SSM integrated detailed teaching (below)

5. SSM integrated page development

1 Preparations

In order to ensure that static resources can be accessed, static resource filtering needs to be set

@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    
    
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
    
    
        registry.addResourceHandler("/pages/**")
            .addResourceLocations("/pages/");
        registry.addResourceHandler("/css/**")
            .addResourceLocations("/css/");
        registry.addResourceHandler("/js/**")
            .addResourceLocations("/js/");
        registry.addResourceHandler("/plugins/**")
            .addResourceLocations("/plugins/");
    }
}

2 list query function

• front-end code

//列表
getAll() {
    
    
    //发送ajax请求
    axios.get("/books").then((res)=>{
    
    
        this.dataList = res.data.data;
    });
}

3 Add function

• front-end code

//弹出添加窗口
handleCreate() {
    
    
    this.dialogFormVisible = true;
    this.resetForm();
},
//重置表单
resetForm() {
    
    
    this.formData = {
    
    };
},
//添加
handleAdd () {
    
    
    //发送ajax请求
    axios.post("/books",this.formData).then((res)=>{
    
    
        console.log(res.data);
        //如果操作成功，关闭弹层，显示数据
        if(res.data.code == 20011){
    
    
            this.dialogFormVisible = false;
            this.$message.success("添加成功");
        }else if(res.data.code == 20010){
    
    
            this.$message.error("添加失败");
        }else{
    
    
            this.$message.error(res.data.msg);
        }
    }).finally(()=>{
    
    
        this.getAll();
    });
},

• Code-behind improvements

@Service
public class BookServiceImpl implements BookService {
    
    
    @Autowired
    private BookDao bookDao;
	//增删改的方法判断了影响的行数是否大于0，而不是固定返回true
    public boolean save(Book book) {
    
    
        return bookDao.save(book) > 0;
    }
	//增删改的方法判断了影响的行数是否大于0，而不是固定返回true
    public boolean update(Book book) {
    
    
        return bookDao.update(book) > 0;
    }
	//增删改的方法判断了影响的行数是否大于0，而不是固定返回true
    public boolean delete(Integer id) {
    
    
        return bookDao.delete(id) > 0;
    }

    public Book getById(Integer id) {
    
    
        if(id < 0){
    
    
            throw new BusinessException(Code.BUSINESS_ERR,"请不要使用你的技术挑战我的耐性!");
            return bookDao.getById(id);
        }
    }
    public List<Book> getAll() {
    
    
        return bookDao.getAll();
    }
}

4 Modification function

• Display pop-up box to query book information

//弹出编辑窗口
handleUpdate(row) {
    
    
    // console.log(row);   //row.id 查询条件
    //查询数据，根据id查询
    axios.get("/books/"+row.id).then((res)=>{
    
    
        // console.log(res.data.data);
        if(res.data.code == 20041){
    
    
            //展示弹层，加载数据
            this.formData = res.data.data;
            this.dialogFormVisible4Edit = true;
        }else{
    
    
            this.$message.error(res.data.msg);
        }
    });
}

• Save modified book information

//编辑
handleEdit() {
    
    
    //发送ajax请求
    axios.put("/books",this.formData).then((res)=>{
    
    
        //如果操作成功，关闭弹层，显示数据
        if(res.data.code == 20031){
    
    
            this.dialogFormVisible4Edit = false;
            this.$message.success("修改成功");
        }else if(res.data.code == 20030){
    
    
            this.$message.error("修改失败");
        }else{
    
    
            this.$message.error(res.data.msg);
        }
    }).finally(()=>{
    
    
        this.getAll();
    });
}

5 delete function

// 删除
handleDelete(row) {
    
    
    //1.弹出提示框
    this.$confirm("此操作永久删除当前数据，是否继续？","提示",{
    
    
        type:'info'
    }).then(()=>{
    
    
        //2.做删除业务
        axios.delete("/books/"+row.id).then((res)=>{
    
    
            if(res.data.code == 20021){
    
    
                this.$message.success("删除成功");
            }else{
    
    
                this.$message.error("删除失败");
            }
        }).finally(()=>{
    
    
            this.getAll();
        });
    }).catch(()=>{
    
    
        //3.取消删除
        this.$message.info("取消删除操作");
    });
}

6. Interceptor

1 Introduction to Interceptor

problem import

Question 1: Who is the object intercepted by the interceptor?

Question 2: What is the difference between an interceptor and a filter?

