Use JPA to complete the addition, deletion and modification check-SpringDataJPA (seven)

Save

    / ** 
     * Save an entity 
     * / 
    @Test 
    public  void testAdd () {
         // Define object 
        Customer c = new Customer (); 
        c.setCustName ( "Chuanzhi Academy" ); 
        c.setCustLevel ( "VIP customer" ); 
        c.setCustSource ( "Network" ); 
        c.setCustIndustry ( "IT Education" ); 
        c.setCustAddress ( "Changping District Beiqijia Town" ); 
        c.setCustPhone ( " 010-84389340 " ); 
        EntityManager em = null ; 
        EntityTransaction tx =null ;
         try {
             // Get entity management object 
            em = JPAUtil.getEntityManager ();
             // Get transaction object 
            tx = em.getTransaction ();
             // Start transaction 
            tx.begin ();
             // Perform operation 
            em.persist (c );
             // commit transaction 
            tx.commit (); 
        } catch (Exception e) {
             // rollback transaction 
            tx.rollback (); 
            e.printStackTrace (); 
        } finally {
             //Release resources 
            em.close (); 
        } 
    }

 

modify

    @Test
     public  void testMerge () {  
         // Define object 
        EntityManager em = null ;   
        EntityTransaction tx = null ;  
         try {  
               // Get entity management object 
              em = JPAUtil.getEntityManager ();
               // Get transaction object 
              tx = em.getTransaction () ;
               // Start transaction 
              tx.begin ();
               // Perform operation 
              Customer c1 = em.find (Customer. Class , 6L ); 
              c1.setCustName ("Jiangsu Chuanzhi Institute" ); 
             em.clear (); // Clear the c1 object from the cache 
              em.merge (c1);
               // Commit transaction 
              tx.commit (); 
        } catch (Exception e) {
               // Rollback transaction 
              tx.rollback (); 
              e.printStackTrace ();   
        } finally {  
             // Release resources 
            em.close ();   
        }     
    }

 

delete

    / ** 
     * Delete 
     * / 
    @Test 
    public  void testRemove () {
         // Define object 
        EntityManager em = null ; 
        EntityTransaction tx = null ;
         try {
             // Get entity management object 
            em = JPAUtil.getEntityManager ();
             // Get transaction object 
            tx = em.getTransaction ();
             // Start transaction 
            tx.begin ();
             // Perform operation 
            Customer c1 = em.find (Customer. class , 6L );
            em.remove (c1); 
            // commit transaction 
            tx.commit (); 
        } catch (Exception e) {
             // rollback transaction 
            tx.rollback (); 
            e.printStackTrace (); 
        } finally {
             // release resource 
            em. close (); 
        } 
    }

 

Query by Id

    / ** 
     * Query one: Use the strategy of immediate loading 
     * / 
    @Test 
    public  void testGetOne () {
         // Define object 
        EntityManager em = null ; 
        EntityTransaction tx = null ;
         try {
             // Get entity management object 
            em = JPAUtil.getEntityManager ( );
             // Get transaction object 
            tx = em.getTransaction ();
             // Start transaction 
            tx.begin ();
             // Perform operation 
            Customer c1 = em.find (Customer. Class , 1L);
             // commit transaction 
            tx.commit (); 
            System.out.println (c1); // output query object 
        } catch (Exception e) {
             // rollback transaction 
            tx.rollback (); 
            e.printStackTrace (); 
        } finally {
             // Release resources 
            em.close (); 
        } 
    } 

    // Query the cache problem of the entity 
    @Test
     public  void testGetOne () {
         // Define the object 
        EntityManager em = null ; 
        EntityTransaction tx= null ;
         try {
             // Get entity management object 
            em = JPAUtil.getEntityManager ();
             // Get transaction object 
            tx = em.getTransaction ();
             // Start transaction 
            tx.begin ();
             // Execute operation 
            Customer c1 = em .find (Customer. class , 1L ); 
            Customer c2 = em.find (Customer. class , 1L ); 
            System.out.println (c1 == c2); // The output result is true, EntityManager also has a cache
             // Commit transactions
            tx.commit (); 
            System.out.println (c1); 
        } catch (Exception e) {
             // rollback transaction 
            tx.rollback (); 
            e.printStackTrace (); 
        } finally {
             // release resource 
            em.close ( ); 
        } 
    } 

    // Lazy loading strategy method: 
    / ** 
     * Query one: Use lazy loading strategy 
     * / 
    @Test 
    public  void testLoadOne () {
         // Define object 
        EntityManager em = null ; 
        EntityTransaction tx = null;
         try {
             // Get entity management object 
            em = JPAUtil.getEntityManager ();
             // Get transaction object 
            tx = em.getTransaction ();
             // Start transaction 
            tx.begin ();
             // Execute operation 
            Customer c1 = em.getReference (Customer. Class , 1L );
             // commit transaction 
            tx.commit (); 
            System.out.println (c1); 
        } catch (Exception e) {
             // rollback transaction 
            tx.rollback ();
            e.printStackTrace (); 
        }finally {
             // Release resources 
            em.close (); 
        } 
    }