序
本文主要研究一下langchain4j的Web Search Engine
步骤
pom.xml
dev.langchain4j
langchain4j-web-search-engine-searchapi
1.0.0-beta2
example
@Test
public void testSearchEngine() {
SearchApiWebSearchEngine searchEngine = SearchApiWebSearchEngine.builder()
.apiKey(System.getenv("SEARCH_API_KEY"))
.engine("baidu")
.build();
WebSearchTool webTool = WebSearchTool.from(searchEngine);
Assistant assistant = AiServices.builder(Assistant.class)
.chatLanguageModel(model)
.tools(webTool)
.chatMemory(MessageWindowChatMemory.withMaxMessages(10))
.build();
String result = assistant.search("今天日期是哪一天");
System.out.println(result);
}输出如下：
根据搜索结果，今天的日期为2025年3月25日（星期二），在农历中则是2025年二月廿六。
更多详细信息您可以访问以下网站：
- [易灵算命网](http://old.d02.cn/suanming/nongli.php)
- [今天几号网](https://www.jintianjihao.com/)
- [快乐日历 - 今天什么日子,今天星期几,农历几月几日@快乐家园](http://www.joyurl.cn/)源码
WebSearchEngine
dev/langchain4j/web/search/WebSearchEngine.java
public interface WebSearchEngine {
/**
* Performs a search query on the web search engine and returns the search results.
*
* @param query the search query
* @return the search results
*/
default WebSearchResults search(String query) {
return search(WebSearchRequest.from(query));
}
/**
* Performs a search request on the web search engine and returns the search results.
*
* @param webSearchRequest the search request
* @return the web search results
*/
WebSearchResults search(WebSearchRequest webSearchRequest);
}langchain4j定义了WebSearchEngine接口，它定义了search方法，根据WebSearchRequest返回WebSearchResults
WebSearchRequest
dev/langchain4j/web/search/WebSearchRequest.java
public class WebSearchRequest {
private final String searchTerms;
private final Integer maxResults;
private final String language;
private final String geoLocation;
private final Integer startPage;
private final Integer startIndex;
private final Boolean safeSearch;
private final Map additionalParams;
private WebSearchRequest(Builder builder){
this.searchTerms = ensureNotBlank(builder.searchTerms,"searchTerms");
this.maxResults = builder.maxResults;
this.language = builder.language;
this.geoLocation = builder.geoLocation;
this.startPage = getOrDefault(builder.startPage,1);
this.startIndex = builder.startIndex;
this.safeSearch = getOrDefault(builder.safeSearch,true);
this.additionalParams = getOrDefault(builder.additionalParams, () -> new HashMap<>());
}
//......
} WebSearchRequest定义了searchTerms、maxResults、language、geoLocation、startPage、startIndex、safeSearch、additionalParams属性
WebSearchResults
dev/langchain4j/web/search/WebSearchResults.java
public class WebSearchResults {
private final Map searchMetadata;
private final WebSearchInformationResult searchInformation;
private final List results;
/**
* Constructs a new instance of WebSearchResults.
*
* @param searchInformation The information about the web search.
* @param results The list of organic search results.
*/
public WebSearchResults(WebSearchInformationResult searchInformation, List results) {
this(null, searchInformation, results);
}
/**
* Constructs a new instance of WebSearchResults.
*
* @param searchMetadata The metadata associated with the web search.
* @param searchInformation The information about the web search.
* @param results The list of organic search results.
*/
public WebSearchResults(Map searchMetadata, WebSearchInformationResult searchInformation, List results) {
this.searchMetadata = searchMetadata;
this.searchInformation = ensureNotNull(searchInformation, "searchInformation");
this.results = results;
}
//......
} WebSearchResults定义了searchMetadata、searchInformation、results属性
SearchApiWebSearchEngine
dev/langchain4j/web/search/searchapi/SearchApiWebSearchEngine.java
public class SearchApiWebSearchEngine implements WebSearchEngine {
private static final String DEFAULT_BASE_URL = "https://www.searchapi.io";
private static final String DEFAULT_ENGINE = "google";
private final String apiKey;
private final String engine;
private final SearchApiClient client;
private final Map optionalParameters;
/**
* @param apiKey Required - the Search API key for accessing their API
* @param baseUrl overrides the default SearchApi base url
* @param timeout the timeout duration for API requests
*
* Default value is 30 seconds.
* @param engine the engine used by Search API to execute the search
*
* Default engine is Google Search.
