java导出txt文件的问题,大量数据就报错

Question

response.setContentType("application/octet-stream"); 
response.addHeader("Content-Disposition","attachment; filename=1.txt"); 
for(Object obj:list){ 
CcCompareCrbt c=(CcCompareCrbt) obj; 
try { 
response.getWriter().print(c.getCompare_type()+"\r"); response.getWriter().print(c.getUser_Type()+"\r"); 
response.getWriter().print(c.getOds_Content()+"\r"); 
response.getWriter().print(c.getHlr_Content()+"\r"); 
response.getWriter().print(c.getCrbt_Content()+"\r"); 
response.getWriter().print(c.getIbp_Content()+"\r"); 
response.getWriter().print(c.getHlr_Id()+"\r"); 
response.getWriter().print(c.getIbp_User_Id()+"\r"); 
response.getWriter().print(c.getCompare_Date()+"\r\n"); 
} catch (IOException e) { 
// TODO Auto-generated catch block 
e.printStackTrace(); 
} 
} 
为什么这样只能导出少量数据，大量数据就不行呢？ 
要怎么样修改这个程序呢？ 
请大家帮我看看，谢谢大家了

Answer 1

response.setContentType("application/octet-stream");
 response.addHeader("Content-Disposition","attachment; filename=1.txt");
 StringBuffer sb=new StringBuffer();
for(Object obj:list){
CcCompareCrbt c=(CcCompareCrbt) obj;
    
sb.append(c.getCompare_type()+"\t");
sb.append(c.getGtn_Telephone()+"\t");
sb.append(c.getUser_Type()+"\t");
sb.append(c.getOds_Content()+"\t");
sb.append(c.getHlr_Content()+"\t");
sb.append(c.getCrbt_Content()+"\t");
sb.append(c.getIbp_Content()+"\t");
sb.append(c.getHlr_Id()+"\t");
sb.append(c.getIbp_User_Id()+"\t");
sb.append(c.getCompare_Date()+"\r\n");

    }
    try {
     response.setContentType("text/html;charset=utf-8");
response.getWriter().print(sb.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
我改用 StringBuffer了，一样读不出大数据量  我表用有 16万的数据

Answer 2

response.write   不适合做大文件的传输，访问量少还行，如果有几个人的话，有可能iis就瘫痪了
不要用   response.write   输出文件，除非这个文件10K都不到。

Answer 3

等待二十秒后抛出错误
java.lang.reflect.InvocationTargetException
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404)
com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:229)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:221)

Answer 4

输出流，查查javadoc就知道了fileWriter

Answer 5

java.io.File f  =   new  java.io.File(filePath);
response.setContentLength(( int ) f.length()); //  设置下载内容大小 
BufferedOutputStream output  =   new  BufferedOutputStream(response.getOutputStream());
byte [] buffer  =   new   byte [ 4096 ]; //  缓冲区 
output.write(buffer,  0 , n);
response.flushBuffer();

Answer 6

没怎么弄清楚什么意思。public String exPortTxt() {
if (form == null){
form = ServletActionContext.getRequest().getSession().getAttribute("form").toString();
System.out.println("TXT中form是"+form);
}
String sql = "";
if (form.equals("0")) {
sql = "select * from (select A.*, rownum RN from (select * from cc_compare_crbt) A )where RN > ? and RN<= ?";
} else if (form.equals("1")) {

sql = ServletActionContext.getRequest().getSession().getAttribute("sql").toString();
} HttpServletResponse response = ServletActionContext.getResponse();
Map map = null;
List list = null;
try {
if(selectFile.trim().length()==0){
selectFile="1";
}
map = comparecrbtservice.exPortQuery(Integer.parseInt(selectFile), sql);
list = (List) map.get("list");
} catch (Exception e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}



response.setContentType("application/octet-stream");
    response.addHeader("Content-Disposition","attachment; filename=1.txt");
    StringBuffer sb=new StringBuffer();
    sb.append("比较名称\t");
    sb.append("CDMA号码\t");
    sb.append("用户类型\t");
    sb.append("ODS情况\t");
    sb.append("HLR情况\t");
    sb.append("CRBT情况\t");
    sb.append("IBP情况\t");
    sb.append("HLRID\t");
    sb.append("IBPUserid\t");
    sb.append("比较时间\r\n");
    for(Object obj:list){
     CcCompareCrbt c=(CcCompareCrbt) obj;
    
sb.append(c.getCompare_type()+"\t");
sb.append(c.getGtn_Telephone()+"\t");
sb.append(c.getUser_Type()+"\t");
sb.append(c.getOds_Content()+"\t");
sb.append(c.getHlr_Content()+"\t");
sb.append(c.getCrbt_Content()+"\t");
sb.append(c.getIbp_Content()+"\t");
sb.append(c.getHlr_Id()+"\t");
sb.append(c.getIbp_User_Id()+"\t");
sb.append(c.getCompare_Date()+"\r\n");

    }
    try {
     response.setContentType("text/html;charset=utf-8");
response.getWriter().print(sb.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

return null;
}为什么弹出下载框后，会停的报空指针异常的错误？我安装了迅雷，迅雷和本地下载一起出来了？