Ajax学习

/**
 * 封装 ajax 响应结果
 */
public class AjaxResult {
	/**响应状态码 */
	private Integer status ;
	/**响应消息*/
	private String msg ;
	/**响应数据   主要是查询接口返回的数据*/
	private Object data ;
	
	public AjaxResult(Integer status, String msg) {
		super();
		this.status = status;
		this.msg = msg;
	}

	public AjaxResult(Integer status, String msg, Object data) {
		super();
		this.status = status;
		this.msg = msg;
		this.data = data;
	}
}

public class Book {
	private String id ;
	private String bookname ;
	private String author ;
	private String publisher ;
	public Book() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Book(String id, String bookname, String author, String publisher) {
		super();
		this.id = id;
		this.bookname = bookname;
		this.author = author;
		this.publisher = publisher;
	}
}  

public class BookService {
	private static Map<String,Book> bookMap = Collections.synchronizedMap(new LinkedHashMap<>()) ;
	static {
		bookMap.put("B001", new Book("B001","西游记","吴承恩","北京图书出版社")) ;
		bookMap.put("B002", new Book("B002","西红楼梦","曹雪芹","上海图书出版社")) ;
		bookMap.put("B003", new Book("B003","三国演义","罗贯中","北京图书出版社")) ;
	}
	public AjaxResult save(Book book) {
		//获得随机id
		String id = UUID.randomUUID().toString() ;
		//设置书籍id
		book.setId(id);
		bookMap.put(id, book);
		return new AjaxResult(201, "添加图书成功") ;
	}
	
	public AjaxResult remove(String id) {
		if(!bookMap.containsKey(id)) {
			return new AjaxResult(500, "502 要删除的图书不存在") ;
		}
		bookMap.remove(id) ;
		return new AjaxResult(200, "删除图书成功！") ;
	}
	
	public AjaxResult find(Book book) {
		//此次忽略 条件 查询
		return new AjaxResult(200, "获取图书列表成功",bookMap.values()) ;
	}
}

@WebServlet({ "/api/getbooks", "/api/addbook", "/api/delbook" })
public class BookController extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private BookService bookService = new BookService() ;

	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.setCharacterEncoding("UTF-8");
		response.setContentType("application/json;charset=UTF-8");
		String requestURI = request.getRequestURI() ;
		requestURI = requestURI.substring((request.getContextPath()+"/api/").length()) ;
		try {
			Method m = this.getClass().getDeclaredMethod(requestURI, HttpServletRequest.class,HttpServletResponse.class) ;
			AjaxResult ajaxResult = (AjaxResult)m.invoke(this, request,response) ;
			String json = JSON.toJSONString(ajaxResult) ;
			PrintWriter out = response.getWriter();
			out.print(json);
			out.flush();
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	protected AjaxResult getbooks(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		if("POST".equals(request.getMethod())) {
			return new AjaxResult(405, "请求的方式不允许！") ;
		}
		return bookService.find(null) ;
	}
	
	protected AjaxResult addbook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		if("GET".equals(request.getMethod())) {
			return new AjaxResult(405, "请求的方式不允许！") ;
		}
		String bookname = request.getParameter("bookname") ;
		String author = request.getParameter("author") ;
		String publisher = request.getParameter("publisher") ;
		Book book = new Book() ;
		book.setBookname(bookname);
		book.setAuthor(author);
		book.setPublisher(publisher);
		return bookService.save(book) ;	
	}
	
	protected AjaxResult delbook(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		if("POST".equals(request.getMethod())) {
			return new AjaxResult(405, "请求的方式不允许！") ;
		}
		String id = request.getParameter("id") ;
		if(id==null || id.equals("")) {
			return new AjaxResult(500, "未指定要删除的图书Id") ;
		}
		return bookService.remove(id) ;
	}
}

/**
 * 功能描述：解决跨域过滤器 
 */
@WebFilter("/api/*")
public class CORSFilter implements Filter {
	private final int time = 20*24*60*60;
	
	public void init(FilterConfig fConfig) throws ServletException {
		
	}
	
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		HttpServletResponse resp = (HttpServletResponse) response;
        // 添加参数，允许任意domain访问
        resp.setHeader("Access-Control-Allow-Origin", "*");
        // 这个allow-headers要配为*，这样才能允许所有的请求头
        resp.setHeader("Access-Control-Allow-Headers", "*");
        resp.setHeader("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");
        resp.setHeader("Access-Control-Max-Age", time+"");
        chain.doFilter(request, resp);
	}

	
	public void destroy() {
		
	}

}