0x01 问题
PreparedStatement stmt = conn.prepareStatement(sql);
...
stmt.executeBatch();
stmt.close();
conn.commit();
这么写数据无法持久化。
0x02 原因
@Override
public void close() throws SQLException {
MySQLConnection locallyScopedConn = this.connection;
if (locallyScopedConn == null) {
return; // already closed
}
synchronized (locallyScopedConn.getConnectionMutex()) {
if (this.isCached && isPoolable() && !this.isClosed) {
clearParameters();
this.isClosed = true;
this.connection.recachePreparedStatement(this);
return;
}
this.isClosed = false;
realClose(true, true);
}
}
// clearParameters内部调用
private void clearParametersInternal(boolean clearServerParameters) throws SQLException {
boolean hadLongData = false;
if (this.parameterBindings != null) {
for (int i = 0; i < this.parameterCount; i++) {
if ((this.parameterBindings[i] != null) && this.parameterBindings[i].isLongData) {
hadLongData = true;
}
this.parameterBindings[i].reset();
}
}
if (clearServerParameters && hadLongData) {
// server端也重置该statement
serverResetStatement();
this.detectedLongParameterSwitch = false;
}
}
实际上PrepareStatement的close方法会先清空Params，然后再缓存该statement。
0x03 解决办法
删除该close语句即可。