解

答案比使用getMetaData方法更復雜,因為getMetaData方法返回的整數類型和完整的類名沒有直接映射.此解決方案需要兩段代碼：

>實現一個方法來獲取java.sql.Types常量整數值.

>創建將該值轉換為類名的方法.

Java類型方法

以下方法檢索元信息：

public String getJavaType( String schema, String object, String column )

throws Exception {

String fullName = schema + '.' + object + '.' + column;

DatabaseMetaData metaData = getConnection().getMetaData();

ResultSet columnMeta = metaData.getColumns( null, schema, object, column );

String javaType = null;

if( columnMeta.first() ) {

int dataType = columnMeta.getInt( "DATA_TYPE" );

javaType = SQLTypeMap.convert( dataType );

}

else {

throw new Exception( "Unknown database column " + fullName + '.' );

}

return javaType;

}

靜態轉換方法

必須將常量整數值轉換為類名.這可以通過以下方式完成：

import java.sql.Types;

/**

* Converts database types to Java class types.

*/

public class SQLTypeMap {

/**

* Translates a data type from an integer (java.sql.Types value) to a string

* that represents the corresponding class.

*

* @param type

* The java.sql.Types value to convert to its corresponding class.

* @return The class that corresponds to the given java.sql.Types

* value, or Object.class if the type has no known mapping.

*/

public static Class> toClass(int type) {

Class> result = Object.class;

switch (type) {

case Types.CHAR:

case Types.VARCHAR:

case Types.LONGVARCHAR:

result = String.class;

break;

case Types.NUMERIC:

case Types.DECIMAL:

result = java.math.BigDecimal.class;

break;

case Types.BIT:

result = Boolean.class;

break;

case Types.TINYINT:

result = Byte.class;

break;

case Types.SMALLINT:

result = Short.class;

break;

case Types.INTEGER:

result = Integer.class;

break;

case Types.BIGINT:

result = Long.class;

break;

case Types.REAL:

case Types.FLOAT:

result = Float.class;

break;

case Types.DOUBLE:

result = Double.class;

break;

case Types.BINARY:

case Types.VARBINARY:

case Types.LONGVARBINARY:

result = Byte[].class;

break;

case Types.DATE:

result = java.sql.Date.class;

break;

case Types.TIME:

result = java.sql.Time.class;

break;

case Types.TIMESTAMP:

result = java.sql.Timestamp.class;

break;

}

return result;

}

}

請注意,不同的數據庫可以在映射上具有不同的變體.

總結

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