Spring Boot搭建Web项目常用功能
搭建WEB项目过程中，哪些点需要注意：
1、技术选型：
前端：freemarker、vue
后端：spring boot、spring mvc
2、如何包装返回统一结构结果数据？
首先要弄清楚为什么要包装统一结构结果数据，这是因为当任意的ajax请求超时或者越权操作时，系统能返回统一的错误信息给到前端，前端通过封装统一的ajax请求统一处理这类错误信息（这样统一就避免每次都需要额外处理）。
那如何包装结构呢？
先封装统一返回结果结构对象 JsonMessage：
public class JsonMessage extends HashMap<String, Object> {
private static final long serialVersionUID = -7149712196874923440L;
public JsonMessage() {
this.put("status", 200);
}
public JsonMessage(boolean status) {
putStatus(status);
}
public JsonMessage(String msg) {
this.put("status", 200);
this.put("msg", msg);
}
public JsonMessage(boolean status, String msg) {
this.put("msg", msg);
putStatus(status);
}
public JsonMessage(String key,Object object) {
this.put("status", 200);
this.put(key, object);
}
public JsonMessage(boolean status, String msg, String key, Object value) {
this.put("msg", msg);
putStatus(status);
this.put(key, value);
}
public JsonMessage putStatusAndMsg(int code, String msg) {
this.put("status", code);
this.put("msg", msg);
return this;
}
public JsonMessage putStatusAndMsg(boolean status, String msg) {
putStatus(status);
this.put("msg", msg);
return this;
}
public JsonMessage putStatus(int code) {
this.put("status", code);
return this;
}
public JsonMessage putStatus(boolean status) {
if(status){
this.put("status", 200);
}else{
this.put("status", 500);
}
return this;
}
public JsonMessage putRedirectUrl(String redirectUrl) {
this.put("url", redirectUrl);
this.put("status", 501);
return this;
}
public JsonMessage putMsg(String msg) {
this.put("msg", msg);
return this;
}
public JsonMessage put(String arg0, Object arg1) {
super.put(arg0, arg1);
return this;
}
}如何处理包装结果给前端呢？
方法一：所有的controller里ajax请求都返回JsonMessage对象；
方法二：通过 ResponseBodyAdvice 处理；
方法三：通过 HandlerMethodReturnValueHandler 拦截@ResponseBody注解或自定义注解 处理（不太懂的童鞋请百度）；
3、如果统一处理异常？
继承 HandlerExceptionResolver 接口即可处理所有异常了，所以这也得分是否ajax请求。然后按不同请求类型处理：
/**
* 统一异常处理，不论是正常跳转请求还是ajax请求都能处理，
*/
@Component
public class GlobalExceptionResolver implements HandlerExceptionResolver {
private static Logger logger = LoggerFactory.getLogger(GlobalExceptionResolver.class);
@Override
public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception e) {
if (handler instanceof HandlerMethod) {
HandlerMethod handlerMethod = (HandlerMethod) handler;
String referer = request.getHeader("Referer");
String exceptionMsg = "系统异常，请稍后操作";
String userId = null;
String userName = null;
Object object = request.getSession().getAttribute(Constant.SESSION_USER);
if (object != null) {
LoginUser user = (LoginUser) object;
userName = user.userName();
userId = user.getUserId();
}
if (e instanceof BusinessException) {
logger.warn(StringUtil.format("业务异常,当前请求URL:{} 操作用户编号：{} {} \n访问来源：{} \n参数：{}", request.getRequestURL(), userId,
userName, referer, JsonUtils.beanToJson(request.getParameterMap())), e);
BusinessException exception = (BusinessException) e;
exceptionMsg = exception.getMessage();
} else {
logger.error(StringUtil.format("系统异常,当前请求URL:{} 操作用户编号：{} {} \n访问来源：{} \n参数：{}", request.getRequestURL(), userId,
userName, referer, JsonUtils.beanToJson(request.getParameterMap())), e);
}
if (AnnotationHandleUtils.isAjaxAnnotation(handlerMethod)) {
JsonMessage jmsg = new JsonMessage(false, exceptionMsg);
try {
WebHelper.write(response, jmsg.toString(), HttpStatus.OK.value());
} catch (IOException e1) {
logger.error("发送数据异常", e1);
}
return new ModelAndView();
}
ModelAndView modelView = new ModelAndView("common/500"); //跳转到500错误页面
return modelView.addObject(Constant.ERROR_MES_KEY, exceptionMsg);
}
return null;
}
}配置servlet 404、500异常跳转地址：
@Bean
public EmbeddedServletContainerCustomizer containerCustomizer() {
return new EmbeddedServletContainerCustomizer() {
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
ErrorPage error404Page = new ErrorPage(HttpStatus.NOT_FOUND, "/common/404.html");
ErrorPage error500Page = new ErrorPage(HttpStatus.INTERNAL_SERVER_ERROR,
"/common/500.html");
ErrorPage errorpage = new ErrorPage("/common/500.html");
container.addErrorPages(error404Page, error500Page,errorpage);
}
};
}
4、如果优雅的处理按钮级别权限？
因为前端采用的是Vue，清楚vue的知道它的表现就是通过model控制view的，所以前端就是在页面渲染 mounted 的时候用ajax去请求，通过返回的字段信息判断是否要显示某按钮或者链接或者视图块。
那后端要如何才能做到验证权限呢？
采用 HandlerMethodReturnValueHandler 拦截所有需要返回权限信息的ajax请求，再根据 methodParameter能获取到method对象，然后就能获取到method上的权限注解信息了再统一调用鉴权服务，再把结果包装到JsonMessage对象返回就可以了。
5、如何配置消息装换器？
首先要弄清楚为什么需要配，因为我们需要按项目要求来下自定义Jackson转换json规范，比如：date类型默认情况是转成时间戳，那这对于前端就需要再装换才可以。再比如null值的对象是否要在json中输出默认是会输出，那我们也可以改成不输出。当然还有其他的就不举例了。
/**
* 通过继承 WebMvcConfigurerAdapter 来配置spring mvc
*
*/
@Configuration
public class ApplicationConfiguration extends WebMvcConfigurerAdapter{
@Autowired
private LoginInterceptor loginInterceptor;
@Autowired
private PermissionInterceptor permissionInterceptor;
@Autowired
private ResponseBodyResolver responseBodyResolver;
/**
* 可以注入spring mvc提供的 RequestMappingHandlerAdapter bean