* @param optionalParameters parameters to be passed on every request of this the engine, they can be overridden by the WebSearchRequest additional parameters for matching keys
*
* Check Search API for more information on available parameters for each engine
*/
@Builder
public SearchApiWebSearchEngine(String apiKey,
String baseUrl,
Duration timeout,
String engine,
Map optionalParameters) {
this.apiKey = ensureNotBlank(apiKey, "apiKey");
this.engine = getOrDefault(engine, DEFAULT_ENGINE);
this.optionalParameters = getOrDefault(copyIfNotNull(optionalParameters), new HashMap<>());
this.client = SearchApiClient.builder()
.timeout(getOrDefault(timeout, ofSeconds(30)))
.baseUrl(getOrDefault(baseUrl, DEFAULT_BASE_URL))
.build();
}
/**
* @param webSearchRequest Check Search API for more information on available additional
* parameters for each engine that can be inside the request
*/
@Override
public WebSearchResults search(WebSearchRequest webSearchRequest) {
SearchApiWebSearchRequest request = SearchApiWebSearchRequest.builder()
.apiKey(apiKey)
.engine(engine)
.query(webSearchRequest.searchTerms())
.optionalParameters(optionalParameters)
.additionalRequestParameters(webSearchRequest.additionalParams())
.build();
SearchApiWebSearchResponse response = client.search(request);
return toWebSearchResults(response);
}
private WebSearchResults toWebSearchResults(SearchApiWebSearchResponse response) {
List organicResults = response.getOrganicResults();
Long totalResults = getTotalResults(response.getSearchInformation());
WebSearchInformationResult searchInformation = WebSearchInformationResult.from(
totalResults,
getCurrentPage(response.getPagination()),
null
);
Map searchMetadata = getOrDefault(response.getSearchParameters(), new HashMap<>());
addToMetadata(searchMetadata, response.getSearchMetadata());
return WebSearchResults.from(
searchMetadata,
searchInformation,
toWebSearchOrganicResults(organicResults));
}
private static long getTotalResults(Map searchInformation) {
if (searchInformation != null && searchInformation.containsKey("total_results")) {
Object totalResults = searchInformation.get("total_results");
return totalResults instanceof Integer
? ((Integer) totalResults).longValue()
: (Long) totalResults; // changes depending on the amount of total_results
}
return 0;
}
private Integer getCurrentPage(Map pagination) {
if (pagination != null && pagination.containsKey("current")) {
return (Integer) pagination.get("current");
}
return null;
}
private void addToMetadata(Map metadata, Map dataToAdd) {
if (dataToAdd != null) {
metadata.putAll(dataToAdd);
}
}
private List toWebSearchOrganicResults(List organicResults) {
return organicResults.stream()
.map(result -> {
Map metadata = new HashMap<>(2);
metadata.put("position", result.getPosition());
return WebSearchOrganicResult.from(
result.getTitle(),
URI.create(result.getLink()),
getOrDefault(result.getSnippet(), ""),
null, // by default google custom search api does not return content
metadata);
})
.collect(Collectors.toList());
}
public static WebSearchEngine withApiKey(String apiKey) {
return builder().apiKey(apiKey).build();
}
}
SearchApiWebSearchEngine实现了WebSearchEngine，它通过SearchApiClient去请求Search API
WebSearchTool
dev/langchain4j/web/search/WebSearchTool.java
public class WebSearchTool {
private final WebSearchEngine searchEngine;
public WebSearchTool(WebSearchEngine searchEngine) {
this.searchEngine = ensureNotNull(searchEngine, "searchEngine");
}
/**
* Runs a search query on the web search engine and returns a pretty-string representation of the search results.
*
* @param query the search user query
* @return a pretty-string representation of the search results
*/
@Tool("This tool can be used to perform web searches using search engines such as Google, particularly when seeking information about recent events.")
public String searchWeb(@P("Web search query") String query) {
WebSearchResults results = searchEngine.search(query);
return format(results);
}
private String format(WebSearchResults results) {
if (isNullOrEmpty(results.results()))
return "No results found.";
return results.results()
.stream()
.map(organicResult -> "Title: " + organicResult.title() + "\n"
+ "Source: " + organicResult.url().toString() + "\n"
+ (organicResult.content() != null ? "Content:" + "\n" + organicResult.content() : "Snippet:" + "\n" + organicResult.snippet()))
.collect(Collectors.joining("\n\n"));
}
/**
* Creates a new WebSearchTool with the specified web search engine.
*
* @param searchEngine the web search engine to use for searching the web
* @return a new WebSearchTool
*/
public static WebSearchTool from(WebSearchEngine searchEngine) {
return new WebSearchTool(searchEngine);
}
}WebSearchTool定义了WebSearchEngine属性，它提供了searchWeb方法，并标注了@Tool注解，该方法执行searchEngine.search(query)，并对结果进行format。
小结
langchain4j定义了WebSearchEngine接口，它定义了search方法，根据WebSearchRequest返回WebSearchResults；它提供了WebSearchTool可以将WebSearchEngine转为tool去跟model集成进行调用。langchain4j-web-search-engine-google-custom提供了google自定义搜索，langchain4j-web-search-engine-searchapi支持search api搜索，langchain4j-community-web-search-engine-searxng支持SearXNG搜索，langchain4j-web-search-engine-tavily支持tavily搜索。