Java XML嵌套的Parser无法正常工作

1 回答

• 0

  The Exception

  您得到的错误是由于您的XML格式不正确，XML的开头似乎不正确，您可以删除

  </service>
  </services>
  

  并替换它

  <problem>
  

  这样您的XML就会以这种方式启动：

  <problem>
    <solutions>
      <solution>
        ..
  

  这将匹配文件的结束标记

  </solution>
    </solutions>
  </problem>
  

  我试了一下，现在可以解析了 .

  Extracting values

  获得有效的XML后，如上所述 .

  假设我们有以下课程

  class Solution {
    private Double cost;
    private List<Route> routes = new ArrayList<>();
    // Getters/Setters
  }
  
  class Route {
    private String driverId;
    private String vehicleId;
    private Double start;
    private Double end;
    private Act act;
    // Getters/Setters
  }
  
  class Act {
    private String type;
    private String serviceId;
    private Double arrTime;
    private Double endTime;
    // Getters/Setters
  }
  

  您需要创建一个处理程序，在读取xml时构建对象

  class MyHandler extends DefaultHandler {
  
    // This will hold the result of the parsing
    private List<Solution> solutions = new ArrayList<>();
  
    // These are local variables used to create the objects
    private Solution solution;
    private Route route;
    private Act act;
  
    // The name of the element we are reading
    private String currentElementName = "";
  
    private static String SOLUTION_TAG = "solution";
    private static String ROUTE_TAG = "route";
    private static String ACT_TAG = "act";
    private static String COST_TAG = "cost";
    private static String DRIVERID_TAG = "driverId";
    private static String VEHICLEID_TAG = "vehicleId";
    private static String START_TAG = "start";
    private static String END_TAG = "end";
    private static String SERVICEID_TAG = "serviceId";
    private static String ARRTIME_TAG = "arrTime";
    private static String ENDTIME_TAG = "endTime";
  
    private static String ACT_TYPE_ATTRIBUTE = "type";
  
    public List<Solution> getSolutions() {
      return solutions;
    }
  
    // Called when we start a new element, that is where we create the objects
    public void startElement(String uri, String localName, String qName, Attributes attributes) {
      currentElementName = qName;
      if (qName.equalsIgnoreCase(SOLUTION_TAG)) {
        solution = new Solution();
      } else  if (qName.equalsIgnoreCase(ROUTE_TAG)) {
        route = new Route();
      } else  if (qName.equalsIgnoreCase(ACT_TAG)) {
        act = new Act();
        act.setType(attributes.getValue(ACT_TYPE_ATTRIBUTE));
      }
    }
  
    // Called when we ending an element, that is where we stick the objects one in an other
    public void endElement(String uri, String localName, String qName) {
      if (qName.equalsIgnoreCase(ACT_TAG)) {
        route.setAct(act);
      } else  if (qName.equalsIgnoreCase(ROUTE_TAG)) {
        solution.getRoutes().add(route);
      } else  if (qName.equalsIgnoreCase(SOLUTION_TAG)) {
        solutions.add(solution);
      }
      currentElementName = "";
    }
  
    // Called when we reading the text inside an element, that is where we set values to the object attributes
    public void characters(char ch[], int start, int length) {
      String s = new String(ch, start, length);
      if(currentElementName.equalsIgnoreCase(COST_TAG)) {
        solution.setCost(Double.valueOf(s));
      } else if(currentElementName.equalsIgnoreCase(DRIVERID_TAG)) {
        route.setDriverId(s);
      } else if(currentElementName.equalsIgnoreCase(VEHICLEID_TAG)) {
        route.setVehicleId(s);
      } else if(currentElementName.equalsIgnoreCase(START_TAG)) {
        route.setStart(Double.valueOf(s));
      } else if(currentElementName.equalsIgnoreCase(END_TAG)) {
        route.setEnd(Double.valueOf(s));
      } else if(currentElementName.equalsIgnoreCase(SERVICEID_TAG)) {
        act.setServiceId(s);
      } else if(currentElementName.equalsIgnoreCase(ARRTIME_TAG)) {
        act.setArrTime(Double.valueOf(s));
      } else if(currentElementName.equalsIgnoreCase(ENDTIME_TAG)) {
        act.setEndTime(Double.valueOf(s));
      }
    }
  }
  

  然后，您可以通过以下方式简单地解析XML：

  MyHandler myHandler = new MyHandler();
  try {
    SAXParserFactory factory = SAXParserFactory.newInstance();
    SAXParser saxParser = factory.newSAXParser();
    saxParser.parse(new InputSource(new StringReader(xml)), myHandler);
  } catch (Exception e) {
    e.printStackTrace();
  }
  

  并且您将所有文件解析为处理程序中的解决方案列表，您可以通过这种方式获得它

  myHandler.getSolutions();
  

  回复于 2024-05-05T07:26:39+08:00