简单LMDB用法

复制编译即可运行

简介：主要运用mdb_put/mdb_cursor_put  |mdb_get/mdb_cursor_get存取数据

makefile

all:g++ -o mdb_demo mdb_demo.cpp liblmdb.a -pthread//需要把liblmdb.a包包含进去，网上可以找到clean:rm -rf mdb_demo core

code

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <iostream>#include <string>#include "lmdb.h"//包含头文件using namespace std;const char *pMdbFilePath = "./MdbFile";//Mdb Classclass Mdb{public:Mdb(){cout << "Im Mdb Constuctor" << endl;}~Mdb(){cout << "Im Desructor" << endl;}//Create Mdb Env, Set Env Mapsize and Open Env bool InitMdbEnv(const char *pMdbFile, int nSize);//Open Mdb Filebool MdbOpen();//Open a Mdb Cursorbool MdbCursorOpen();//Put Data Into Mdb Filebool MdbPut(char* pkey, char* pValue);//Get Data From Mdb Filebool MdbGet(char* pkey, char* pData);//Using Cursor Get Data From Mdb Filebool MdbCursorGet(char* pKey, char *pData);//Using Cursor Restore Data Into Mdb Filebool MdbCursorPut(char* pKey, char* pData);//Transition Beginbool MdbTxnBegin();//Transition Commit, Current Transiton endbool MdbTxnCommit();//Transition Abortvoid MdbTxnAbort();//Mdb Cursor Handle Closevoid MdbCursorClose();//Mdb File Closevoid MdbClose();//Mdb Env Closevoid MdbEnvClose();private:MDB_env *env;MDB_dbi dbi;MDB_txn *txn;MDB_cursor *cursor;};void Mdb::MdbTxnAbort(){mdb_txn_abort(txn);return ;}void Mdb::MdbCursorClose(){mdb_cursor_close(cursor);return ;}bool Mdb::MdbCursorPut(char* pKey, char* pData){MDB_val key, data;key.mv_size = strlen(pKey)+1;key.mv_data = pKey;data.mv_size = strlen(pData)+1;data.mv_data = pData;if(mdb_cursor_put(cursor, &key, &data, MDB_NODUPDATA)) { cout << "MdbCursorPut Failed!!!" <<endl; return false; }return true;}bool Mdb::MdbCursorGet(char* pKey, char *pData){MDB_val key, data;key.mv_size = strlen(pKey)+1;key.mv_data = pKey;if(mdb_cursor_get(cursor, &key, &data, MDB_NEXT)) { cout << "mdb_cursor_get Failed Or No Data!!!" <<endl; return false; }strcpy(pData, (char*)data.mv_data);strcpy(pKey, (char*)key.mv_data);return true;}bool Mdb::MdbCursorOpen(){if(mdb_cursor_open(txn, dbi, &cursor)) { cout << "mdb_cursor_open Failed!!!" << endl; return false; }return true;}bool Mdb::InitMdbEnv(const char *pMdbFile, int nSize){int rc=(mdb_env_create(&env) ||mdb_env_set_mapsize(env, nSize) ||mdb_env_open(env, pMdbFile, 0, 0664));if(rc) { cout << "Initialize " << pMdbFile << "Mdb Fialed!!!" << endl; return false; }return true;}bool Mdb::MdbTxnBegin(){if(mdb_txn_begin(env, NULL, 0, &txn)) {cout << "mdb_open failed!!!" << endl; return false;}return true;}bool Mdb::MdbOpen(){if(mdb_open(txn, NULL, 0, &dbi)) {cout << "mdb_txn_beginfailed!!!" << endl; return false;}return true;}void Mdb::MdbClose(){mdb_close(env, dbi);return ;}void Mdb::MdbEnvClose(){mdb_env_close(env);return ;}bool Mdb::MdbPut(char* pKey, char* pData){MDB_val key, data;key.mv_size = strlen(pKey)+1;key.mv_data = pKey;data.mv_size = strlen(pData)+1;data.mv_data = pData;int rc = mdb_put(txn, dbi, &key, &data, MDB_NOOVERWRITE);if(rc == MDB_MAP_FULL) { cout << "Mdb File is full, Alert!!!" << endl; return false; }return true;}bool Mdb::MdbTxnCommit(){if(mdb_txn_commit(txn)) { cout << "mdb_txn_commit failed" << endl; return false; }return true;}bool Mdb::MdbGet(char* pKey, char* pData){MDB_val key, data;key.mv_size = strlen(pKey)+1;key.mv_data = pKey;if(mdb_get(txn, dbi, &key, &data)) { cout << "mdb_get failed!!!" << endl; return false; }strcpy(pData, (char*)data.mv_data);return true;}int main(int argc,char *argv[]){Mdb mdb; //Create a Mdb Objiectmdb.InitMdbEnv(pMdbFilePath, 200*1024*1024);//Initialize Mdb Env and Specifc Mdb File Max Sizemdb.MdbOpen();//Open a Mdb File//************mdb_put Restore Data*******************char cKey[10]="";char cValue[100]="Im value";mdb.MdbTxnBegin();//Begin a Transitionfor(int i=0; i<100; i++) {sprintf(cKey, "%06d", i);mdb.MdbPut(cKey, cValue);//mdb_put Restore Data}mdb.MdbTxnCommit();//Commit Transition//*****************************************************//************mdb_get Get items Form Database**********char cKey1[]="000002";char cValue1[100]="";mdb.MdbTxnBegin();mdb.MdbGet(cKey1, cValue1);mdb.MdbTxnCommit();cout << "Key:000002:" << cValue1 << endl;//*****************************************************//************mdb_cursor_put Using Cursor Restore Data*******char cKey2[10]="";char cValue2[100]="I m Cursor Values";mdb.MdbTxnBegin();mdb.MdbCursorOpen();for(int i=101; i<201; i++) {sprintf(cKey2, "%06d", i);mdb.MdbCursorPut(cKey2, cValue2);}mdb.MdbCursorClose();mdb.MdbTxnCommit();//***********************************************************//***********mdb_cursor_get Using Cursor Get Data************mdb.MdbTxnBegin();mdb.MdbCursorOpen();char cKey3[10]="";char cValue3[100]="";while (mdb.MdbCursorGet(cKey3, cValue3)) {cout << "Key: " << cKey3 << "    data: " << cValue3 << endl;}mdb.MdbCursorClose();mdb.MdbTxnAbort();//***********************************************************mdb.MdbClose();//Close Mdb Filemdb.MdbEnvClose();//Close Mdb Envreturn 0;}