getTypeInfo()的DatabaseMetaData接口的方法用于获得由底层数据库支持的所有数据类型的说明。
此方法返回一个ResultSet对象，该对象描述了受支持的数据类型。该对象保存以下详细信息的值（作为列名）-
| 栏名 | 数据类型 | 描述 |
|---|---|---|
| TYPE_NAME | 串 | 数据类型的名称。 |
| 数据类型 | 整型 | 表示此数据类型的整数值。 |
| 精确 | 整型 | 此数据类型的最大精度。 |
| LITERAL_PREFIX | 串 | 前缀用于引用字符串文字。 |
| LITERAL_SUFFIX | 串 | 后缀用于引用字符串文字。 |
| 区分大小写 | 布尔值 | 确定此数据类型是否区分大小写 |
| UNSIGNED_ATTRIBUTE | 布尔值 | 确定此数据类型是否为未签名的属性。 |
| FIXED_PREC_SCALE | 布尔值 | 确定当前数据类型是否可以用作货币值。 |
| 自动递增 | 布尔值 | 确定当前数据类型是否可用于自动增量。 |
| LOCAL_TYPE_NAME | 串 | 此数据类型的本地化版本。 |
获取DatabaseMetaData对象-
确保您的数据库已启动并正在运行。
使用registerDriver()DriverManager类的方法注册驱动程序。传递与基础数据库相对应的驱动程序类的对象。
使用getConnection()DriverManager类的方法获取连接对象。将URL和数据库中的用户密码作为字符串变量传递给数据库。
使用getMetaData()Connection接口的方法获取有关当前连接的DatabaseMetaData对象。
最后，通过调用getTypeInfo()DatabaseMetaData接口的方法来获取ResultSet对象，其中包含受支持的数据类型的描述。
下面的JDBC程序建立与MySQL数据库的连接，检索所有数据类型的描述。
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DatabaseMetadata_getTypeInfo {
public static void main(String args[]) throws SQLException {
//注册驱动程序
DriverManager.registerDriver(new com.mysql.jdbc.Driver());
//获得连接
String url = "jdbc:mysql://localhost/mydatabase";
Connection con = DriverManager.getConnection(url, "root", "password");
System.out.println("Connection established......");
//检索元数据对象
DatabaseMetaData metaData = con.getMetaData();
//检索数据库中的列
ResultSet info = metaData.getTypeInfo();
//打印列名称和大小
while (info.next()) {
System.out.println("Data type name: "+info.getString("TYPE_NAME"));
System.out.println("Integer value representing this datatype: "+info.getInt("DATA_TYPE"));
System.out.println("Maximum precision of this datatype: "+info.getInt("PRECISION"));
if(info.getBoolean("CASE_SENSITIVE")) {
System.out.println("Current datatype is case sensitive ");
} else {
System.out.println("Current datatype is not case sensitive ");
}
if(info.getBoolean("AUTO_INCREMENT")) {
System.out.println("Current datatype can be used for auto increment");
} else {
System.out.println("Current datatype can not be used for auto increment");
}
System.out.println(" ");
}
}
}输出结果
Connection established...... Data type name: BIT Integer value representing this datatype: -7 Maximum precision of this datatype: 1 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: BOOL Integer value representing this datatype: -7 Maximum precision of this datatype: 1 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: TINYINT Integer value representing this datatype: -6 Maximum precision of this datatype: 3 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: TINYINT UNSIGNED Integer value representing this datatype: -6 Maximum precision of this datatype: 3 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: BIGINT Integer value representing this datatype: -5 Maximum precision of this datatype: 19 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: BIGINT UNSIGNED Integer value representing this datatype: -5 Maximum precision of this datatype: 20 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: LONG VARBINARY Integer value representing this datatype: -4 Maximum precision of this datatype: 16777215 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: MEDIUMBLOB Integer value representing this datatype: -4 Maximum precision of this datatype: 16777215 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: LONGBLOB Integer value representing this datatype: -4 Maximum precision of this datatype: 2147483647 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: BLOB Integer value representing this datatype: -4 Maximum precision of this datatype: 65535 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: TINYBLOB Integer value representing this datatype: -4 Maximum precision of this datatype: 255 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: VARBINARY Integer value representing this datatype: -3 Maximum precision of this datatype: 255 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: BINARY Integer value representing this datatype: -2 Maximum precision of this datatype: 255 Current datatype is case sensitive Current datatype can not be used for auto increment Data type name: LONG VARCHAR Integer value representing this datatype: -1 Maximum precision of this datatype: 16777215 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: MEDIUMTEXT Integer value representing this datatype: -1 Maximum precision of this datatype: 16777215 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: LONGTEXT Integer value representing this datatype: -1 Maximum precision of this datatype: 2147483647 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: TEXT Integer value representing this datatype: -1 Maximum precision of this datatype: 65535 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: TINYTEXT Integer value representing this datatype: -1 Maximum precision of this datatype: 255 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: CHAR Integer value representing this datatype: 1 Maximum precision of this datatype: 255 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: NUMERIC Integer value representing this datatype: 2 Maximum precision of this datatype: 65 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: DECIMAL Integer value representing this datatype: 3 Maximum precision of this datatype: 65 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: INTEGER Integer value representing this datatype: 4 Maximum precision of this datatype: 10 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: INTEGER UNSIGNED Integer value representing this datatype: 4 Maximum precision of this datatype: 10 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: INT Integer value representing this datatype: 4 Maximum precision of this datatype: 10 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: INT UNSIGNED Integer value representing this datatype: 4 Maximum precision of this datatype: 10 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: MEDIUMINT Integer value representing this datatype: 4 Maximum precision of this datatype: 7 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: MEDIUMINT UNSIGNED Integer value representing this datatype: 4 Maximum precision of this datatype: 8 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: SMALLINT Integer value representing this datatype: 5 Maximum precision of this datatype: 5 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: SMALLINT UNSIGNED Integer value representing this datatype: 5 Maximum precision of this datatype: 5 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: FLOAT Integer value representing this datatype: 7 Maximum precision of this datatype: 10 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: DOUBLE Integer value representing this datatype: 8 Maximum precision of this datatype: 17 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: DOUBLE PRECISION Integer value representing this datatype: 8 Maximum precision of this datatype: 17 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: REAL Integer value representing this datatype: 8 Maximum precision of this datatype: 17 Current datatype is not case sensitive Current datatype can be used for auto increment Data type name: VARCHAR Integer value representing this datatype: 12 Maximum precision of this datatype: 255 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: ENUM Integer value representing this datatype: 12 Maximum precision of this datatype: 65535 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: SET Integer value representing this datatype: 12 Maximum precision of this datatype: 64 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: DATE Integer value representing this datatype: 91 Maximum precision of this datatype: 0 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: TIME Integer value representing this datatype: 92 Maximum precision of this datatype: 0 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: DATETIME Integer value representing this datatype: 93 Maximum precision of this datatype: 0 Current datatype is not case sensitive Current datatype can not be used for auto increment Data type name: TIMESTAMP Integer value representing this datatype: 93 Maximum precision of this datatype: 0 Current datatype is not case sensitive Current datatype can not be used for auto increment