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通过DatabaseMetaData对象获得数据库元数据信息

2015-04-18 16:23 465 查看
转自 http://www.pinhuba.com/other/101097.htm
DatabaseMetaData类是java.sql包中的类,利用它可以获取我们连接到的数据库的结构、存储等很多信息。如:

获得数据库的一些相关信息、获得该用户下面的所有表、获得该用户下面的所有视图、获得数据库中所有方案名称、获得表或视图中的所有列信息、获得一个表的索引信息、获得一个表的主键信息、获得一个表的外键信息。

package com.zsw.test;

import java.sql.Connection;

import java.sql.DatabaseMetaData;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

public class DatabaseMetaDateApplication {

private DatabaseMetaData dbMetaData = null;

private Connection con = null;

public DatabaseMetaDateApplication() {

this.getDatabaseMetaData();

}

private void getDatabaseMetaData() {

try {

if (dbMetaData == null) {

Class.forName("com.mysql.jdbc.Driver");

String url = "jdbc:mysql://localhost:3306/creation_cms";

String user = "root";

String password = "root";

con = DriverManager.getConnection(url, user, password);

dbMetaData = con.getMetaData();

}

} catch (ClassNotFoundException e) {

e.printStackTrace();

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得数据库的一些相关信息

*/

public void getDataBaseInformations() {

try {

System.out.println("数据库已知的用户: " + dbMetaData.getUserName());

System.out.println("数据库的系统函数的逗号分隔列表: " + dbMetaData.getSystemFunctions());

System.out.println("数据库的时间和日期函数的逗号分隔列表: " + dbMetaData.getTimeDateFunctions());

System.out.println("数据库的字符串函数的逗号分隔列表: " + dbMetaData.getStringFunctions());

System.out.println("数据库供应商用于 'schema' 的首选术语: " + dbMetaData.getSchemaTerm());

System.out.println("数据库URL: " + dbMetaData.getURL());

System.out.println("是否允许只读:" + dbMetaData.isReadOnly());

System.out.println("数据库的产品名称:" + dbMetaData.getDatabaseProductName());

System.out.println("数据库的版本:" + dbMetaData.getDatabaseProductVersion());

System.out.println("驱动程序的名称:" + dbMetaData.getDriverName());

System.out.println("驱动程序的版本:" + dbMetaData.getDriverVersion());

System.out.println();

System.out.println("数据库中使用的表类型");

ResultSet rs = dbMetaData.getTableTypes();

while (rs.next()) {

System.out.println(rs.getString(1));

}

rs.close();

System.out.println();

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得该用户下面的所有表

*/

public void getAllTableList(String schemaName) {

try {

// table type. Typical types are "TABLE", "VIEW", "SYSTEM TABLE",

// "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM".

String[] types = { "TABLE" };

ResultSet rs = dbMetaData.getTables(null, schemaName, "%", types);

while (rs.next()) {

String tableName = rs.getString("TABLE_NAME"); // 表名

String tableType = rs.getString("TABLE_TYPE"); // 表类型

String remarks = rs.getString("REMARKS"); // 表备注

System.out.println(tableName + "-" + tableType + "-" + remarks);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得该用户下面的所有视图

*/

public void getAllViewList(String schemaName) {

try {

String[] types = { "VIEW" };

ResultSet rs = dbMetaData.getTables(null, schemaName, "%", types);

while (rs.next()) {

String viewName = rs.getString("TABLE_NAME"); // 视图名

String viewType = rs.getString("TABLE_TYPE"); // 视图类型

String remarks = rs.getString("REMARKS");// 视图备注

System.out.println(viewName + "-" + viewType + "-" + remarks);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得数据库中所有方案名称

*/

public void getAllSchemas() {

try {

ResultSet rs = dbMetaData.getSchemas();

while (rs.next()) {

String tableSchem = rs.getString("TABLE_SCHEM");

System.out.println(tableSchem);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得表或视图中的所有列信息

