java 读取postgresql数据库结构生成XML格式

 

import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
 
import org.jdom2.Document;
import org.jdom2.Element;
import org.jdom2.output.XMLOutputter;
 
 
publicclass getDBStructure {
 
    /**
     * @param args
     * @throws SQLException
     * @throws ClassNotFoundException
     */
    publicstaticvoid main(String[] args)throws SQLException, ClassNotFoundException {
       //TODO Auto-generated method stub
 
       DataBaseUtil db = new DataBaseUtil();
       DatabaseMetaData dbmt;
        
     
       dbmt = db.getConn().getMetaData();
        
       Statement st = db.getConn().createStatement();
        
       ResultSet tableSet = dbmt.getTables(null,"%", "%",new String[]{"TABLE"});
        
       Element root = new Element("POSTGIS_DB_XML"); 
        root.setAttribute("VERSION","1.0");
       Document Doc = new Document(root);
        Element elements = new Element("Tables"); 
        Element elementtable =null;
       while (tableSet.next()){
          
          
           String tableName = tableSet.getString(3);//获取数据库中表名称
            
           elementtable = new Element("table"); 
           elementtable.setAttribute("tableName",tableName );
          
           ResultSet columnSet = dbmt.getColumns(null,"%", tableName,"%");
           ResultSetMetaData rsmd = columnSet.getMetaData();
           intnumberOfColumns = rsmd.getColumnCount();//表中列个数
           Element elementcolumn =null;
          
            while(columnSet.next()){
 
              String columnName = columnSet.getString("COLUMN_NAME");//获取列名称
    String TYPE_NAME = columnSet.getString("TYPE_NAME");//列字段类型
               
              elementcolumn = new Element("column"); 
              elementcolumn.setAttribute("columnName", columnName);
              elementcolumn.setAttribute("TYPE_NAME", TYPE_NAME);
 
              elementtable.addContent(elementcolumn);
           }
            
            elements.addContent(elementtable);
       }
      
        root.addContent(elements);
        XMLOutputter XMLOut = new XMLOutputter(); 
        String xml = XMLOut.outputString(Doc);
        System.out.println(xml);
 
        
    }
}

在这里依赖一个类DatabaseMetaData，这个对象可以从数据库连接来获取。有了它万事大吉了，想知道什么问它即可：

 

//获取所有表
ResultSet tableSet = databaseMetaData.getTables(null, "%", "%", new String[]{"TABLE"});

//获取所有列

ResultSet columnSet = dbmt.getColumns(null,"%", tableName,"%");

//获取列个数

intnumberOfColumns = rsmd.getColumnCount();

 

下面就是如何从数据库读取表信息了。

引入 jdom2的相关JAR文件，数据库自己选择（这里我用的是PostgreSQL数据库）

//数据库连接

 

publicclass DataBaseUtil {
    privatestatic Connectionconn =null;
 
    @SuppressWarnings("unchecked")
    publicstatic Connection getConn()throws ClassNotFoundException, SQLException
    {
     
      if (conn==null)
      {
         Class.forName("org.postgresql.Driver");
        String url = "jdbc:postgresql://localhost:5432/postgis" ;
        conn = DriverManager.getConnection(url,"postgres" , "12345" );
 
      }
      returnconn;
    }
 
}
 

 

 

//生成XML格式