mysql日期加流水号为主键_日期流水号主键生成器

最新推荐文章于 2024-01-11 15:49:46 发布

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最新推荐文章于 2024-01-11 15:49:46 发布

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文章标签： mysql日期加流水号为主键

本文链接：https://blog.youkuaiyun.com/weixin_33487811/article/details/113555307

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该博客介绍了一个实现MySQL中日期加流水号作为主键的生成器类`DateSeqGenerator`，该类继承自`IdentifierGenerator`并实现了`Configurable`接口。它通过配置参数获取表名、列名、长度等信息，并根据当前日期和最大流水号生成唯一的主键。类内部包含了从数据库获取当前日期、最大标识和生成新标识的方法。

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public class DateSeqGenerator implements IdentifierGenerator,

Configurable {

// logger

private static final Log log = LogFactory.getLog(DateSeqGenerator.class);

// reference to the underlying generator to which we delegate the work

private String currentDate = "";

//上次生成标识的日期前缀

private long day;

//下一个Sequence值

private long next;

//末位序号的位数限制

private int length = 4;

//从数据库获取当前最大标识的Sql语句

private String sql;

//标识返回值的JAVA类别

private Class returnClass;

/**

* Construct a new DateSeqGenerator

public DateSeqGenerator() {

super();

}

/* (non-Javadoc)

* @see org.hibernate.id.IdentifierGenerator#generate(org.hibernate.engine.SessionImplementor, java.lang.Object)

public Serializable generate(SessionImplementor session, Object object)

throws SQLException, HibernateException

{

if (sql!=null) {

getNext( session );

}

long currentDay = getCurrentDay();

if(currentDay != day){

day = currentDay;

next = 1l;

}

return IdentifierGeneratorFactory.createNumber(day * Math.pow(10l,length) + (next++), returnClass);

}

/* (non-Javadoc)

* @see org.hibernate.id.Configurable#configure(org.hibernate.type.Type, java.util.Properties, org.hibernate.dialect.Dialect)

public void configure(Type type, Properties params, Dialect dialect)

throws MappingException

{

String tableList = params.getProperty("tables");

if (tableList==null) tableList = params.getProperty(PersistentIdentifierGenerator.TABLES);

String[] tables = StringHelper.split(", ", tableList);

String column = params.getProperty("column");

if (column==null) column = params.getProperty(PersistentIdentifierGenerator.PK);

String numLength = params.getProperty("length");

if(numLength == null)

length = 4;

else

length = Integer.parseInt(numLength);

String schema = params.getProperty(PersistentIdentifierGenerator.SCHEMA);

String catalog = params.getProperty(PersistentIdentifierGenerator.CATALOG);

returnClass = type.getReturnedClass();

StringBuffer buf = new StringBuffer();

for ( int i=0; i

if (tables.length>1) {

buf.append("select ").append(column).append(" from ");

}

buf.append( Table.qualify(catalog, schema, tables[i], d.getSchemaSeparator() ) );

if ( i

}

if (tables.length>1) {

buf.insert(0, "( ").append(" ) ids_");

column = "ids_." + column;

}

sql = "select max(" + column + ") from " + buf.toString();

}

/**

* 从数据库检索已有数据标识的最大值

* @param session

* @return

//从数据库获取已有数据的最大ID标识，确定下一标识的值

private void getNext( SessionImplementor session ) {

Connection conn = session.connection();

log.debug("fetching initial value: " + sql);

try {

PersistentIdentifierGenerator.SQL.debug(sql);

PreparedStatement st = conn.prepareStatement(sql);

ResultSet rs = null;

try {

rs = st.executeQuery();

if ( rs.next() ) {

next = rs.getLong(1);

if ( rs.wasNull())

next = 1l;

else{

day = Long.parseLong(next.substring(0,8)) + 1; }

next = Long.parseLong((next + "").substring(8));

}

else {

next = 1l;

}

sql=null;

log.debug("first free id: " + next);

}

finally {

if (rs!=null) rs.close();

st.close();

}

catch (SQLException sqle) {

throw JDBCExceptionHelper.convert(

session.getFactory().getSQLExceptionConverter(),

sqle,

"could not fetch initial value",

sql

);

}

/**

* 从数据库服务器获取当前日期

* @return long 数据库当前日期，日期格式为'yyyymmdd'

private long getCurrentDay(){

String cDate = null;

/**此部分代码省略**/

/** 从数据库获取当前日期,返回格式为'yyyymmdd',“20060316”**/

return cDate;

}

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2011-09-15 11:18