首先介绍一下jpa常用的注解
- @Entity
- @Table
- @Basic
- @Column
- @GeneratedValue
- @Id
@Entity
将java类声明为实体类，将映射到指定的数据库表，如声明User类加上@Entity数据库中将会自动创建
对应的user表
@Id
标注声明类属性为注解也可标注与对应属性的get方法上
@Table
当实体类与其映射的数据库表名不同名时需要使用 @Table 标注说明，该标注与 @Entity 标注并列使用，置于实体类声明语句之前，可写于单独语句行，也可与声明语句同行。
@@GeneratedValue
@GeneratedValue 用于标注主键的生成策略，通过 strategy 属性指定。默认情况下，JPA 自动选择一个最适合底层数据库的主键生成策略：SqlServer 对应 identity，MySQL 对应 auto increment。
@Column
@Column 标注的常用属性是 name，用于设置映射数据库表的列名。此外，该标注还包含其它多个属性，如：unique 、nullable、length 等。
User
代码语言：javascript复制@Data
@Entity
public class User {
@Id // 主键注解
@GeneratedValue
private long id;
@Column(nullable = false, unique = true)
private String userName;
@Column(nullable = false)
private String password;
@Column(nullable = false)
private int age;
}
数据访问层
代码语言：javascript复制public interface UserRepository extends JpaRepository<User, Long> {
User findById(long id);
void deleteById(Long id);
}
业务层
代码语言：javascript复制@Service
public class UserServiceImpl implements UserService{
@Autowired
private UserRepository userRepository;
@Override
public List<User> getUserList() {
return userRepository.findAll();
}
@Override
public User findUserById(long id) {
return userRepository.findById(id);
}
@Override
public void save(User user) {
userRepository.save(user);
}
@Override
public void edit(User user) {
userRepository.save(user);
}
@Override
public void delete(long id) {
userRepository.deleteById(id);
}
}
Controller
代码语言：javascript复制@Controller
public class UserController {
@Autowired
UserService userService;
@RequestMapping("/")
public String index() {
return "redirect:/list";
}
@RequestMapping("/list")
public String list(Model model) {
List<User> users=userService.getUserList();
model.addAttribute("users", users);
return "user/list";
}
@RequestMapping("/toAdd")
public String toAdd() {
return "user/userAdd";
}
@RequestMapping("/add")
public String addUser(User user){
userService.save(user);
return "redirect:/list";
}
@RequestMapping("/toEdit")
public String toEdit(Model model,Long id) {
User user=userService.findUserById(id);
model.addAttribute("user", user);
return "user/userEdit";
}
@RequestMapping("/edit")
public String edit(User user) {
userService.edit(user);
return "redirect:/list";
}
@RequestMapping("/delete")
public String delete(Long id) {
userService.delete(id);
return "redirect:/list";
}
}
list
代码语言：javascript复制<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8"/>
<title>userList</title>
<link rel="stylesheet" th:href="@{/css/bootstrap.css}"></link>
</head>
<body class="container">
<br/>
<h1>用户列表</h1>
<br/><br/>
<div class="with:80%">
<table class="table table-hover">
<thead>
<tr>
<th>#</th>
<th>User Name</th>
<th>Password</th>
<th>Age</th>
<th>Edit</th>
<th>Delete</th>
</tr>
</thead>
<tbody>
<tr th:each="user : ${users}">
<th scope="row" th:text="${user.id}"></th>
<td th:text="${user.userName}">neo</td>
<td th:text="${user.password}">Otto</td>
<td th:text="${user.age}"></td>
<td><a th:href="@{/toEdit(id=${user.id})}">edit</a></td>
<td><a th:href="@{/delete(id=${user.id})}">delete</a></td>
</tr>
</tbody>
</table>
</div>
<div class="form-group">
<div class="col-sm-2 control-label">
<a href="/toAdd" th:href="@{/toAdd}" class="btn btn-info">add</a>
</div>
</div>
</body>
</html>
