利用Lombok注解使得代码简化，和MP的lambdaQuery。

pom.xml

@@ -35,6 +35,12 @@
             <version>3.3.0</version>
         </dependency>
 
+        <dependency>
+            <groupId>cn.hutool</groupId>
+            <artifactId>hutool-all</artifactId>
+            <version>5.8.15</version>
+        </dependency>
+
         <dependency>
             <groupId>com.mysql</groupId>
             <artifactId>mysql-connector-j</artifactId>

src/main/java/com/watu/demo1/Controller/UserController.java

@@ -1,18 +1,20 @@
 package com.watu.demo1.Controller;
 
+import cn.hutool.core.bean.BeanUtil;
 import com.watu.demo1.Service.IUserPlusService;
-import com.watu.demo1.mapper.UserMapper;
 import com.watu.demo1.pojo.DTO.UserDTO;
 import com.watu.demo1.pojo.entity.User;
+import com.watu.demo1.pojo.query.UserQuery;
 import com.watu.demo1.pojo.vo.UserVO;
+import lombok.RequiredArgsConstructor;
 import org.springframework.beans.BeanUtils;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.*;
 
 import java.util.List;
 
 @RestController
 @RequestMapping("v1/Plus/")
+@RequiredArgsConstructor
 public class UserController {
 //    @Autowired(required = false)
 //    private UserMapper userMapper;
@@ -51,24 +53,37 @@ public class UserController {
 //        return (insert != 0) ? "添加成功" : "添加失败";
 //    }
 
-    @Autowired
-    IUserPlusService service;
+    private final IUserPlusService service;
+
     @PostMapping("add")
     public void addNewUser(@RequestBody UserDTO userDTO) {
         service.addUser(userDTO);
     }
+
     @GetMapping("delete/{id}")
     public void delete(@PathVariable Long id) {
         service.deleteById(id);
     }
+
     @PostMapping("select")
     public void select(@RequestBody UserDTO userDTO) {
         service.selectByName(userDTO);
     }
+
     @PostMapping("update/d1")
     public void update(@RequestBody UserDTO userDTO) {
         service.updateById(userDTO);
     }
 
 
+    /**复杂的条件查询*/
+    /**条件多，定义对象去封装，，，哦~~师傅之前可能是这个意思*/
+    /**
+     * 是可以在Controller直接调用一些list方法的，但是代码会臃肿，可以自定义方法。
+     */
+    @GetMapping("/list")
+    public List<UserVO> queryInFo(UserQuery query) {
+        List<User> users=service.queryUsers(query.getAge(),query.getId(),query.getName(),query.getVersion());
+        return BeanUtil.copyToList(users,UserVO.class);
+    }
 }

src/main/java/com/watu/demo1/Service/IUserPlusService.java

@@ -1,9 +1,12 @@
 package com.watu.demo1.Service;
 
+import com.baomidou.mybatisplus.extension.service.IService;
 import com.watu.demo1.pojo.DTO.UserDTO;
 import com.watu.demo1.pojo.entity.User;
 
-public interface IUserPlusService {
+import java.util.List;
+
+public interface IUserPlusService extends IService<User>{
     /**
      *增
      * 插入类别数据
@@ -37,4 +40,6 @@ public interface IUserPlusService {
      * @return 受影响的行数
      * */
     int updateById(UserDTO userDTO);
+
+    List<User> queryUsers(Integer age, String id, String name, Integer version);
 }

src/main/java/com/watu/demo1/Service/Impl/UserPlusServiceImpl.java

@@ -1,21 +1,27 @@
 package com.watu.demo1.Service.Impl;
 
 
-import com.sun.org.apache.bcel.internal.generic.NEW;
+import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import com.watu.demo1.Service.IUserPlusService;
+import com.watu.demo1.mapper.UserPlusMapper;
 import com.watu.demo1.pojo.DTO.UserDTO;
 import com.watu.demo1.pojo.entity.User;
 import com.watu.demo1.pojo.vo.UserVO;
 import com.watu.demo1.repository.IUserPlusRepository;
 import org.springframework.beans.BeanUtils;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
+import java.util.List;
+
 @Service
-public class UserPlusServiceImpl implements IUserPlusService {
-    @Autowired
+public class UserPlusServiceImpl extends ServiceImpl<UserPlusMapper, User> implements IUserPlusService {
+
     private IUserPlusRepository iUserPlusRepository;
 
+    public UserPlusServiceImpl(IUserPlusRepository iUserPlusRepository) {
+        this.iUserPlusRepository = iUserPlusRepository;
+    }
+
     @Override
     public void addUser(UserDTO userDTO) {
         /**在这里就可以用到之前在Repository中定义的CountByName的方法，用来查看库中是否已经存在相同的名字*/
@@ -48,5 +54,17 @@ public class UserPlusServiceImpl implements IUserPlusService {
         return iUserPlusRepository.updateById(userVO);
     }
 
+    @Override
+    public List<User> queryUsers(Integer age, String id, String name, Integer version) {
+        //TODO使用Wrapper来实现
+        /*用lambdaQuery*/
+        return lambdaQuery()
+                .eq( name!= null, User::getName, name)
+                .eq(version!=null,User::getVersion,version)
+                .lt(age!=null,User::getAge,age)  //小于 等于 le
+                .gt(id!=null,User::getId,id)   //大于   等于 ge
+                .list();  //判断查多个，就是list，就一个 就 one();分页就page();是否存在exist();数量 count();;
+    }
+
 
 }

src/main/java/com/watu/demo1/pojo/query/UserQuery.java

@@ -0,0 +1,11 @@
+package com.watu.demo1.pojo.query;
+
+import lombok.Data;
+
+@Data
+public class UserQuery {
+    private String name;
+    private String id;
+    private Integer age;
+    private Integer version;
+}

src/main/java/com/watu/demo1/repository/Impl/UserPlusRepositoryImpl.java

@@ -5,14 +5,15 @@ import com.watu.demo1.mapper.UserPlusMapper;
 import com.watu.demo1.pojo.entity.User;
 import com.watu.demo1.pojo.vo.UserVO;
 import com.watu.demo1.repository.IUserPlusRepository;
+import lombok.RequiredArgsConstructor;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Repository;
 
 @Repository
+@RequiredArgsConstructor
 public class UserPlusRepositoryImpl implements IUserPlusRepository {
-    @Autowired
-    private UserPlusMapper userPlusMapper;
+    private final UserPlusMapper userPlusMapper;
 
     /**
      * 增  插入一个数据

src/main/resources/application.properties

@@ -4,4 +4,5 @@ spring.datasource.password=!QAZ1qaz
 
 
 mybatis.mapper-locations=classpath:mappers/*.xml
+
 mybatis-plus.mapper-locations=classpath:mappers/*.xml