JGraphT如何导出加权图并进行导入？

JGraphT提供了多种方式来导出和导入图形数据。为了导出加权图，我们可以使用GraphExporter类和WeightedGraphFormat类将带有权重的图导出为指定格式（如GraphML格式），并使用GraphImporter类将其导入。

以下是一个示例代码，将一个加权图导出为GraphML格式，并从该格式导入同一图形：

import org.jgrapht.Graph;
import org.jgrapht.graph.DefaultWeightedEdge;
import org.jgrapht.graph.SimpleWeightedGraph;
import org.jgrapht.io.*;
import java.io.*;
import java.util.*;

public class WeightedGraphExportImport {

    public static void main(String[] args) throws IOException {

        // Create a weighted graph
        Graph<String, DefaultWeightedEdge> graph = new SimpleWeightedGraph<>(DefaultWeightedEdge.class);
        graph.addVertex("A");
        graph.addVertex("B");
        graph.addVertex("C");
        graph.addEdge("A", "B");
        graph.addEdge("B", "C");
        DefaultWeightedEdge e1 = graph.addEdge("A", "C");
        graph.setEdgeWeight(e1, 2.5);

        // Export the graph to GraphML format
        WeightedGraphExporter<String, DefaultWeightedEdge> exporter = new WeightedGraphExporter<>(
                new VertexNameProvider<String>() {
                    @Override
                    public String getVertexName(String s) {
                        return s;
                    }
                },
                new EdgeNameProvider<DefaultWeightedEdge>() {
                    @Override
                    public String getEdgeName(DefaultWeightedEdge defaultWeightedEdge) {
                        return null;
                    }
                },
                new DoubleEdgeWeightProvider<DefaultWeightedEdge>() {
                    @Override
                    public Double getEdgeWeight(DefaultWeightedEdge defaultWeightedEdge) {
                        return graph.getEdgeWeight(defaultWeightedEdge);
                    }
                });
        Writer writer = new StringWriter();
        exporter.exportGraph(graph, writer);
        String graphML = writer.toString();
        System.out.println("Exported graph in GraphML format:\n" + graphML);

        // Import the graph from GraphML format
        WeightedGraphImporter<String, DefaultWeightedEdge> importer = new WeightedGraphImporter<>(
                new VertexProvider<String>() {
                    @Override
                    public String buildVertex(String s, Map<String, Attribute> map) {
                        return s;
                    }
                },
                new EdgeProvider<String, DefaultWeightedEdge>() {
                    @Override
                    public DefaultWeightedEdge buildEdge(String s, String s2, String s3, Map<String, Attribute> map) {
                        return graph.getEdge(s2,