Week 1-8: Spring Boot 学习计划完整项目

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

week4/src/main/java/com/learn/service/mp/StudentMpService.java

@@ -0,0 +1,88 @@
+package com.learn.service.mp;
+
+import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
+import com.baomidou.mybatisplus.core.metadata.IPage;
+import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
+import com.learn.entity.Student;
+import com.learn.repository.mp.StudentMapper;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.List;
+import java.util.Optional;
+
+@Service
+public class StudentMpService {
+
+    private final StudentMapper mapper;
+
+    public StudentMpService(StudentMapper mapper) { this.mapper = mapper; }
+
+    @Transactional
+    public Student add(Student s) { mapper.insert(s); return s; }
+
+    @Transactional(readOnly = true)
+    public List<Student> list() {
+        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
+        w.orderByDesc(Student::getScore);
+        return mapper.selectList(w);
+    }
+
+    @Transactional(readOnly = true)
+    public Optional<Student> getById(Long id) {
+        return Optional.ofNullable(mapper.selectById(id));
+    }
+
+    @Transactional(readOnly = true)
+    public List<Student> search(String keyword) {
+        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
+        w.like(Student::getName, keyword).or().like(Student::getEmail, keyword);
+        w.orderByDesc(Student::getScore);
+        return mapper.selectList(w);
+    }
+
+    @Transactional
+    public Optional<Student> update(Long id, Student updated) {
+        Student existing = mapper.selectById(id);
+        if (existing == null) return Optional.empty();
+        if (updated.getName() != null) existing.setName(updated.getName());
+        if (updated.getAge() > 0) existing.setAge(updated.getAge());
+        if (updated.getEmail() != null) existing.setEmail(updated.getEmail());
+        if (updated.getScore() >= 0) existing.setScore(updated.getScore());
+        mapper.updateById(existing);
+        return Optional.of(existing);
+    }
+
+    @Transactional
+    public boolean delete(Long id) { return mapper.deleteById(id) > 0; }
+
+    @Transactional(readOnly = true)
+    public IPage<Student> page(int pageNum, int pageSize, String keyword) {
+        Page<Student> page = new Page<>(pageNum, pageSize);
+        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
+        if (keyword != null && !keyword.trim().isEmpty()) {
+            w.like(Student::getName, keyword).or().like(Student::getEmail, keyword);
+        }
+        w.orderByDesc(Student::getScore);
+        return mapper.selectPage(page, w);
+    }
+
+    @Transactional(readOnly = true)
+    public long count() { return mapper.selectCount(null); }
+
+    @Transactional(readOnly = true)
+    public long countExcellent(int minScore) {
+        LambdaQueryWrapper<Student> w = new LambdaQueryWrapper<>();
+        w.ge(Student::getScore, minScore);
+        return mapper.selectCount(w);
+    }
+
+    @Transactional
+    public Student updateAvatar(Long id, String filename) {
+        Student s = mapper.selectById(id);
+        if (s == null) throw new RuntimeException("学生不存在");
+        s.setAvatar(filename);
+        mapper.updateById(s);
+        return s;
+    }
+}