JAVA类型和SQL类型的匹配

类别:Java 点击:0 评论:0 推荐:

已动态创建表为例

(1)
    public class DataType {
      private int code;
      private String SQLType;
      private String localType = null;
      private String params = null;
      private boolean needsSetting = true;
      public DataType(int code, String SQLType) {
       this.code = code;
       this.SQLType = SQLType;
       }
       public boolean needsToBeSet() {
       return needsSetting;
      }
       public int getCode() {
       return code;
      }
       public String getSQLType() {
       return SQLType;
      }
       public String getLocalType() {
       return localType;
      }
       public String getParams() {
       return params;
      }
     public void setLocalTypeAndParams(String local, String p) {
       if (needsSetting) {
        localType = local;
        params = p;
        needsSetting = false;
       }
      }
     }

(2)
   import java.sql.*;
   public class SQLTypesCreate {
      public static void main(String [ ] args) {
       String url="jdbc:oracle:thin:@localhost:1521:oral";
         String user="SYSTEM";
         String pass="manager";
       try {
        Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
       } catch(Exception e){System.out.println(e);}
       try {
        Connection con = DriverManager.getConnection(url, user,pass);
        Statement     stmt = con.createStatement();
        String tableName;
                             // 创建表语句中的表名变量
        String columnName;
                             // 列名变量
        String sqlType;
                             // 数据类型变量
                             // 以上三个变量都是为了创建建表语句服务的
       DataType [ ] typeArray = {
   new DataType(java.sql.Types.BIT, "BIT"),
   new DataType(java.sql.Types.TINYINT, "TINYINT"),
   new DataType(java.sql.Types.SMALLINT, "SMALLINT"),
   new DataType(java.sql.Types.INTEGER, "INTEGER"),
   new DataType(java.sql.Types.BIGINT, "BIGINT"),
   new DataType(java.sql.Types.FLOAT, "FLOAT"),
   new DataType(java.sql.Types.REAL, "REAL"),
   new DataType(java.sql.Types.DOUBLE, "DOUBLE"),
   new DataType(java.sql.Types.NUMERIC, "NUMERIC"),
   new DataType(java.sql.Types.DECIMAL, "DECIMAL"),
   new DataType(java.sql.Types.CHAR, "CHAR"),
   new DataType(java.sql.Types.VARCHAR, "VARCHAR"),
   new DataType(java.sql.Types.LONGVARCHAR, "LONGVARCHAR"),
   new DataType(java.sql.Types.DATE, "DATE"),
   new DataType(java.sql.Types.TIME, "TIME"),
   new DataType(java.sql.Types.TIMESTAMP, "TIMESTAMP"),
   new DataType(java.sql.Types.BINARY, "BINARY"),
   new DataType(java.sql.Types.VARBINARY, "VARBINARY"),
   new DataType(java.sql.Types.LONGVARBINARY, "LONGVARBINARY"),
   new DataType(java.sql.Types.NULL, "NULL"),
   new DataType(java.sql.Types.OTHER, "OTHER"),
        };
        //创建一个数组用用jdbc SQl数据类型的代码和名字初始化,其它为null
        //注意,以上出现的名字全部都是Types类中出现的
               DatabaseMetaData dbmd = con.getMetaData();
        //创建DatabaseMetaData对象,用来获取数据库的属性
        ResultSet rs = dbmd.getTypeInfo();
        //获取数据库支持的SQL数据类型
        while (rs.next()){
         int codeNumber = rs.getInt("DATA_TYPE");
         String dbmsName = rs.getString("TYPE_NAME");
         String createParams = rs.getString("CREATE_PARAMS");
        // 以下是本地数据库支持的数据类型在jdbc中的映射号,本地名,参数
        //System.out.println(codeNumber+" "+dbmsName+" "+createParams);
        for (int i = 0; i < typeArray.length; i++) {
          if (typeArray[i].getCode() == codeNumber) {
          // 如果typeArray中的元素代码等于本地数据库类型的代码,
          // 就可以把typeArray中的类型名设成从DatabaseMetaData获得的本地名
           typeArray[i].setLocalTypeAndParams(
             dbmsName, createParams);
             System.out.println("匹配的code,SQLType,localType,params有:");
             System.out.println(typeArray[i].getCode()+" "+
                            typeArray[i].getSQLType()+" "+
                            typeArray[i].getLocalType()+" "+
                            typeArray[i].getParams());
         }
          // 设定数组中的数据库中的类型名和参数,打印出所有匹配的
         }
          // end for
        }//end while
        String tableNamePrompt = "输入表名 " +  "并回车 ";
        tableName = getInput(tableNamePrompt);
        String createTableString = "create table " + tableName + " (";
        String commaAndSpace = ", ";
        boolean firstTime = true;
        while (true){
              System.out.println("");
              String columnNamePrompt = "输入列名 " +"或不输入任何数据然后回车: ";
         columnName = getInput(columnNamePrompt);
         if (firstTime) {
          if (columnName.length() == 0) {
           System.out.print("至少需要一列;");
           System.out.println(" 请重试");
           continue;
          } else {
           createTableString += columnName + " ";
           // 继续形成创建表的字符串
           firstTime = false;
          }
         } else if (columnName.length() == 0) {
           break;
           // 不输入列时那么创建语句的过程结束
         } else {
          createTableString += commaAndSpace
           + columnName + " ";
         }
         // 在成功接收到列名后,以下显示可用的类型名
         System.out.println("");
         System.out.println("可用的类型名为:  ");
         for (int i = 0; i < typeArray.length; i++) {
          if (! typeArray[i].needsToBeSet()) {
          // 如果设置了本地数据库中的名和参数,说明这个jdbc类型可以用
           System.out.println(typeArray[i].getSQLType());
          // 返回jdbc中对应的SQL类型名
          } 
         }
         System.out.println("");
      int index;
         while (true) {//循环直到输入可用的类型
          String typePrompt = "从列表中输入列的类型 " +
            "并回车";
          sqlType = getInput(typePrompt);
          for (index = 0; index < typeArray.length; index++) {
           if (typeArray[index].getSQLType().
            equalsIgnoreCase(sqlType)){
           // 比较两个字符串是否相等,不区分大小写
           // 如果有相等的说明输入的类型是jdbc允许的类型,就跳出
            break;
           }
          }
          if (index < typeArray.length) {
           // 如果index小于typeArray数组的个数,说明有匹配的
           break;
           // 跳出while(true)循环
          }
          System.out.println("");
          System.out.print(sqlType + " 与允许的类型不匹配");
         