1.1 Interceptor concept and function

• Interceptor (Interceptor) is a mechanism for dynamically intercepting method calls, and dynamically intercepts the execution of controller methods in SpringMVC
• effect:
  1. Execute preset code before and after the specified method call
  2. Block execution of the original method
  3. Summary: Enhanced
• Core principle: AOP thought

1.2 The difference between interceptors and filters

• Different ownership: Filter belongs to Servlet technology, Interceptor belongs to SpringMVC technology
• The interception content is different: Filter enhances all access, and Interceptor only enhances SpringMVC access

2 Getting Started Case

problem import

What interface does an interceptor need to implement?

2.1 Interceptor code implementation

[Step 1] Define the interceptor

Method: define a class and implement the HandlerInterceptor interface

@Component //注意当前类必须受Spring容器控制
//定义拦截器类，实现HandlerInterceptor接口
public class ProjectInterceptor implements HandlerInterceptor {
    
    
    @Override
    //原始方法调用前执行的内容
    //返回值类型可以拦截控制的执行，true放行，false终止
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
        System.out.println("preHandle..."+contentType);
        return true;
    }

    @Override
    //原始方法调用后执行的内容
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
    
        System.out.println("postHandle...");
    }

    @Override
    //原始方法调用完成后执行的内容
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
    
        System.out.println("afterCompletion...");
    }
}

[Step 2] Configure the loading interceptor

@Configuration
public class SpringMvcSupport extends WebMvcConfigurationSupport {
    
    
    @Autowired
    private ProjectInterceptor projectInterceptor;

    @Override
    protected void addInterceptors(InterceptorRegistry registry) {
    
    
        //配置拦截器
        registry.addInterceptor(projectInterceptor)
            .addPathPatterns("/books","/books/*");
    }
}

Use the standard interface WebMvcConfigurer to simplify development (note: strong intrusion)

@Configuration
@ComponentScan({
    
    "com.sun.controller"})
@EnableWebMvc
//实现WebMvcConfigurer接口可以简化开发，但具有一定的侵入性
public class SpringMvcConfig implements WebMvcConfigurer {
    
    
    @Autowired
    private ProjectInterceptor projectInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
    
    
        //配置多拦截器
        registry.addInterceptor(projectInterceptor)
            .addPathPatterns("/books","/books/*");
    }
}

2.2 Interceptor process analysis

3 Interceptor parameters

problem import

The postHandle() and afterCompletion() methods are both executed after the processor method is executed. What is the difference?

3.1 Preprocessing

//原始方法调用前执行的内容
//返回值类型可以拦截控制的执行，true放行，false终止
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
    System.out.println("preHandle..."+contentType);
    return true;
}

• parameter

  1. request: request object
  2. response: response object
  3. handler: The invoked processor object is essentially a method object, which repackages the Method object in reflection technology

• Return value
  If the return value is false, the intercepted processor will not be executed.

3.2 Post-processing

//原始方法调用后执行的内容
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
    
    System.out.println("postHandle...");
}

• Parameter
  modelAndView: If the processor execution is completed and has a return result, you can read the corresponding data and page information and jump

Note: If an exception occurs in the handler method, the method will not be executed

3.3 Processing after completion

//原始方法调用完成后执行的内容
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
    
    System.out.println("afterCompletion...");
}

• Parameter
  ex: If an exception object occurs during the execution of the processor, it can be handled separately for the exception

Note: This method will execute regardless of whether an exception occurs inside the handler method.

4 Interceptor chain configuration

problem import

What is an interceptor chain?

4.1 Multiple Interceptor Configurations

• Define the second interceptor

@Component
public class ProjectInterceptor2 implements HandlerInterceptor {
    
    
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    
    
        System.out.println("preHandle...222");
        return false;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
    
        System.out.println("postHandle...222");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
    
        System.out.println("afterCompletion...222");
    }
}

• Configure the second interceptor

@Configuration
@ComponentScan({
    
    "com.itheima.controller"})
@EnableWebMvc
//实现WebMvcConfigurer接口可以简化开发，但具有一定的侵入性
public class SpringMvcConfig implements WebMvcConfigurer {
    
    
    @Autowired
    private ProjectInterceptor projectInterceptor;
    @Autowired
    private ProjectInterceptor2 projectInterceptor2;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
    
    
        //配置多拦截器
        registry.addInterceptor(projectInterceptor)
            .addPathPatterns("/books","/books/*");
        registry.addInterceptor(projectInterceptor2)
            .addPathPatterns("/books","/books/*");
    }
}

4.2 Multiple connector workflow analysis

• When multiple interceptors are configured, an interceptor chain is formed
• The running order of the interceptor chain refers to the order in which the interceptors are added
• When the interception of the original processor occurs in the interceptor, the subsequent interceptors will all terminate
• When the interceptor is interrupted, only the afterCompletion operation configured in the previous interceptor will be run