自动分表

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Date;

public abstract class AIPkCountSplitTable<T> {
public abstract T mapRsRow(ResultSet rs) throws SQLException;
public abstract boolean createTable(Connection con, int autokeyStart) throws SQLException;

private String tableName;
private String pkColName;
private int splitCount;

public String getTableName() {
return tableName;
}
public void setTableName(String tableName) {
this.tableName = tableName;
}
public String getPkColName() {
return pkColName;
}
public void setPkColName(String pkColName) {
this.pkColName = pkColName;
}
public int getSplitCount() {
return splitCount;
}
public void setSplitCount(int splitCount) {
this.splitCount = splitCount;
}

private void setStmtArg(PreparedStatement prepStatement, Object[] params) throws SQLException
{
if(null == params)
return;
for(int i = 0; i < params.length; ++i)
{
Object param = params[i];
if (param instanceof Integer) {
int value = ((Integer) param).intValue();
prepStatement.setInt(i + 1, value);
} else if (param instanceof String) {
String s = (String) param;
prepStatement.setString(i + 1, s);
} else if (param instanceof Double) {
double d = ((Double) param).doubleValue();
prepStatement.setDouble(i + 1, d);
} else if (param instanceof Float) {
float f = ((Float) param).floatValue();
prepStatement.setFloat(i + 1, f);
} else if (param instanceof Long) {
long l = ((Long) param).longValue();
prepStatement.setLong(i + 1, l);
} else if (param instanceof Boolean) {
boolean b = ((Boolean) param).booleanValue();
prepStatement.setBoolean(i + 1, b);
} else if (param instanceof Date) {
Date d = (Date) param;
prepStatement.setDate(i+1, new java.sql.Date(d.getTime()));
}
}
}

private boolean renameTable(Connection con, int tbIdx) throws SQLException{
String newTableName = tableName + tbIdx;
String sql = "RENAME TABLE " + tableName + " TO " + newTableName;
Statement st = con.createStatement();
st.executeUpdate(sql);
return true;
}
private int  selectMaxId(Connection con) throws SQLException{
int maxId = -1;
String sql = "SELECT MAX("+ pkColName +") FROM " + tableName;
PreparedStatement st = con.prepareStatement(sql);
ResultSet rs = st.executeQuery(sql);
if(rs.next())
maxId = rs.getInt(1);
rs.close();
return maxId;
}
private int  selectCount(Connection con, String tbname,
String sqlWhere, Object[] args) throws SQLException
{
int cnt = 0;
String sql = "SELECT COUNT(*) FROM " + tbname + " " + sqlWhere;
PreparedStatement st = con.prepareStatement(sql);
this.setStmtArg(st, args);
ResultSet rs = st.executeQuery(sql);
if(rs.next())
cnt = rs.getInt(1);
rs.close();
return cnt;
}
public boolean deleteById(Connection con, int id) throws SQLException
{
try{
String sql = "DELETE FROM " + tableName + " WHERE " + pkColName + "=?";
PreparedStatement st = con.prepareStatement(sql);
st.setInt(1, id);
if(1 == st.executeUpdate())
return true;
}catch(SQLException ex){}
int idx = id / splitCount;
String acTableName = this.tableName + idx;
String sql2 = "DELETE FROM " + acTableName + " WHERE " + pkColName + "=?";
PreparedStatement st2 = con.prepareStatement(sql2);
st2.setInt(1, id);
if(1 == st2.executeUpdate())
return true;
return false;
}
// where xxx=? and yyy=?
public int delete(Connection con, String sqlWhere, Object[] args) throws SQLException
{
int nupdate = 0;
int maxId = selectMaxId(con);
int tableIdx = maxId / splitCount;
++tableIdx;
for(int i = 0 ; i < tableIdx; ++i){
String subTableName = "";
if(i == tableIdx-1)
subTableName = this.tableName;
else
subTableName = this.tableName + i;
String sql = "DELETE FROM " + subTableName + " " +  sqlWhere;
PreparedStatement st = con.prepareStatement(sql);
this.setStmtArg(st, args);
nupdate += st.executeUpdate();
}
return nupdate;
}
private boolean innerInsert(Connection con, PreparedStatement insStmt, T value,
PreparedStmtParamSetter<T> paramSetter) throws SQLException
{
int id = -1;
paramSetter.setParams(insStmt, value);
if(1 == insStmt.executeUpdate()){
ResultSet keys = insStmt.getGeneratedKeys();
if(keys.next()){
Integer generatedId = keys.getInt(1);
id = generatedId.intValue();
}else{ return false;}
}else{ return false;}

