传统 CRUD

1、显示员工列表

① 思路

images

② 代码

[1]配置 SpringMVC 配置文件

images

1
2
3
4
5
6
7
8
9
10
11
<!-- 自动扫描的包 -->
<context:component-scan base-package="com.atguigu.demo.component"/>

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

<!-- 加入SpringMVC标配 -->
<mvc:annotation-driven/>

注意：加入 mvc:annotation-driven 时不要导错名称空间

错误的名称空间是：

xmlns:mvc=”http://www.springframework.org/schema/cache"

正确的名称空间是：

xmlns:mvc=”http://www.springframework.org/schema/mvc"

如果使用了 cache 名称空间，那么 Web 应用启动时会抛出下面异常：

org.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from class path resource [spring-mvc.xml];

Caused by: java.lang.NoClassDefFoundError: org/aopalliance/intercept/MethodInterceptor

Caused by: java.lang.ClassNotFoundException: org.aopalliance.intercept.MethodInterceptor

[2]配置 web.xml

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
    <servlet>
        <!-- 配置SpringMVC的前端控制器：DispatcherServlet -->
        <servlet-name>dispatcherServlet</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>

        <!-- 使用DispatcherServlet的初始化参数指定Spring配置文件的位置 -->
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:spring-mvc.xml</param-value>
        </init-param>

        <!-- 借助load-on-startup标签将Servlet设置为随Web应用一起启动 -->
        <load-on-startup>1</load-on-startup>
    </servlet>

     <!-- 匹配所有请求，使用『/』 -->
    <servlet-mapping>
        <servlet-name>dispatcherServlet</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

<!-- 解决字符乱码问题 -->
<filter>
    <filter-name>CharacterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>

    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>

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

[3]EmpController 代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
@Controller
public class EmpController {

    @Autowired
    private EmpService empService;

    @RequestMapping("/show/list")
    public String showList(Model model) {

        // 1.调用EmpService的方法查询数据
        List<Employee> employeeList = empService.getEmpList();

        // 2.将数据存入模型
        model.addAttribute("employeeList", employeeList);

        // 3.转发请求，到JSP页面上显示数据
        return "emp-list";
    }
}

[4]EmpService 代码

1
2
3
4
5
6
7
8
9
10
@Service
public class EmpService {

    @Autowired
    private EmpDao empDao;

    public List<Employee> getEmpList() {
        return empDao.getEmpList();
    }
}

[5]页面展示数据

(1)导入 JSTL 的 jar 包

images

(2)在页面引入标签库
1
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
(3)JSTL 标签
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
<table>
  <tr>
    <th>员工编号</th>
    <td>员工姓名</td>
    <td>社会保险号</td>
    <td>所属部门</td>
    <td colspan="2">操作</td>
  </tr>
  <c:if test="${empty requestScope.employeeList}">
    <tr>
      <td colspan="6">抱歉！没有查询到数据！</td>
    </tr>
  </c:if>
  <c:if test="${not empty requestScope.employeeList}">
    <c:forEach items="${requestScope.employeeList}" var="employee">
      <tr>
        <td>${employee.empId}</td>
        <td>${employee.empName}</td>
        <td>${employee.ssn}</td>
        <td>${employee.department.deptName}</td>
        <td>删除</td>
        <td>编辑</td>
      </tr>
    </c:forEach>
  </c:if>
  <tr>
    <td colspan="6" style="text-align: center">添加员工数据</td>
  </tr>
</table>
(4)编写显示员工列表超链接
1
<a href="${pageContext.request.contextPath}/show/list">显示员工列表</a>

2、删除员工数据

① 思路

[1]删除本身

images

[2]删除之后页面跳转

images

② 代码

[1]编写删除超链接

1
2
3
<a href="${pageContext.request.contextPath}/removeEmp?empId=${employee.empId}"
  >删除</a
>

[2]EmpController 代码

1
2
3
4
5
6
7
8
9
10
11
@RequestMapping("/removeEmp")
public String removeEmp(
        // 接收请求参数
        @RequestParam("empId") String empId) {

    // 执行删除
    empService.removeEmp(empId);

    // 前往结果页面
    return "emp-list";
}

[3]EmpService 代码

1
2
3
public void removeEmp(String empId) {
    empDao.removeEmp(empId);
}

[4]删除后页面跳转

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
@RequestMapping("/removeEmp")
public String removeEmp(
        // 接收请求参数
        @RequestParam("empId") String empId, Model model) {

    // 执行删除
    empService.removeEmp(empId);

