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155 lines
4.8 KiB
155 lines
4.8 KiB
#include "leveldb/db.h"
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#include <iostream>
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#include <sstream>
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#include <vector>
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#include <string>
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#include <cassert>
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using namespace std;
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using namespace leveldb;
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// 定义字段类型别名
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using Field = std::pair<std::string, std::string>;
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using FieldArray = std::vector<Field>;
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// 二进制序列化函数
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std::string SerializeValue(const FieldArray& fields) {
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std::ostringstream oss;
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uint32_t num_fields = fields.size();
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// 写入字段数量
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oss.write(reinterpret_cast<const char*>(&num_fields), sizeof(num_fields));
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// 写入每个字段的长度和内容
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for (const auto& field : fields) {
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uint32_t name_length = field.first.size();
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uint32_t value_length = field.second.size();
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// 写入字段名长度和字段名
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oss.write(reinterpret_cast<const char*>(&name_length), sizeof(name_length));
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oss.write(field.first.data(), name_length);
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// 写入字段值长度和字段值
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oss.write(reinterpret_cast<const char*>(&value_length), sizeof(value_length));
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oss.write(field.second.data(), value_length);
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}
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return oss.str();
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}
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// 二进制反序列化函数
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FieldArray ParseValue(const std::string& value_str) {
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FieldArray fields;
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std::istringstream iss(value_str);
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uint32_t num_fields = 0;
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iss.read(reinterpret_cast<char*>(&num_fields), sizeof(num_fields)); // 读取字段数量
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for (uint32_t i = 0; i < num_fields; ++i) {
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uint32_t name_length = 0, value_length = 0;
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// 读取字段名长度和字段名
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iss.read(reinterpret_cast<char*>(&name_length), sizeof(name_length));
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std::string field_name(name_length, '\0');
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iss.read(&field_name[0], name_length);
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// 读取字段值长度和字段值
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iss.read(reinterpret_cast<char*>(&value_length), sizeof(value_length));
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std::string field_value(value_length, '\0');
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iss.read(&field_value[0], value_length);
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fields.emplace_back(field_name, field_value);
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}
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return fields;
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}
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// 查询函数：根据字段查找所有包含该字段的 Key
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std::vector<std::string> FindKeysByField(leveldb::DB* db, const Field& field) {
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std::vector<std::string> keys;
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Iterator* it = db->NewIterator(ReadOptions());
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for (it->SeekToFirst(); it->Valid(); it->Next()) {
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std::string key = it->key().ToString();
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std::string value = it->value().ToString();
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FieldArray fields = ParseValue(value);
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// 查找是否有匹配的字段
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for (const auto& f : fields) {
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if (f.first == field.first && f.second == field.second) {
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keys.push_back(key);
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break;
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}
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}
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}
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delete it;
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return keys;
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}
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int main() {
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// 创建 LevelDB 数据库
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DB* db = nullptr;
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Options op;
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op.create_if_missing = true;
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Status status = DB::Open(op, "testdb", &db);
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assert(status.ok());
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// 插入两条数据，包含多个字段
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FieldArray fields1 = {
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{"name", "Customer#000000001"},
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{"address", "IVhzIApeRb"},
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{"phone", "25-989-741-2988"}
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};
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db->Put(WriteOptions(), "k_1", SerializeValue(fields1));
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FieldArray fields2 = {
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{"name", "Customer#000000002"},
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{"address", "N3qjPOETGc"},
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{"phone", "12-345-678-9012"}
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};
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db->Put(WriteOptions(), "k_2", SerializeValue(fields2));
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// 插入带有特殊字符的字段
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FieldArray fields3 = {
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{"name", "Customer=000000003"},
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{"address", "N3qj;POETGc"},
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{"phone", "12-345-678-9012"}
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};
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db->Put(WriteOptions(), "k_3", SerializeValue(fields3));
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// 读取并反序列化数据
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string value_ret1, value_ret2, value_ret3;
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db->Get(ReadOptions(), "k_1", &value_ret1);
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db->Get(ReadOptions(), "k_2", &value_ret2);
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db->Get(ReadOptions(), "k_3", &value_ret3);
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cout << "Deserialized fields for key k_1:" << endl;
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for (const auto& field : ParseValue(value_ret1)) {
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cout << field.first << ": " << field.second << endl;
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}
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cout << "\nDeserialized fields for key k_2:" << endl;
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for (const auto& field : ParseValue(value_ret2)) {
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cout << field.first << ": " << field.second << endl;
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}
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cout << "\nDeserialized fields for key k_3:" << endl;
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for (const auto& field : ParseValue(value_ret3)) {
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cout << field.first << ": " << field.second << endl;
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}
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// 查询功能测试：查找所有 name = "Customer#000000001" 的 key
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Field search_field = {"name", "Customer#000000001"};
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auto keys = FindKeysByField(db, search_field);
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// 输出查询结果
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cout << "\nFound keys for field " << search_field.first << " = " << search_field.second << ":" << endl;
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for (const auto& key : keys) {
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cout << key << endl;
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}
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delete db;
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return 0;
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}
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