Quick learning - comprehensive case restull CRUD

Keywords: Java Spring Attribute JSP

Chapter 7 comprehensive case

7.1 restrl? Crud? Requirements

7.1.1 display all employee information

URI: emps
Request method: GET
Display effect

7.1.2 add operation - go to add page

Show add page:
URI: emp
Request method: GET
Display effect

7.1.3 add operation - add employee

Add employee information:
URI: emp
Request method: POST
Display effect: finish adding and redirect to the list page.

7.1.4 delete

URL: emp/{id}
Request method: DELETE
Effect after deletion: delete the corresponding record from the data table

7.1.5 modify - go to modify page

URI: emp/{id}
Request method: GET
Display effect: echo the form.

7.1.6 modify - modify employee

URI: emp
Request mode: PUT
Display effect: finish the modification and redirect to the list page.

7.1.7 related categories

Service layer is omitted for teaching convenience

Entity class: Employee, Department
Handler: EmployeeHandler
Dao: EmployeeDao,DepartmentDao

7.1.8 relevant pages

list.jsp
input.jsp
edit.jsp

7.2 build development environment

Copy jar package

com.springsource.net.sf.cglib-2.2.0.jar
com.springsource.org.aopalliance-1.0.0.jar
com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
spring-aop-4.0.0.RELEASE.jar
spring-aspects-4.0.0.RELEASE.jar
commons-logging-1.1.3.jar
spring-beans-4.0.0.RELEASE.jar
spring-context-4.0.0.RELEASE.jar
spring-core-4.0.0.RELEASE.jar
spring-expression-4.0.0.RELEASE.jar
spring-jdbc-4.0.0.RELEASE.jar
spring-orm-4.0.0.RELEASE.jar
spring-tx-4.0.0.RELEASE.jar
spring-web-4.0.0.RELEASE.jar
spring-webmvc-4.0.0.RELEASE.jar

Create configuration file: add context,mvc,beans namespace to 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/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
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">
 
<!-- To configure a scanned package: com.atguigu.springmvc.crud -->
<context:component-scan base-package="com.atguigu.springmvc"/>
 
<!-- Configure view resolver: forward by default -->
<bean id="internalResourceViewResolver" 
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/"/>
<property name="suffix" value=".jsp"></property>
</bean> 
</beans>

Configure core controller: web.xml

<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> 
	<servlet-mapping>
	<servlet-name>springDispatcherServlet</servlet-name>
	<url-pattern>/</url-pattern>
</servlet-mapping>

Convert a POST request to a PUT or DELETE request

  <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>

Create related pages

/WEB-INF/views/list.jsp
index.jsp

Add entity class
Increase DAO class

@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);
    }
 
    public Collection<Employee> getAll(){
        return employees.values();
    }
 
    public Employee get(Integer id){
        return employees.get(id);
    }
 
    public void delete(Integer id){
        employees.remove(id);
    }
}

@Repository
public class DepartmentDao {
 
    private static Map<Integer, Department> departments = null;
 
    static{
        departments = new LinkedHashMap<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);
    }
 
}

7.3 display all employee information

Add page link

<a href="empList">To Employee List</a>

Add processor

@Controller
public class EmployeeHandler {
 
    @Autowired
    private EmployeeDao employeeDao ;
 
    @RequestMapping("/empList")
    public String empList(Map<String,Object> map){
        map.put("empList", employeeDao.getAll());        //Store in request domain by default        
        return "list";
    } 
}

For tags not traversed in spring MVC, you need to use jstl tags for collection traversal to add jstl tag library jar package

