springmvc学习第三天

利用spring mvc 实现crud

1.导入jar包

commons-logging-1.2.jar
jstl.jar
spring-aop-4.1.6.RELEASE.jar
spring-beans-4.1.6.RELEASE.jar
spring-context-4.1.6.RELEASE.jar
spring-core-4.1.6.RELEASE.jar
spring-expression-4.1.6.RELEASE.jar
spring-web-4.1.6.RELEASE.jar
spring-webmvc-4.1.6.RELEASE.jar
standard.jar

2.配置web.xml

<?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"
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">

<!-- 配置 SpringMVC 的 DispatcherServlet -->
<!-- The front controller of this Spring Web application, responsible for handling all application requests -->
<servlet>
　　　　<servlet-name>springDispatcherServlet</servlet-name>
　　　　<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
　　<init-param>
　　　　<param-name>contextConfigLocation</param-name>
　　　　<param-value>classpath:springmvc.xml</param-value>
　　</init-param>
　　<load-on-startup>1</load-on-startup>
</servlet>

<!-- Map all requests to the DispatcherServlet for handling -->
<servlet-mapping>
　　<servlet-name>springDispatcherServlet</servlet-name>
　　<url-pattern>/</url-pattern>
</servlet-mapping>

<!-- 配置 HiddenHttpMethodFilter: 把 POST 请求转为 DELETE、PUT 请求 -->
<filter>
　　<filter-name>HiddenHttpMethodFilter</filter-name>
　　<filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class>
</filter>

<filter-mapping>
　　<filter-name>HiddenHttpMethodFilter</filter-name>
　　<url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>

3.配置springmvc.xml

<?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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd">

<!-- 配置自动扫描的包 -->
<context:component-scan base-package="com.atguigu.springmvc"></context:component-scan>

<!-- 配置视图解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
　　<property name="prefix" value="/WEB-INF/views/"></property>
　　<property name="suffix" value=".jsp"></property>
</bean>

<!--

为什么要使用default-servlet-handler(在jsp页面中使用jQuery，如果不设置，则会提示找不到资源文件)

SpringMVC 处理静态资源:
1. 为什么会有这样的问题:
优雅的 REST 风格的资源URL 不希望带 .html 或 .do 等后缀
若将 DispatcherServlet 请求映射配置为 /,
则 Spring MVC 将捕获 WEB 容器的所有请求, 包括静态资源的请求, SpringMVC 会将他们当成一个普通请求处理,
因找不到对应处理器将导致错误。
2. 解决: 在 SpringMVC 的配置文件中配置 <mvc:default-servlet-handler/>

处理细节
default-servlet-handler 将在 SpringMVC 上下文中定义一个 DefaultServletHttpRequestHandler,
它会对进入 DispatcherServlet 的请求进行筛查, 如果发现是没有经过映射的请求, 就将该请求交由 WEB 应用服务器默认的
Servlet 处理. 如果不是静态资源的请求，才由 DispatcherServlet 继续处理

一般 WEB 应用服务器默认的 Servlet 的名称都是 default.
若所使用的 WEB 服务器的默认 Servlet 名称不是 default，则需要通过 default-servlet-name 属性显式指定

-->
<mvc:default-servlet-handler/>

<!--当配置了<mvc:default-servlet-handler/>，原先的正常的地址也会报404，配置这个就可以解决问题-->

<mvc:annotation-driven conversion-service="conversionService"></mvc:annotation-driven>
</beans>

4、实体类

Department类

package com.atguigu.springmvc.crud.entities;

public class Department {

private Integer id;
private String departmentName;

public Department() {
// TODO Auto-generated constructor stub
}

public Department(int i, String string) {
this.id = i;
this.departmentName = string;
}

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getDepartmentName() {
return departmentName;
}

public void setDepartmentName(String departmentName) {
this.departmentName = departmentName;
}

@Override
public String toString() {
return "Department [id=" + id + ", departmentName=" + departmentName
+ "]";
}

}

Employee类

package com.atguigu.springmvc.crud.entities;

import java.util.Date;

import javax.validation.constraints.Past;

import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.NotEmpty;
import org.springframework.format.annotation.DateTimeFormat;
import org.springframework.format.annotation.NumberFormat;

public class Employee {

private Integer id;
@NotEmpty
private String lastName;

@Email
private String email;
//1 male, 0 female
private Integer gender;

private Department department;

@Past
@DateTimeFormat(pattern="yyyy-MM-dd")
private Date birth;

