JGraphT-Dijkstra最短路径/最小成本路径

使用JGraphT实现Dijkstra算法查找最短路径或最小成本路径的示例代码如下：

import org.jgrapht.Graph;
import org.jgrapht.GraphPath;
import org.jgrapht.alg.interfaces.ShortestPathAlgorithm;
import org.jgrapht.alg.interfaces.ShortestPathAlgorithm.SingleSourcePaths;
import org.jgrapht.alg.shortestpath.DijkstraShortestPath;
import org.jgrapht.graph.DefaultWeightedEdge;
import org.jgrapht.graph.SimpleDirectedWeightedGraph;

public class DijkstraShortestPathExample {

    public static void main(String[] args) {
        //创建一个加权有向图
        Graph<String, DefaultWeightedEdge> graph =
                new SimpleDirectedWeightedGraph<>(DefaultWeightedEdge.class);

        // 添加顶点
        graph.addVertex("A");
        graph.addVertex("B");
        graph.addVertex("C");
        graph.addVertex("D");

        // 添加边和权重
        DefaultWeightedEdge edge1 = graph.addEdge("A", "B");
        graph.setEdgeWeight(edge1, 1);

        DefaultWeightedEdge edge2 = graph.addEdge("B", "C");
        graph.setEdgeWeight(edge2, 2);

        DefaultWeightedEdge edge3 = graph.addEdge("C", "D");
        graph.setEdgeWeight(edge3, 1);

        DefaultWeightedEdge edge4 = graph.addEdge("A", "D");
        graph.setEdgeWeight(edge4, 4);

        // 使用Dijkstra算法查找最短路径
        ShortestPathAlgorithm<String, DefaultWeightedEdge> dijkstraAlg =
                new DijkstraShortestPath<>(graph);
        SingleSourcePaths<String, DefaultWeightedEdge> dijkstraPaths =
                dijkstraAlg.getPaths("A");
        GraphPath<String, DefaultWeightedEdge> dijkstraPath = dijkstraPaths.getPath("D");

        if (dijkstraPath != null) {
            System.out.println("Dijkstra最短路径：" + dijkstraPath.getVertexList() +
                    "，path weight：" + dijkstraPath.getWeight());
        }

        //使用Dijkstra算法查找最小成本路径
        ShortestPathAlgorithm<String, DefaultWeightedEdge> dijkstraAlg2 =
                new DijkstraShortestPath<>(graph, edge -> graph.getEdgeWeight(edge));
        SingleSourcePaths<String, DefaultWeightedEdge> dijkstraPaths2 =
                dijkstraAlg2.getPaths("A");
        GraphPath<String, DefaultWeightedEdge> dijkstraPath2 = dijkstraPaths2.getPath("D");

        if (dijkstraPath2 != null) {
            System.out.println("Dijkstra最小成本路径：" + dijkstraPath2.getVertexList() +
                    "，path cost：" + dijkstraPath2.getWeight());
        }
    }
}

上面的示例代码创建了一个加权有向图，并使用Dijkstra算法查找了最短路径和最小成本路径。

可以使用该示例代码作为一个基础，为不同的场景和需求编写定制的代码。