package com.lnjecit.generator.util;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import java.sql.*;import java.util.ArrayList;import java.util.List;public class DatabaseUtil {    private final static Logger LOGGER = LoggerFactory.getLogger(DatabaseUtil.class);    private static final String DRIVER = "com.mysql.jdbc.Driver";    private static final String URL = "jdbc:mysql://localhost:3306/javaweb?useUnicode=true&characterEncoding=utf8";    private static final String USERNAME = "root";    private static final String PASSWORD = "mysql";    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(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
     
       getTableNames() {        List
      
        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
       
         getColumnNames(String tableName) {        List
        
          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
         
           getColumnTypes(String tableName) {        List
          
            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
           
             getColumnComments(String tableName) { List
            
              columnTypes = new ArrayList<>(); //与数据库的连接 Connection conn = getConnection(); PreparedStatement pStemt = null; String tableSql = SQL + tableName; List
             
               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
              
                tableNames = getTableNames(); System.out.println("tableNames:" + tableNames); for (String tableName : tableNames) { System.out.println("ColumnNames:" + getColumnNames(tableName)); System.out.println("ColumnTypes:" + getColumnTypes(tableName)); System.out.println("ColumnComments:" + getColumnComments(tableName)); } }}