@NumberFormat(pattern="#,###,###.#")
private Float salary;

public Integer getId() {
return id;
}

public void setId(Integer id) {
this.id = id;
}

public String getLastName() {
return lastName;
}

public void setLastName(String lastName) {
this.lastName = lastName;
}

public String getEmail() {
return email;
}

public void setEmail(String email) {
this.email = email;
}

public Integer getGender() {
return gender;
}

public void setGender(Integer gender) {
this.gender = gender;
}

public Department getDepartment() {
return department;
}

public void setDepartment(Department department) {
this.department = department;
}

public Date getBirth() {
return birth;
}

public void setBirth(Date birth) {
this.birth = birth;
}

public Float getSalary() {
return salary;
}

public void setSalary(Float salary) {
this.salary = salary;
}

@Override
public String toString() {
return "Employee [id=" + id + ", lastName=" + lastName + ", email="
+ email + ", gender=" + gender + ", department=" + department
+ ", birth=" + birth + ", salary=" + salary + "]";
}

public Employee(Integer id, String lastName, String email, Integer gender,
Department department) {
super();
this.id = id;
this.lastName = lastName;
this.email = email;
this.gender = gender;
this.department = department;
}

public Employee() {
// TODO Auto-generated constructor stub
}
}

5、dao类

DepartmentDao类

package com.atguigu.springmvc.crud.dao;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Repository;

import com.atguigu.springmvc.crud.entities.Department;

@Repository
public class DepartmentDao {

private static Map<Integer, Department> departments = null;

static{
departments = new HashMap<Integer, Department>();

departments.put(101, new Department(101, "D-AA"));
departments.put(102, new Department(102, "D-BB"));
departments.put(103, new Department(103, "D-CC"));
departments.put(104, new Department(104, "D-DD"));
departments.put(105, new Department(105, "D-EE"));
}

public Collection<Department> getDepartments(){
return departments.values();
}

public Department getDepartment(Integer id){
return departments.get(id);
}

}

EmployeeDao类

package com.atguigu.springmvc.crud.dao;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

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

import com.atguigu.springmvc.crud.entities.Department;
import com.atguigu.springmvc.crud.entities.Employee;

@Repository
public class EmployeeDao {

private static Map<Integer, Employee> employees = null;

@Autowired
private DepartmentDao departmentDao;

static{
employees = new HashMap<Integer, Employee>();

employees.put(1001, new Employee(1001, "E-AA", "aa@163.com", 1, new Department(101, "D-AA")));
employees.put(1002, new Employee(1002, "E-BB", "bb@163.com", 1, new Department(102, "D-BB")));
employees.put(1003, new Employee(1003, "E-CC", "cc@163.com", 0, new Department(103, "D-CC")));
employees.put(1004, new Employee(1004, "E-DD", "dd@163.com", 0, new Department(104, "D-DD")));
employees.put(1005, new Employee(1005, "E-EE", "ee@163.com", 1, new Department(105, "D-EE")));
}

private static Integer initId = 1006;

public void save(Employee employee){
if(employee.getId() == null){
employee.setId(initId++);
}

employee.setDepartment(departmentDao.getDepartment(employee.getDepartment().getId()));
employees.put(employee.getId(), employee);//此处不可以写为employees.put(initId , employee);否则删除功能将出现问题
}

public Collection<Employee> getAll(){
return employees.values();
}

public Employee get(Integer id){
return employees.get(id);
}

public void delete(Integer id){
employees.remove(id);
}
}

6、处理类

EmployeeHandler 类

package com.atguigu.springmvc.crud.handlers;

import java.util.Map;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.Errors;
import org.springframework.validation.FieldError;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

import com.atguigu.springmvc.crud.dao.DepartmentDao;
import com.atguigu.springmvc.crud.dao.EmployeeDao;
import com.atguigu.springmvc.crud.entities.Employee;

@Controller
public class EmployeeHandler {

@Autowired
private EmployeeDao employeeDao;

@Autowired
private DepartmentDao departmentDao;

//更新操作

@ModelAttribute

//只有在更新的时候，前台通过<form:hidden path="id"/>才会传过来一个id的值，

//使用@RequestParam可以取到，设置为不是一定要获取到此id ：required=false，因为每一次请求都会调用该方法
public void getEmployee(@RequestParam(value="id",required=false) Integer id,     
Map<String, Object> map){
if(id != null){
map.put("employee", employeeDao.get(id));//键employee为Employee第一个字母小写
}
}

@RequestMapping(value="/emp", method=RequestMethod.PUT)
public String update(Employee employee){
employeeDao.save(employee);

return "redirect:/emps";
}

//表单回显 如果传回去的employee，有值，form标签将会自动显示出来
@RequestMapping(value="/emp/{id}", method=RequestMethod.GET)
public String input(@PathVariable("id") Integer id, Map<String, Object> map){
map.put("employee", employeeDao.get(id));
map.put("departments", departmentDao.getDepartments());
return "input";
}

//删除操作
@RequestMapping(value="/emp/{id}", method=RequestMethod.DELETE)
public String delete(@PathVariable("id") Integer id){
employeeDao.delete(id);
return "redirect:/emps";
}

