最后，我們共同學習CURD的D - Destory刪除操作。 # 定制路由 ``` <!-- 刪除 --> <action name="delete" class="teacher.Delete"> <result name="success">/jsp/teacher/success.jsp</result> <result name="error">/jsp/teacher/error.jsp</result> </action> ``` # V 使用success.jsp # C ``` package teacher; import entity.Teacher; public class Delete { private int id; private Teacher teacher; public int getId() { return id; } public void setId(int id) { this.id = id; } // 該execute方法將被自動調用， 方法的返回類型必須為String public String execute() { return "success"; } } ``` # C&V測試 [http://localhost:8080/javaee/teacher/delete?id=1](http://localhost:8080/javaee/teacher/delete?id=1) # M - entity ``` public Boolean delete() { // 創建會話（這里的session也是會話的意思，我們以前接觸的http中的session，處理的是用戶與服務器的對話） Session session = MysqlJavaee.getCurrentSession(); // 開啟事務（使用緩沖池進行數據庫的連接） Transaction transaction = session.beginTransaction(); // 在這里，必須使用try catch finally語句。來確定會話正常關閉. // 否則，當操作數據庫產生錯誤時，你可能需要重啟mysql服務 try { // 刪除 session.delete(this); // 提交事務 transaction.commit(); // 捕獲異常 } catch (HibernateException e) { // 如果事務執行異常，則回滾事務 if (null != transaction) { transaction.rollback(); } // 打印異常 e.printStackTrace(); } finally { // 如果session處于開啟狀態，則關閉session if (session.isOpen()) { // 關閉會話 session.close(); } } return true; } ``` ## 單元測試 ``` @Test public void delete() { Teacher teacher = Teacher.getTeacherById(1); System.out.println("更新操作前"); System.out.println(teacher.toString()); // 刪除 teacher.setName("hello1"); teacher.delete(); // 查看結果 teacher = Teacher.getTeacherById(1); System.out.println("更新操作后"); System.out.println(teacher.toString()); } ``` # M - server ``` public static Boolean deleteById(int id) { Teacher teacher = Teacher.getTeacherById(id); return teacher.delete(); } ``` ## 單元測試 ``` @Test public void delete() { Teacher teacher = Teacher.getTeacherById(2); System.out.println("刪除前"); System.out.println(teacher.toString()); TeacherServer.deleteById(2); teacher = Teacher.getTeacherById(2); System.out.println("刪除后"); System.out.println(teacher.toString()); } ``` 控制臺: ``` 刪除前 Teacher [id=2, name=李四, username=lisi, email=lisi@yunzhiclub.com, sex=false, password=456] Hibernate: select teacher0_.id as id1_0_0_, teacher0_.email as email2_0_0_, teacher0_.name as name3_0_0_, teacher0_.password as password4_0_0_, teacher0_.sex as sex5_0_0_, teacher0_.username as username6_0_0_ from Teacher teacher0_ where teacher0_.id=? Hibernate: delete from Teacher where id=? Hibernate: select teacher0_.id as id1_0_0_, teacher0_.email as email2_0_0_, teacher0_.name as name3_0_0_, teacher0_.password as password4_0_0_, teacher0_.sex as sex5_0_0_, teacher0_.username as username6_0_0_ from Teacher teacher0_ where teacher0_.id=? 刪除后 ``` # C&M `// 該execute方法將被自動調用， 方法的返回類型必須為String public String execute() { TeacherServer.deleteById(id); return "success"; }`· ## 集成測試 我們在數據表中，找到一條可以刪除的數據。比如ID為4 則輸入[http://localhost:8080/javaee/teacher/delete?id=4](http://localhost:8080/javaee/teacher/delete?id=4)進行測試。 > 當要刪除的數據存在時，會提示操作成功。當要刪除的數據不存在，將得到一個異常。我們在下一章解決這個問題。