java读取oracle数据库数据，之后生成xml格式字符串，在线求解。

Question

你用dom4j  jdom 来做很简单

Answer 1

目前使用Iterator<TestFile> it = list.iterator();while (it.hasNext()) {file = it.next(); 这样方式只能显示所有数据，不能分层次显示出来，急求解决办法。应该是需要递归，未实现出来。

Answer 2

这个算法本身不算复杂，主要就两个个关键点：
1、利用Oracle提供的父子连接：connect by prior my_id = parent_id; 就可以得到有序结果。
2、写一个递归函数来根据结果集产生带层次结构的XML就行了。

Answer 3

import java.io.FileWriter;
import java.io.IOException;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.DocumentHandler;public class BuildBookDemo {//将数据加载到xml    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String[][] data={
                {"1001","wuxia","tianlongbabu1","50","jinyong","1968","cn"},
                {"1002","wuxia","tianlongbabu2","50","jinyong","1968","cn"},
                {"1003","xuanhuan","tianlongbabu3","50","jinyong","1968","cn"},
                {"1004","wuxia","tianlongbabu4","50","jinyong","1968","cn"}
        };
        buildBook(data,"mybook.xml");    }
    public static void buildBook(String[][] data,String filename){
        Document doc=DocumentHelper.createDocument();
        Element rootElmt=doc.addElement("booklist");
        for(String[] book:data){
            Element bookElmt=rootElmt.addElement("book");
            Element title=bookElmt.addElement("title");
            title.setText(book[2]);
            Element prise=bookElmt.addElement("price");
            prise.setText(book[3]);
            Element author=bookElmt.addElement("author");
            author.setText(book[4]);
            Element year=bookElmt.addElement("year");
            year.setText(book[5]);
            bookElmt.addAttribute("isbn",book[0]);
            bookElmt.addAttribute("catalog",book[1]);
            title.addAttribute("lang", book[6]);
            
        }
        outputXml(doc,filename);
    }
    private static void outputXml(Document doc, String filename) {
        // TODO Auto-generated method stub
        try {
            FileWriter fw=new FileWriter(filename);
            OutputFormat format=OutputFormat.createPrettyPrint();
            format.setEncoding("utf-8");
            XMLWriter xw=new XMLWriter(fw,format);
            xw.write(doc);
            xw.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    }
数据读出来，生产xml

Answer 4

思路好说，用递归
fun(int pid,grade){
String sql ="select * from table where pid ="+pid;
//求出结果放入List<List<String>> lists 把 id ，pid 成对放入list中
遍历list
for(List alist：lists){
int count=1;
String str ="<file" + pid==0?"":count + " id=\""+ alist.get(0) +"\" parentid=\""+alist.get(1) +"\"> \r\n </file" + pid==0?"":count> \r\n";
fun(alist.get(0),grade+1);
count++;
}
}

Answer 5

尝试写个伪代码：
String export(rs, upperid) {
  if (upperid == 0) rs.next();
  String ret = "";
  while (!rs.eof()) {
    String pid = rs.get(pid);
    if (pid.equals(upperid)) {
      String id = rs.get(id);
      ret += "<file " ....;
      if (rs.next()) ret += export(rs, id);
      ret +="</file>";
    } else {
      break;
    }
  }
  return ret;
}执行：export(rs, 0);