//将departments放入到request域对象中，用于部门信息在前台的显示
@RequestMapping(value="/emp", method=RequestMethod.POST)
public String save(Employee employee, 
Map<String, Object> map){

map.put("departments", departmentDao.getDepartments());
map.put("employee", new Employee());//用于设置<form:form modelAttribute="employee">
return "input";

}

///保存操作

@RequestMapping(value="/add",method=RequestMethod.POST)
public String save(Employee employee){
employeeDao.save(employee);
return "redirect:/springmvc/listall";
}

//显示全部employee信息
@RequestMapping("/emps")
public String list(Map<String, Object> map){
map.put("employees", employeeDao.getAll());
return "list";
}

}

7、jsp页面

index.jsp

<a href="emps">List All Employees</a>

list.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!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>Insert title here</title>
<!--此处一定在要springmvc的配置文件中设置<mvc:default-servlet-handler/>-->
<script type="text/javascript" src="scripts/jquery-1.9.1.min.js"></script>
<script type="text/javascript">

//将delete 的get请求，通过jQuery变成delete请求
$(function(){
$(".delete").click(function(){
var href = $(this).attr("href");
$("form").attr("action", href).submit();
return false;
});
})
</script>
</head>
<body>

<form action="" method="POST">
<input type="hidden" name="_method" value="DELETE"/>
</form>

<c:if test="${empty requestScope.employees }">
没有任何员工信息.
</c:if>
<c:if test="${!empty requestScope.employees }">
<table border="1" cellpadding="10" cellspacing="0">
<tr>
<th>ID</th>
<th>LastName</th>
<th>Email</th>
<th>Gender</th>
<th>Department</th>
<th>Edit</th>
<th>Delete</th>
</tr>

<c:forEach items="${requestScope.employees }" var="emp">
<tr>
<td>${emp.id }</td>
<td>${emp.lastName }</td>
<td>${emp.email }</td>
<td>${emp.gender == 0 ? 'Female' : 'Male' }</td>
<td>${emp.department.departmentName }</td>
<td><a href="emp/${emp.id}">Edit</a></td>
<td><a class="delete" href="emp/${emp.id}">Delete</a></td>
</tr>
</c:forEach>
</table>
</c:if>

<br><br>

<a href="emp">Add New Employee</a>

</body>
</html>

input.jsp

<%@page import="java.util.HashMap"%>
<%@page import="java.util.Map"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<!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>Insert title here</title>
</head>
<body>

<!--
1. WHY 使用 form 标签呢 ?
可以更快速的开发出表单页面, 而且可以更方便的进行表单值的回显
2. 注意:
可以通过 modelAttribute 属性指定绑定的模型属性,
若没有指定该属性，则默认从 request 域对象中读取 command 的表单 bean
如果该属性值也不存在，则会发生错误。
-->
<br><br>
<form:form action="${pageContext.request.contextPath }/emp" method="POST"
modelAttribute="employee">

<c:if test="${employee.id == null }">
<!-- path 属性对应 html 表单标签的 name 属性值 -->
LastName: <form:input path="lastName"/>
</c:if>
<c:if test="${employee.id != null }">
<form:hidden path="id"/>
<input type="hidden" name="_method" value="PUT"/>
<%-- 对于 _method 不能使用 form:hidden 标签, 因为 modelAttribute 对应的 bean 中没有 _method 这个属性 --%>
<%--
<form:hidden path="_method" value="PUT"/>
--%>
</c:if>

<br>
Email: <form:input path="email"/>
<br>
<%
Map<String, String> genders = new HashMap();
genders.put("1", "Male");
genders.put("0", "Female");

request.setAttribute("genders", genders);
%>
Gender:
<br>
<form:radiobuttons path="gender" items="${genders }" delimiter="<br>"/>
<br>

<!--
本文主要记录一些作者在使用spring mvc过程中遇到的一些以及解决办法，以备日后查询或者供其他网友阅读，每个问题的解决办法肯定不止一种，如果你也遇到过类似问题，并且有独特的见解，我会很高兴你能留言给我，谢谢。 :)

1、 前台提交form，tomcat返回 http status 400 The request sent by the client was syntactically incorrect，控制台无任何错误输出。

这是因为前台form表单中的某些参数 和 后台接受的参数类型不一致导致的。即参数名称相同，但是类型不一致。spring mvc在绑定参数的时候出现异常，所以返回400错误。但是坑爹的地方在于，这个异常会被spring mvc吃掉，不会显示在控制台中。

解决办法：检查form表单中的参数和后台的参数对应，看是否有参数名相同但是类型不一致的情况。或者把当前日志设为debug 级别，然后在日志中即可看到spring 抛出的异常信息，即可发现哪个参数出现了错误。 -->

Department: <form:select path="department.id"  //注意此处的设置一定要为department.id 与itemValue="id"的类型保持一致，否则会出现400异常
items="${departments }" itemLabel="departmentName" itemValue="id"></form:select>
<br>
<input type="submit" value="Submit"/>
</form:form>

</body>
</html>