springMVC02-黑马-笔记

SpringMVC

1.SSM整合
2.统一结果封装
- 表现层与前端数据传输协议实现
3.统一异常处理
- 项目异常处理方案
4.前后台协议联调
- 列表功能
- 添加功能
- 修改功能
- 删除功能
拦截器

1.SSM整合

2.统一结果封装

为了封装返回的结果数据:创建结果模型类，封装数据到data属性中
为了封装返回的数据是何种操作及是否操作成功:封装操作结果到code属性中
操作失败后为了封装返回的错误信息:封装特殊消息到message(msg)属性中

public class Result{
	private Object data;
	private Integer code;
	private String msg;
}

注意:Result类名及类中的字段并不是固定的，可以根据需要自行增减提供若干个构造方法，方便操作。

表现层与前端数据传输协议实现

package com.itheima.controller;

public class Result {
    private Object data;
    private Integer code;
    private String msg;

    public Result() {
    }

    //构造方法是方便对象的创建
    public Result(Integer code,Object data) {
        this.data = data;
        this.code = code;
    }
    //构造方法是方便对象的创建
    public Result(Integer code, Object data, String msg) {
        this.data = data;
        this.code = code;
        this.msg = msg;
    }

    public Object getData() {
        return data;
    }

    public void setData(Object data) {
        this.data = data;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

package com.itheima.controller;

//状态码
public class Code {
    public static final Integer SAVE_OK = 20011;
    public static final Integer DELETE_OK = 20021;
    public static final Integer UPDATE_OK = 20031;
    public static final Integer GET_OK = 20041;

    public static final Integer SAVE_ERR = 20010;
    public static final Integer DELETE_ERR = 20020;
    public static final Integer UPDATE_ERR = 20030;
    public static final Integer GET_ERR = 20040;

}

package com.itheima.controller;

import com.itheima.domain.Book;
import com.itheima.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/books")
public class BookController {
    @Autowired
    private BookService bookService;

    @PostMapping
    public Result save(@RequestBody Book book) {
        boolean flag = bookService.save(book);
        return new Result(flag ? Code.SAVE_OK:Code.SAVE_ERR,flag);
    }

    @PutMapping
    public Result update(@RequestBody Book book) {
        boolean flag = bookService.update(book);
        return new Result(flag ? Code.UPDATE_OK:Code.UPDATE_ERR,flag);
    }

    @DeleteMapping("/{id}")
    public Result delete(@PathVariable Integer id) {
        boolean flag = bookService.delete(id);
        return new Result(flag ? Code.DELETE_OK:Code.DELETE_ERR,flag);
    }


    @GetMapping("/{id}")
    public Result getById(@PathVariable Integer id) {
        Book book = bookService.getById(id);
        Integer code = book != null ? Code.GET_OK:Code.GET_ERR;
        String msg = book != null ? "":"数据查询失败请重试";
        return new Result(code,book,msg);
    }

    @GetMapping
    public Result getAll() {
        List bookList = bookService.getAll();
        Integer code = bookList != null ? Code.GET_OK:Code.GET_ERR;
        String msg = bookList != null ? "":"数据查询失败请重试";
        return new Result(code,bookList,msg);
    }

}

3.统一异常处理

异常的种类及出现异常的原因:

框架内部抛出的异常：因使用不合规导致
数据层抛出的异常：因外部服务器故障导致（例如：服务器访问超时）
业务层抛出的异常：因业务逻辑书写错误导致（例如：遍历业务书写操作，导致索引异常等）
表现层抛出的异常：因数据收集、校验等规则导致（例如：不匹配的数据类型间导致异常）
工具类抛出的异常：因工具类书写不严谨不够健壮导致（例如：必要释放的连接长期未释放等）

所有的异常均抛出到表现层进行处理

package com.itheima.controller;

import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
public class ProjectExceptionAdvice {
    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex){
        System.out.println("抓住异常了！");
        return new Result(666,null,"嘿嘿,异常你哪里跑！");
    }
}

项目异常处理方案

业务异常（BusinessException）
发送对应消息传递给用户，提醒规范操作
系统异常（SystemException）
发送固定消息传递给用户，安抚用户
发送特定消息给运维人员，提醒维护
记录日志
其他异常（Exception）
发送固定消息传递给用户，安抚用户
发送特定消息给运维人员，提醒维护
记录日志

package com.itheima.exception;

public class SystemException extends RuntimeException {


    private Integer code;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public SystemException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public SystemException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

}

package com.itheima.exception;

public class BusinessException extends RuntimeException {


    private Integer code;

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public BusinessException(Integer code, String message) {
        super(message);
        this.code = code;
    }

    public BusinessException(Integer code, String message, Throwable cause) {
        super(message, cause);
        this.code = code;
    }

}

package com.itheima.controller;

import com.itheima.exception.BusinessException;
import com.itheima.exception.SystemException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice
public class ProjectExceptionAdvice {

    @ExceptionHandler(SystemException.class)
    public Result doSystemException(SystemException ex){
        //记录日志
        //发送消息给运维
        //发送邮件给开发人员,ex对象发送给开发人员
        return new Result(ex.getCode(),null,ex.getMessage());
    }

    @ExceptionHandler(BusinessException.class)
    public Result doBusinessException(BusinessException ex){
        return new Result(ex.getCode(),null,ex.getMessage());
    }

    @ExceptionHandler(Exception.class)
    public Result doException(Exception ex){
        //记录日志
        //发送消息给运维
        //发送邮件给开发人员,ex对象发送给开发人员
        return new Result(Code.SYSTEM_UNKNOW_ERR,null,"系统繁忙，请稍后再试！");
    }
}

    public Book getById(Integer id) {
        //模拟业务异常，包装成自定义异常
        if(id == 1){
            throw new BusinessException(Code.BUSINESS_ERR,"请不要使用你的技术挑战我的 耐性!");
        }
        //模拟系统异常，将可能出现的异常进行包装，转换成自定义异常
        try {
            int i =1/0;
        } catch (ArithmeticException e) {
            throw new SystemException(Code.SYSTEM_TIMEOUT_ERR,"服务器访问超时，请重 试!",e);
        }
        return bookDao.getById(id);
    }

4.前后台协议联调列表功能

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

添加功能

//弹出添加窗口
                handleCreate() {
                    this.dialogFormVisible = true;
                    this.resetForm();
                },

//重置表单
                resetForm() {
                    this.formData = {};
                },

//添加
                handleAdd () {
                    axios.post("/books",this.formData).then((res)=>{
                        //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();
                    });
                },

修改功能

handleUpdate(row) {
                    //console.log(row);
                    //查询数据，根据id
                    axios.get("/books/"+row.id).then((res)=>{
                        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);
                        }
                    });
                },

//编辑
                handleEdit() {
                    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();
                    });
                },

删除功能

// 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.$message.error("删除失败");
                            }
                        }).finally(()=>{
                            this.getAll();
                        });
                    }).cache(()=>{
                        //3.取消删除
                        this.$message.info("取消删除操作");
                    });
                }
            }
        })

拦截器

拦截器（Interceptor）是一种动态拦截方法调用的机制，在SpringMVC中动态拦截控制器方法的执行

package com.itheima.controller.interceptpr;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

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

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

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

package com.itheima.config;

import com.itheima.controller.interceptpr.ProjectInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

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

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

    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/pages/**").addResourceLocations("/pages/");
    }
}

简化：

@Configuration
@ComponentScan({"com.itheima.controller"})
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer{
    @Autowired
    private ProjectInterceptor projectInterceptor;

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

springMVC02-黑马-笔记

Java相关栏目本月热门文章