]);
                        ps.setString(4,temp[3]);
                        ps.setString(5,temp[4]);
                        ps.setInt(6,Integer.parseInt(temp[5]));
                        ps.setString(7,temp[6]);
                        ps.setString(8,temp[7]);
                        ps.executeUpdate();
                        ps.close();     

                    }   
                    db.conn.commit();
                    db.conn.setAutoCommit(true);
                    db.conn.close();
                    br.close(); 
        file.delete();  

       //  RequestDispatcher rd = req.getRequestDispatcher("./status/status.jsp");
        //  rd.forward(req, res);
          out.print("success");
     //     out.println("</html>");
    }
    else
    {
        out.println(file+" is not a file");
    }           

   }catch(Exception ex) {
    out.println("file name= "+fileName);
      // out.println("DBEX= "+ex );
        out.println("<font size='30' color='red'>Error Code 017 - Recommended date format = m/d/yyyy.</font>");
        out.println("<font size='30' color='red'>Check the column order</font>"+ex);    
      //file.delete();  
     //  RequestDispatcher rd = req.getRequestDispatcher("./status/error.jsp");
//  rd.forward(req, res);
   }finally{
                    try{
                        db.conn.close();
                        br.close();
                    }catch(Exception e){}
                }
   }
    @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, java.io.IOException {

       doPost(request, response);  
   } 
}

**** 这是表格 ** ****

<form name="file_proc" id="file_proc" method = "post" action="../file_upld" enctype="multipart/form-data">
    <br/><br/><br/><br/>
    <p align="center">
<input type="file" id="file" name="file" size="50" /><br/>
<br/>
<input type="submit" class="buttons" value="Upload File" />br/><br/><br/>
     </p>
</form>

上传 Controller 代码...

 package file_proc;
import DBConn.DBConn;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.sql.PreparedStatement;
import java.util.Iterator;
import java.util.List;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


@WebServlet(name="file_upld", urlPatterns = {"/file_upld"}) 

public class file_upld extends HttpServlet {

   private boolean isMultipart;
   private String filePath;
   private int maxFileSize = 50 * 1024;
   private int maxMemSize = 10 * 1024;
   private File file ;

/*   public void init( ){
      // Get the file location where it would be stored.
      filePath = 
             getServletContext().getInitParameter("file-upload"); 
   }*/
    @Override
   public void doPost(HttpServletRequest req, HttpServletResponse res)throws ServletException, java.io.IOException {
      // Check that we have a file upload request
       java.io.PrintWriter out = res.getWriter( );
    //   out.println("entered");
      isMultipart = ServletFileUpload.isMultipartContent(req);

      res.setContentType("text/html");

      if( !isMultipart ){
         out.println("!multipart");
         System.out.println("here");
         return;
      }
      DiskFileItemFactory factory = new DiskFileItemFactory();
      // maximum size that will be stored in memory
      factory.setSizeThreshold(maxMemSize);
      // Location to save data that is larger than maxMemSize.
      factory.setRepository(new File("c:/temp"));
      // Create a new file upload handler
      ServletFileUpload upload = new ServletFileUpload(factory);
      // maximum file size to be uploaded.
      upload.setSizeMax( maxFileSize );
 ServletContext servletContext = getServletContext();
    String path = servletContext.getRealPath("/");
     BufferedReader br=null;
     String fileName="";
     DBConn db = new DBConn();

      try{ 
      // Parse the request to get file items.
          System.out.println("here1"+req);
      List fileItems = upload.parseRequest(req);

      // Process the uploaded file items
      Iterator i = fileItems.iterator();

/*      out.println("<html>");
      out.println("<head>");
      out.println("<title>Upload</title>");  
      out.println("</head>");
      out.println("<body>");*/
      while ( i.hasNext () ) 
      {
         FileItem fi = (FileItem)i.next();
         if ( !fi.isFormField () )  
         {
            // Get the uploaded file parameters
            String fieldName = fi.getFieldName();
            fileName = fi.getName();
            String contentType = fi.getContentType();
            boolean isInMemory = fi.isInMemory();
            long sizeInBytes = fi.getSize();
            // Write the file
            if( fileName.lastIndexOf("\\") >= 0 ){
               file = new File( "c:/Temp/" + 
               fileName.substring( fileName.lastIndexOf("\\"))) ;
            }else{
               file = new File( "c:/Temp/"+ 
               fileName.substring(fileName.lastIndexOf("\\")+1)) ;
            }
            if(!file.exists())
            {
                File fold=new File(file.getParent());
                fold.mkdirs();
            }
            fi.write( file ) ;
            System.out.println("Uploaded Filename: " + fileName + "<br>");
         }
      }
      }catch(Exception ce)
      {
            out.println("<font size='30' color='red'>Error Code 016</font>");
        //out.println("Exception1: "+ce);
      }
 //read uploaded file and insert into table********************************************  

    //      String newline = System.getProperty("line.separator");
//  File file = new File(path+"//"+fileName);
            //  file.createNewFile();
try{

    if(file.isFile())
    {
         br = new BufferedReader(new FileReader(file));
    String str="";
    String temp[]=null;


        file.canWrite();
        file.canRead();
        file.setWritable(true);

        db.conn.setAutoCommit(false);
        while((str=br.readLine())!=null)
                    {
                        temp=str.split("    ");

