如何使用java写一个agent
1.此处先不使用继承，单独一个类写一个agent原型
public class MyReActAgent {private static final Logger logger = LoggerFactory.getLogger(MyReActAgent.class);private ChatModel llm;private ToolExecutor toolExecutor;private List<Tool> tools;private InMemoryMemory memory;private int maxIterations = 5;private String systemPrompt = null;public MyReActAgent(ChatModel llm, List<Tool> tools) {this.llm = llm;this.tools = tools;this.toolExecutor = new ToolExecutor(tools);this.memory = new InMemoryMemory(10); // 初始化记忆}public MyReActAgent(ChatModel llm, List<Tool> tools, String systemPrompt) {this(llm, tools);this.systemPrompt = systemPrompt;}public String run(String input) {logger.info("Agent started with input: {}", input);memory.add("user", input);StringBuilder fullPrompt = new StringBuilder();if (systemPrompt != null && !systemPrompt.isEmpty()) {fullPrompt.append(systemPrompt).append("\n\n");}buildToolPrompt(fullPrompt);fullPrompt.append("Begin!\n").append("Question: ").append(input).append("\n");for (int i = 0; i < maxIterations; i++) {logger.debug("Starting iteration {}/{}", i + 1, maxIterations);String response = llm.chat(fullPrompt.toString());logger.debug("LLM Response: {}", response);// 检查是否有工具调用if (hasToolCall(response)) {ToolCall toolCall = extractToolCall(response);if (toolCall != null) {String toolName = toolCall.getFunction().getName();String args = toolCall.getFunction().getArguments();logger.info("Tool selected: {} with args: {}", toolName, args);String observation = toolExecutor.execute(toolCall);logger.info("Tool executed. Observation: {}", observation);// 记录到记忆memory.add("assistant", "Action: " + toolName + ", Input: " + args);memory.add("system", "Observation: " + observation);// 更新 promptfullPrompt.append("Thought: I need to use a tool.\n").append("Action: ").append(toolName).append("\n").append("Action Input: ").append(args).append("\n").append("Observation: ").append(observation).append("\n");} else {String finalAnswer = response;logger.info("Final answer generated: {}", finalAnswer);memory.add("assistant", finalAnswer);return finalAnswer;}} else {String finalAnswer = response;logger.info("Final answer generated: {}", finalAnswer);memory.add("assistant", finalAnswer);return finalAnswer;}}String fallback = "I couldn't find a solution within " + maxIterations + " steps.";logger.warn("Max iterations reached. Returning fallback.");memory.add("assistant", fallback);return fallback;}/*** 检查响应中是否包含工具调用* @param response 模型响应* @return 如果包含工具调用返回true，否则返回false*/private boolean hasToolCall(String response) {// 检查响应中是否包含Action关键词return response != null && response.contains("Action:") && response.contains("Action Input:");}/*** 从模型响应中提取工具调用信息* @param response 模型响应* @return ToolCall对象，如果未找到则返回null*/private ToolCall extractToolCall(String response) {try {// 使用正则表达式提取Action和Action InputPattern actionPattern = Pattern.compile("Action:\\s*(\\w+)");Pattern inputPattern = Pattern.compile("Action Input:\\s*(\\{.*?\\}|\\[.*?\\]|\".*?\"|\\d+(?:\\.\\d+)?|true|false|null)");Matcher actionMatcher = actionPattern.matcher(response);Matcher inputMatcher = inputPattern.matcher(response);if (actionMatcher.find() && inputMatcher.find()) {String toolName = actionMatcher.group(1);String arguments = inputMatcher.group(1);// 创建ToolCall对象ToolCall toolCall = new ToolCall();toolCall.setType("function");FunctionCall functionCall = new FunctionCall(toolName, arguments);toolCall.setFunction(functionCall);return toolCall;}} catch (Exception e) {logger.error("Error extracting tool call from response: {}", e.getMessage(), e);}return null;}private void buildToolPrompt(StringBuilder prompt) {prompt.append("Answer the following question. You can use tools.