<el-menu-item index="/addbook" >增加新图书</el-menu-item>点击后没实现跳转

这个问题可能是由于以下原因导致的：

1. 没有正确配置路由。你需要在路由配置文件中添加 `/addbook` 路由，并指定要跳转的页面组件。
2. 没有在点击事件中编写跳转逻辑。你需要在点击事件中使用 `this.$router.push('/addbook')` 或类似的代码来实现跳转。

你可以检查一下这两个方面，看看是否有问题。如果还是不行，可以提供更多的代码或错误信息，方便我更好地帮你解决问题。

相关问题

java使用builder设计模式解析这段xml：<?xml version="1.0" encoding="UTF-8"?><bookstore> <book category="children"> <title lang="en">Harry Potter</title> <author>J.K. Rowling</author> <year>2005</year> <price>29.99</price> </book> <book category="web"> <title lang="en">Learning XML</title> <author>Erik T. Ray</author> <year>2003</year> <price>39.95</price> </book></bookstore>

首先，我们需要定义一个Book类来表示XML中的每个书籍。这个类需要有四个属性：category、title、author和price。

然后，我们可以定义一个BookBuilder类来构建Book对象。BookBuilder类应该具有以下方法：

1. setCategory(String category)：设置book的category属性。
2. setTitle(String title)：设置book的title属性。
3. setAuthor(String author)：设置book的author属性。
4. setYear(int year)：设置book的year属性。
5. setPrice(double price)：设置book的price属性。
6. build()：构建一个Book对象并返回。

接下来，我们可以定义一个Bookstore类来表示整个XML文档。这个类应该具有一个List<Book>属性来存储所有的书籍。

最后，我们需要创建一个BookstoreBuilder类来解析XML文档并构建Bookstore对象。BookstoreBuilder类应该具有以下方法：

1. parseDocument(InputStream inputStream)：解析XML文档并返回一个Bookstore对象。

下面是完整的代码实现：

Book.java

public class Book {
    private String category;
    private String title;
    private String author;
    private int year;
    private double price;

    public Book(String category, String title, String author, int year, double price) {
        this.category = category;
        this.title = title;
        this.author = author;
        this.year = year;
        this.price = price;
    }

    // getters and setters
}

BookBuilder.java

public class BookBuilder {
    private String category;
    private String title;
    private String author;
    private int year;
    private double price;

    public BookBuilder setCategory(String category) {
        this.category = category;
        return this;
    }

    public BookBuilder setTitle(String title) {
        this.title = title;
        return this;
    }

    public BookBuilder setAuthor(String author) {
        this.author = author;
        return this;
    }

    public BookBuilder setYear(int year) {
        this.year = year;
        return this;
    }

    public BookBuilder setPrice(double price) {
        this.price = price;
        return this;
    }

    public Book build() {
        return new Book(category, title, author, year, price);
    }
}

Bookstore.java

import java.util.ArrayList;
import java.util.List;

public class Bookstore {
    private List<Book> books;

    public Bookstore() {
        books = new ArrayList<>();
    }

    public void addBook(Book book) {
        books.add(book);
    }

    // getters and setters
}

BookstoreBuilder.java

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.IOException;
import java.io.InputStream;

public class BookstoreBuilder {
    public Bookstore parseDocument(InputStream inputStream) {
        Bookstore bookstore = new Bookstore();

        try {
            SAXParserFactory factory = SAXParserFactory.newInstance();
            SAXParser saxParser = factory.newSAXParser();
            DefaultHandler handler = new DefaultHandler() {
                private BookBuilder bookBuilder;
                private String currentElement;

                @Override
                public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
                    switch (qName) {
                        case "book":
                            bookBuilder = new BookBuilder();
                            bookBuilder.setCategory(attributes.getValue("category"));
                            break;
                        case "title":
                        case "author":
                        case "year":
                        case "price":
                            currentElement = qName;
                            break;
                    }
                }