// 达到分表灵界先删除插入成功的，从旧表中删除，生成新表在插入
// 保证新建的表中有一条数据，select Max(pk) 才管用
if(0 == id % this.splitCount){
String delSql = "DELETE FROM " + this.tableName + " WHERE " + this.pkColName + "=" + id;
Statement delStmt = con.createStatement();
if(1 != delStmt.executeUpdate(delSql))
return false;
// 从0开始命名表，才能用 id/splitCount直接做表名索引 1999/2000 ＝ 0, 2000/2000=1,2000在表1中
int tbIdx = id / splitCount - 1 ;
renameTable(con, tbIdx);
createTable(con, id);
paramSetter.setParams(insStmt, value);
if(1 == insStmt.executeUpdate()){
ResultSet keys = insStmt.getGeneratedKeys();
if(keys.next()){
Integer generatedId = keys.getInt(1);
id = generatedId.intValue();
}else{ return false;}
}else{ return false;}
}
paramSetter.setId(value, id);
return true;
}
//" (col1, col2) values(?, 1,?)"
public boolean insert(Connection con, String sql, T value, PreparedStmtParamSetter<T> paramSetter)
throws SQLException{
String insSql = "INSERT INTO " + this.tableName + sql;
PreparedStatement insStmt = con.prepareStatement(insSql,Statement.RETURN_GENERATED_KEYS);
return innerInsert(con, insStmt, value, paramSetter);
}
public boolean insertBatch(Connection con, String sql, List<T> values,
PreparedStmtParamSetter<T> paramSetter) throws SQLException
{
if(null == values || values.size() == 0)
return true;
String insSql = "INSERT INTO " + this.tableName + sql;
PreparedStatement insStmt = con.prepareStatement(insSql,Statement.RETURN_GENERATED_KEYS);
for(int i = 0; i < values.size(); ++i)
{
T value = values.get(i);
if(!innerInsert(con, insStmt, value, paramSetter))
return false;
}
return true;
}
private List<T> innerSelectAll(Connection con, String sqlWhere, Object[] args, int startTbIdx)
throws SQLException
{
// 5999/2000 = 2,以前有0,1两张表
int maxId = selectMaxId(con);
int tableIdx = maxId / splitCount;
++tableIdx; // 加成3，表名索引为2，就是当前表了，便于在一个循环中处理完
List<T> elems = new ArrayList<T>();
for(int i = startTbIdx ; i < tableIdx; ++i){
String subTableName = "";
if(i == tableIdx-1)
subTableName = this.tableName;
else
subTableName = this.tableName + i;
String sql = "SELECT * FROM " + subTableName + " " + sqlWhere;
PreparedStatement st = con.prepareStatement(sql);
this.setStmtArg(st, args);
ResultSet rs = st.executeQuery();
while(rs.next()){
elems.add(mapRsRow(rs));
}
rs.close();
}
return elems;
}
// where xx=?
public List<T> select(Connection con, String sqlWhere, Object[] args) throws SQLException
{
return innerSelectAll(con, sqlWhere, args, 0);
}
// 15 30 20 45
public List<T> selectPage(Connection con, String sqlWhere, Object[] args, int offset, int limit)
throws SQLException
{
int maxId = selectMaxId(con);
int tableIdx = maxId / splitCount;
++tableIdx;
List<T> elems = new ArrayList<T>();
int startTbIdx = tableIdx;
int offsetCnt = 0;
// 找到偏移起始表索引
if(0 != offset){
for(int i = 0 ; i < tableIdx; ++i){
String subTableName = "";
if(i == tableIdx-1)
subTableName = this.tableName;
else
subTableName = this.tableName + i;
int cnt = this.selectCount(con, subTableName, sqlWhere, args);
offsetCnt += cnt;
// 累计条数，0-i个表中的条数超过offset，说明要从第i个表开始偏移
if(offsetCnt > offset){
// offset 减去 0到i－1的总条数，就是在当前表中的偏移
offset = offset - (offsetCnt-cnt);
startTbIdx = i;
break;
}
}
}
if(startTbIdx >= tableIdx)
return elems;
if(-1 == limit)
return innerSelectAll(con, sqlWhere, args, startTbIdx);
int newLimit = limit;
for(int i = startTbIdx ; i < tableIdx; ++i){
String subTableName = "";
if(i == tableIdx-1)
subTableName = this.tableName;
else
subTableName = this.tableName + i;
String sql = "SELECT * FROM " + subTableName + " " + sqlWhere + "LIMIT " + offset + "," + newLimit;
PreparedStatement st = con.prepareStatement(sql);
this.setStmtArg(st, args);
ResultSet rs = st.executeQuery();
while(rs.next()){
elems.add(mapRsRow(rs));
--newLimit;
}
rs.close();
offset = 0; // 只是第一张需要偏移
if(newLimit <= 0) // never less than
break;
}
return elems;
}

