摘要: 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。
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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