                @Override
                public void endElement(String uri, String localName, String qName) throws SAXException {
                    switch (qName) {
                        case "book":
                            bookstore.addBook(bookBuilder.build());
                            bookBuilder = null;
                            break;
                        case "title":
                        case "author":
                        case "year":
                        case "price":
                            currentElement = null;
                            break;
                    }
                }

                @Override
                public void characters(char[] ch, int start, int length) throws SAXException {
                    if (currentElement != null) {
                        String value = new String(ch, start, length);
                        switch (currentElement) {
                            case "title":
                                bookBuilder.setTitle(value);
                                break;
                            case "author":
                                bookBuilder.setAuthor(value);
                                break;
                            case "year":
                                bookBuilder.setYear(Integer.parseInt(value));
                                break;
                            case "price":
                                bookBuilder.setPrice(Double.parseDouble(value));
                                break;
                        }
                    }
                }
            };
            saxParser.parse(inputStream, handler);
        } catch (ParserConfigurationException | SAXException | IOException e) {
            e.printStackTrace();
        }

        return bookstore;
    }
}

现在我们可以使用以下代码来解析XML文档并获取所有的书籍：

InputStream inputStream = new FileInputStream("bookstore.xml");
BookstoreBuilder bookstoreBuilder = new BookstoreBuilder();
Bookstore bookstore = bookstoreBuilder.parseDocument(inputStream);

List<Book> books = bookstore.getBooks();
for (Book book : books) {
    System.out.println(book.getTitle() + " by " + book.getAuthor());
}

#include <iostream> #include <cstring> using namespace std; class Book { public: string title; string author; string publisher; string date; Book(string t, string a,string p,string d) { title=t; author=a; publisher=p; date=d; } ~Book(){} }; class Library { public: Book book[100]; int n; Library(){n=0;} void AddBook(Bookb) { book[n++]=b; } void DeleteBook(string t) { for (int i=0;i<n;i++) { if(book[i]->title==t) { delete book[i]; book[i]=NULL; for(int j=i;j<n-1;j++) { book[j]=book[j+1]; } n--; } } cout<<"未找到题目为"<<t<<"的书籍"<<endl; } void ShowBook() { cout<<"书籍显示"<<endl; for(int i=0;i<n;i++) { cout<<book[i]->title<<" "<<book[i]->author<<" "<<book[i]->publisher<<" "<<book[i]->date<<endl; } } BookFindBook(string t) { for (int i=0;i<n;i++) { if(book[i]->title==t) { return book[i]; } } cout<<"未找到题目为"<<t<<"的书籍"<<endl; return NULL; } ~Library() { for(int i=0;i<n;i++) { delete book[i]; } } }; int main() { Library l; int input; string t,a,p,d; cout << "------------------菜单栏------------------" << endl; cout << "1.图书信息添加" << endl; cout << "2.图书信息删除" << endl; cout << "3.图书信息查看" << endl; cout << "4.图书信息查找" << endl; cout << "0.退出" << endl; while(1) { cout << "请选择功能" << endl; cin >> input; switch (input) { case 1: { cout<<"请输入添加的图书书名："; cin>>t; cout<<"请输入添加的图书作者："; cin>>a; cout<<"请输入添加的图书出版社："; cin>>p; cout<<"请输入添加的图书出版日期："; cin>>d; Bookb=new Book(t,a,p,d); l.AddBook(b); break; } case 2: { cout<<"请输入删除的图书书名："; cin>>t; l.DeleteBook(t); break; } case 3: { l.ShowBook(); break; } case 4: { cout<<"请输入查找的图书书名："; cin>>t; Book *b=l.FindBook(t); if(b!=NULL) { cout<<"查询结果为："<<b->title<<" "<<b->author<<" "<<b->publisher<<" "<<b->date<<endl; } break; } case 0: { cout<<"已退出"<<endl; return 0; } } } }优化这段程序