          System.out.println("");
         }
         String params;
         String localTypeName;
         params = typeArray[index].getParams();
           // 获取类型的参数,此时的index是输入的类型在数组中的索引
         localTypeName = typeArray[index].getLocalType();
           // 获取数据库中这种类型名
         String paramString;
             String parameterPrompt = "输入 " + params + ":  ";
          paramString = "(" + getInput(parameterPrompt) + ")";
         createTableString += localTypeName + paramString;
           // 注意,形成创建表字符串的是用本地类型名,不是用jdbc中的类型名
           // 前面输入的时候用的是jdbc中的名字
        }
           // 创建语句输入部分结束
        createTableString += ")";
        System.out.println("");
        System.out.print("你输入的创建表的语句是:");
       
        System.out.println(createTableString);
        System.out.println("");
           stmt.execute(createTableString);
           // 执行创建表的语句
          rs=dbmd.getColumns(null,"SYSTEM",tableName.toUpperCase(),"%");
          System.out.println("表的信息为:表名,列名,类型号,类型名");
          while(rs.next()) {
          System.out.print(rs.getString("TABLE_NAME")+" ");
          System.out.print(rs.getString("COLUMN_NAME")+" ");
          System.out.print(rs.getInt("DATA_TYPE")+" ");
          System.out.println(rs.getString("TYPE_NAME"));
          }
            rs.close();
        stmt.close();
        con.close();
       } catch(SQLException ex) {
        System.err.println("SQLException: " + ex.getMessage());
       } 
      }
      public static String getInput(String prompt) throws SQLException {
        System.out.print(prompt);
        System.out.flush();
    //清除所有字符
        try {
         java.io.BufferedReader bin;
    //创建从字符输入流中读取文本的对象
         bin = new java.io.BufferedReader(
    //字符流为参数
          new java.io.InputStreamReader(System.in));
    //字节流为参数,转化成字符流
             String result = bin.readLine();
        return result;
    //返回字符串
       } catch(Exception e) {
        System.out.println(e);
        return "";
     }
      }
     }

本文地址:http://com.8s8s.com/it/it9825.htm