高分求解决dom4j一次写入2W条数据内存溢出,在线等

[dilaomimi]

dom4j有一个write Element的方法,在循环中写入文件的话,没有根节点和文件头,想问问各位有没解决办法,以下是部分代码:
public class FriendsViewByTableName
{

private XMLWriter writer = null;

//调用dom4j中的一个类来解决中文问题,在得到writer时把format传进去
OutputFormat format = OutputFormat.createPrettyPrint();

public void viewData(Adm_chgtmp adm)
{
/** 指定XML编码 */
format.setEncoding("GBK");

String tableName = null;
String columnName = null;
String columnValue = null;

Element friendElement = null;
Element ageElement = null;
Document document = null;
String sql = "";
String sql1 = "";

ResultSet rs = null;
ResultSet rs1 = null;
dbcon connect = null;

String TMPID = adm.getTMPID();
String TMPDESC = adm.getTMPDESC();
String ALLROWS = adm.getALLROWS();
String MARKISNEW = adm.getMARKISNEW();
String DELETEON = adm.getDELETEON();
String TMPDATA =adm.getTMPDATA();
String ISNEW = adm.getISNEW();
Timestamp LASTUPDATE = adm.getLASTUPDATE();

List list = stringToken(TMPDATA);
Iterator it = list.iterator();
try
{
document = DocumentHelper.createDocument();

Element friendsElement = document.addElement("DATA");

//document.setRootElement(friendsElement);

// try {
// writer.processingInstruction("xml version=\"1.0\"", "encoding=\"GBK\"");
// } catch (SAXException e1) {
// // TODO Auto-generated catch block
// e1.printStackTrace();
// }
while(it.hasNext())
{
tableName = (String)it.next();
sql ="select * from " + tableName +" where ISNEW = 1 ";
sql1 = "select * from syscolumns where id=object_id('"+ tableName + "')" ;
try{
connect = new dbcon();
rs = connect.executeQuery(sql);
rs1 = connect.executeQuery(sql1);
rs1.last();
int row = rs1.getRow();
String column[] = new String[row];
rs1.beforeFirst();


System.out.println(row);

while(rs1.next())
{
for(int i=0;i<row;i++)
{
column[i] = rs1.getString("name");
rs1.next();
}
}




while(rs.next())
{
friendElement = friendsElement.addElement(tableName);

for(int i = 0;i<column.length;i++)
{
columnName = column[i];

columnValue = rs.getString(columnName);
System.out.println("列名:"+columnName);
System.out.println("值:"+columnValue);
ageElement = friendElement.addElement(columnName);
ageElement.setText((columnValue+"").toString().trim());
}

// writer.write(friendElement);
// friendElement.clearContent();//释放这个Element的空间,不然会导致内存耗尽
//friendsElement.clearContent();
}
//writer.write(friendsElement);

} catch( SQLException e){
e.printStackTrace();

} catch( Exception e){
e.printStackTrace();

}
finally
{
try
{
if(rs!=null)
rs.close();
if(rs1!=null)
rs1.close();
connect.closeConnect();
}
catch(SQLException e)
{
e.printStackTrace();

}

}
writer = new XMLWriter(new FileWriter(new File("C:/exp/friend.xml"),true),format);
writer.write(document);
System.out.println("创建文件成功");

}

} catch (IOException e)
{
e.printStackTrace();
}
finally
{
if(writer != null)
{
try
{
writer.close();
}
catch(Exception err)
{
err.printStackTrace();
}
}
}


}
public List stringToken(String tableName)
{
List list = new ArrayList();
StringTokenizer stok = new StringTokenizer(tableName,",");
while(stok.hasMoreElements())
{
list.add(stok.nextToken());
}
return list;
}
}

[dilaomimi]

谢谢你,实在非常非常感谢你anhy(鎏),这个问题按照你写的已经解决了,顺便说一下,我在writer.write(friendElement);这一句后加了一句friendElement.clearContent();这样好象就是在循环里面释放了这个Element,已经不出问题了,真是太高兴了,谢谢你~~!虽说大恩不言谢,我给你分结帖拉~~~~:)

[anhy]

DOM4J支持将一个Document或任何的Node通过write方法输出
因为数据量较大建议不要在内存建立Document，而是降一个一个Node的输出

[dilaomimi]

楼上的朋友,请问你有没有例子?如果一个一个NODE输出,我的根节点可以完整的包含所有子节点吗?你仔细看我的代码,我试过输出子节点,但是这样我的文件就没了根节点,对dom4j不熟悉,望指点

[ABCatai]

up

[zhj92lxs]

看看

[fengmingjie]

数据量有10M吗，网上的测试是10M的数据会溢出的，你试着调大java的stack size的大小试试，具体的方法如下
设置一下stack size的大小 java 后跟参数即可设置，具体参数如下：
-Xms size set initial Java heap size
-Xmx size set maximum Java heap size
-Xss size set java thread stack size

[dilaomimi]

数据量没有10M,大概是4M的样子,网上写10M会溢出是说DOM之类的方式,想想DOM4J怎么也是评价很高的开源包,不会连这点问题都处理不了的,主要是对API不熟,熟悉的兄弟帮忙顶啊,很急!!!