\n");prompt.append("Available tools:\n");for (Tool tool : tools) {prompt.append("- ").append(tool.getName()).append(": ").append(tool.getDescription()).append("\n Parameters: ").append(tool.getParametersSchema()).append("\n");}prompt.append("\nUse the following format:\n").append("Thought: you should always think about what to do\n").append("Action: the action to take, should be one of [").append(String.join(", ", tools.stream().map(Tool::getName).toArray(String[]::new))).append("]\n").append("Action Input: the input to the action, can be JSON object, array, string, number, boolean or null\n").append("Observation: the result of the action\n").append("... (Thought/Action/Observation can repeat)\n").append("Thought: I now know the final answer\n").append("Final Answer: the final answer to the original input question\n\n");}// 获取记忆内容（可用于调试或上下文增强）public InMemoryMemory getMemory() {return memory;}// 设置最大迭代次数public void setMaxIterations(int maxIterations) {if (maxIterations <= 0) {throw new IllegalArgumentException("maxIterations must be positive");}this.maxIterations = maxIterations;}// 设置系统提示词public void setSystemPrompt(String systemPrompt) {this.systemPrompt = systemPrompt;}// 获取系统提示词public String getSystemPrompt() {return systemPrompt;}
}2. ReacAct agent 需要支持记忆、工具调用等功能
创建工具类，工具需要有工具描述、工具名称、工具执行的具体逻辑。
public interface Tool {String getName();String getDescription();String getParametersSchema(); // JSON SchemaString execute(String arguments); // arguments 是 JSON 字符串
}public class ToolExecutor {private final Map<String, Tool> toolRegistry;public ToolExecutor(List<Tool> tools) {this.toolRegistry = new HashMap<>();for (Tool tool : tools) {toolRegistry.put(tool.getName(), tool);}}public String execute(ToolCall toolCall) {String toolName = toolCall.getFunction().getName();String arguments = toolCall.getFunction().getArguments();Tool tool = toolRegistry.get(toolName);if (tool == null) {return "{\"error\": \"Tool not found: " + toolName + "\"}";}return tool.execute(arguments);}
}3.示例：一个实现的工具
public class WeatherTool implements Tool {private static final ObjectMapper mapper = new ObjectMapper(); // 共享实例@Overridepublic String getName() {return "get_weather";}@Overridepublic String getDescription() {return "获取指定城市的天气信息";}@Overridepublic String getParametersSchema() {return """{"type": "object","properties": {"location": {"type": "string","description": "城市名称"}},"required": ["location"]}""";}@Overridepublic String execute(String arguments) {try {JsonNode node = mapper.readTree(arguments);if (!node.has("location")) {return "{\"error\": \"Missing required field: location\"}";}String location = node.get("location").asText();// 模拟天气数据return String.format("{\"location\": \"%s\", \"temperature\": \"28°C\", \"condition\": \"Sunny\"}", location);} catch (Exception e) {return String.format("{\"error\": \"Invalid JSON: %s\"}", e.getMessage());}}}4. 工具调用需要的参数封装
public class ToolCall {@JsonProperty("id")private String id;@JsonProperty("type")private String type;@JsonProperty("function")private FunctionCall function;// Getters and Setterspublic String getId() { return id; }public void setId(String id) { this.id = id; }public String getType() { return type; }public void setType(String type) { this.type = type; }public FunctionCall getFunction() { return function; }public void setFunction(FunctionCall function) { this.function = function; }
}public class FunctionCall {@JsonProperty("name")private String name;@JsonProperty("arguments")private String arguments; // JSON string// 构造函数public FunctionCall() {}public FunctionCall(String name, String arguments) {this.name = name;this.arguments = arguments;}// Getters and Setterspublic String getName() { return name; }public void setName(String name) { this.name = name; }public String getArguments() { return arguments; }public void setArguments(String arguments) { this.arguments = arguments; }
}5. 调用agent
reActAgent = new MyReActAgent(openAiChatModel, availableTools);
response = reActAgent.run(userMessageText);