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• 《SpringBoot接口服务处理Whitelabel Error Page》
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• 《Java Webproject转换为基于Maven的Webproject》
• 《Maven Webproject执行异常:Maven.multiModuleProjectDirectory system propery is not set的问题》
• 《Maven执行异常:Exception in thread “main” java.lang.UnsupportedClassVersionError》

1.0 异常说明

SpringBoot搭建的接口服务。假设请求非注冊类的无效接口地址，则返回该页面。主要问题就是没有对异常请求做处理。

举例，定义有效接口地址如：http://ip/user, http://ip/age。则其他地址均为无效地址，若请求则返回上述Whitelabel Error Page页面。

2.0 异常处理

主要是加入一个AppErrorController的Controller类，这里我定义了异常返回页面。

package com.autonavi.controller;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.web.ErrorAttributes;
import org.springframework.boot.autoconfigure.web.ErrorController;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.servlet.ModelAndView;


/**
 * <p>Author: loongshawn
 * <p>Date: 16-03-17
 * <p>Version: 1.0
 */
@Controller
public class AppErrorController implements ErrorController{

    private static final Logger logger = LoggerFactory.getLogger(AppErrorController.class);

    private static AppErrorController appErrorController;

     /**
     * Error Attributes in the Application
     */
    @Autowired
    private ErrorAttributes errorAttributes;

    private final static String ERROR_PATH = "/error";

    /**
     * Controller for the Error Controller
     * @param errorAttributes
     * @return 
     */ 

    public AppErrorController(ErrorAttributes errorAttributes) {
        this.errorAttributes = errorAttributes;
    }

    public AppErrorController() {
        if(appErrorController == null){
            appErrorController = new AppErrorController(errorAttributes);
        }
    }

    /**
     * Supports the HTML Error View
     * @param request
     * @return
     */
    @RequestMapping(value = ERROR_PATH, produces = "text/html")
    public ModelAndView errorHtml(HttpServletRequest request) {
        return new ModelAndView("greeting", getErrorAttributes(request, false));
    }

    /**
     * Supports other formats like JSON, XML
     * @param request
     * @return
     */
    @RequestMapping(value = ERROR_PATH)
    @ResponseBody
    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
        Map<String, Object> body = getErrorAttributes(request, getTraceParameter(request));
        HttpStatus status = getStatus(request);
        return new ResponseEntity<Map<String, Object>>(body, status);
    }

    /**
     * Returns the path of the error page.
     *
     * @return the error path
     */
    @Override
    public String getErrorPath() {
        return ERROR_PATH;
    }


    private boolean getTraceParameter(HttpServletRequest request) {
        String parameter = request.getParameter("trace");
        if (parameter == null) {
            return false;
        }
        return !"false".equals(parameter.toLowerCase());
    }

    private Map<String, Object> getErrorAttributes(HttpServletRequest request,
                                                   boolean includeStackTrace) {     
        RequestAttributes requestAttributes = new ServletRequestAttributes(request);       
        Map<String, Object> map = this.errorAttributes.getErrorAttributes(requestAttributes,includeStackTrace);  
        String URL = request.getRequestURL().toString();
        map.put("URL", URL);        
        logger.debug("AppErrorController.method [error info]: status-" + map.get("status") +", request url-" + URL);            
        return map;
    }

    private HttpStatus getStatus(HttpServletRequest request) {
        Integer statusCode = (Integer) request
                .getAttribute("javax.servlet.error.status_code");
        if (statusCode != null) {
            try {
                return HttpStatus.valueOf(statusCode);
            }
            catch (Exception ex) {
            }
        }
        return HttpStatus.INTERNAL_SERVER_ERROR;
    }   

}

这个类实现了ErrorController接口，用来处理请求的各种异常。当中定义了一个greeting的html模版，用来显示返回结果。初始化此类模版须要在pom中加入下面依赖：

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>

这个依赖主要是给SpringBoot中载入html等类型的模版服务。其支持的模版类型例如以下：

 Template modes:
[THYMELEAF]     * XHTML
[THYMELEAF]     * XML
[THYMELEAF]     * HTML5
[THYMELEAF]     * LEGACYHTML5
[THYMELEAF]     * VALIDXHTML
[THYMELEAF]     * VALIDXML

SpringBoot项目配置模版路径的方法例如以下：

1、在main的resources路径下新建templates目录

2、在templates目录中新建模版文件greeting.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Error Pages</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
    <p th:text="‘Url:‘ + ${URL}" />
    <p th:text="‘Error:‘ + ${error}" />
    <p th:text="‘Status:‘ + ${status}" />
    <p th:text="‘Timestamp:‘ + ${timestamp}" />
</body>
</html>

3.0 处理结果

无效请求地址均会返回此页面，仅仅是当中的返回值不同。