[anhy]

请参考以下代码修改，试试：
==========================================
package arith;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.StringTokenizer;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.xml.sax.helpers.AttributesImpl;

public class FriendsViewByTableName
{

private XMLWriter writer = null;

//调用dom4j中的一个类来解决中文问题,在得到writer时把format传进去
OutputFormat format = OutputFormat.createPrettyPrint();

public void viewData(Adm_chgtmp adm)
{
/** 指定XML编码 */
format.setEncoding("GBK");

String tableName = null;
String columnName = null;
String columnValue = null;

Element friendElement = null;
Element ageElement = null;
Document document = null;
String sql = "";
String sql1 = "";

ResultSet rs = null;
ResultSet rs1 = null;
dbcon connect = null;

String TMPID = adm.getTMPID();
String TMPDESC = adm.getTMPDESC();
String ALLROWS = adm.getALLROWS();
String MARKISNEW = adm.getMARKISNEW();
String DELETEON = adm.getDELETEON();
String TMPDATA =adm.getTMPDATA();
String ISNEW = adm.getISNEW();
Timestamp LASTUPDATE = adm.getLASTUPDATE();

List list = stringToken(TMPDATA);
Iterator it = list.iterator();
try
{
writer = new XMLWriter(new FileWriter(new File("C:/exp/friend.xml"),true),format);
writer.startDocument();
AttributesImpl a = new AttributesImpl();


writer.startElement("","","DATA",a);

while(it.hasNext())
{
tableName = (String)it.next();
sql ="select * from " + tableName +" where ISNEW = 1 ";
sql1 = "select * from syscolumns where id=object_id('"+ tableName + "')" ;
try{
connect = new dbcon();
rs = connect.executeQuery(sql);
rs1 = connect.executeQuery(sql1);
rs1.last();
int row = rs1.getRow();
String column[] = new String[row];
rs1.beforeFirst();


System.out.println(row);

while(rs1.next())
{
for(int i=0;i<row;i++)
{
column[i] = rs1.getString("name");
rs1.next();
}
}




while(rs.next())
{
friendElement = DocumentHelper.createElement(tableName);

for(int i = 0;i<column.length;i++)
{
columnName = column[i];

columnValue = rs.getString(columnName);
System.out.println("列名:"+columnName);
System.out.println("值:"+columnValue);
ageElement = friendElement.addElement(columnName);
ageElement.setText((columnValue+"").toString().trim());
}
writer.write(friendElement);

}

} catch( SQLException e){
e.printStackTrace();

} catch( Exception e){
e.printStackTrace();

}
finally
{
try
{
if(rs!=null)
rs.close();
if(rs1!=null)
rs1.close();
connect.closeConnect();
}
catch(SQLException e)
{
e.printStackTrace();

}

}

}
writer.endElement("","","DATA");
writer.endDocument();
System.out.println("创建文件成功");


} catch (IOException e)
{
e.printStackTrace();
}
finally
{
if(writer != null)
{
try
{
writer.close();
}
catch(Exception err)
{
err.printStackTrace();
}
}
}


}
public List stringToken(String tableName)
{
List list = new ArrayList();
StringTokenizer stok = new StringTokenizer(tableName,",");
while(stok.hasMoreElements())
{
list.add(stok.nextToken());
}
return list;
}
}

==============================

[dilaomimi]

dom4j是支持sax的,我现在也是用的SAX,代码如下,请您帮我看看,万分感谢
public static void main(String args[])
{
SAXReader sax = new SAXReader();
sax.addHandler("/DATA/user01", new UserHandler());
try {
sax.read(new File("c:/exp/friend.xml"));
} catch (DocumentException e) {
e.printStackTrace();
}
}
public static class UserHandler implements ElementHandler
{
Element e = null;
public void onStart(ElementPath path) {
e = path.getCurrent();
path.addHandler("USERID", new NameHandler());
path.addHandler("FNAME", new NameHandler());
path.addHandler("ORGID", new NameHandler());
path.addHandler("ORGNAME", new NameHandler());
path.addHandler("FROMORG", new NameHandler());
System.out.println(path.getPath()+"***************************");
//System.out.println(e.getName()+":"+e.getText());

}
public void onEnd(ElementPath path) {
path.removeHandler("USERID");
path.removeHandler("FNAME");
path.removeHandler("ORGID");
path.removeHandler("ORGNAME");
path.removeHandler("FROMORG");
}

}
public static class NameHandler implements ElementHandler
{
Element e = null;

public void onStart(ElementPath path) {

System.out.println(path.getPath());
}
public void onEnd(ElementPath path) {
e = path.getCurrent();
System.out.println(e.getName()+":"+e.getText());

}

[anhy]

sax.read(new File("c:/exp/friend.xml"));
改为
sax.read(new FileInputStream("c:/exp/friend.xml"));
或sax.read(new FileReader("c:/exp/friend.xml"));
试试

如果还不行，建议调大JVM内存