[散修弟子]JAVA-1818|2017年05月24日的日报-技能树.IT修真院

发表于： 2017-05-24 11:05:27

1 1222

‍‍‍‍

‍‍今日目标：收尾任务2，完成剩余的接口并且全部使用POSTMAN测试通过。‍‍‍‍‍‍‍‍‍‍‍‍‍‍

1.之前接口有些设计不当，思考之后决定删除PATCH操作，删除学员也应该根据自增id精确删除。

2.修改之前的代码，POST操作出现的诡异错误让我意识到单独写Service类并且提交事务、关闭会话的重要性。

3.修改Mapper，删除方法的返回值改为void，Update方法返回值改为int，表示受到影响的自增id数目。

4.发现之前获取单个和多个学生，使用了两个jsp页面，现在统一在服务端跳转到result.jsp，使用EL表达式显示结果。

在增加Service类的时候遇到如下问题：

Controller中：

……
@Autowired
StudentService studentService;
……

Service中：

@Service
public class StudentService {
……

Tomcat启动时报错。

Error creating bean with name 'studentController': Unsatisfied dependency expressed through field 'studentService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.qhs.rest.service.StudentService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Google出的结果：

在springmvc-servlet.xml中，之前component-scan只扫描了Controller包

将其改为扫描rest包，启动报错解决


<context:component-scan base-package="com.qhs.rest" />

也让我体会到了IoC的快感，Controller中不必自己new对象了，真正体会到了什么叫低耦合。。

在测试根据id精确获取学员的时候遇到如下问题：

Request processing failed; nested exception is java.lang.IllegalStateException: Ambiguous handler methods mapped for HTTP path 'http://localhost:8080/REST/student/43': {public org.springframework.web.servlet.ModelAndView com.qhs.rest.controller.StudentController.getStudentsByName(java.lang.String,java.lang.Integer) throws java.io.IOException, public org.springframework.web.servlet.ModelAndView com.qhs.rest.controller.StudentController.getStudentsById(java.lang.Integer) throws java.io.IOException}

StackOverflow上看到的一个办法是让换一下参数：

https://stackoverflow.com/questions/35155916/handling-ambiguous-handler-methods-mapped-in-rest-application-with-spring

在测试根据id删除学员的时候。。。遇到这个异常

### SQL: delete * from signup where id = ?

### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '* from signup where id = 43' at line 1] with root cause

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '* from signup where id = 43' at line 1

原来是我的SQL语句写错了……我sql基础还真是差

最后测试根据id修改学员信息的时候……又遇到了异常。。

### SQL: <script> update signupupdate_at = (UNIX_TIMESTAMP(now())*1000<set><if test="name != null">name=?,</if><if test="qq != null">price=?,</if><if test="major != null">price=?,</if><if test="start_date != null">price=?,</if><if test="school != null">price=?,</if><if test="onlineclass != null">price=?,</if><if test="onlineno != null">price=?,</if><if test="diarylink != null">price=?,</if><if test="aim != null">price=?,</if><if test="recommender != null">price=?,</if><if test="censor != null">price=?,</if><if test="wherefrom != null">price=?,</if></set>where id = ?</script>

### Cause: org.apache.ibatis.binding.BindingException: Parameter 'name' not found. Available parameters are [student, param1]] with root cause

org.apache.ibatis.binding.BindingException: Parameter 'name' not found. Available parameters are [student, param1]

和昨天的一样，需要改成student.属性。

SQL: <script> update signupupdate_at = (UNIX_TIMESTAMP(now())*1000<set><if test="student.name != null">name=?,</if><if test="student.qq != null">qq=?,</if><if test="student.major != null">major=?,</if><if test="student.start_date != null">start_date=?,</if><if test="student.school != null">school=?,</if><if test="student.onlineclass != null">onlineclass=?,</if><if test="student.onlineno != null">onlineno=?,</if><if test="student.diarylink != null">diarylink=?,</if><if test="student.aim != null">aim=?,</if><if test="student.recommender != null">recommender=?,</if><if test="student.censor != null">censor=?,</if><if test="student.wherefrom != null">wherefrom=?,</if></set>where id = ?</script>

### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '<script> update signupupdate_at = (UNIX_TIMESTAMP(now())*1000<set><if test="stud' at line 1] with root cause

嗨呀好气呀，这不是意味着我这个动态sql完全没有用么？

先吃个饭，下午再搞

尝试注释掉所有if判断语句，就留一个update_at

### SQL: <script>update `signup` update_at = (UNIX_TIMESTAMP(now())*1000 where id = ?</script>

### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '<script>update `signup` update_at = (UNIX_TIMESTAMP(now())*1000 where id = 27</s' at line 1] with root cause

别人说能用script标签包裹来实现动态sql都是骗人的哇哇哇