<%@ 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>
</head>
<body>

	<c:if test="${empty requestScope.empList }">
	Sorry, no employees found!
	</c:if>
	<c:if test="${!empty requestScope.empList }">
	<table border="1" cellpadding="10" cellspacing="0">                
	<tr>
	<td>EmpId</td>
	<td>LastName</td>
	<td>Gender</td>
	<td>Email</td>
	<td>DepartmentName</td>
	<td>Edit</td>
	<td>Delete</td>
	</tr>
	<c:forEach items="${requestScope.empList }" var="emp">
	<tr>
	<td>${emp.id }</td>
	<td>${emp.lastName }</td>
	<td>${emp.gender==0?"Female":"Male" }</td>
	<td>${emp.email }</td>
	<td>${emp.department.departmentName }</td>
	<td><a href="">Edit</a></td>
	<td><a href="">Delete</a></td>
	</tr>                
	</c:forEach>        
	</table>
	</c:if>
	 
</body>
</html>

7.4 add restul CRUD

Add connection to list.jsp

<a href="empInput">Add Employee</a>

Add processor method

    @RequestMapping(value="/empInput",method= RequestMethod.GET)
    public String empInput(Map<String,Object> map){
        map.put("deptList", departmentDao.getDepartments());
        //Troubleshooting error: java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute
        Employee employee = new Employee();
        //map.put("command", employee);
        map.put("employee", employee);
        return "add";
    }

Show add page

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="java.util.*"%>
<%@ taglib prefix="form" 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>Insert title here</title>
</head>
<body>
 
<!-- 
1.Why use SpringMVC Of form Label
① Rapid development
② Form echo display
2.Can pass modelAttribute Specifies the model properties of the binding,
//If this property is not specified, the bean of the form that looks up the command from the request field by default
//If the property also does not exist, an error occurs.
 -->
 <form:form action="empAdd" method="POST" modelAttribute="employee">
         LastName : <form:input path="lastName"/><br><br>
         Email : <form:input path="email"/><br><br>
         <%
                 Map<String,String> map = new HashMap<String,String>();
                 map.put("1", "Male");
                 map.put("0","Female");
                 request.setAttribute("genders", map);
         %>
        Gender : <br><form:radiobuttons path="gender" items="${genders }" delimiter="<br>"/><br><br>
         DeptName : 
                 <form:select path="department.id" 
                                                 items="${deptList }" 
                                                 itemLabel="departmentName" 
                                                 itemValue="id"></form:select><br><br>
                 <input type="submit" value="Submit"><br><br>
 </form:form> 
</body>
</html>

When the form information is displayed, an error will be reported:

HTTP Status 500 - 
 
type Exception report
message 
description The server encountered an internal error () that prevented it from fulfilling this request.
exception 
org.apache.jasper.JasperException: An exception occurred processing JSP page /WEB-INF/views/add.jsp at line 18
15:                         ② Form echo display
16:          -->
17:          <form:form action="empAdd" method="POST">
18:                  LastName : <form:input path="lastName"/>
19:                  Email : <form:input path="email"/>
20:                  <%
21:                          Map<String,String> map = new HashMap<String,String>();
Stacktrace:
        org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:505)
        org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:410)
        org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:337)
        org.apache.jasper.servlet.JspServlet.service(JspServlet.java:266)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:209)
        org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:266)
        org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1225)
        org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1012)
        org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959)
        org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
        org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:931)
        org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:822)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
        org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)
        javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
        org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
root cause 
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute
        org.springframework.web.servlet.support.BindStatus.<init>(BindStatus.java:141)

7.5 using Spring's form tags

Through the form tag of spring MVC, the attributes in the model data can be bound with HTML form elements, so that the form data can be edited more easily and the form value can be echoed
form tags

In general, GET request is used to GET the form page, and POST request is used to submit the form page, so the URL of getting the form page and submitting the form page is the same.
As long as the contract meets the best conditions,form:form The tag does not need to specify the URL of the form submission through the action attribute
You can specify the bound model attribute through the modelAttribute attribute. If you do not specify this attribute, the command's form bean will be read from the request domain object by default. If the attribute value does not exist, an error will occur.

