SpringMVC第五天(SSM整合)
表现层数据封装
设置统一数据返回结果类
public class Result{
private Object data;
private Integer code;
private String msg;
}设置统一数据返回结果编码
package com.cacb.controller;
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;
}
根据情况设定合理的Result
package com.cacb.controller;
public class Result {
private Object data;
private Integer code;
private String msg;
public Result(Integer code ,Object data, String msg) {
this.data = data;
this.code = code;
this.msg = msg;
}
public Result(Integer code ,Object data) {
this.data = data;
this.code = code;
}
public Result() {
}
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.cacb.controller;
import com.cacb.domain.Book;
import com.cacb.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
import static com.cacb.controller.Code.*;
@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?SAVE_OK:SAVE_ERR,flag);
}
@PutMapping
public Result update(@RequestBody Book book) {
boolean flag = bookService.update(book);
return new Result(flag?UPDATE_OK:UPDATE_ERR,flag);
}
@DeleteMapping( "/{id}")
public Result delete(@PathVariable Integer id) {
boolean flag = bookService.delete(id);
return new Result(flag?DELETE_OK:DELETE_ERR,flag);
}
@GetMapping("/{id}")
public Result getById(@PathVariable Integer id) {
Book book = bookService.getById(id);
Integer code = book != null ? GET_OK:GET_ERR;
String msg = book != null ? "" : "数据查询失败";
return new Result(code,book,msg) ;
}
@GetMapping
public Result getAll() {
List bookList = bookService.getAll();
Integer code = bookList != null ? GET_OK:GET_ERR;
String msg = bookList != null ? "" : "数据查询失败";
return new Result(code,bookList,msg) ;
}
}
异常处理器
出现异常常见位置与常见诱因如下
1.框架内部抛出的异常：因使用不合规导致
2.数据层抛出的异常：因为外部服务器故障导致(例如：服务器访问超时)
3.业务层抛出的异常：因业务逻辑书写错误导致(例如：不匹配的数据类型间导致异常)
4.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)
5.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：必要时放的连接长期未释放等)
各层均会出现异常，为集中处理各层所有的异常
应该： 所有的异常均抛出到表现层进行处理
异常处理器
集中的、统一的处理项目中出现的异常
package com.cacb.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("处理异常");
return new Result(1111,null);
}
}项目异常处理方案
项目异常分类
业务异常(BusinessException)
规范的用户行为产生的异常
不规范的用户行为操作产生的异常
（发送对应消息传递给用户，提醒规范操作）
系统异常(SystemException)
项目运行过程中可预计且无法避免的异常
（发送固定信息传递给用户，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)
编程人员未预期到的异常
（发送固定信息传递给用户，安抚用户）
（发送特定消息给运维人员，提醒维护）
（纳入预期范围内）
（记录日志）
处理步骤
第一步、自定义项目系统级异常
package com.cacb.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;
}
}
第二步、自定义项目业务级异常
package com.cacb.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;
}
}
第三步、自定义异常编码
public static final Integer SYSTEM_ERR = 50001;
public static final Integer BUSINESS_ERR = 50002;
public static final Integer SYSTEM_UNKNOW_ERR = 59999;第四步、触发自定义异常
@Override
public boolean delete(Integer id) {
if (id < 0)
{
throw new BusinessException(Code.BUSINESS_ERR,"输入ID非法！");
}
bookDao.delete(id);
return true;
}第五步、拦截并处理异常
package com.cacb.controller;
import com.cacb.exception.BusinessException;
import com.cacb.exception.SystemException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import static com.cacb.controller.Code.SYSTEM_UNKNOW_ERR;
@RestControllerAdvice
public class ProjectExceptionAdvice {
@ExceptionHandler(SystemException.class)
public Result doException(SystemException ex){
//记录日志
//发消息给运维
//发送邮件给开哦发人员，ex对象发送给2开发人员
return new Result(ex.getCode(),null,ex.getMessage());
}
@ExceptionHandler(BusinessException.class)
public Result doException(BusinessException ex){
//记录日志
//发消息给运维
//发送邮件给开哦发人员，ex对象发送给2开发人员
return new Result(ex.getCode(),null,ex.getMessage());
}
@ExceptionHandler(Exception.class)
public Result doException(Exception ex){
return new Result(SYSTEM_UNKNOW_ERR,null,ex.getMessage());
}
}