*/

public void getTableColumns(String schemaName, String tableName) {

try {

ResultSet rs = dbMetaData.getColumns(null, schemaName, tableName, "%");

while (rs.next()) {

String tableCat = rs.getString("TABLE_CAT");// 表目录(可能为空)

String tableSchemaName = rs.getString("TABLE_SCHEM");// 表的架构(可能为空)

String tableName_ = rs.getString("TABLE_NAME");// 表名

String columnName = rs.getString("COLUMN_NAME");// 列名

int dataType = rs.getInt("DATA_TYPE"); // 对应的java.sql.Types类型

String dataTypeName = rs.getString("TYPE_NAME");// java.sql.Types类型

// 名称

int columnSize = rs.getInt("COLUMN_SIZE");// 列大小

int decimalDigits = rs.getInt("DECIMAL_DIGITS");// 小数位数

int numPrecRadix = rs.getInt("NUM_PREC_RADIX");// 基数(通常是10或2)

int nullAble = rs.getInt("NULLABLE");// 是否允许为null

String remarks = rs.getString("REMARKS");// 列描述

String columnDef = rs.getString("COLUMN_DEF");// 默认值

int sqlDataType = rs.getInt("SQL_DATA_TYPE");// sql数据类型

int sqlDatetimeSub = rs.getInt("SQL_DATETIME_SUB"); // SQL日期时间分?

int charOctetLength = rs.getInt("CHAR_OCTET_LENGTH"); // char类型的列中的最大字节数

int ordinalPosition = rs.getInt("ORDINAL_POSITION"); // 表中列的索引(从1开始)

/**

* ISO规则用来确定某一列的为空性。 是---如果该参数可以包括空值; 无---如果参数不能包含空值

* 空字符串---如果参数为空性是未知的

*/

String isNullAble = rs.getString("IS_NULLABLE");

/**

* 指示此列是否是自动递增 是---如果该列是自动递增 无---如果不是自动递增列 空字串---如果不能确定它是否

* 列是自动递增的参数是未知

*/

String isAutoincrement = rs.getString("IS_AUTOINCREMENT");

System.out.println(tableCat + "-" + tableSchemaName + "-" + tableName_ + "-" + columnName + "-" + dataType + "-" + dataTypeName + "-" + columnSize + "-" + decimalDigits + "-" + numPrecRadix + "-" + nullAble + "-" + remarks + "-" + columnDef
+ "-" + sqlDataType + "-" + sqlDatetimeSub + charOctetLength + "-" + ordinalPosition + "-" + isNullAble + "-" + isAutoincrement + "-");

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得一个表的索引信息

*/

public void getIndexInfo(String schemaName, String tableName) {

try {

ResultSet rs = dbMetaData.getIndexInfo(null, schemaName, tableName, true, true);

while (rs.next()) {

boolean nonUnique = rs.getBoolean("NON_UNIQUE");// 非唯一索引(Can

// index values

// be

// non-unique.

// false when

// TYPE is

// tableIndexStatistic

// )

String indexQualifier = rs.getString("INDEX_QUALIFIER");// 索引目录(可能为空)

String indexName = rs.getString("INDEX_NAME");// 索引的名称

short type = rs.getShort("TYPE");// 索引类型

short ordinalPosition = rs.getShort("ORDINAL_POSITION");// 在索引列顺序号

String columnName = rs.getString("COLUMN_NAME");// 列名

String ascOrDesc = rs.getString("ASC_OR_DESC");// 列排序顺序:升序还是降序

int cardinality = rs.getInt("CARDINALITY"); // 基数

System.out.println(nonUnique + "-" + indexQualifier + "-" + indexName + "-" + type + "-" + ordinalPosition + "-" + columnName + "-" + ascOrDesc + "-" + cardinality);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得一个表的主键信息

*/

public void getAllPrimaryKeys(String schemaName, String tableName) {

try {

ResultSet rs = dbMetaData.getPrimaryKeys(null, schemaName, tableName);

while (rs.next()) {

String columnName = rs.getString("COLUMN_NAME");// 列名

short keySeq = rs.getShort("KEY_SEQ");// 序列号(主键内值1表示第一列的主键,值2代表主键内的第二列)

