我想这样做;
我有一项工作要改进学习Spring，Hibernate和JPA的CRUD应用程序。所以我想做很多很多例子，但我要求别人这样做。
我想获得员工的驾驶执照和更新信息。我可以使用Spring forEach从Web数据库中获取员工的信息到CheckBox。如果员工拥有哪个驾驶执照，则必须检查关系CheckBoxes。我可以更新这些信息。
例如，员工已获得＆＃34; A1＆＃34;和＆＃34; M＆＃34;类。我可以获取并绑定数据。
我创建了＆＃34;员工＆＃34;，＆＃34; driving_licenses＆＃34;的表格。 我创建了＆＃34; employee_driving_licenses＆＃34;对于商店员工的驾驶执照：
员工：
id int
last_name nvarchar(20)
first_name nvarchar(10)
driving_licenses：
id int
code nvarchar(5)
employee_driving_licenses：
employee_id int
driving_license_id int
我创建了表的模型类并添加了JPA注释。我有Employee和DrivingLicense实体Java类：
Employee.java
@Entity
@Table(name = "employees")
public class Employee {
private int id;
private String last_name;
private String first_name;
private java.util.Collection<DrivingLicense> driving_licenses = new HashSet<DrivingLicense>();
@GeneratedValue(strategy = GenerationType.AUTO)
@Id
@Column
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@NotEmpty(message = "Please enter Last Name")
@Column
public String getLast_name() {
return last_name;
}
public void setLast_name(String last_name) {
this.last_name = last_name;
}
@NotEmpty(message = "Please enter First Name")
@Column
public String getFirst_name() {
return first_name;
}
@ManyToMany(fetch = FetchType.EAGER, mappedBy = "employees")
public java.util.Collection<DrivingLicense> getDriving_licenses() {
return driving_licenses;
}
public void setDriving_licenses(
java.util.Collection<DrivingLicense> driving_licenses) {this.driving_licenses = driving_licenses;
}
}
DrivingLicense.java
@Entity
@Table(name = "driving_licenses")
public class DrivingLicense {
private int id;
private String code;
private java.util.Collection<Employee> employees = new HashSet<Employee>();
@Override
public int hashCode() {
return new Long(id).hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (!(obj instanceof DrivingLicense)) {
return false;
}
return this.id == ((DrivingLicense) obj).getId();
}
@GeneratedValue(strategy = GenerationType.AUTO)
@Id
@Column
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@Column
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
@ManyToMany(fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.MERGE })
@JoinTable(name = "employee_driving_licenses", joinColumns = { @JoinColumn(name = "driving_license_id", nullable = false, updatable = false) }, inverseJoinColumns = { @JoinColumn(name = "employee_id", nullable = false, updatable = false) })
public java.util.Collection<Employee> getEmployees() {
return employees;
}
public void setEmployees(java.util.Collection<Employee> employees) {
this.employees = employees;
}
}
我创建了应用程序DAO，服务，控制器和视图类/页面。
EmployeeController.java：
@RequestMapping(value = "index", method = RequestMethod.POST)
public String employee(@Valid @ModelAttribute("employee") Employee employee,
BindingResult result, @RequestParam String action,
java.util.Map<String, Object> map) {
boolean isValid = true;
if (result.hasErrors()) {
isValid = false;
}
Employee employeeResult = new Employee();
switch (action.toLowerCase()) {
case "add":
if (isValid)
employeeService.add(employee);
employeeResult = employee;
break;
case "edit":
if (isValid)
employeeService.edit(employee);
employeeResult = employee;
break;
}
map.put("drivingLicenseList", drivingLicenseService.findActiveDrivingLicense());
map.put("employee", employeeResult);
map.put("activeEmployeeList", employeeService.findActiveEmployees());
return "employee";
}
employee.jsp：
<c:forEach var="drive_licenses" items="${drivingLicenseList}">
<form:checkbox path="driving_licenses"
value="${drive_licenses }" label="${drive_licenses.code }" />
</c:forEach>
当我想更新员工的驾驶执照时，我收到的错误代码如下：
{employee=com.ay.model.Employee@573cb29c, org.springframework.validation.BindingResult.employee=org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'employee' on field 'driving_licenses': rejected value [com.ay.model.DrivingLicense@1,com.ay.model.DrivingLicense@7,com.ay.model.DrivingLicense@8,com.ay.model.Driving License@9]; codes [typeMismatch.employee.driving_licenses,typeMismatch.driving_licenses,typeMismatch.java.util.Collection,typeMis match]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.driving_licenses,driving_licenses]; arguments []; default message [driving_licenses]]; default message [Failed to convert property value of type 'java.lang.String[]' to required type 'java.util.Collection' for property 'driving_licenses'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [com.ay.model.DrivingLicense] for property 'driving_licenses[0]': no matching editors or conversion strategy found]}
如何获取Collection类型的值？请给我建议。
而且，如果我添加此代码
value="${drive_licenses }"
在employee.jsp的网页上，我可以正常看到浏览器上的对象值。实际上我首先添加了这段代码
value="${drive_licenses.id }"
但CheckBox上未检查员工的驾驶执照，并且每个CheckBoxes值都为空。什么是真正的语法？
感谢您的支持。
答案 0 :(得分：0)
这个部分太多了。大致是：
一个：创建一个包装器表单：
public class EmployeeForm{
private Employee employee;
//Driving licence needs a 'boolean' selected field
//Mark as @Transient so not persisted
//Otherwise create another wrapper/dto which has this boolean field
//Spring MVC can only bind to indexed fields e.g. List
private List<DrivingLicence> allAvailableLicences;
public EmployeeForm(Employee employee, Collecion<DrivingLicence> licenes){
//set instance vars
}
//getters
//setters
}
两个：将以下内容添加到您的控制器：
//CALLED ON BOTH GET AND POST TO SET UP THE FORM
//FOR EDITING EXISTING EMPLOYEE REPLACE NEW EMPLOYEE WITH THE RELEVANT LOOKUP
@ModelAttribute("employeeForm")
public EmployeeForm getEmployeeForm(@RequestParam("employeeId", required = false) Long employeeId){
return new EmployeeForm(new Employee(), drivingLicenseService.findActiveDrivingLicense());
}
<强>三：
更改您的JSP表单以绑定到employeeForm：您可以使用嵌套属性，例如employee.name前面的路径属性。对于绑定许可证，您需要使用下面的索引表示法，即将列表中索引x处的许可证设置为选中。
<c:forEach var="licence" items="${employeeForm.allAvailableLicences}" varStatus="loop">
<form:checkbox path="licence[${loop.index]}.selected" label="${licence.code }" />
</c:forEach>
四：
更新表单提交处理程序：
@RequestMapping(value = "index", method = RequestMethod.POST)
public String employee(@Valid @ModelAttribute("employeeForm") EmployeeForm employeeForm,
BindingResult result, @RequestParam String action) {
//validation etc
Employee employee = employeeForm.getEmployee();
for(DrivingLicence licence : employeeForm.getAllAvailableLicences()){
//our indexed foem check box set the 'selected' field true
//if selected add to the employee
}
//save updated employee
return "nextPage";
}