这个是基本的连接数据库代码(注意要加入连接oracle数据库的jar包):

导入的数据库就是String sc="jdbc:oracle:thin:@192.168.1.223:1521:test";对应的test数据库,所有的表结构都可以导出来。(需要修改为自己对应的ip和端口和数据库名称,上面的是我的地址和数据库)
Java代码 收藏代码

import java.sql.Connection; 


 import java.sql.DriverManager; 


 import java.sql.ResultSet; 


 import java.sql.SQLException; 


 import java.sql.Statement; 




 public class ConnectionOracle { 




 /** 


 * @param args 


 */ 


 String sd="oracle.jdbc.driver.OracleDriver"; 


 // String sc="jdbc:oracle:thin:@192.168.1.170:1521:cst"; 


 String sc="jdbc:oracle:thin:@192.168.1.223:1521:test"; 


 String userName = "adminss"; 


 String password = "123456"; 


 // String sd="com.mysql.jdbc.Driver"; 


 // String sc="jdbc:mysql://localhost:3306/payManagerDB?useUnicode=true&characterEncoding=utf8"; 


 Connection con=null; 


 Statement stmt=null; 


 ResultSet rs=null; 



 public ConnectionOracle() 


 { 


 try 


 { 


 Class.forName(sd); 


 } 


 catch(Exception e) 


 { 


 System.err.println(e.getMessage()); 


 } 


 } 


 public static void main(String[] args) { 


 // TODO Auto-generated method stub 



 } 


 public ResultSet executeQuery(String sql) throws SQLException 


 { 


 con=DriverManager.getConnection(sc,userName,password); 


 Statement stmt=con.createStatement(); 


 rs=stmt.executeQuery(sql); 


 return rs; 


 } 


 public void executeUpdate(String sql) throws SQLException 


 { 


 con=DriverManager.getConnection(sc,userName,password); 


 Statement stmt=con.createStatement(); 


 stmt.executeUpdate(sql); 


 } 


 public void close() throws SQLException 


 { 


 if(rs!=null) 


 rs.close(); 


 if(stmt!=null) 


 stmt.close(); 


 if(con!=null) 


 con.close(); 


 } 


 }



下面的代码读取数据库中所有表以及结构到excel中(如果出现问题,首先看是不是你已经打开了这个excel,要先关闭):


Java代码 收藏代码

import java.io.File; 


 import java.io.FileOutputStream; 


 import java.sql.ResultSet; 


 import java.sql.SQLException; 


 import java.util.ArrayList; 


 import java.util.Iterator; 


 import java.util.List; 




 import org.apache.poi.hssf.usermodel.HSSFCell; 


 import org.apache.poi.hssf.usermodel.HSSFCellStyle; 


 import org.apache.poi.hssf.usermodel.HSSFFont; 


 import org.apache.poi.hssf.usermodel.HSSFRichTextString; 


 import org.apache.poi.hssf.usermodel.HSSFRow; 


 import org.apache.poi.hssf.usermodel.HSSFSheet; 


 import org.apache.poi.hssf.usermodel.HSSFWorkbook; 


 import org.apache.poi.hssf.util.Region; 




 /** 


 * 将oracle中的数据表结构导入到excel中保存 


 * @class DataToExcel 


 * @description 


 * @author 李智慧 


 * @copyRight copyright(c) 2011 广东南航易网通电子商务有限公司,Rights Reserved 


 * @time Dec 27, 2011 10:02:08 AM 


 */ 


 public class DataToExcel { 


 public static void main(String[] args) { 


 String result = ""; 


 List listAll = new ArrayList(); 


 System.out.println("正在读取数据库中所有的表"); 


 try { 


 List tableList = getTableList(); 


 System.out.println("数据库表读取完成"); 


 for(int i=0;i<tableList.size();i++){ 


 String[] strings = (String[]) tableList.get(i); 


 String tableName = strings[0].toString(); 


