Hands on Teaching: XML modeling

Previous review ：XML File parsing operation _ Little Alfie _ The blog of -CSDN Blog

XML Is a commonly used configuration file , But in the last article XML The code of the file cannot be rewritten every time it is needed , Modeling in this issue （OOP thought ） Is a good solution （ Will parse XML The code of the file becomes object-oriented data ）

This issue is wonderful ( From the first step to the last step, teach hand in hand )

Catalog

XML Modeling steps

1、 Construction of environment

2、 The import related jar package

3、 Build related packages and MVC Configuration file for

4、 adopt config.xml Format establishment related model classes

5、 Custom exception

5、 Observe MVC Configuration file for config.xml To write code

6、 Model class code writing

7、 Factory ConfigModelFactory To write

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XML Modeling steps

1、 Construction of environment

(1) Select a workspace and click Launch

(2.1) Click preferences

(2.2)  Enter the workspace and set the encoding format to UTF-8

(2.3) take JSP The encoding format of is also set to UTF-8

 (3.1) New dynamic project ( The project name can be all lowercase ）

(3.2) To configure tomcat Environmental Science

Choose your computer tomcat The file path of the server  

 (3.3) To configure JDK

Choose your computer JDK File path , Usually placed in C disc  

 

 

 

  Finally, you can set the font to the size and format you want

  

(4) Generate XML The configuration file

2、 The import related jar package

• To import jar package

• In the project build path after

3、 Build related packages and MVC Configuration file for

Package name specification ：com/org. Company name . Project name . Module name

1. com.xyf.mvc.framework： The framework package
2. resources Files under the source package ： Put custom MVC Configuration file for config.xml

• config.xml Code display （ Write a follow-up package 、 class 、 The basis of the code ！）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE config>
<config>
<action type="org.lisen.mvc.action.StudentAction" path="/studentAction">
<forward path="/students/studentList.jsp" redirect="false" name="students"/>
</action>
</config>

4、 adopt config.xml Format Establish relevant model classes

Class name specification ： Hump nomenclature with capital letters

Model class naming ：

• ConfigModel：Config Node model
• ActionModel：Action Node model
• ForwardModel：Farword Node model

5、 Custom exception

Exception class naming + Code writing （ The key is the exception name ）

• ActionDuplicateDefinitionException：Action There is a duplicate definition exception in the element

public class ActionDuplicateDefinitionException extends RuntimeException {	
	public ActionDuplicateDefinitionException() {
		super();
	}	
	public ActionDuplicateDefinitionException(String msg) {
		super(msg);
	}	
	public ActionDuplicateDefinitionException(String msg, Throwable c) {
		super(msg, c);
	}
}

• ActionNotFoundException：

public class ActionNotFoundException extends RuntimeException {	
	public ActionNotFoundException() {
		super();
	}	
	public ActionNotFoundException(String msg) {
		super(msg);
	}	
	public ActionNotFoundException(String msg, Throwable c) {
		super(msg, c);
	}
}

•  ForwardDuplicateDefinitionException：Forward There is a duplicate definition exception in the element

public class ForwardDuplicateDefinitionException extends RuntimeException {	
	public ForwardDuplicateDefinitionException() {
		super();
	}	
	public ForwardDuplicateDefinitionException(String msg) {
		super(msg);
	}	
	public ForwardDuplicateDefinitionException(String msg, Throwable c) {
		super(msg, c);
	}
}

•  ForwardNotFoundException：

public class ForwardNotFoundException extends RuntimeException {	
	public ForwardNotFoundException() {
		super();
	}
	public ForwardNotFoundException(String msg) {
		super(msg);
	}	
	public ForwardNotFoundException(String msg, Throwable c) {
		super(msg, c);
	}
}

5、 Observe MVC Configuration file for config.xml To write code

Observe config.xml You know

• One config There can be multiple nodes action node
• action Nodes have type and path Two attributes
• action Node has forward node
• forward Nodes have three attributes ......

6、 Model class code writing

The root node ConfigModel class

public class ConfigModel {
	
//	 One config There can be multiple nodes action node 
//	 discharge key==path and value==ActionModel class / object : Find action
//	 initialization ：new HashMap<>()
	private Map<String, ActionModel> actionMap=new HashMap<>();
	
	/**
	 *  take path Put in key, keep path No repetition 
	 *  Traverse ActionModel object , adopt ActionModel Object acquisition path attribute 
	 * @param  Pass in ActionModel This class / object 
	 */
    public void put(ActionModel action) {
    	if(actionMap.containsKey(action.getPath())) {
    		throw new ActionDuplicateDefinitionException("Action path= "+action.getPath()+" Duplicate definition");
    	}
    	actionMap.put(action.getPath(), action);
    }
    
