针对Student表的DAO设计实例
完整代码以及junit,mysql--connector包下载地址 : https://github.com/CasterWx/MyStudentDao
表信息:
代码:
dao包----impl包----StudentDAOImpl.java
1 package dao.impl; 2 3 import dao.IStudentDAO; 4 import domain.Student; 5 6 import java.sql.*; 7 import java.util.ArrayList; 8 import java.util.List; 9 10 public class StudentDAOImpl implements IStudentDAO { 11 public static Connection connection = null ; 12 13 public void setConnection() { 14 try { 15 Class.forName("com.mysql.jdbc.Driver"); 16 System.out.println("连接成功"); 17 }catch (Exception e){ 18 System.out.println("连接失败"); 19 } 20 try{ 21 connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/JavaJDBC","root","root"); 22 }catch (Exception e){ 23 } 24 } 25 26 public void shutdownConnection(){ 27 try { 28 if(connection!=null){ 29 connection.close(); 30 } 31 }catch (Exception e){ 32 } 33 } 34 @Override 35 public void save(Student student) { 36 setConnection(); 37 Statement statement = null ; 38 try { 39 statement = connection.createStatement(); 40 // sql语句:查询对应id 41 String sql = "INSERT INTO t_student(id,name,age) VALUES(" + student.getId()+",'"+student.getName()+"',"+student.getAge()+")"; 42 statement.executeUpdate(sql); 43 }catch (Exception e){ 44 }finally { 45 try{ 46 if (statement!=null){ 47 statement.close(); 48 } 49 }catch (Exception e){ 50 } 51 } 52 shutdownConnection(); 53 } 54 55 @Override 56 public void delete(Student student) { 57 Long id = student.getId() ; 58 delete(id); 59 } 60 61 @Override 62 public void delete(Long id) { 63 setConnection(); 64 Statement statement = null ; 65 try { 66 statement = connection.createStatement(); 67 // sql语句:查询对应id 68 String sql = "DELETE FROM t_student WHERE id="+id; 69 statement.executeUpdate(sql); 70 }catch (Exception e){ 71 }finally { 72 try{ 73 if (statement!=null){ 74 statement.close(); 75 } 76 }catch (Exception e){ 77 } 78 } 79 shutdownConnection(); 80 } 81 82 @Override 83 public void update(Long id, Student student) { 84 setConnection(); 85 Statement statement = null ; 86 try { 87 statement = connection.createStatement(); 88 // sql语句:查询对应id 89 String sql = "UPDATE t_student SET name='"+ student.getName() +"',age="+student.getAge() +" WHERE id="+id; 90 statement.executeUpdate(sql); 91 }catch (Exception e){ 92 }finally { 93 try{ 94 if (statement!=null){ 95 statement.close(); 96 } 97 }catch (Exception e){ 98 } 99 } 100 101 shutdownConnection(); 102 } 103 104 @Override 105 public void update(Student student) { 106 Long id = student.getId() ; 107 update(id,student); 108 } 109 110 @Override 111 public Student get(Long id) { 112 setConnection(); 113 Statement statement = null ; 114 ResultSet resultSet = null ; 115 Student student = null ; 116 try { 117 statement = connection.createStatement(); 118 // sql语句:查询对应id 119 String sql = "SELECT * FROM t_student where id="+id ; 120 resultSet = statement.executeQuery(sql); 121 if(resultSet.next()){ 122 student = new Student() ; 123 student.setId(resultSet.getLong("id")); 124 student.setName(resultSet.getString("name")); 125 student.setAge(resultSet.getLong("age")); 126 return student ; 127 } 128 }catch (Exception e){ 129 }finally { 130 try{ 131 if (statement!=null){ 132 statement.close(); 133 } 134 }catch (Exception e){ 135 }finally { 136 try{ 137 if(resultSet!