spring3 jsp页面使用报错，附连接数据库的spring MVC annotation 案例

在写一个使用spring3 的form标签的例子时，一直报错，错误信息为：java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute 。具体信息为：

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute
	at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:141)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getBindStatus(AbstractDataBoundFormElementTag.java:174)
	at org.springframework.web.servlet.tags.form.AbstractDataBoundFormElementTag.getPropertyPath(AbstractDataBoundFormElementTag.java:194)
	at org.springframework.web.servlet.tags.form.LabelTag.autogenerateFor(LabelTag.java:129)
	at org.springframework.web.servlet.tags.form.LabelTag.resolveFor(LabelTag.java:119)
	at org.springframework.web.servlet.tags.form.LabelTag.writeTagContent(LabelTag.java:89)
	at org.springframework.web.servlet.tags.form.AbstractFormTag.doStartTagInternal(AbstractFormTag.java:102)
	at org.springframework.web.servlet.tags.RequestContextAwareTag.doStartTag(RequestContextAwareTag.java:79)
	at org.apache.jsp.WEB_002dINF.jsp.register_jsp._jspx_meth_sf_005flabel_005f0(register_jsp.java:255)
	at org.apache.jsp.WEB_002dINF.jsp.register_jsp._jspService(register_jsp.java:140)
	at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
	at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
	at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
	at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:250)
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1047)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:817)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
	at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
	at java.lang.Thread.run(Thread.java:662)

在网上找了好长时间都不是原因所在，一直在想form标签中的modelAttribute是怎么跟project中相应的类联系在一起的，同事说是根据中的path attribute跟相应类中的field对应起来，由spring像注入一样给每个field赋值。所以一直在JSP页面查找原因，网上找的也都是改JSP页面，结果还是没有解决掉。

错误信息是“对于bean name 'xxxx' 既没有BindingResult也没有普通的目标对象可以用来作为请求属性”。突然想到在进入form表单页面之前，要有一个'xxxx'对象才可以在表单的标签中识别出来，所以在进入该JSP页面之前的Controller类里面相应的方法里面加上一个'xxxx'的对象。解决如下：

return new ModelAndView("register").addObject(new User());

已经验证这样修改之后就不会报错。

例子的结构如图：

web.xml 的内容：

	springMVCForm

	
		springMVCForm
		org.springframework.web.servlet.DispatcherServlet
	

	
		springMVCForm
		*.do
	

	
		contextConfigLocation
		/WEB-INF/springMVCForm-servlet.xml
	

	
		org.springframework.web.context.ContextLoaderListener
	

	
		index.jsp
	

springMVCForm-servlet.xml 的内容：

	

	

	
		
			
				classpath:db-config.properties
			
		
	

	
	
		
			${db.dirverClass}
		
		
			${db.url}
		
		
			${db.username}
		
		
			${db.password}
		
	

	
		
	
	
		
	

	

	

	
	
		
		
		
	

db-config.properties的内容：

db.url= jdbc:mysql://localhost:3306/springmvcdb?useUnicode=true&characterEncoding=utf8

db.username=root

db.password=

db.dirverClass= com.mysql.jdbc.Driver

UserDao.class的内容：

package org.spring.wayne.dao;

import org.spring.wayne.dao.basic.BasicDao;

@Repository
public class UserDao extends BasicDao {

	public void addUser(User user) {
		String SQL = "INSERT INTO TBL_USER(USERNAME ,PASSWORD) VALUES('" + user.getUserName() + "' ,'"
				+ user.getPassword() + "')";
		getJdbcTemplate().execute(SQL);
	}

}

BasicDao.class的内容：

package org.spring.wayne.dao.basic;

import org.springframework.beans.factory.annotation.Autowired;

public class BasicDao {

	@Autowired
	private JdbcTemplate jdbcTemplate;

	@Autowired
	private NamedParameterJdbcTemplate namedParameterJdbcTemplate;

	public JdbcTemplate getJdbcTemplate() {
		return jdbcTemplate;
	}

	public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
		this.jdbcTemplate = jdbcTemplate;
	}

	public NamedParameterJdbcTemplate getNamedParameterJdbcTemplate() {
		return namedParameterJdbcTemplate;
	}

	public void setNamedParameterJdbcTemplate(NamedParameterJdbcTemplate namedParameterJdbcTemplate) {
		this.namedParameterJdbcTemplate = namedParameterJdbcTemplate;
	}
}

UserService.class的内容：

package org.spring.wayne.service;

import org.spring.wayne.web.form.User;

public interface UserService {

	public void addUser(User user);

}

UserServiceImpl.class的内容：

package org.spring.wayne.service.impl;

import org.spring.wayne.dao.UserDao;
@Service
public class UserServiceImpl implements UserService {
	@Autowired
	private UserDao userDao;

	@Override
	public void addUser(User user) {
		userDao.addUser(user);
	}

}

RegController.class的内容：

package org.spring.wayne.web.controller;

import javax.validation.Valid;

@Controller
public class RegController {

	@Autowired
	private UserService userService;

	@RequestMapping("/register.do")
	public String handler(@ModelAttribute("user") @Valid User user, BindingResult result, Model model) {
		if (!result.hasErrors()) {
			model.addAttribute("userName", user.getUserName());
			model.addAttribute("password", user.getPassword());
			userService.addUser(user);
			return "welcome";
		} else
			return "register";
	}
}

WelcomeController.class的内容：

package org.spring.wayne.controller;

import org.spring.wayne.web.form.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class WelcomeController {

	@RequestMapping("/welcome.do")
	public ModelAndView handler() {
		return new ModelAndView("register").addObject(new User());
	}
}

User.class的内容：

package org.spring.wayne.web.form;

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

import org.hibernate.validator.constraints.NotEmpty;

public class User {

	private String errors;

	@NotNull
	@NotEmpty(message = "This cannot be null")
	@Size(min = 4, max = 6, message = "length is wrong")
	private String userName;

	@NotNull
	@NotEmpty
	@Size(min = 6, max = 10)
	private String password;

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getErrors() {
		return errors;
	}

	public void setErrors(String errors) {
		this.errors = errors;
	}
}

index.jsp的内容：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
    + request.getServerName() + ":" + request.getServerPort()
    + path + "/";
%>







	

		Click here to start
	

register.jsp的内容：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib prefix="sf" uri="http://www.springframework.org/tags/form"%>









	
		
		

			
Register
			

				

					
UserName:
					
					

					
					

					
				
				

					
Password:
					
					

					
					

					
				
				

					

					
				
			
		
	

welcome.jsp的内容：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>







	Welcome, ${userName }, your password is ${password }!
	

	
This item has been inserted into the table !

用到的jar包包括spring3中的dist目录下的所有jar包，validation-api，hibernate-validator，slf4j-api，slf4j-log4j，log4j，commons-logging，tomcat-dbcp，mysql-connector-java-5.1.12-bin包。

运行截图如下：

运行project后的界面：

点击page中的链接后如图所示：

当UserName和Password为空时提示错误信息：

输入符合要求的UserName和Password跳转到下一个页面：

现在查询数据库可以看到一条记录：

该Spring MVC JUnit测试实例请点击（Spring MVC JUnit Test测试实例 附：读取WEB-INF下配置文件的方法）

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