使用 webResource 删除 RESTful 应用程序中的记录的问题

Question

我正在尝试使用 webResource.type.delete 删除记录。但是，我无法使用此方法删除。我试过使用 POSTMAN，我可以通过这个实用程序删除记录。我在执行中没有收到任何错误，只是servlet没有进入资源删除记录。

源码如下：

DeletePolicy.java（主 servlet）：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter printWriter = response.getWriter();

        Client client= Client.create();
        WebResource webResource= client.resource("http://localhost:8080/clientLibrary/webapi/policy");

        //create an object of RequestDispatcher 
        RequestDispatcher rd = request.getRequestDispatcher("GetPolicy"); 

        // send the client data available with req of delete to req of getPolicy with include() 
        rd.include(request, response);

        List<Policy> policies = (List<Policy>) request.getAttribute("policies");

        printWriter.print("List of policies in Delete: ");

        for(Policy policy : policies) {
             printWriter.println("<li>"+"ID: "+policy.getId()+"<br>"+"Max Number of Books: "+policy.getMax_books()+"<br>"+"Year of Book: "+policy.getYear_book()+"<br>"+"Activated: "+policy.getActivate()+"<br></li><br>");
         }

        //Show to the user the possible options to delete using radio button
        request.setAttribute("policies", policies);

        RequestDispatcher rd2 = getServletConfig().getServletContext().getRequestDispatcher("/showRecordsToDelete.jsp");
        rd2.include(request,response);

        printWriter.println("I am comming back from showRecordsToDelete.jsp");

        //Receive the id from showRecordsToDelete.jsp
        String policyID = request.getParameter("id");

        ClientResponse rs = webResource.type(MediaType.APPLICATION_JSON).delete(ClientResponse.class);

        //Receive the answer and provide status to user
        printWriter.print("Delete a policy");
}

PolicyResource.java：

@Path("/policy")
public class policyResource {
    policyDB db = new policyDB();
    policyService PolicyService = new policyService();

    @DELETE
    @Path("/{policyID}")
    @Produces(MediaType.APPLICATION_JSON)   
    public String removeBook(@PathParam("policyID") int ID){
        System.out.println("id :"+ID);
        boolean removed= PolicyService.deletePolicy(ID);
        String answer="Removed successfully";
        if(removed = false){
            answer="Not removed";
        }
        return answer;
    }   
}

PolicyDB.java

/** Delete a policy
     * @param id
     * @return true if everything is done otherwise returns false
     */
    public boolean delete(int id) {
        Connection c = null;
        System.out.println("delete id :"+id);
        c = accessDB();
        if (c != null) {
            try {
                Statement stmt = null;
                // Execute a query
                stmt = c.createStatement();
                String sql = "DELETE FROM POLICIES WHERE ID='"+ id +"';";
                System.out.println(sql);
                stmt.executeUpdate(sql);
                c.commit();

                stmt.close();
                c.close();
            } catch ( Exception e ) {
                // Handle errors for Class.forName
                System.err.println( e.getClass().getName() + ": " + e.getMessage() );
                return false;
            }
        }
        System.out.println("Deleted "+id);
        return true;

    }

提前感谢您的帮助

Answer 1

问题通过以下方式解决，包括策略 URL 中的 ID：

protected void doDelete(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String policyID = request.getParameter("id");
        if (policyID == null) return;

        Client client= Client.create();
        WebResource webResource= client.resource("http://localhost:8080/clientLibrary/webapi/policy/"+policyID);

        ClientResponse rs = webResource.accept("application/json")
                .type("application/json").delete(ClientResponse.class);

        // display response
        String output = rs.getEntity(String.class);
        System.out.println("Output from Server .... ");
        System.out.println(output + "\n");
    }