    /**
     *  look for path
     * @param  Pass in path
     * @return  Can't find path Throw an exception , Find and return path
     */
    public ActionModel find(String path) {
    	if(!actionMap.containsKey(path)) {
    		throw new ActionNotFoundException("Action path ="+path+" not found");
    	}
    	return actionMap.get(path);
    }
    
}

ActionModel class

public class ActionModel {
	
//	 There are two nodes 
	private String type;
	private String path;
	
//	 Contains elements forward： adopt action find forward
	private Map<String, ForwardModel> forwardMap =new HashMap<>();
	
//	 take name Put in key, keep name No repetition 
	public void put(ForwardModel forward) {
		if(forwardMap.containsKey(forward.getName())) {
			throw new ForwardDuplicateDefinitionException("forward name = "+forward.getName()+" DuplicateDefinition");
		}
		forwardMap.put(forward.getName(), forward);
	}
	
//	 look for name
	public ForwardModel find(String name) {
		if(!forwardMap.containsKey(name)) {
			throw new ForwardNotFoundException("forward name ="+name+" not found");
		}
		return forwardMap.get(name);
	}
	
	public String getType() {
		return type;
	}
	public void setType(String type) {
		this.type = type;
	}
	public String getPath() {
		return path;
	}
	public void setPath(String path) {
		this.path = path;
	}

	@Override
	public String toString() {
		return "ActionModel [type=" + type + ", path=" + path + ", forwardMap=" + forwardMap + "]";
	}	
}

ForwardModel class

public class ForwardModel extends RuntimeException{
	// Three attributes 
	private String name;
	private String path;
	private boolean redirect;
	
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPath() {
		return path;
	}
	public void setPath(String path) {
		this.path = path;
	}
	public boolean isRedirect() {
		return redirect;
	}
	public void setRedirect(boolean redirect) {
		this.redirect = redirect;
	}
	
	// take redirect Convert string in to boolean Method of type 
	public void setRedirect(String redirect) {
		//this= The current class 
		this.redirect =Boolean.valueOf(redirect);
	}
	
	@Override
	public String toString() {
		return "ForwardModel [name=" + name + ", path=" + path + ", redirect=" + redirect + "]";
	}	
}

7、 Factory ConfigModelFactory To write

Write factory class ConfigModelFactory The purpose of is to use the singleton pattern in this class , And only for XML Read the contents of the file once , After reading, put it into the model object written in the previous step

/**
 *  Single instance factory class 
 *  Let's analyze XML The code of is executed only once 
 */
@SuppressWarnings("unchecked")
public final class ConfigModelFactory {
	// The singleton pattern 
	private ConfigModelFactory() {}
	// Root node model 
	private static ConfigModel config = new ConfigModel();
	// Read only once config Data in , And fill in the model 
	static {
		try {
		// read 
		InputStream is=XmlReader.class.getResourceAsStream("/config.xml");
		SAXReader reader=new SAXReader();
		
		Document doc = reader.read(is);
		// Get the node under the root element through the root element action(xml The number structure in !)
		Element rootElement = doc.getRootElement();
		List<Element> actions = rootElement.selectNodes("action");
		
		for (Element e : actions) {
			String path = e.attributeValue("path");
			String type = e.attributeValue("type");
			
			// Put it in the model 
			ActionModel action=new ActionModel();
			action.setPath(path);
			action.setType(type);
			
			// adopt action Element acquisition actions The nodes below forward
			List<Element> forward1 = e.selectNodes("forward");
			for (Element f : forward1) {
				String name = f.attributeValue("name");
				String fPath = f.attributeValue("path");
				String redirect = f.attributeValue("redirect");
				
				// Put it in the model 
				ForwardModel forward=new ForwardModel();
				forward.setName(name);
				forward.setPath(fPath);
				forward.setRedirect(redirect);
				// take forward Put in action
				action.put(forward);
				}
			// After the cycle is completed action Put in the root node 
			config.put(action);
			}
		} catch (DocumentException e) {
			e.printStackTrace();
		}
	}
	
	public static ConfigModel getConfig() {
		return config;
	}
	
    // test 
	public static void main(String[] args) {
		ConfigModel config = ConfigModelFactory.getConfig();
		// adopt action Medium path(xml There is /) look for action
		ActionModel action = config.find("/studentAction");
		System.out.println(action);
		// adopt forward Medium name look for forward,xml No middle /
		ForwardModel forward = action.find("students");
		System.out.println(forward);
	}
	
}

Summary ： It's right to be here config.xml The modeling operation of the file has been completed , But there are still some small bug, For example, if you are in config.xml Of path No incoming from “/”, Will also successfully model , This is obviously not right , So please look forward to the next article (●'◡'●)