SpringMVC异常处理、SSM整合

╰+攻爆jí腚メ 2022-03-18 03:50 236阅读 0赞

**1. 异常处理**

SpringMVC：  HandlerExceptionResolver接口，

该接口的每个实现类 都是异常的一种处理方式：

**a.**  
    ExceptionHandlerExceptionResolver： 主要提供了@ExceptionHandler注解，并通过该注解处理异常

//该方法 可以捕获本类中  抛出的ArithmeticException异常
        @ExceptionHandler({ArithmeticException.class,ArrayIndexOutOfBoundsException.class  })
        public String handlerArithmeticException(Exception e) {
            System.out.println(e +"============");
            return "error" ;
        }

@ExceptionHandler标识的方法的参数 必须在异常类型(Throwable或其子类) ，不能包含其他类型的参数

异常处理路径：最短优先    
如果有方法抛出一个ArithmeticException异常，而该类中 有2个对应的异常处理法你发：

@ExceptionHandler({Exception.class  })
    public ModelAndView handlerArithmeticException2(Exception e) {}

@ExceptionHandler({ArithmeticException.class  })
     public ModelAndView handlerArithmeticException1(Exception e) {}

则优先级：  最短优先。

@ExceptionHandler默认只能捕获 当前类中的异常方法。  
如果发生异常的方法  和处理异常的方法 不在同一个类中：@ControllerAdvice

**总结：如果一个方法用于处理异常，并且只处理当前类中的异常：@ExceptionHandler  
          如果一个方法用于处理异常，并且处理所有类中的异常： 类前加@ControllerAdvice、 处理异常的方法前加      @ExceptionHandler**

**b.**  
ResponseStatusExceptionResolver：自定义异常显示页面 @ResponseStatus

@ResponseStatus(value=HttpStatus.FORBIDDEN,reason="数组越界222!!!")
    public class MyArrayIndexOutofBoundsException extends Exception {//自定义异常
    
    }

@ResponseStatus也可以标志在方法前：

@RequestMapping("testMyException")
    public String testMyException(@RequestParam("i") Integer i) throws MyArrayIndexOutofBoundsException {
       if(i == 3) {
           throw new MyArrayIndexOutofBoundsException();//抛出异常
        }
            return "success" ;
    }

@RequestMapping("testMyException2")
    public String testMyException2(@RequestParam("i") Integer i) {
       if(i == 3) {
          return "redirect:testResponseStatus" ;//跳转到某一个 异常处理方法里
       }
       return "success" ;
    }

**c. 异常处理的实现类：**  
 DefaultHandlerExceptionResolver:SPringMVC在一些常见异常的基础上（300 500  405），新增了一些异常，例如：  
 \* @see org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler  
 \* @see \#handleNoSuchRequestHandlingMethod  
 \* @see \#handleHttpRequestMethodNotSupported  ：如果springmvc的处理方法限制为post方式，如果实际请求为get,则会触发此异常显示的页面  
 \* @see \#handleHttpMediaTypeNotSupported  
 \* @see \#handleMissingServletRequestParameter  
 \* @see \#handleServletRequestBindingException  
 \* @see \#handleTypeMismatch  
 \* @see \#handleHttpMessageNotReadable  
 \* @see \#handleHttpMessageNotWritable  
 \* @see \#handleMethodArgumentNotValidException  
 \* @see \#handleMissingServletRequestParameter  
 \* @see \#handleMissingServletRequestPartException  
 \* @see \#handleBindException

**d.**  
**SimpleMappingExceptionResolver：通过配置来实现异常的处理**

<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
      
      
      <property name="exceptionMappings">
           <props>
                  
                  <prop key="java.lang.ArithmeticException">
                      error
                  </prop>
                  <prop key="java.lang.NullPointerException">
                           error
                  </prop>
                        
           </props>
       </property>
    </bean>

**2. SSM整合**

**SSM整合：**  
**Spring - SpringMVC -  MyBatis **

* 1 . Spring -  MyBatis   :    需要整合：将 MyBatis 的 SqlSessionFactory 交给Spring*

*   2. Spring - SpringMVC  ：  就是将 Spring - SpringMVC 各自配置一遍*

**思路：  
    SqlSessionFactory -> SqlSession ->StudentMapper ->CRUD  
    可以发现 ，MyBatis最终是通过SqlSessionFactory来操作数据库，  
    Spring整合MyBatis 其实就是 将MyBatis的SqlSessionFactory 交给Spring**

**SM整合步骤：**  
1. jar  
mybatis-spring.jar    spring-tx.jar    spring-jdbc.jar        spring-expression.jar  
spring-context-support.jar    spring-core.jar        spring-context.jar  
spring-beans.jar    spring-aop.jar    spring-web.jar    commons-logging.jar  
commons-dbcp.jar    ojdbc.jar    mybatis.jar    log4j.jar    commons-pool.jar

2. 类-表

Student类 -student表

3. -（与Spring整合时，conf.xml可省）--MyBatis配置文件conf.xml（**数据源、mapper.xml**） --可省，将该文件中的配置 全部交由spring管理

**spring 配置文件 applicationContext.xml**

4. 通过mapper.xml将 类、表建立映射关系

5.  
之前使用MyBatis:    conf.xml ->SqlSessionFacotry

现在整合的时候，需要通过Spring管理SqlSessionFacotry ，因此 产生qlSessionFacotry 所需要的数据库信息 不在放入conf.xml  而需要放入spring配置文件中  
**配置Spring配置文件**（applicationContext.xml）  （Web项目）：  
**web.xml配置    **

<context-param>
    	<param-name>contextConfigLocation</param-name>
    	<param-value>classpath:applicationContext.xml</param-value>
    </context-param>
    
