获取数据库表结构

开发中或许会用到获取数据库表结构，这里我写个获取mysql表结构的例子

在JDK1.8的环境中，用到的包如下

<!-- mysql驱动 -->

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>6.0.5</version>

</dependency>

<!-- log4j -->

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${org.slf4j.version}</version>

</dependency>

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${org.slf4j.version}</version>

</dependency>

<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>

</dependency>

jdbc配置文件jdbc.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/ai_say?serverTimezone=UTC&useTimezone=true&zeroDateTimeBehavior=convertToNull&autoReconnect=true&useUnicode=true&rewriteBatchedStatements=TRUE
user=root
password=123456
remarks=true
useInformationSchema=truePropertiesUtil.java用来加载配置文件
package com.ai.generator.util;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.util.Enumeration;
import java.util.Properties;

public class PropertiesUtil {

Properties properties;

public PropertiesUtil(Properties properties) {
this.properties = properties;
}

public Properties getProperties() {
return properties;
}

public String getProperty(String key) {
return getProperties().getProperty(key);
}

public static Properties loadProperties(String resourceName)
throws IOException {
Properties properties = new Properties();
Enumeration<URL> urls = PropertiesUtil.class.getClassLoader()
.getResources(resourceName);
while (urls.hasMoreElements()) {
URL url = (URL) urls.nextElement();
InputStream input = null;
try {
URLConnection con = url.openConnection();
con.setUseCaches(false);
input = con.getInputStream();
properties.load(input);
} finally {
if (input != null) {
input.close();
}
}
}
return properties;
}

}
SqlTable.java、SqlColumn.java、SqlPrimaryKey.java分别是表、列、主键实体类

package com.ai.generator.entity.sql;

/**
* 数据库表
*/
public class SqlTable {

/**
* 备注
*/
private String sqlTableName;

/**
* 备注
*/
private String sqlTableRemarks;

public String getSqlTableName() {
return sqlTableName;
}

public void setSqlTableName(String sqlTableName) {
this.sqlTableName = sqlTableName;
}

public String getSqlTableRemarks() {
return sqlTableRemarks;
}

public void setSqlTableRemarks(String sqlTableRemarks) {
this.sqlTableRemarks = sqlTableRemarks;
}

}

package com.ai.generator.entity.sql;

/**
* 数据库表
*/
public class SqlColumn {

/**
* 列名
*/
private String columnName;

/**
* 对应的java.sql.Types类型
*/
private int dataType;

/**
* java.sql.Types类型
*/
private String typeName; //

/**
* 列大小
*/
private int columnSize;

/**
* 小数位数
*/
private int decimalDigits;

/**
* 基数（通常是10或2）
*/
private int numPrecRadix;

/**
* 是否允许为null
*/
private int nullable;

/**
* 列描述
*/
private String remarks;

/**
* 默认值
*/
private String columnDef;

/**
* SQL日期时间分
*/
private int sqlDatetimeSub;

/**
* char类型的列中的最大字节数
*/
private int charOctetLength;

/**
* 表中列的索引（从1开始）
*/
private int ordinalPosition;
/**
* 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---如果参数为空性是未知的
*/
private String isNullable;

/**
* 指示此列是否自动增加 YES --- 如果该列自动增加 NO --- 如果该列不自动增加 空字符串 --- 如果不能确定该列是否是自动增加参数
*/
private String isAutoincrement;

public String getColumnName() {
return columnName;
}

public void setColumnName(String columnName) {
this.columnName = columnName;
}

public int getDataType() {
return dataType;
}

public void setDataType(int dataType) {
this.dataType = dataType;
}

public String getTypeName() {
return typeName;
}

public void setTypeName(String typeName) {
this.typeName = typeName;
}

public int getColumnSize() {
return columnSize;
}

public void setColumnSize(int columnSize) {
this.columnSize = columnSize;
}

public int getDecimalDigits() {
return decimalDigits;
}

public void setDecimalDigits(int decimalDigits) {
this.decimalDigits = decimalDigits;
}

public int getNumPrecRadix() {
return numPrecRadix;
}

public void setNumPrecRadix(int numPrecRadix) {
this.numPrecRadix = numPrecRadix;
}

public int getNullable() {
return nullable;
}

public void setNullable(int nullable) {
this.nullable = nullable;
}

public String getRemarks() {
return remarks;
}

public void setRemarks(String remarks) {
this.remarks = remarks;
}

public String getColumnDef() {
return columnDef;
}

public void setColumnDef(String columnDef) {
this.columnDef = columnDef;
}

public int getSqlDatetimeSub() {
return sqlDatetimeSub;
}

public void setSqlDatetimeSub(int sqlDatetimeSub) {
this.sqlDatetimeSub = sqlDatetimeSub;
}

public int getCharOctetLength() {
return charOctetLength;
}

public void setCharOctetLength(int charOctetLength) {
this.charOctetLength = charOctetLength;
}

public int getOrdinalPosition() {
return ordinalPosition;
}

public void setOrdinalPosition(int ordinalPosition) {
this.ordinalPosition = ordinalPosition;
}

public String getIsNullable() {
return isNullable;
}

public void setIsNullable(String isNullable) {
this.isNullable = isNullable;
}

public String getIsAutoincrement() {
return isAutoincrement;
}

public void setIsAutoincrement(String isAutoincrement) {
this.isAutoincrement = isAutoincrement;
}

