根据实际情况,overload一下构造方法即可。
package com.util; import java.util.ArrayList; import java.util.Hashtable; import java.util.List; /** * dijkstra算法,求最短路径 */ public class DijkstraUtil { private RoutePlanner planner = new RoutePlanner(); private Graph g = new Graph(); public DijkstraUtil() { List<Node> list = new ArrayList<Node>(); Node aNode = new Node("A"); list.add(aNode); // A -> B Edge aEdge1 = new Edge(); aEdge1.setStartNodeID(aNode.getId()); aEdge1.setEndNodeID("B"); aEdge1.setWeight(10); aNode.getEdgeList().add(aEdge1); // A -> C Edge aEdge2 = new Edge(); aEdge2.setStartNodeID(aNode.getId()); aEdge2.setEndNodeID("C"); aEdge2.setWeight(20); aNode.getEdgeList().add(aEdge2); // A -> E Edge aEdge3 = new Edge(); aEdge3.setStartNodeID(aNode.getId()); aEdge3.setEndNodeID("E"); aEdge3.setWeight(30); aNode.getEdgeList().add(aEdge3); // ***************** B Node ******************* Node bNode = new Node("B"); list.add(bNode); // B -> C Edge bEdge1 = new Edge(); bEdge1.setStartNodeID(bNode.getId()); bEdge1.setEndNodeID("C"); bEdge1.setWeight(5); bNode.getEdgeList().add(bEdge1); // B -> E Edge bEdge2 = new Edge(); bEdge2.setStartNodeID(bNode.getId()); bEdge2.setEndNodeID("E"); bEdge2.setWeight(10); bNode.getEdgeList().add(bEdge2); // ***************** C Node ******************* Node cNode = new Node("C"); list.add(cNode); // C -> D Edge cEdge1 = new Edge(); cEdge1.setStartNodeID(cNode.getId()); cEdge1.setEndNodeID("D"); cEdge1.setWeight(30); cNode.getEdgeList().add(cEdge1); // ***************** D Node ******************* Node dNode = new Node("D"); list.add(dNode); // ***************** E Node ******************* Node eNode = new Node("E"); list.add(eNode); // E -> D Edge eEdge1 = new Edge(); eEdge1.setStartNodeID(eNode.getId()); eEdge1.setEndNodeID("D"); eEdge1.setWeight(20); eNode.getEdgeList().add(eEdge1); g.setM_nodeList(list); } public RoutePlanResult plan(String originID, String targetID) throws Exception { return planner.plan(g.getM_nodeList(), originID, targetID); } public PlanCourse plan(String originID) throws Exception { return planner.plan(g.getM_nodeList(), originID); } public class Edge { private String startNodeID; private String endNodeID; private double weight; public String getStartNodeID() { return startNodeID; } public void setStartNodeID(String startNodeID) { this.startNodeID = startNodeID; } public String getEndNodeID() { return endNodeID; } public void setEndNodeID(String endNodeID) { this.endNodeID = endNodeID; } public double getWeight() { return weight; } public void setWeight(double weight) { this.weight = weight; } } public class Node { private String id; private List<Edge> edgeList; public Node(String id) { this.id = id; this.edgeList = new ArrayList<Edge>(); } public String getId() { return id; } public void setId(String id) { this.id = id; } public List<Edge> getEdgeList() { return edgeList; } public void setEdgeList(List<Edge> edgeList) { this.edgeList = edgeList; } } public class Graph { private List<Node> m_nodeList = null; public List<Node> getM_nodeList() { return m_nodeList; } public void setM_nodeList(List<Node> m_nodeList) { this.m_nodeList = m_nodeList; } } class PassedPath { private String curNodeID; private boolean beProcessed; private double weight; private List<String> passedIDList; public PassedPath(String ID) { this.curNodeID = ID; this.weight = Double.MAX_VALUE; this.passedIDList = new ArrayList<String>(); this.beProcessed = false; } public String getCurNodeID() { return curNodeID; } public void setCurNodeID(String curNodeID) { this.curNodeID = curNodeID; } public boolean isBeProcessed() { return beProcessed; } public void setBeProcessed(boolean beProcessed) { this.beProcessed = beProcessed; } public double getWeight() { return weight; } public void setWeight(double weight) { this.weight = weight; } public List<String> getPassedIDList() { return passedIDList; } public void setPassedIDList(List<String> passedIDList) { this.passedIDList = passedIDList; } } class PlanCourse { private Hashtable<String, PassedPath> htPassedPath; public PlanCourse(List<Node> nodeList, String originID) throws Exception { this.htPassedPath = new Hashtable<String, PassedPath>(); Node originNode = null; for (Node node : nodeList) { if (originID.equals(node.getId())) { originNode = node; } else { PassedPath pPath = new PassedPath(node.getId()); this.htPassedPath.put(node.getId(), pPath); } } if (originNode == null) { throw new Exception("The origin node is not exist !"); } this.InitializeWeight(originNode); } private void InitializeWeight(Node originNode) { if ((originNode.getEdgeList() == null) || (originNode.getEdgeList().size() == 0)) { return; } for (Edge edge : originNode.getEdgeList()) { PassedPath pPath = getPassedPath(edge.getEndNodeID()); if (pPath == null) { continue; } pPath.getPassedIDList().add(originNode.getId()); pPath.setWeight(edge.getWeight()); } } public PassedPath getPassedPath(String nodeID) { return this.htPassedPath.get(nodeID); } } class RoutePlanner { public RoutePlanResult plan(List<Node> nodeList, String originID, String destID) throws Exception { PlanCourse planCourse = plan(nodeList, originID); return this.getResult(planCourse, destID); } public PlanCourse plan(List<Node> nodeList, String originID) throws Exception { PlanCourse planCourse = new PlanCourse(nodeList, originID); Node curNode = this.getMinWeightRudeNode(planCourse, nodeList, originID); while (curNode != null) { PassedPath curPath = planCourse.getPassedPath(curNode.getId()); for (Edge edge : curNode.getEdgeList()) { PassedPath targetPath = planCourse.getPassedPath(edge.getEndNodeID()); double tempWeight = curPath.getWeight() + edge.getWeight(); if (tempWeight < targetPath.getWeight()) { targetPath.setWeight(tempWeight); targetPath.getPassedIDList().clear(); for (int i = 0; i < curPath.getPassedIDList().size(); i++) { targetPath.getPassedIDList().add(curPath.getPassedIDList().get(i)); } targetPath.getPassedIDList().add(curNode.getId()); } } planCourse.getPassedPath(curNode.getId()).setBeProcessed(true); curNode = this.getMinWeightRudeNode(planCourse, nodeList, originID); } return planCourse; } private RoutePlanResult getResult(PlanCourse planCourse, String destID) { PassedPath pPath = planCourse.getPassedPath(destID); if (pPath.getWeight() == Integer.MAX_VALUE) { RoutePlanResult result1 = new RoutePlanResult(null, Integer.MAX_VALUE); return result1; } String[] passedNodeIDs = new String[pPath.getPassedIDList().size()]; for (int i = 0; i < passedNodeIDs.length; i++) { passedNodeIDs[i] = pPath.getPassedIDList().get(i); } RoutePlanResult result = new RoutePlanResult(passedNodeIDs, pPath.getWeight()); return result; } private Node getMinWeightRudeNode(PlanCourse planCourse, List<Node> nodeList, String originID) { double weight = Double.MAX_VALUE; Node destNode = null; for (int i = 0; i < nodeList.size(); i++) { Node node = (Node) nodeList.get(i); if (originID.equals(node.getId())) { continue; } PassedPath pPath = planCourse.getPassedPath(node.getId()); if (pPath.isBeProcessed()) { continue; } if (pPath.getWeight() < weight) { weight = pPath.getWeight(); destNode = node; } } return destNode; } } public class RoutePlanResult { public RoutePlanResult(String[] passedNodes, double value) { m_resultNodes = passedNodes; m_value = value; } private String[] m_resultNodes; private double m_value; public String[] getM_resultNodes() { return m_resultNodes; } public void setM_resultNodes(String[] m_resultNodes) { this.m_resultNodes = m_resultNodes; } public double getM_value() { return m_value; } public void setM_value(double m_value) { this.m_value = m_value; } public String getStringResult() { String result; StringBuffer sb = new StringBuffer("["); for (int i = 0; i < m_resultNodes.length; i++) sb.append(m_resultNodes[i] + ","); if (sb.length() > 1) result = sb.substring(0, sb.length() - 1) + "]"; else result = sb.append("]").toString(); return result; } } }
调用方法如下:
import com.util.DijkstraUtil; import com.util.DijkstraUtil.RoutePlanResult; /** 最短路径 **/ public class Test { public static void main(String[] args) throws Exception { DijkstraUtil du = new DijkstraUtil(); RoutePlanResult result = du.plan("A", "D"); System.out.println(result.getM_value()); System.out.println(result.getStringResult()); } }