以前有小伙伴在公众号留言问过如何通过java获取数据库的所有表、及表里字段的信息，只是私信回复过。
在最近的项目中架构部提出了一个数据源的配置需求，就是需要配置公司所有系统的数据库、表等信息，便于大数据部门抽数时过滤某些表的敏感字段，如身份证号、手机号等敏感字段。
需要后端动态连接数据库，及获取相应数据库的表、字段等信息，就对这方面的东西进行了简单的整理，给出示例代码。便于以后还有小伙伴遇到这类问题，可以参考。
示例代码如下：
public class DatabaseUtilTest {private static final Logger logger = LoggerFactory.getLogger(DatabaseUtilTest.class);private static final String DRIVER = "com.mysql.jdbc.Driver";private static final String DATABASE_URL = "jdbc:mysql://ip:3306/databasename?useUnicode=true&characterEncoding=utf8";private static final String USERNAME = "xxx";private static final String PASSWORD = "xxx";private static final String SQL = "SELECT * FROM ";// 数据库操作static {try {Class.forName(DRIVER);} catch (ClassNotFoundException e) {logger.error("can not load jdbc driver", e);}}/*** 获取数据库连接** @return*/public static Connection getConnection() {Connection conn = null;try {conn = DriverManager.getConnection(DATABASE_URL, USERNAME, PASSWORD);} catch (SQLException e) {logger.error("get connection failure", e);}return conn;}/*** 关闭数据库连接* @param conn*/public static void closeConnection(Connection conn) {if(conn != null) {try {conn.close();} catch (SQLException e) {logger.error("close connection failure", e);}}}/*** 获取数据库下的所有表名*/public static List<String> getTableNames() {List<String> tableNames = new ArrayList<>();Connection conn = getConnection();ResultSet rs = null;try {//获取数据库的元数据DatabaseMetaData db = conn.getMetaData();//从元数据中获取到所有的表名rs = db.getTables(null, null, null, new String[] { "TABLE" });while(rs.next()) {tableNames.add(rs.getString(3));}} catch (SQLException e) {logger.error("getTableNames failure", e);} finally {try {rs.close();closeConnection(conn);} catch (SQLException e) {logger.error("close ResultSet failure", e);}}return tableNames;}/*** 获取表中所有字段名称* @param tableName 表名* @return*/public static List<String> getColumnNames(String tableName) {List<String> columnNames = new ArrayList<>();//与数据库的连接Connection conn = getConnection();PreparedStatement pStemt = null;String tableSql = SQL + tableName;try {pStemt = conn.prepareStatement(tableSql);//结果集元数据ResultSetMetaData rsmd = pStemt.getMetaData();//表列数int size = rsmd.getColumnCount();for (int i = 0; i < size; i++) {columnNames.add(rsmd.getColumnName(i + 1));}} catch (SQLException e) {logger.error("getColumnNames failure", e);} finally {if (pStemt != null) {try {pStemt.close();closeConnection(conn);} catch (SQLException e) {logger.error("getColumnNames close pstem and connection failure", e);}}}return columnNames;}/*** 获取表中所有字段类型* @param tableName* @return*/public static List<String> getColumnTypes(String tableName) {List<String> columnTypes = new ArrayList<>();//与数据库的连接Connection conn = getConnection();PreparedStatement pStemt = null;String tableSql = SQL + tableName;try {pStemt = conn.prepareStatement(tableSql);//结果集元数据ResultSetMetaData rsmd = pStemt.getMetaData();//表列数int size = rsmd.getColumnCount();for (int i = 0; i < size; i++) {columnTypes.add(rsmd.getColumnTypeName(i + 1));}} catch (SQLException e) {logger.error("getColumnTypes failure", e);} finally {if (pStemt != null) {try {pStemt.close();closeConnection(conn);} catch (SQLException e) {logger.error("getColumnTypes close pstem and connection failure", e);}}}return columnTypes;}/*** 获取表中字段的所有注释* @param tableName* @return*/public static List<String> getColumnComments(String tableName) {List<String> columnTypes = new ArrayList<>();//与数据库的连接Connection conn = getConnection();PreparedStatement pStemt = null;String tableSql = SQL + tableName;List<String> columnComments = new ArrayList<>();//列名注释集合ResultSet rs = null;try {pStemt = conn.prepareStatement(tableSql);rs = pStemt.executeQuery("show full columns from " + tableName);while (rs.next()) {columnComments.add(rs.getString("Comment"));}} catch (SQLException e) {e.printStackTrace();} finally {if (rs != null) {try {rs.close();closeConnection(conn);} catch (SQLException e) {logger.error("getColumnComments close ResultSet and connection failure", e);}}}return columnComments;}public static void main(String[] args) {List<String> tableNames = getTableNames();System.out.println("tableNames:" + tableNames);for (String tableName : tableNames) {System.out.println("================start==========================");System.out.println("==============================================");System.out.println("ColumnNames:" + getColumnNames(tableName));System.out.println("ColumnTypes:" + getColumnTypes(tableName));System.out.println("ColumnComments:" + getColumnComments(tableName));System.out.println("==============================================");System.out.println("=================end=======================");}}}
如是获取多个数据库的信息，上面的DATABASE_URL,USERNAME,PASSWORD可以动态替换。
出于安全性的考虑，在实际的编码中建议数据库的用户名和密码不要硬编码在代码中，即使出现也建议进行加密处理。数据库的用户名和密码是非常非常敏感的信息，任何时候都需要非常注意！！！
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