                //      PreparedStatement ps = db.conn.prepareStatement("INSERT INTO file_proc VALUES(?,?,?,?,?,?,?,?,?,STR_TO_DATE(?,'%m/%d/%Y'))");
                        PreparedStatement ps = db.conn.prepareStatement("INSERT INTO file_proc(run_date,zone,location,bank,file_type,num_rec,ex_sett_date,ex_stat_date) "
                                                        + "VALUES(STR_TO_DATE(?,'%m/%d/%Y'),?,?,?,?,?,STR_TO_DATE(?,'%m/%d/%Y'),STR_TO_DATE(?,'%m/%d/%Y'))");
                        ps.setString(1,temp[0]);
                        ps.setString(2,temp[1]);
                        ps.setString(3,temp[2]);
                        ps.setString(4,temp[3]);
                        ps.setString(5,temp[4]);
                        ps.setInt(6,Integer.parseInt(temp[5]));
                        ps.setString(7,temp[6]);
                        ps.setString(8,temp[7]);
                        ps.executeUpdate();
                        ps.close();     

                    }   
                    db.conn.commit();
                    db.conn.setAutoCommit(true);
                    db.conn.close();
                    br.close(); 
        file.delete();  

       //  RequestDispatcher rd = req.getRequestDispatcher("./status/status.jsp");
        //  rd.forward(req, res);
          out.print("success");
     //     out.println("</html>");
    }
    else
    {
        out.println(file+" is not a file");
    }           

   }catch(Exception ex) {
    out.println("file name= "+fileName);
      // out.println("DBEX= "+ex );
        out.println("<font size='30' color='red'>Error Code 017 - Recommended date format = m/d/yyyy.</font>");
        out.println("<font size='30' color='red'>Check the column order</font>"+ex);    
      //file.delete();  
     //  RequestDispatcher rd = req.getRequestDispatcher("./status/error.jsp");
//  rd.forward(req, res);
   }finally{
                    try{
                        db.conn.close();
                        br.close();
                    }catch(Exception e){}
                }
   }
    @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, java.io.IOException {

       doPost(request, response);  
   } 
}

**** 这是表格 ** ****

<form name="file_proc" id="file_proc" method = "post" action="../file_upld" enctype="multipart/form-data">
    <br/><br/><br/><br/>
    <p align="center">
<input type="file" id="file" name="file" size="50" /><br/>
<br/>
<input type="submit" class="buttons" value="Upload File" />br/><br/><br/>
     </p>
</form>

这是 log4j 的东西，它显示了 filter.java 的错误，我没有在当前的 servlet 中使用它。

[ERROR] 29:05(file_upld.java:doPost:172) failed!

java.lang.NullPointerException at file_proc.file_upld.doPost(file_upld.java:120) at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at filter.filter.doFilter(filter.java:16) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) at java.lang.Thread.run(Thread.java:722)

这里是 filter.javapackage 过滤器；

import java.io.IOException;
import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;

public class filter implements Filter{

    private FilterConfig config=null;
    @Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException 
{
    HttpServletResponse hsr = (HttpServletResponse) res;
    hsr.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1.
    hsr.setHeader("Pragma", "no-cache"); // HTTP 1.0.
    hsr.setDateHeader("Expires", 0); // Proxies.
    chain.doFilter(req, res);
}
    @Override
    public void destroy() { }
    @Override
  public void init(FilterConfig config) {
  this.config = config;
  }
}

最佳答案

您的具体问题是由错误的异常处理和与 Controller 的紧耦合 View 引起的。

从您的代码中过滤噪音后，它大致如下:

File file = null;

try {
    // ... 
    file = new File(...);
    // ... 
} catch (Exception e) {
    out.println("...");
}

try {
    if (file.isFile())
        // ...
    } else {
        // ...
    }
} catch (Exception e) {
    out.println("...");
}

NullPointerException 在 if (file.isFile()) block 所在的行被抛出。因此，这意味着第一个 try block 引发了异常，因此将 file 保留为 null。

问题的原因有两个:

  1. 第一个 try block 不是在异常时从 servlet 方法返回，而是错误地继续代码流。
  2. 如果 file 不为 null，第二个 try block 不会预先检查。

然而，您的具体问题要大得多。您完全吞下了异常并打印不相关的 HTML 代码，而不是抛出它们和/或记录异常。

按如下方式替换您的 catch block :

} catch (Exception e) {
    throw new ServletException(e);
}

默认情况下，这种异常将被记录并完整显示在 HTTP 500 错误页面中，包括堆栈跟踪。堆栈跟踪为您提供了丰富的信息来了解问题并解决问题。

与具体问题无关，代码中还有很多其他的概念和设计错误，但到目前为止与具体问题没有直接关系。然而，我建议暂停一下，阅读一些合理的 Servlet 书籍/教程/资源。这段代码似乎只是根据在谷歌中找到的片段拼凑而成，而不是经过深思熟虑编写的。第一步是了解 servlet 的实际工作方式:How do servlets work? Instantiation, sessions, shared variables and multithreading

关于java - 公共(public)文件上传(Apache)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12816083/

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