String pkName = rs.getString("PK_NAME"); // 主键名称

System.out.println(columnName + "-" + keySeq + "-" + pkName);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

/**

* 获得一个表的外键信息

*/

public void getAllExportedKeys(String schemaName, String tableName) {

try {

ResultSet rs = dbMetaData.getExportedKeys(null, schemaName, tableName);

while (rs.next()) {

String pkTableCat = rs.getString("PKTABLE_CAT");// 主键表的目录(可能为空)

String pkTableSchem = rs.getString("PKTABLE_SCHEM");// 主键表的架构(可能为空)

String pkTableName = rs.getString("PKTABLE_NAME");// 主键表名

String pkColumnName = rs.getString("PKCOLUMN_NAME");// 主键列名

String fkTableCat = rs.getString("FKTABLE_CAT");// 外键的表的目录(可能为空)出口(可能为null)

String fkTableSchem = rs.getString("FKTABLE_SCHEM");// 外键表的架构(可能为空)出口(可能为空)

String fkTableName = rs.getString("FKTABLE_NAME");// 外键表名

String fkColumnName = rs.getString("FKCOLUMN_NAME"); // 外键列名

short keySeq = rs.getShort("KEY_SEQ");// 序列号(外键内值1表示第一列的外键,值2代表在第二列的外键)。

/**

* hat happens to foreign key when primary is updated:

* importedNoAction - do not allow update of primary key if it

* has been imported importedKeyCascade - change imported key to

* agree with primary key update importedKeySetNull - change

* imported key to NULL if its primary key has been updated

* importedKeySetDefault - change imported key to default values

* if its primary key has been updated importedKeyRestrict -

* same as importedKeyNoAction (for ODBC 2.x compatibility)

*/

short updateRule = rs.getShort("UPDATE_RULE");

/**

* What happens to the foreign key when primary is deleted.

* importedKeyNoAction - do not allow delete of primary key if

* it has been imported importedKeyCascade - delete rows that

* import a deleted key importedKeySetNull - change imported key

* to NULL if its primary key has been deleted

* importedKeyRestrict - same as importedKeyNoAction (for ODBC

* 2.x compatibility) importedKeySetDefault - change imported

* key to default if its primary key has been deleted

*/

short delRule = rs.getShort("DELETE_RULE");

String fkName = rs.getString("FK_NAME");// 外键的名称(可能为空)

String pkName = rs.getString("PK_NAME");// 主键的名称(可能为空)

/**

* can the evaluation of foreign key constraints be deferred

* until commit importedKeyInitiallyDeferred - see SQL92 for

* definition importedKeyInitiallyImmediate - see SQL92 for

* definition importedKeyNotDeferrable - see SQL92 for

* definition

*/

short deferRability = rs.getShort("DEFERRABILITY");

System.out.println(pkTableCat + "-" + pkTableSchem + "-" + pkTableName + "-" + pkColumnName + "-" + fkTableCat + "-" + fkTableSchem + "-" + fkTableName + "-" + fkColumnName + "-" + keySeq + "-" + updateRule + "-" + delRule + "-" + fkName + "-"
+ pkName + "-" + deferRability);

}

} catch (SQLException e) {

e.printStackTrace();

}

}

public void colseCon() {

try {

if (con != null) {

con.close();

}

} catch (SQLException e) {

e.printStackTrace();

}

}

public static void main(String[] args) {

DatabaseMetaDateApplication metaData = new DatabaseMetaDateApplication();

// metaData.getDataBaseInformations();

// metaData.getAllTableList(null);

// metaData.getAllViewList(null);

// metaData.getAllSchemas();

// metaData.getTableColumns(null, "zsc_admin");

// metaData.getIndexInfo(null, "zsc_admin");

// metaData.getAllPrimaryKeys(null, "zsc_admin");

metaData.getAllExportedKeys(null, "zsc_admin");

}

}
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