}

package com.ai.generator.entity.sql;

public class SqlPrimaryKey {

/**
* 列名
*/
private String columnName;

/**
* 多列主键中列的序列号
*/
private short keySeq;

/**
* 主键的名称
*/
private String pkName;

public String getColumnName() {
return columnName;
}

public void setColumnName(String columnName) {
this.columnName = columnName;
}

public short getKeySeq() {
return keySeq;
}

public void setKeySeq(short keySeq) {
this.keySeq = keySeq;
}

public String getPkName() {
return pkName;
}

public void setPkName(String pkName) {
this.pkName = pkName;
}

}

SqlManage.java封装了一些对数据库的操作

package com.ai.generator.service.manage;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.ai.generator.entity.sql.SqlColumn;
import com.ai.generator.entity.sql.SqlPrimaryKey;
import com.ai.generator.entity.sql.SqlTable;
import com.ai.generator.util.PropertiesUtil;

public class SqlManage {

private static Logger logger = LoggerFactory.getLogger(SqlManage.class);

private Connection connection;

private DatabaseMetaData databaseMetaData;

public SqlManage(ConfigManage configManage) {
if (connection == null) {
synchronized (this) {
if (connection == null) {
initialize(configManage.getJdbcConfig());
}
}
}
}

/**
* 创建JDBC
*/
private void initialize(String jdbcConfigPath) {

Properties properties = null;
4000
try {
properties = PropertiesUtil.loadProperties(jdbcConfigPath);
} catch (IOException e) {
logger.error("加载jdbc配置文件失败");
}

if (properties == null || properties.isEmpty()) {
logger.error("未加载到jdbc配置文件");
}

try {
Class.forName(properties.getProperty("driver"));
if (connection == null || connection.isClosed()) {
connection = DriverManager.getConnection(
properties.getProperty("url"), properties);

databaseMetaData = connection.getMetaData();
}
} catch (SQLException | ClassNotFoundException e) {
logger.error("连接数据库失败,请检查驱动或jdbc配置后在试");
}

}

/**
* 获取所有表
*/
public List<SqlTable> getTables() {
logger.debug("获取所有表");
List<SqlTable> list = new ArrayList<SqlTable>();
try {
ResultSet result = databaseMetaData.getTables(
connection.getCatalog(), null, "%", null);
while (result.next()) {
SqlTable table = new SqlTable();
table.setSqlTableName(result.getString("TABLE_NAME"));
table.setSqlTableRemarks(result.getString("REMARKS"));
list.add(table);
}
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}

/**
* 获取表主键
*/
public SqlPrimaryKey getPrimaryKeys(SqlTable table) throws Exception {
logger.debug("获取表主键");
List<SqlPrimaryKey> list = new ArrayList<SqlPrimaryKey>();
try {
ResultSet result = databaseMetaData.getPrimaryKeys(
connection.getCatalog(), null, table.getSqlTableName());
while (result.next()) {
SqlPrimaryKey primaryKey = new SqlPrimaryKey();
primaryKey.setColumnName(result.getString("COLUMN_NAME"));
primaryKey.setKeySeq(result.getShort("KEY_SEQ"));
primaryKey.setPkName(result.getString("PK_NAME"));
list.add(primaryKey);
}
result.close();
} catch (SQLException e) {
e.printStackTrace();
}
if (list == null || list.size() > 1) {
logger.error("表没有主键或者复合主键,请检查表主键");
throw new Exception("表没有主键或者复合主键,请检查表主键");
}
return list == null || list.isEmpty() ? null : list.get(0);
}

/**
* 获取表的所有列
*/
public List<SqlColumn> getColumns(SqlTable table) {
logger.debug("获取表的所有列");
List<SqlColumn> list = new ArrayList<SqlColumn>();
try {
ResultSet rs = databaseMetaData.getColumns(connection.getCatalog(),
null, table.getSqlTableName(), "%");
while (rs.next()) {
SqlColumn column = new SqlColumn();

column.setColumnName(rs.getString("COLUMN_NAME"));
column.setDataType(rs.getInt("DATA_TYPE"));
column.setTypeName(rs.getString("TYPE_NAME"));
column.setColumnSize(rs.getInt("COLUMN_SIZE"));
column.setDecimalDigits(rs.getInt("DECIMAL_DIGITS"));
column.setNumPrecRadix(rs.getInt("NUM_PREC_RADIX"));
column.setNullable(rs.getInt("NULLABLE"));
column.setRemarks(rs.getString("REMARKS"));
column.setColumnDef(rs.getString("COLUMN_DEF"));
column.setSqlDatetimeSub(rs.getInt("SQL_DATETIME_SUB"));
column.setCharOctetLength(rs.getInt("CHAR_OCTET_LENGTH"));
column.setOrdinalPosition(rs.getInt("ORDINAL_POSITION"));
column.setIsNullable(rs.getString("IS_NULLABLE"));
column.setIsAutoincrement(rs.getString("IS_AUTOINCREMENT"));

list.add(column);
}
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}

}

实体类上的注释都很清楚。