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LangGraph4j 学习系列(3)-循环工作流

news 2026/3/26 19:54:31

接上节继续，本节将演示条件工作流如何用langgraph4j实现。

注：循环工作流可以看成条件工作流的一个变种。node1 -> node2 -> node1 这样就形成了1个死循环（loop)，为了能跳出死循环，用条件边来判定跳出时机。

一、定义节点

public class Node1Action implements NodeAction<AgentState> {@Overridepublic Map<String, Object> apply(AgentState state) throws Exception {System.out.println("current Node: node-1");return Map.of("myData", "node1-my-value","node1Key", "node1-value");}
}

public class Node2Action implements NodeAction<AgentState> {@Overridepublic Map<String, Object> apply(AgentState state) throws Exception {System.out.println("current Node: node-2");return Map.of("myData", "node2-my-value","node2Key", "node2-value");}
}

二、完整示例

public class LoopGraphApplication {public static void main(String[] args) throws GraphStateException {StateGraph<AgentState> sequenceGraph = getLoopGraph();System.out.println(sequenceGraph.getGraph(GraphRepresentation.Type.MERMAID, "loop Graph", true).content());sequenceGraph.compile().invoke(Map.of("loopCount", 0L)).ifPresent(c -> {System.out.println(c.data());});}private static final int MAX_LOOP_ITERATIONS = 3;public static StateGraph<AgentState> getLoopGraph() throws GraphStateException {return new StateGraph<>(AgentState::new).addNode("node-1", node_async(new Node1Action())).addNode("node-2", node_async(new Node2Action())).addEdge(GraphDefinition.START, "node-1").addEdge("node-2", "node-1")//循环的跳出条件比较简单，3次后退出，这里就不单独定义EdgeAction类了，用lambda表达式.addConditionalEdges("node-1", state -> {long count = getLoopCount(state);System.out.println("loop Count: " + count);if (count >= MAX_LOOP_ITERATIONS) {return CompletableFuture.completedFuture("exit");}return CompletableFuture.completedFuture("continue");}, Map.of("exit", GraphDefinition.END,"continue", "node-2"));}private static long getLoopCount(AgentState state) {Optional<Object> loopCount = state.value("loopCount");if (loopCount.isEmpty()) {return 0L;}Object v = loopCount.get();if (v instanceof Number n) {return n.longValue();}return Long.parseLong(v.toString());}}

三、运行结果

current Node: node-1
loop Count: 0
current Node: node-2
current Node: node-1
loop Count: 1
current Node: node-2
current Node: node-1
loop Count: 2
current Node: node-2
current Node: node-1
loop Count: 3
{node1Key=node1-value, loopCount=3, node2Key=node2-value, myData=node1-my-value}

示例代码：https://github.com/yjmyzz/langgraph4j-study/tree/main/src/main/java/org/bsc/langgraph4j/agent/_08_loop

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