*/
@Autowired
private RequestMappingHandlerAdapter requestMappingHandlerAdapter;
@Autowired
private DateConverter dateConverter;
/**
* 添加interceptors
*/
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(loginInterceptor);
registry.addInterceptor(permissionInterceptor);
super.addInterceptors(registry);
}
/**
* 配置消息转换器
*/
@Override
public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.add(new ByteArrayHttpMessageConverter());
converters.add(mappingJackson2HttpMessageConverter()); //配置jackson2
super.configureMessageConverters(converters);
}
public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter(){
MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
mappingJackson2HttpMessageConverter.setSupportedMediaTypes(
Lists.newArrayList(MediaType.TEXT_PLAIN,MediaType.APPLICATION_JSON_UTF8));
ObjectMapper objectMapper= new ObjectMapper();
//属性命名规则，这个一般不需要配
objectMapper.setPropertyNamingStrategy(new LowerCasePropertyNamingStrategy());
objectMapper.configure(MapperFeature.ALLOW_EXPLICIT_PROPERTY_RENAMING, true);
objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
//默认date属性格式，可以其它的
objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
return mappingJackson2HttpMessageConverter;
}
@Override
public void addReturnValueHandlers(List<HandlerMethodReturnValueHandler> returnValueHandlers) {
returnValueHandlers.add(responseBodyResolver);
super.addReturnValueHandlers(returnValueHandlers);
}
/**
* 配置属性编辑器，主要是当前端form提交字符串时转成date类型
*/
@PostConstruct
public void webBindingInitializer(){
requestMappingHandlerAdapter.setWebBindingInitializer(dateConverter);
}
}
@Component
public class DateConverter implements WebBindingInitializer{
@Override
public void initBinder(WebDataBinder binder, WebRequest request) {
binder.setAutoGrowCollectionLimit(Integer.MAX_VALUE);
// CustomDateEditor只要继承PropertyEditorSupport
CustomDateEditor dateEditor = new CustomDateEditor(CustomDateEditor.TIMEFORMAT, true);
//注册自定义的属性编辑器 表示如果命令对象有Date类型的属性，将使用该属性编辑器进行类型转换
binder.registerCustomEditor(Date.class, dateEditor);
}
}
6、项目示例：
6.1 项目依赖 pom.xml：
<?xml version="1.0"?>
<project
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.2.RELEASE</version>
<relativePath />
</parent>
<artifactId>web-demo</artifactId>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>
<!-- spring-boot -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>${mybatis.spring.boot.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- <dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>-->
</dependencies>
</project>
application.properties：
logging.config=classpath:conf/xml/logback.xml
#freemarker config info
spring.freemarker.templateEncoding=UTF-8
spring.freemarker.cache=false
spring.freemarker.charset=UTF-8
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=false
spring.freemarker.expose-session-attributes=false
spring.freemarker.request-context-attribute=rc
spring.freemarker.templateLoaderPath=classpath:/templates/pages
#这没加后缀是因为在代码里手动标名后缀
spring.freemarker.suffix=
spring.freemarker.view-names=*.html
#server config
server.session.timeout=1800
server.contextPath=/demo
server.port=8080
#server.compression.enabled=true
#server.compression.min-response-size=1024
#server.tomcat.max-threads=500
#resource config
spring.resources.chain.cache=false
spring.resources.static-locations=classpath:/static/
#spring.resources.cache-period=60
#cache config
spring.cache.type=guava
#缓存最大数量1000条, 缓存失效时间5分钟
spring.cache.guava.spec=maximumSize=1000,expireAfterAccess=10m
spring.http.multipart.max-file-size=5Mb
spring.http.multipart.max-request-size=5Mb
spring.http.multipart.enabled=true6.2 启动类：
@PropertySource(value={"classpath:conf/env/datasource.properties",
"classpath:conf/env/message.properties",
"classpath:conf/env/config.properties"})
@SpringBootApplication
@EnableTransactionManagement
@EnableAutoConfiguration(exclude=RabbitAutoConfiguration.class)
@EnableCaching
@MapperScan("com.test.demo.persistence")
@ComponentScan(value={"com.test.demo"})
//导入spring xml文件
//@ImportResource(locations = { "classpath*:/spring.xml" })
public class WebDemoApplication {
private final static Logger logger = LogManager.getLogger(WebDemoApplication.class);
public static void main(String[] args) {
System.setProperty("spring.config.location", "classpath:conf/env/application.properties");
SpringApplication.run(WebDemoApplication .class, args);
logger.info("start completed ！");
}
@Bean
public EmbeddedServletContainerCustomizer containerCustomizer() {
return new embeddedServletContainerCustomizer() {
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
ErrorPage error404Page = new ErrorPage(HttpStatus.NOT_FOUND, "/common/404.html");
ErrorPage error500Page = new ErrorPage(HttpStatus.INTERNAL_SERVER_ERROR, "/common/500.html");
ErrorPage errorpage = new ErrorPage("/common/500.html");
container.addErrorPages(error404Page, error500Page,errorpage);
}
};
}
}
