从数据库读取表名和字段，返回json串，显示为树结构

/**
 * 
 * File: QueryTableDaoImpl.java
 * Description:
 * <<从数据库中查询当前数据库表信息>>
 *
 * Notes:
 * <<查询数据库表结构，在web界面中以tree的形式展示>>
 * Revision History:
 * <<Create>>
 */
@Component("queryTableDao")
public class QueryTableDaoImpl extends BaseDAOImpl implements QueryTableDao {
	
	@Autowired(required=true)
	@Qualifier("sessionFactory")
	public void setMySessionFactory(SessionFactory sessionFactory) {
		super.setSessionFactory(sessionFactory);
	}
	@Override
	public void createTable(List<ParseObject> paseObject,String tablename) {
		new CreateTable().CreateDatabaseTable(CreateSql.SqlCreate(paseObject, tablename));
	}
	Connection conn = null; 
	PreparedStatement pst = null;
	
	/**
	 * Description:
	 * <<从数据库中查询当前数据库表的详细信息>>
	 * Notes:
	 * <<已过滤为zq_开头，不显示id，并且表字段转为汉语的表>>
	 */
	@SuppressWarnings("deprecation")
	@Override
	public String queryTablesName() {
		ResultSet resultset = null;
		//获取当前数据链接
		conn = this.getHibernateTemplate().getSessionFactory().getCurrentSession().connection();				
		StringBuffer result = new StringBuffer("[");
		String columnName = "";
		String columnNameCN = "";
		String columnType = "";
		String columnString = "";
		
		try{  
			//查询表名
			resultset = conn.getMetaData().getTables(null, null, null, new String[]{ "TABLE" });
			List<String> tableArr = new ArrayList<String>();
			while(resultset.next()){
				String tableName = resultset.getString(3);
				//过滤表名，只显示zq_表格
				if (null != tableName && ("zq_").equals(tableName.substring(0,3))){
					tableArr.add(tableName);
				}
			}
			//zq表存在时
			if (tableArr.size() != 0){
				for (int i = 0; i < tableArr.size(); i++) {
					result.append("{");
					result.append("\"text\":" + "\"" + ChangeUTF_16.deUnicode(tableArr.get(i).substring(3)) + "\"");				
					//通过表名查询表字段
					pst = conn.prepareStatement("SELECT * FROM " + tableArr.get(i));
					ResultSetMetaData rsd = pst.executeQuery().getMetaData();
					result.append(",\"children\":");
					result.append(" [");
					
					for(int j = 0; j < rsd.getColumnCount() - 1; j++) {
						columnName = rsd.getColumnName(j + 1);
						//过滤id并将列名转为汉语
						if (!"id".equals(columnName)){
							columnNameCN = ChangeUTF_16.deUnicode(columnName.substring(2));
							columnType = rsd.getColumnTypeName(j + 1);
							columnString = columnNameCN + " (" + columnType + ")";
							result.append("{\"text\":\"" + columnString + "\"},");
						}
					}
					//过滤掉每个表最后一个字段的“，”
					columnName = rsd.getColumnName(rsd.getColumnCount());
					columnType = rsd.getColumnTypeName(rsd.getColumnCount());
					if (!"id".equals(columnName)){
						columnNameCN = ChangeUTF_16.deUnicode(columnName.substring(2));
						columnString = columnNameCN + " (" + columnType + ")";
						result.append("{\"text\":\"" + columnString + "\"}");
						result.append("]");
						result.append("},");
					}
				}
			}
			//zq表不存在
			else{
				result.append("{\"text\":\"----You don't have zq table!\"}}");
			}
			//过滤掉每个表最后一个表的“，”
			result = result.deleteCharAt(result.toString().length() - 1);
		    result.append("]");
		    
		}catch(SQLException e) {  
		       throw new RuntimeException(e);  
		} finally {  
			 if(resultset != null){
			    	try {
			    		resultset.close();
					} catch (SQLException e) {
						e.printStackTrace();
					} finally{
						resultset = null;
					}
			    }
		    if(pst != null){
		    	try {
					pst.close();
				} catch (SQLException e) {
					e.printStackTrace();
				} finally{
					pst = null;
				}
		    }
		    if(conn != null){
		    	try {
		    		conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				} finally{
					conn = null;
				}
		    }
		}

		return result.toString();
	}			
}