java獲取數(shù)據(jù)庫MetaData

? 元數(shù)據(jù)(MetaData)，即數(shù)據(jù)的描述信息的數(shù)據(jù)（表）。數(shù)據(jù)庫的表的表名，表的屬性名，表的存儲位置，表的列數(shù)啊等等都是表的描述信息，而這些描述信息就是元數(shù)據(jù)啦。

1.DatabaseMetaData類

該類是數(shù)據(jù)庫的描述對象通過Connection對象的getMetaData()方法獲取。

public void testDatabaseMetaData() throws SQLException {String url = "jdbc:mysql://127.0.0.1:3306/test?useSSL=false&serverTimezone=UTC";String user = "root" ; String password = "root";//這里隨便創(chuàng)建一個連接Connection conn= DriverManager.getConnection(url,user,password);DatabaseMetaData dbMetaData = conn.getMetaData();//獲取數(shù)據(jù)庫產(chǎn)品名稱String productName = dbMetaData.getDatabaseProductName();//獲取數(shù)據(jù)庫版本號String productVersion = dbMetaData.getDatabaseProductVersion();//獲取數(shù)據(jù)庫用戶名String userName = dbMetaData.getUserName();//獲取數(shù)據(jù)庫連接URLString userUrl = dbMetaData.getURL();//獲取數(shù)據(jù)庫驅(qū)動String driverName = dbMetaData.getDriverName();//獲取數(shù)據(jù)庫驅(qū)動版本號String driverVersion = dbMetaData.getDriverVersion();//查看數(shù)據(jù)庫是否允許讀操作boolean isReadOnly = dbMetaData.isReadOnly();//查看數(shù)據(jù)庫是否支持事務(wù)操作boolean supportsTransactions = dbMetaData.supportsTransactions(); }

2.ParameterMetaData類

這個是參數(shù)的元數(shù)據(jù)對象，通過getParameterMetaData()獲取

public void testParameterMetaData() throws SQLException {String url = "jdbc:mysql://127.0.0.1:3306/test?useSSL=false&serverTimezone=UTC";String user = "root" ; String password = "root";//這里隨便創(chuàng)建一個連接Connection conn= DriverManager.getConnection(url,user,password);String sql = "SELECT * FROM student WHERE name = ?;"; preparedStatement ps = conn.prepareStatement(sql);ParameterMetaData paramMetaData = st.getParameterMetaData();//獲取參數(shù)個數(shù)int paramCount = paramMetaData.getParameterCount();//獲取參數(shù)類型（參數(shù)下標(biāo)以1開始）String paramTypeName = paramMetaData.getParameterTypeName(1); }

3.ResultSetMetaData類

數(shù)據(jù)集的元數(shù)據(jù)類，通過ResultSet的getMetaData()獲取。

public void testParameterMetaData() throws SQLException {String url = "jdbc:mysql://127.0.0.1:3306/test?useSSL=false&serverTimezone=UTC";String user = "root" ; String password = "root";//這里隨便創(chuàng)建一個連接Connection conn= DriverManager.getConnection(url,user,password);String sql = "SELECT * FROM student WHERE name = ?;"; preparedStatement ps = conn.prepareStatement(sql);ps.setString(1,"Tom"); //"Tom"為傳入值ResultSet rs = ps.executeQuery();ResultSetMetaData rsm = rs.getMetaData();//獲取列數(shù)int count = metaData.getColumnCount();//獲取列名和列類型for(int i =1;i<=count;i++)System.out.println("列名"+rsm.getColumnName(i)+"類型"+rsm.getColumnTypeName(i))}

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