 List list = new ArrayList(); 


 list.add(tableName); 


 list.add(getStructOfTable(tableName)); 


 System.out.println("正在生成表"+tableName+"的结构"); 


 listAll.add(list); 


 } 


 result = TableStructInfoToExcel(listAll,"D:"); 


 System.out.println("数据库中表结构导入已完成"); 


 } catch (Exception e) { 


 // TODO Auto-generated catch block 


 e.printStackTrace(); 


 File file = new File(e.getMessage().toString()); 


 if(file.exists()){ 


 file.delete(); 


 } 


 } 


 System.out.println(result); 


 //showView(list); 


 } 



 /** 


 * 获取数据库中所有的表 


 * @return 


 */ 


 public static List getTableList(){ 


 String sql = "select object_name From user_objects Where object_type='TABLE'"; 


 return getResult(sql,1); 


 } 



 /** 


 * 根据表明 


 * @param tableName 


 * @return 


 */ 


 public static List getStructOfTable(String tableName){ 


 String sql = "SELECT u.column_name,u.data_type,u.data_length,u.data_precision,u.data_Scale,u.nullable,u.data_default,c.comments FROM user_tab_columns u,user_col_comments c"+ 


 " WHERE u.table_name='"+tableName+"' and u.table_name=c.table_name and c.column_name=u.column_name"; 


 return getResult(sql,8); 


 } 



 /** 


 * 获取结果的公用类 


 * @param sql 


 * @param length 


 * @return 


 */ 


 public static List getResult(String sql,int length){ 


 List list = new ArrayList(); 


 ResultSet rs=null; 


 ConnectionOracle c=new ConnectionOracle(); 


 try { 


 rs=c.executeQuery(sql); 


 while(rs.next()){ 


 String[] string = new String[length]; 


 for(int i=1;i<length+1;i++){ 


 string[i-1] = rs.getString(i); 


 } 


 list.add(string); 


 } 


 c.close(); 


 } catch (SQLException e) { 


 e.printStackTrace(); 


 } 


 return list; 


 } 



 /** 


 * 输出对应list中的数据 


 * @param list 


 */ 


 public static void showView(List list){ 


 for (Iterator iterator = list.iterator(); iterator.hasNext();) { 


 String[] name = (String[]) iterator.next(); 


 for (int i = 0; i < name.length; i++) { 


 System.out.println(name[i]); 


 } 


 } 


 } 



 /** 


 * 将数据导入到excel中 


 * @param list 


 * @param tableName 


 * @param path 


 * @return 


 * @throws Exception 


 */ 


 public static String TableStructInfoToExcel(List list,String path) throws Exception { 


 String FileName=""; 


 FileOutputStream fos = null; 


 HSSFRow row = null; 


 HSSFCell cell = null; 


 HSSFCellStyle style = null; 


 HSSFFont font = null; 


 int currentRowNum = 0; 


 String[] tableFiled = {"column_name","data_type","data_length","data_precision","data_Scale","nullable","data_default","comments"}; 


 try{ 


 FileName = path +"\\"+"CSN数据库中表结构.xls"; 


 fos = new FileOutputStream(FileName); 


 //创建新的sheet并设置名称 


 HSSFWorkbook wb = new HSSFWorkbook(); 


 HSSFSheet s = wb.createSheet(); 


 wb.setSheetName(0, "CSN数据库表结构"); 


 style = wb.createCellStyle(); 


 font = wb.createFont(); 



 for(int z=0;z<list.size();z++){ 


 List listBean = (List) list.get(z); 


 //新建一行,再在行上面新建一列 


 row = s.createRow(currentRowNum); 


 int pad = currentRowNum; 


 currentRowNum++; 