    // 前往结果页面
    // 方案1：直接返回逻辑视图名称，前往emp-list.jsp
    // 问题：到达页面后发现没有数据
    // 原因：没有将employeeList数据存入请求域
    // return "emp-list";

    // 方案2：调用showList()方法
    // 问题1：破坏程序的结构
    // 问题2：在页面上刷新浏览器会导致再次执行删除操作，浪费系统资源
    // return showList(model);

    // 方案3：将请求转发到/show/list
    // 问题：在页面上刷新浏览器会导致再次执行删除操作，浪费系统资源
    // return "forward:/show/list";

    // 方案4：将请求重定向到/show/list
    return "redirect:/show/list";
}

3、添加员工数据

① 思路

[1]前往添加数据的表单页面

images

[2]提交表单执行保存

images

② 代码

[1]添加员工信息超链接

1
<a href="${pageContext.request.contextPath}/to/add/page">添加员工数据</a>

[2]EmpController 代码

1
2
3
4
5
6
7
8
9
10
11
12
@RequestMapping("/to/add/page")
public String toAddPage(Model model) {

    // 1.查询全部部门信息
    List<Department> departmentList = empService.getDeptList();

    // 2.存入模型
    model.addAttribute("departmentList", departmentList);

    // 3.返回逻辑视图名称
    return "emp-add";
}

[3]EmpService 代码

1
2
3
4
5
6
@Autowired
private DeptDao deptDao;

public List<Department> getDeptList() {
    return deptDao.getDeptList();
}

[4]表单页面

1
2
3
4
5
6
7
8
9
10
11
12
13
14
<form action="${pageContext.request.contextPath}/save/emp" method="post">
  员工姓名：<input type="text" name="empName" /><br />
  社会保险号：<input type="text" name="ssn" /><br />
  所属部门：
  <select name="department.deptId">
    <c:forEach items="${requestScope.departmentList}" var="dept">
      <option value="${pageScope.dept.deptId}">
        ${pageScope.dept.deptName}
      </option>
    </c:forEach>
  </select>
  <br />
  <button type="submit">保存</button>
</form>

[5]EmpController 代码

1
2
3
4
5
6
7
@RequestMapping("/save/emp")
public String saveEmp(Employee employee) {

    empService.saveEmp(employee);

    return "redirect:/show/list";
}

[6]EmpService 代码

1
2
3
public void saveEmp(Employee employee) {
    empDao.saveEmp(employee);
}

4、更新员工数据

① 思路

[1]前往更新数据的表单页面

images

[2]提交表单执行更新

images

② 代码

[1]编辑员工信息超链接

1
2
3
<a href="${pageContext.request.contextPath}/editEmp?empId=${employee.empId}"
  >编辑</a
>

[2]EmpController 代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
@RequestMapping("/editEmp")
public String toEditPage(@RequestParam("empId") String empId, Model model) {

    // 1.根据empId查询对应Employee对象
    Employee employee = empService.getEmpById(empId);

    // 2.将Employee对象存入模型
    model.addAttribute("employee", employee);

    // 3.查询全部的部门信息
    List<Department> deptList = empService.getDeptList();

    // 4.将deptList存入模型
    model.addAttribute("deptList", deptList);

    return "emp-edit";
}

[3]EmpService 代码

1
2
3
public Employee getEmpById(String empId) {
    return empDao.getEmpById(empId);
}

[4]表单页面

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
<form action="${pageContext.request.contextPath}/update/emp" method="post">
  <input type="hidden" name="empId" value="${requestScope.employee.empId}" />
  <input type="hidden" name="ssn" value="${requestScope.employee.ssn}" />

  员工姓名：<input
    type="text"
    name="empName"
    value="${requestScope.employee.empName}"
  /><br />
  社会保险号： ${requestScope.employee.ssn}<br />
  所属部门：
  <!-- 下拉列表回显：让部门列表中在页面一打开时就显示当前员工所属部门 -->
  <!-- 1、下拉列表设置默认被选中。给option标签设置selected="selected"属性。 -->
  <!-- 2、需要找到那个设置selected="selected"属性的option标签。 -->
  <!-- 3、将当前部门的deptId和员工的deptId进行比较 -->
  <select name="department.deptId">
    <c:forEach items="${requestScope.deptList}" var="dept">
      <!-- 将遍历得到的deptId和员工的deptId进行比较 -->
      <c:if
        test="${requestScope.employee.department.deptId == pageScope.dept.deptId}"
      >
        <!-- 二者相等时设置option被选中 -->
        <option value="${pageScope.dept.deptId}" selected="selected">
          ${pageScope.dept.deptName}
        </option>
      </c:if>
      <c:if
        test="${requestScope.employee.department.deptId != pageScope.dept.deptId}"
      >
        <!-- 二者不相等时不设置option被选中 -->
        <option value="${pageScope.dept.deptId}">
          ${pageScope.dept.deptName}
        </option>
      </c:if>
    </c:forEach>
  </select>
  <br />
  <button type="submit">更新</button>
</form>

