获取数据库的信息的手段，转载

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<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("ColumnNames:" + getColumnNames(tableName));
System.out.println("ColumnTypes:" + getColumnTypes(tableName));
System.out.println("ColumnComments:" + getColumnComments(tableName));
}
}
}