Spring MVC provides multiple form component tags, such as form:input/,form:select/ To bind the property values of form fields, their common properties are as follows:

path: form field, corresponding to the name attribute of html element, supporting cascade attribute
htmlEscape: whether to convert the HTML special characters of the form value. The default value is true
cssClass: CSS style class name corresponding to form component
cssErrorClass: CSS style adopted when data of form component is wrong

form:input, form:password, form:hidden, form:textarea: text, password, hidden, textarea tags corresponding to HTML forms
form:radiobutton: radio box component label. When the attribute value of the form bean is equal to the value value, the radio box is selected
form:radiobuttons: radio box group label, used to construct multiple radio boxes

items: can be a List, String [] or Map
itemValue: Specifies the value value of radio. Can be a property value of a bean in a collection
itemLabel: Specifies the label value of radio
Delimiter: multiple radio boxes can be specified with delimiter

form:checkbox: a checkbox component. Use to construct a single check box
form:checkboxs: used to construct multiple checkboxes. Use the same way as form:radiobuttons label
form:select: used to construct the drop-down box component. Use the same way as form:radiobuttons label
form:option: drop-down box option component label. Use the same way as form:radiobuttons label
form:errors: display errors corresponding to form components or data validation

< form: errors path = "*" / >
< form: errors path = "user *" / >
< form: errors path = "username" / >: display errors for specific form object properties

7.6 add employee experiment code

form

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="java.util.*"%>
<%@ taglib prefix="form" 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>Insert title here</title>
</head>
<body>
 
<!-- 
1.Why use SpringMVC Of form Label
① Rapid development
② Form echo display
2.Can pass modelAttribute Specifies the model properties of the binding,
//If this property is not specified, the bean of the form that looks up the command from the request field by default
//If the property also does not exist, an error occurs.
 -->
 <form:form action="empAdd" method="POST" modelAttribute="employee">
         LastName : <form:input path="lastName" /><br><br>
         Email : <form:input path="email" /><br><br>
         <%
                 Map<String,String> map = new HashMap<String,String>();
                 map.put("1", "Male");
                 map.put("0","Female");
                 request.setAttribute("genders", map);
         %>
         Gender : <br><form:radiobuttons path="gender" items="${genders }" delimiter="<br>"/><br><br>
         DeptName : 
                 <form:select path="department.id" 
                                                 items="${deptList }" 
                                                 itemLabel="departmentName" 
                                                 itemValue="id"></form:select><br><br>
                 <input type="submit" value="Submit"><br><br>
 </form:form> 
</body>
</html>

Controller method

@Controller
public class EmployeeHandler {
    @RequestMapping(value="/empAdd",method=RequestMethod.POST)
    public String empAdd(Employee employee){
        employeeDao.save(employee);
        return "redirect:/empList";
    }
}

7.7 delete & process static resources

7.7.1 delete experiment code

Page link

<td><a href="/empDelete/${emp.id }">Delete</a></td>

Controller method

@RequestMapping(value="/empDelete/{id}" ,method=RequestMethod.DELETE)
public String empDelete(@PathVariable("id") Integer id){
	employeeDao.delete(id);
	return "redirect:/empList";
}

7.7.2 HiddenHttpMethodFilter

The request is initiated and cannot be executed, because the delete request must be converted to the delete request through the post request with the help of: HiddenHttpMethodFilter filter

7.7.3 need to use jQuery to transform request mode

Add jQuery library file

/scripts/jquery-1.9.1.min.js

jQuery library file does not work

Warning: No mapping found for HTTP request with URI [/SpringMVC 03 RESTFul CRUD/scripts/jquery-1.9.1.min.js] in DispatcherServlet with name'springDispatcherServlet'

3. Solution: Spring MVC deals with static resources
① Why is there such a problem
Elegant REST style resource URL s do not want to have suffixes such as. html or. Do. If the dispatcher servlet request mapping is configured as /, then spring MVC will capture all requests of WEB containers, including static resource requests. Spring MVC will treat them as a common request, because it will cause an error if no corresponding processor is found.
② Solution: configure in the configuration file of spring MVC mvc:default-servlet-handler/
4. After configuration, the original request is not easy to use
Need to configure < MVC: annotation driven / >