=null){ 138 resultSet.close(); 139 } 140 }catch (Exception e){ 141 } 142 } 143 } 144 shutdownConnection(); 145 return null; 146 } 147 148 @Override 149 public ArrayList<Student> list() { 150 ArrayList<Student> list = new ArrayList<Student>() ; 151 setConnection(); 152 Statement statement = null ; 153 ResultSet resultSet = null ; 154 Student student = null ; 155 try { 156 statement = connection.createStatement(); 157 // sql语句:查询对应id 158 String sql = "SELECT * FROM t_student" ; 159 resultSet = statement.executeQuery(sql); 160 161 while(resultSet.next()){ 162 student = new Student() ; 163 student.setId(resultSet.getLong("id")); 164 student.setName(resultSet.getString("name")); 165 student.setAge(resultSet.getLong("age")); 166 list.add(student) ; 167 } 168 return list ; 169 }catch (Exception e){ 170 }finally { 171 try{ 172 if (statement!=null){ 173 statement.close(); 174 } 175 }catch (Exception e){ 176 }finally { 177 try{ 178 if(resultSet!=null){ 179 resultSet.close(); 180 } 181 }catch (Exception e){ 182 } 183 } 184 } 185 shutdownConnection(); 186 return list; 187 } 188 189 }
dao包----IStudentDAO接口
1 package dao; 2 3 import domain.Student; 4 5 import java.util.ArrayList; 6 import java.util.List; 7 8 /** 9 * Student对象的CRUD操作 10 * */ 11 public interface IStudentDAO { 12 // ----------------------------------增-------------------------------------------- 13 14 /** 15 * 保存学生对象 16 * @param student 17 * */ 18 void save(Student student); 19 20 // ----------------------------------删-------------------------------------------- 21 22 /** 23 * 根据删除指定学生 24 * @param student 学生对象 25 * */ 26 27 void delete(Student student) ; 28 /** 29 * 根据主键删除指定学生 30 * @param id 学生对象主键 31 * */ 32 void delete(Long id) ; 33 34 // ----------------------------------改-------------------------------------------- 35 /** 36 * 更新指定学生信息 37 * @param id 学生对象主键 38 * @param student 学生对象 39 * */ 40 void update(Long id,Student student) ; 41 /** 42 * 根据主键删除指定学生 43 * @param student 学生对象 44 * */ 45 void update(Student student); 46 47 // ----------------------------------查-------------------------------------------- 48 49 /** 50 * 查询指定id的学生对象 51 * @param id 学生对象主键 52 * @return Student if id存在,返回Student对象,否则返回null 53 */ 54 Student get(Long id) ; 55 /** 56 * 查询所有学生对象 57 * @return 所有学生对象 58 * */ 59 ArrayList<Student> list() ; 60 }
domain包-----Student.java
1 package domain; 2 3 public class Student { 4 private long id ; 5 private String name ; 6 private long age ; 7 public void getString(){ 8 System.out.println("Student(id="+id+",name="+name+",age="+age+")"); 9 } 10 public void setId(long id){ 11 this.id = id ; 12 } 13 public void setName(String name){ 14 this.name = name ; 15 } 16 public void setAge(long age){ 17 this.age = age ; 18 } 19 20 public long getId() { 21 return id; 22 } 23 24 public long getAge() { 25 return age; 26 } 27 28 public String getName() { 29 return name; 30 } 31 }
test包----StudentDAOTest
1 package test; 2 3 import dao.IStudentDAO; 4 import dao.impl.StudentDAOImpl; 5 import domain.Student; 6 import org.junit.Test; 7 8 import java.util.ArrayList; 9 import java.util.List; 10 11 public class StudentDAOTest { 12 IStudentDAO iStudentDAO = new StudentDAOImpl(); 13 @Test 14 public void testSave() { 15 Student student = new Student() ; 16 student.setId(164L); 17 student.setName("Wber"); 18 student.setAge(100L); 19 iStudentDAO.save(student); 20 } 21 @Test 22 public void testDelete() { 23 iStudentDAO.delete(161L); 24 } 25 @Test 26 public void testUpdate() { 27 Student student = new Student() ; 28 student.setId(161L); 29 student.setName("wa"); 30 student.setAge(15L); 31 iStudentDAO.update(161L,student); 32 } 33 @Test 34 public void testGet() { 35 iStudentDAO.get(162L).getString(); 36 } 37 @Test 38 public void testList() { 39 ArrayList<Student> list = iStudentDAO.list() ; 40 for(int i=0;i<list.size();i++){ 41 list.get(i).getString(); 42 } 43 } 44 }
