leveldb

LevelDB在windows平台下的编译很麻烦，但是在linux中，安装和编译过程非常简单，主要步骤如下：

下载源码：

 https://code.google.com/p/leveldb/

LevelDB编译 

下载完成后，进入leveldb目录，使用make指令进行源码编译。

• cd leveldb    
• make all 

此时，leveldb目录内会生成libleveldb.a文件，然后将/include/leveldb目录内头文件全部复制到系统头文件目录/usr/include下

     cp -r ./include/leveldb /usr/include/

安装完毕。

LevelDB测试程序

#include <assert.h>                                                               
#include <string>                                                                 
#include <leveldb/db.h>                                                        
#include <iostream>     
#include "leveldb/write_batch.h"
                                                          
                                                                                  
                                                                                  
int main()                                                                        
{                                                                                 
    // Open a database                                                            
    leveldb::DB* db;                                                              
    leveldb::Options options;                                                     
    options.create_if_missing = true;                                             
    leveldb::Status status = leveldb::DB::Open(options, "/tmp/testdb", &db);      
    assert(status.ok());                                                          
                                                                                  
    // Write <key1, value1>                                                       
    const int WRITE_TIMES = 10000;                                                
    int i = 0;                                                                    
    std::string key = "key";                                                      
    std::string value = "value";                                                  
    status = db->Put(leveldb::WriteOptions(), key, value);                        
    assert(status.ok());   
                                                  
    status = db->Put(leveldb::WriteOptions(), "testkey", "testValue");                                                          
                                                                                  
    // Read value1 by key1                                                        
    status = db->Get(leveldb::ReadOptions(), key, &value);                        
    assert(status.ok());                                                          
    std::cout << value << std::endl;  
        
    status = db->Get(leveldb::ReadOptions(), "testkey", &value);                        
    assert(status.ok());                                                          
    std::cout << value << std::endl;  
        
    leveldb::Slice msg1=leveldb::Slice("testkey");  

    status = db->Delete(leveldb::WriteOptions(), msg1);           
    if(status.ok())   
        std::cout<<"success delete the key of testkey"<<std::endl;      
        
    status = db->Get(leveldb::ReadOptions(), "testkey", &value);                        
    if(status.ok())
    {                                                           
        std::cout << value << std::endl;  
    }
    else
    {
        std::cout<<"cannot get the key of testkey"<<std::endl;  
    }       
    
                                   
    std::cout<<"Add some records into this leveldb."<<std::endl;  
    leveldb::WriteBatch batch;
    batch.Put("2013-0", "20132014-0");
    batch.Put("2013-1", "20132014-1");
    batch.Put("2013-2", "20132014-2");
    batch.Put("2013-3", "20132014-3");
    batch.Put("2013-4", "20132014-4");
    batch.Put("2013-5", "20132014-5");
    batch.Put("2013-6", "20132014-6");
    batch.Put("2013-7", "20132014-7");
      status = db->Write(leveldb::WriteOptions(), &batch);
    if(status.ok())
    {                                                           
        std::cout << "batch write many records success." << std::endl;  
    }
    else
    {
        std::cout<<"batch write many records failed."<<std::endl;  
    }    
          
        
    std::cout<<"It's time to print all information about this leveldb."<<std::endl;      
    leveldb::Iterator* it = db->NewIterator(leveldb::ReadOptions());
    for (it->SeekToFirst(); it->Valid(); it->Next()) 
    {
      std::cout << it->key().ToString() << ": "  << it->value().ToString() << std::endl;
    }
                                                                          
    // Delete databse                                                             
    delete db;                                                                    
                                                                                  
    return 0;                                                                     
}                                                                                 

 

运行结果：

 

参考文献：

http://blog.csdn.net/cszhangchao/article/details/25245759

http://blog.csdn.net/cszhangchao/article/details/25340827

http://blog.csdn.net/dyllove98/article/details/9412763

http://www.cnblogs.com/haippy/archive/2011/12/04/2276064.html

http://dirlt.com/leveldb.html#sec-1-1