 //设置样式 


 font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD); //字体加粗 


 style.setFont(font); 


 style.setAlignment(HSSFCellStyle.ALIGN_CENTER);//水平居中 


 style.setFillForegroundColor((short) 13);// 设置背景色 


 style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND); 


 style.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框 


 style.setBorderLeft(HSSFCellStyle.BORDER_THIN);//左边框 


 style.setBorderTop(HSSFCellStyle.BORDER_THIN);//上边框 


 style.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框 


 for(int i=0;i<tableFiled.length;i++){ 


 cell = row.createCell((short) i); 


 cell.setCellValue(""); 


 cell.setCellStyle(style); 


 } 


 row.getCell((short) 0).setCellValue("数据库表"+listBean.get(0).toString()+"的结构"); 


 //创建第二行 


 row = s.createRow(currentRowNum); 


 currentRowNum++; 


 for(int i=0;i<tableFiled.length;i++){ 


 //创建多列并设置每一列的值和宽度 


 cell = row.createCell((short) i); 


 cell.setCellValue(new HSSFRichTextString(tableFiled[i])); 


 s.setColumnWidth((short)i,(short)5000); 


 } 


 List list2 = (List) listBean.get(1); 


 for(int i=0;i<list2.size();i++){ 


 row = s.createRow(currentRowNum); 


 currentRowNum++; 


 String[] strings = (String[]) list2.get(i); 


 for(int j=0;j<strings.length;j++){ 


 cell = row.createCell((short) j); 


 cell.setCellValue(new HSSFRichTextString(strings[j])); 


 } 


 } 


 //合并单元格 


 s.addMergedRegion(new Region(pad,(short)0,pad,(short)(tableFiled.length-1))); 


 currentRowNum ++; 


 } 



 wb.write(fos); 


 fos.close(); 


 }catch (Exception e) { 


 e.printStackTrace(); 


 fos.close(); 


 throw new Exception(FileName); 


 } 


 return FileName; 


 }



最后总结一下:
关键性的代码:
一:读取数据库中的所有表
Java代码 收藏代码

select object_name From user_objects Where object_type='TABLE';



二:读取对应表中的结构,下面测试是用CITYNB(这里没有加主键和外键信息,以后加上,有兴趣的朋友可以自己完成,弄好以后,希望给我借鉴一下,呵呵,相互学习嘛,如果还有问题,
Java代码 收藏代码

SELECT u.column_name,u.data_type,u.data_length,u.data_precision,u.data_Scale,u.nullable,u.data_default,c.comments FROM user_tab_columns u,user_col_comments c 

 WHERE u.table_name='CITYNB' and u.table_name=c.table_name and c.column_name=u.column_name;


因为需要写数据库文档,所以需要把数据库里边的表结构在word中用表格列出来,之前一直用powerdesigner,感觉有些麻烦,后来在网上找到了一段sql语句,经测试完全符合我的需求,不敢独享,语句如下:

SELECT t1.Table_Name AS "表名称", 

t3.comments AS "表说明", 

t1.Column_Name AS "字段名称", 

t1.Data_Type AS "数据类型", 

t1.Data_Length AS "长度", 

t1.NullAble AS "是否为空", 

t2.Comments AS "字段说明", 

t1.Data_Default "默认值" 


FROM cols t1 left join user_col_comments t2 

on t1.Table_name=t2.Table_name and t1.Column_Name=t2.Column_Name 

left join user_tab_comments t3 

on t1.Table_name=t3.Table_name 

WHERE NOT EXISTS ( SELECT t4.Object_Name FROM User_objects t4 

WHERE t4.Object_Type='TABLE' 

AND t4.Temporary='Y' 

AND t4.Object_Name=t1.Table_Name ) 

ORDER BY t1.Table_Name, t1.Column_ID;


查询完成后,粘贴指定的列即可

spool C:\sql_ddl.txt; 

select dbms_metadata.get_ddl('TABLE','TABLE_NAME') FROM dual; 

spool off;



-- TABLE_NAME 是你的表名

-- 然后打开C:\sql_ddl.txt文件,里面有你要的代码!