Create SpringBoot整合MongoDB.md

Author: JavaCodeMing

doc/SpringBoot整合MongoDB.md

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+```
+1.引入web依赖和mongodb依赖:
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-data-mongodb</artifactId>
+    </dependency>
+    <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
+2.Mongo Shell或者Mongo Compass工具创建数据库testdb,并新增user文档:
+    (1)使用Mongo Shell:
+        1)创建数据库testdb: use testdb
+        2)新增user文档: db.createCollection(user)
+    (2)使用Mongo Compass工具创建数据库: 图形化操作
+3.配置文件application.yml里配置Mongo DB:
+    spring:
+        data:
+            mongodb:
+                host: localhost
+                # MongoDB的默认端口为27017
+                port: 27017
+                database: testdb
+4.创建User实体类:
+    // 声明文档对象,名称为user
+    @Document(collection = "user")
+    public class User {
+        //@Id标注主键字段
+        @Id 
+        private String id;
+        private String name;
+        private Integer age;
+        private String description;
+        // get set 略
+    }
+    (String类型的主键值插入MongoDB时会自动生成;若对象中某属性为非表字段,
+    可用注解@Transient排除)
+5.编写Mapper接口:
+    @Repository
+    public interface UserMapper extends MongoRepository<User, String> {
+        //通过年龄段,用户名,描述(模糊查询)(自定义方法)
+        List<User> findByAgeBetweenAndNameEqualsAndDescriptionIsLike(Integer from,
+            Integer to, String name, String description);
+    }
+    (MongoRepository提供了一些增删改查的方法,通过继承可直接使用)
+    (自定义方法,在输入findBy后,IDEA会根据实体对象的属性和SQL的各种关键字自动组合提示)
+6.编写Service接口:
+    public interface UserService {
+        // 查询文档内所有数据
+        List<User> selectAll();
+        // 通过id查询文档内的数据
+        Optional<User> selectById(String id);
+        // 向文档内插入一条记录
+        User create(User user);
+        // 通过id更新文档内容
+        void updateById(String id,User user);
+        // 通过id删除文档内容
+        void deleteById(String id);
+        // 通过条件进行模糊查询,并将结果进行分页
+        Page<User> selectByCondition(int size, int page, User user);
+    }
+7.编写Service实现类:
+    @Service
+    public class UserServiceImpl implements UserService {
+        // 排序和分页需要使用MongoTemplate对象来完成
+        @Autowired
+        private MongoTemplate template;
+        @Autowired
+        private UserMapper mapper;
+        @Override
+        public List<User> selectAll() {
+            return this.mapper.findAll();
+        }
+        @Override
+        public Optional<User> selectById(String id) {
+            return this.mapper.findById(id);
+        }
+        @Override
+        public User create(User user) {
+            user.setId(null);
+            return this.mapper.save(user);
+        }
+        @Override
+        public void updateById(String id, User user) {
+            this.mapper.findById(id)
+                    .ifPresent(
+                            u -> {
+                                u.setName(user.getName());
+                                u.setAge(user.getAge());
+                                u.setDescription(user.getDescription());
+                                this.mapper.save(u);
+                            }
+                    );
+        }
+        @Override
+        public void deleteById(String id) {
+            this.mapper.findById(id)
+                    .ifPresent( user -> this.mapper.deleteById(id));
+        }
+        // size表示每页显示的条数,page表示当前页码数(0表示第一页)
+        // 通过name和description来模糊查询用户信息再分页,并且查询结果使用age字段降序排序
+        @Override
+        public Page<User> selectByCondition(int size, int page, User user) {
+            Query query = new Query();
+            Criteria criteria = new Criteria();
+            if(!StringUtils.isEmpty(user.getName())){
+                criteria.and("name").is(user.getName());
+            }
+            if(!StringUtils.isEmpty(user.getDescription())){
+                criteria.and("description").regex(user.getDescription());
+            }
+            query.addCriteria(criteria);
+            Sort sort = new Sort(Sort.Direction.DESC,"age");
+            PageRequest pageable = PageRequest.of(page, size, sort);
+            List<User> users = template.find(query.with(pageable), User.class);
+            return PageableExecutionUtils.getPage(users,pageable,
+                ()-> template.count(query,User.class));
+        }
+    }
+8.编写controller: (RESTful风格)
+    @RestController
+    public class UserController {
+        @Autowired
+        private UserService service;
+        @GetMapping("/user/")
+        public List<User> getUsers(){
+            return this.service.selectAll();
+        }
+        @GetMapping("/user/{id}")
+        public User getUser(@PathVariable String id){
+            return this.service.selectById(id).orElse(null);
+        }
+        @PostMapping("/user/")
+        public User createUser(User user){
+            return this.service.create(user);
+        }
+        @DeleteMapping("/user/{id}")
+        public void deleteUser(@PathVariable String id){
+            this.service.deleteById(id);
+        }
+        @PutMapping("/user/{id}")
+        public void updateUser(@PathVariable String id,User user){
+            this.service.updateById(id,user);
+        }
+        @GetMapping("/user/condition")
+        public Page<User> getUserByCondition(int size,int page,User user){
+            return this.service.selectByCondition(size, page, user);
+        }
+    }
+```