spring3 jsp页面使用<form:form modelAttribute="xxxx" action="xxxx">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.<init>(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<form:input path="field"/>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：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>springMVCForm</display-name>

    <servlet>
        <servlet-name>springMVCForm</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>springMVCForm</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/springMVCForm-servlet.xml</param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>

springMVCForm-servlet.xml 的内容：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <mvc:annotation-driven />

    <context:component-scan base-package="org.spring.wayne" />

    <bean id="config"
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:db-config.properties</value>
            </list>
        </property>
    </bean>

    <!-- 获取数据源 -->
    <bean id="dataSource" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource">
        <property name="driverClassName">
            <value>${db.dirverClass}</value>
        </property>
        <property name="url">
            <value>${db.url}</value>
        </property>
        <property name="username">
            <value>${db.username}</value>
        </property>
        <property name="password">
            <value>${db.password}</value>
        </property>
    </bean>

    <bean name="namedParameterJdbcTemplate"
        class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
        <constructor-arg ref="dataSource" />
    </bean>
    <bean name="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <constructor-arg ref="dataSource" />
    </bean>

    <bean
        class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />

    <bean
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />

    <!-- 对模型视图名称的解析，即在模型视图名称添加前后缀,在requestmapping输入的地址后自动调用该类进行视图解析 -->
    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/jsp/" /><!-- 跳转页面的前缀路径
            如 /web-inf/jsp/ -->
        <property name="suffix" value=".jsp"></property><!-- 跳转页面后缀 如 helloWorld.jsp -->
    </bean>
</beans>

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 + "/";
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>The Index Page</title>
</head>
<body>
    <h3>
        <a href="<%=basePath %>welcome.do">Click here to start</a>
    </h3>
</body>
</html>

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"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>The Register Page</title>
<script type="text/javascript">
    function doSubmit() {
        var sf = document.getElementById("sf");
        sf.submit();
    }
</script>
<style type="text/css">
.errors {
    font-size: 12px;
    color: red;
}
</style>
</head>
<body>
    <sf:form id="sf" method="POST" modelAttribute="user"
        action="register.do">
        <sf:errors path="errors" />
        <fieldset>
            <legend>Register</legend>
            <table cellspacing="0">
                <tr>
                    <td><sf:label path="userName">UserName:</sf:label>
                    </td>
                    <td><sf:input path="userName" />
                    </td>
                    <td><sf:errors path="userName" class="errors" />
                    </td>
                </tr>
                <tr>
                    <td><sf:label path="password">Password:</sf:label>
                    </td>
                    <td><sf:password path="password" />
                    </td>
                    <td><sf:errors path="password" class="errors" />
                    </td>
                </tr>
                <tr>
                    <td colspan="2"><input type="button" value="Submit"
                        onClick="doSubmit()">
                    </td>
                </tr>
            </table>
        </fieldset>
    </sf:form>
</body>
</html>

welcome.jsp的内容：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>The Welcome Page</title>
</head>
<body>
    Welcome, ${userName }, your password is ${password }!
    <br>
    <h3>This item has been inserted into the table !</h3>
</body>
</html>

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）