这段程序可以进行如下的优化：

1. 对输入进行错误处理，避免输入非法字符导致程序崩溃。

2. 在 Library 类中添加一个私有成员变量 max_len，表示 book 数组的最大长度，避免数组越界的错误。

3. 在 AddBook 方法中，当 book 数组已满时需要进行扩容。

4. 在 DeleteBook 和 FindBook 方法中，可以使用引用来避免对对象进行拷贝，提高程序效率。

5. 修改 ShowBook 方法的输出格式，让输出更加美观。

下面是修改后的程序：

#include <iostream> 
#include <cstring> 

using namespace std;

class Book {
public:
    string title;
    string author;
    string publisher;
    string date;

    Book(string t, string a, string p, string d) {
        title = t;
        author = a;
        publisher = p;
        date = d;
    }

    ~Book() {}
};

class Library {
private:
    Book* book;
    int n;
    int max_len;

public:
    Library() {
        n = 0;
        max_len = 100;
        book = new Book[max_len];
    }

    void AddBook(Book& b) {
        if (n >= max_len) {
            max_len *= 2;
            Book* new_book = new Book[max_len];
            memcpy(new_book, book, n * sizeof(Book));
            delete[] book;
            book = new_book;
        }

        book[n++] = b;
    }

    void DeleteBook(string t) {
        for (int i = 0; i < n; i++) {
            if (book[i].title == t) {
                for (int j = i; j < n - 1; j++) {
                    book[j] = book[j + 1];
                }
                n--;
                return;
            }
        }

        cout << "未找到题目为 " << t << " 的书籍" << endl;
    }

    void ShowBook() {
        cout << "------------------书籍显示------------------" << endl;
        cout << "书名\t\t作者\t\t出版社\t\t出版日期" << endl;
        for (int i = 0; i < n; i++) {
            cout << book[i].title << "\t\t" << book[i].author << "\t\t" << book[i].publisher << "\t\t" << book[i].date << endl;
        }
    }

    Book& FindBook(string t) {
        for (int i = 0; i < n; i++) {
            if (book[i].title == t) {
                return book[i];
            }
        }

        cout << "未找到题目为 " << t << " 的书籍" << endl;
        static Book null_book("", "", "", "");
        return null_book;
    }

    ~Library() {
        if (book) {
            delete[] book;
        }
    }
};

int main() {
    Library l;
    int input;
    string t, a, p, d;

    cout << "------------------菜单栏------------------" << endl;
    cout << "1.图书信息添加" << endl;
    cout << "2.图书信息删除" << endl;
    cout << "3.图书信息查看" << endl;
    cout << "4.图书信息查找" << endl;
    cout << "0.退出" << endl;

    while (1) {
        cout << "请选择功能: ";
        cin >> input;

        switch (input) {
            case 1: {
                cout << "请输入添加的图书书名：";
                cin >> t;
                cout << "请输入添加的图书作者：";
                cin >> a;
                cout << "请输入添加的图书出版社：";
                cin >> p;
                cout << "请输入添加的图书出版日期：";
                cin >> d;
                Book b(t, a, p, d);
                l.AddBook(b);
                break;
            }

            case 2: {
                cout << "请输入删除的图书书名：";
                cin >> t;
                l.DeleteBook(t);
                break;
            }

            case 3: {
                l.ShowBook();
                break;
            }

            case 4: {
                cout << "请输入查找的图书书名：";
                cin >> t;
                Book& b = l.FindBook(t);
                if (b.title != "") {
                    cout << "查询结果为：" << b.title << "\t\t" << b.author << "\t\t" << b.publisher << "\t\t" << b.date << endl;
                }
                break;
            }

            case 0: {
                cout << "已退出" << endl;
                return 0;
            }

            default: {
                cout << "输入错误，请重新选择功能" << endl;
                break;
            }
        }
    }
}