    <listener>
    	<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

6.使用Spring整合MyBatis ：将MyBatis的SqlSessionFactory 交给Spring

**applicationContext.xml配置：**

<bean id="studentService" class="org.lanqiao.service.impl.StudentServiceImpl">
    	<property name="studentMapper"  ref="studentMapper"></property>
    </bean>
    
    
    <bean  id="config" class="org.springframework.beans.factory.config.PreferencesPlaceholderConfigurer">
    	<property name="locations">
    	    <array>
    			<value>classpath:db.properties</value>
    		</array>
    	</property>
    	
    </bean>
    
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    	<property name="driverClassName" value="${driver}"></property>
    	<property name="url" value="${url}"></property>
    	<property name="username" value="${username}"></property>
    	<property name="password" value="${password}"></property>
    </bean>
    
    
    
    
    
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    	<property name="dataSource" ref="dataSource"></property>
    	
    	<property name="mapperLocations" value="classpath:org/lanqiao/mapper/*.xml">        
       </property>
    </bean>
    
    
    
    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    	<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
    	<property name="basePackage" value="org.lanqiao.mapper"></property>
    	
     </bean>

===================================================  
7.继续整合SpringMVC：将springmvc加入项目即可   
     a. 加入SpringMVC需要的jar  
        spring-webmvc.jar

b. 给项目加入SpringMVC支持  
        ***web.xml文件中配置 :*dispatcherServlet**

<servlet>
    	<servlet-name>springDispatcherServlet</servlet-name>
    	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    	<init-param>
    	    <param-name>contextConfigLocation</param-name>
    		<param-value>classpath:applicationContext-controller.xml</param-value>
    	</init-param>
    	<load-on-startup>1</load-on-startup>
    </servlet>
    
    <servlet-mapping>
    	<servlet-name>springDispatcherServlet</servlet-name>
    	<url-pattern>/</url-pattern>
    </servlet-mapping>

c. 编写springmvc配置文件：  
       **applicationContext-controller.xml文件配置**：视图解析器、基础配置

<context:component-scan base-package="org.lanqiao.controller"></context:component-scan>
    	
    
    <bean  class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    	<property name="prefix" value="/views/"></property>
    	<property name="suffix" value=".jsp"></property>
    </bean>
    
    
    <mvc:annotation-driven></mvc:annotation-driven>

===================================

案例

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDU2OTk5MQ_size_16_color_FFFFFF_t_70][]

Student.java类

package org.lanqiao.entity;
    public class Student {
    	private int stuNo;
    	private String stuName;
    	private int stuAge ;	
    	
    	public int getStuNo() {
    		return stuNo;
    	}
    	public void setStuNo(int stuNo) {
    		this.stuNo = stuNo;
    	}
    	public String getStuName() {
    		return stuName;
    	}
    	public void setStuName(String stuName) {
    		this.stuName = stuName;
    	}
    	public int getStuAge() {
    		return stuAge;
    	}
    	public void setStuAge(int stuAge) {
    		this.stuAge = stuAge;
    	} 	
    }

index.jsp

StudentController.java

@RequestMapping("controller")
    @Controller//StudentController加入Ioc容器
    public class StudentController {
    	//控制器依赖于Service
    	@Autowired
    	@Qualifier("studentService") 
    	private StudentService  studentService;
    		
    	public void setStudentService(StudentService studentService) {
    		this.studentService = studentService;
    	}
    
    	@RequestMapping("queryStudentByNo/{stuno}")
    	public String queryStudentByNo(@PathVariable("stuno") Integer stuNo ,Map<String,Object> map) {
    		Student student = studentService.queryStudentByNo(stuNo) ;
    		map.put("student", student) ;
    		return "result" ;
    	}  
    	
    	@RequestMapping("addStudent")
    	public String addStudent(Student student) {
    		studentService.addStudent(student) ;
    		return "result" ;
    	}  
    }

StudentService.java

package org.lanqiao.service;
    
    import org.lanqiao.entity.Student;
    
    public interface StudentService {
    	Student queryStudentByNo(int stuNo);
    	void addStudent(Student student);
    }

StudentServiceImpl.java

package org.lanqiao.service.impl;
    import org.lanqiao.entity.Student;
    import org.lanqiao.mapper.StudentMapper;
    import org.lanqiao.service.StudentService;
    
    public class StudentServiceImpl implements StudentService {
    	//service依赖于dao(mapper)
    	private StudentMapper  studentMapper ;	
    	public void setStudentMapper(StudentMapper studentMapper) {
    		this.studentMapper = studentMapper;
    	}
    	@Override
    	public Student queryStudentByNo(int stuNo) {
    		return  studentMapper.queryStudentByStuno(stuNo) ;
    	}
    	@Override
    	public void addStudent(Student student) {
    		studentMapper.addStudent(student);
    	}
    }

StudentMapper.xml文件

<mapper namespace="org.lanqiao.mapper.StudentMapper">	
    	<select id="queryStudentByStuno" parameterType="int" resultType="org.lanqiao.entity.Student"  >
    		select * from student where stuno = #{stuNo}
    	</select>	
    	
    	<insert id="addStudent" parameterType="org.lanqiao.entity.Student" >
    		insert into student(stuno,stuname,stuage) values(#{stuNo},#{stuName},#{stuAge})
    	</insert>
    </mapper>

StudentMapper.java类

package org.lanqiao.mapper;
    
    import org.lanqiao.entity.Student;
    
    public interface StudentMapper {
    	public void addStudent(Student student	);
    
    	Student queryStudentByStuno(int stuno);
    }

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