7.7.4 about < MVC: default servlet handler / > function

<!-- 
< MVC: default servlet handler / > a DefaultServletHttpRequestHandler will be defined in the context of spring MVC,
It will screen the requests entering the dispatcher servlet. If it is found that the requests are unmapped,
The request will be submitted to the default Servlet of the WEB application server for processing. If it is not a static resource request, the dispatcher Servlet will continue to process it
 In general, the default Servlet name of WEB application server is default.
If the default Servlet name of the WEB server you are using is not default, you need to explicitly specify it through the default Servlet name attribute        
Reference: Catalina · home / config / web.xml
    <servlet>
        <servlet-name>default</servlet-name>
        <servlet-class>org.apache.catalina.servlets.DefaultServlet</servlet-class>
        <init-param>
            <param-name>debug</param-name>
            <param-value>0</param-value>
        </init-param>
        <init-param>
            <param-name>listings</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
The default value of the tag attribute default servlet name is "default", which can be omitted.        
<mvc:default-servlet-handler/>        
 -->
<mvc:default-servlet-handler default-servlet-name="default"/>

7.7.5 converting to DELETE request through jQuery

<td><a class="delete" href="empDelete/${emp.id }">Delete</a></td>

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

<script type="text/javascript" src="scripts/jquery-1.9.1.min.js"></script>
<script type="text/javascript">
$(function(){
	$(".delete").click(function(){
		var href = $(this).attr("href");
		$("form").attr("action",href).submit();
		return false ;
	});
});
</script>

7.7.6 delete operation flow diagram

7.8 modify

7.8.1 query employee object according to id and echo the form

Page link

<td><a href="empEdit/${emp.id }">Edit</a></td>

Controller method

    //Modify employee - form echo
    @RequestMapping(value="/empEdit/{id}",method=RequestMethod.GET)
    public String empEdit(@PathVariable("id") Integer id, Map<String,Object> map){
        map.put("employee", employeeDao.get(id));
        map.put("deptList",departmentDao.getDepartments());
        return "edit";
    }

Modify page

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" import="java.util.*"%>
<%@ 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 use SpringMVC Of form Label
① Rapid development
② Form echo display
2.Can pass modelAttribute Specifies the model properties of the binding,
//If this property is not specified, the bean of the form that looks up the command from the request field by default
//If the property also does not exist, an error occurs.
//To modify the function, you need to add an absolute path. The relative path will report an error. The path is not correct
 -->
 <form:form action="${pageContext.request.contextPath }/empUpdate" 
method="POST" modelAttribute="employee">                        
<%--
         LastName : <form:input path="lastName" /><br><br>
          --%>
                 <form:hidden path="id"/>
                 <input type="hidden" name="_method" value="PUT">
                 <%-- Don't use it here form:hidden Tag, otherwise an error will be reported. 
<form:hidden path="_method" value="PUT"/>
                         Spring No value Properties, while,path The specified value does not exist in the model object(_method)，So an error will be reported during echo.
                         org.springframework.beans.NotReadablePropertyException: 
                         Invalid property '_method' of bean class [com.atguigu.springmvc.crud.entities.Employee]: 
                         Bean property '_method' is not readable or has an invalid getter method: 
                         Does the return type of the getter match the parameter type of the setter?
                  --%>
                          
         Email : <form:input path="email" /><br><br>
         <%
                 Map<String,String> map = new HashMap<String,String>();
                 map.put("1", "Male");
                 map.put("0","Female");
                 request.setAttribute("genders", map);
         %>
         Gender : <br><form:radiobuttons path="gender" items="${genders }" delimiter="<br>"/><br><br>
         DeptName : 
                 <form:select path="department.id" 
                                                 items="${deptList }" 
                                                 itemLabel="departmentName" 
                                                 itemValue="id"></form:select><br><br>
                 <input type="submit" value="Submit"><br><br>
 </form:form>
</body>
</html>

7.8.2 submit form and modify data

Controller method

    @RequestMapping(value="/empUpdate",method=RequestMethod.PUT)
    public String empUpdate(Employee employee){
        employeeDao.save(employee);              
        return "redirect:/empList";
    }

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