public T selectById(Connection con, int id) throws SQLException{
T elem = null;
String sql = "SELECT * FROM " + this.tableName + " WHERE " + this.pkColName + "=?";
PreparedStatement st = con.prepareStatement(sql);
st.setInt(1, id);
ResultSet rs = st.executeQuery();
if(rs.next())
elem = mapRsRow(rs);
rs.close();
if(null != elem)
return elem;
int idx = id / splitCount;
String acTableName = this.tableName + idx;
String sql2 = "SELECT * FROM " + acTableName + " WHERE " + this.pkColName + "=?";
PreparedStatement st2 = con.prepareStatement(sql2);
st2.setInt(1, id);
ResultSet rs2 = st2.executeQuery();
if(rs2.next())
elem = mapRsRow(rs2);
rs2.close();
return elem;
}
// set xx=?, yy=?
public boolean updateById(Connection con, String setSql, Object[] args, int id) throws SQLException
{
try{
String sql1 = "UPDATE " + this.tableName + " " + setSql + " WHERE " + this.pkColName + "=?";
PreparedStatement st1 = con.prepareStatement(sql1);
this.setStmtArg(st1, args);
st1.setInt(args.length+1, id);
if(1 == st1.executeUpdate())
return true;
}catch(SQLException e){}

int idx = id / splitCount;
String acTableName = this.tableName + idx;

String sql2 = "UPDATE " + acTableName + " "+ setSql + " WHERE " + this.pkColName + "=?";
PreparedStatement st2 = con.prepareStatement(sql2);
this.setStmtArg(st2, args);
st2.setInt(args.length+1, id);
if(1 == st2.executeUpdate())
return true;
return false;
}
// set xx=?, yy =? where cc=? and zz=2
public int update(Connection con, String setSql, Object[] args) throws SQLException
{
int nupdate = 0;
int maxId = selectMaxId(con);
int tableIdx = maxId / splitCount;
++tableIdx;
for(int i = 0 ; i < tableIdx; ++i){
String subTableName = "";
if(i == tableIdx-1)
subTableName = this.tableName;
else
subTableName = this.tableName + i;
String sql = "UPDATE " + subTableName + " " +  setSql;
PreparedStatement st = con.prepareStatement(sql);
this.setStmtArg(st, args);
nupdate += st.executeUpdate();
}
return nupdate;
}
}