[5]EmpController 代码

1
2
3
4
5
6
7
@RequestMapping("/update/emp")
public String updateEmp(Employee employee) {

    empService.updateEmp(employee);

    return "redirect:/show/list";
}

[6]EmpService 代码

1
2
3
public void updateEmp(Employee employee) {
    empDao.updateEmp(employee);
}

5、用来测试的数据

1、实体类

①Department

1
2
private String deptId;
private String deptName;

②Employee

1
2
3
4
private String empId;
private String empName;
private String ssn;
private Department department;

2、Dao

①DeptDao

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
package com.atguigu.demo.component.dao;

import com.atguigu.demo.entity.Department;
import org.springframework.stereotype.Repository;

import java.util.*;

@Repository
public class DeptDao {

    private static Map<String, Department> dataMap;
    private static Map<String, Department> namedMap;

    static {
        dataMap = new HashMap<>();
        namedMap = new HashMap<>();

        Department
                department = new Department(UUID.randomUUID().toString(), "市场部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

        department = new Department(UUID.randomUUID().toString(), "销售部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

        department = new Department(UUID.randomUUID().toString(), "行政部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

        department = new Department(UUID.randomUUID().toString(), "人事部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

        department = new Department(UUID.randomUUID().toString(), "技术部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

        department = new Department(UUID.randomUUID().toString(), "公关部");
        dataMap.put(department.getDeptId(), department);
        namedMap.put(department.getDeptName(), department);

    }

    public static Department getDeptByName(String deptName) {
        return namedMap.get(deptName);
    }

    public static Department getDeptById(String uuid) {
        return dataMap.get(uuid);
    }

    public List<Department> getDeptList() {
        return new ArrayList<>(dataMap.values());
    }
}

②EmpDao

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
package com.atguigu.demo.component.dao;

import com.atguigu.demo.entity.Department;
import com.atguigu.demo.entity.Employee;
import org.springframework.stereotype.Repository;

import java.util.*;

@Repository
public class EmpDao {

    private static Map<String, Employee> dataMap;

    static {
        dataMap = new HashMap<>();

        String empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "乔峰", "SSN001", DeptDao.getDeptByName("市场部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "虚竹", "SSN002", DeptDao.getDeptByName("市场部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "段誉", "SSN003", DeptDao.getDeptByName("市场部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "鸠摩智", "SSN004", DeptDao.getDeptByName("技术部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "萧远山", "SSN005", DeptDao.getDeptByName("技术部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "慕容复", "SSN006", DeptDao.getDeptByName("技术部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "段正淳", "SSN007", DeptDao.getDeptByName("公关部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "段延庆", "SSN008", DeptDao.getDeptByName("公关部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "丁春秋", "SSN009", DeptDao.getDeptByName("销售部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "无崖子", "SSN010", DeptDao.getDeptByName("人事部")));

        empId = UUID.randomUUID().toString();
        dataMap.put(empId, new Employee(empId, "慕容博", "SSN011", DeptDao.getDeptByName("人事部")));
    }

    public void saveEmp(Employee employee) {

        String empId = UUID.randomUUID().toString();
        employee.setEmpId(empId);

        String deptId = employee.getDepartment().getDeptId();
        Department department = DeptDao.getDeptById(deptId);
        employee.setDepartment(department);

        dataMap.put(empId, employee);
    }

    public void removeEmp(String empId) {
        dataMap.remove(empId);
    }

    public void updateEmp(Employee employee) {

        String deptId = employee.getDepartment().getDeptId();
        Department department = DeptDao.getDeptById(deptId);
        employee.setDepartment(department);

        dataMap.put(employee.getEmpId(), employee);
    }

    public Employee getEmpById(String empId) {
        return dataMap.get(empId);
    }

    public List<Employee> getEmpList() {
        return new ArrayList<>(dataMap.values());
    }
}

3、解决字符乱码问题

配置 web.xml

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
<filter>
    <filter-name>CharacterEncodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>

    <init-param>
        <param-name>encoding</param-name>
        <param-value>UTF-8</param-value>
    </init-param>

    <init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
    </init-param>
</filter>

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