spring mvc中的数据绑定错误

Question

我正在尝试使用Spring MVC中的form标记创建一个简单的表单。传递用户名只有一个名为uname的字段 在整个程序中，我使用的是基于Java的注释而没有xml文件，但是我遇到了这个恼人的错误，并且不知道如何修复它。

SEVERE: Neither BindingResult nor plain target object for bean name 'user' available as request attribute
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute
    at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:144)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:168)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:188)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:154)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:141)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:132)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:116)
    at org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:422)
    at org.springframework.web.servlet.tags.form.InputTag.writeTagContent(InputTag.java:142)
    at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:84)
    at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
    at org.apache.jsp.Home_jsp._jspx_meth_form_005finput_005f0(Home_jsp.java:213)
    at org.apache.jsp.Home_jsp._jspx_meth_form_005fform_005f0(Home_jsp.java:177)
    at org.apache.jsp.Home_jsp._jspService(Home_jsp.java:132)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

Jun 07, 2016 1:56:33 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/first] threw exception [An exception occurred processing JSP page /Home.jsp at line 14

11: <body>
12: <form:form method="post" action="vv" commandName="user">
13: Name:
14: <form:input path="uname"/>
15: <input type="submit" value="Login"/>
16: 
17: </form:form>


Stacktrace:] with root cause
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute
    at org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:144)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:168)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:188)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getName(AbstractDataBoundFormElementTag.java:154)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.autogenerateId(AbstractDataBoundFormElementTag.java:141)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.resolveId(AbstractDataBoundFormElementTag.java:132)
    at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.writeDefaultAttributes(AbstractDataBoundFormElementTag.java:116)
    at org.springframework.web.servlet.tags.form.AbstractHtmlElementTag.writeDefaultAttributes(AbstractHtmlElementTag.java:422)
    at org.springframework.web.servlet.tags.form.InputTag.writeTagContent(InputTag.java:142)
    at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:84)
    at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:80)
    at org.apache.jsp.Home_jsp._jspx_meth_form_005finput_005f0(Home_jsp.java:213)
    at org.apache.jsp.Home_jsp._jspx_meth_form_005fform_005f0(Home_jsp.java:177)
    at org.apache.jsp.Home_jsp._jspService(Home_jsp.java:132)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:438)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:396)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:340)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

回到Home.jsp

%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form:form method="post" action="vv" commandName="user">
Name:
<form:input path="uname"/>
<input type="submit" value="Login"/>

</form:form>
</body>
</html>

控制器

package one;

import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("vv")
public class MainC {

    @RequestMapping(method=RequestMethod.GET)
    public String pp(ModelMap m)
    {
        User u=new User();
        m.addAttribute("user",u);
        return "Home";
    }
    @RequestMapping(method=RequestMethod.POST)
    public String pp1(@ModelAttribute("user") User user, BindingResult br)
    {
        if(user.getUname().length()!=0)
        return "Success";
        else
            return "Failure";

    }

}

配置

package one;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.view.InternalResourceViewResolver;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages={"one"})
public class Conf {

    @Bean(name="viewResolver")
    public InternalResourceViewResolver ii()
    {
        InternalResourceViewResolver i=new InternalResourceViewResolver();
        i.setPrefix("/");
        i.setSuffix(".jsp");
        return i;
    }

}

初始化剂

package one;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

public class WebInit implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext arg0) throws ServletException {
        // TODO Auto-generated method stub

        AnnotationConfigWebApplicationContext cxt=new AnnotationConfigWebApplicationContext();
        cxt.register(Conf.class);
        arg0.addListener(new ContextLoaderListener(cxt));
        ServletRegistration.Dynamic srv=arg0.addServlet("HelloWeb", new DispatcherServlet(cxt));
        srv.setLoadOnStartup(1);
        srv.addMapping("/");


    }

}

用户

package one;

public class User {

    private String uname;


    public void setUname(String uname) {
        this.uname = uname;
    }

    public String getUname() {
        return uname;
    }

}

Answer 1

问题是提供空白bean对象的方法永远不会被执行。这就是为什么错误：bean名称的普通目标对象＆＃39;用户＆＃39;不可用即将到来。

<强>解决方案

if ABAddressBookGetAuthorizationStatus() != .Authorized {
    return
}
var error: Unmanaged<CFError>?
if let addressBook: ABAddressBook? = ABAddressBookCreateWithOptions(nil, &error)?.takeRetainedValue() {
    ABAddressBookRequestAccessWithCompletion(addressBook) { granted, error in
        if error == nil && granted {
            if let contacts = ABAddressBookCopyArrayOfAllPeople(addressBook)?.takeRetainedValue() as? NSArray {
                for contact in contacts {
                    print("new contact")
                }
            }
        }
    }
} else {
    print(error?.takeRetainedValue())
}