Spring API 开发简单示例及技巧-白红宇

目录.png

以用户登录为栗子，示例API请求时处理技巧，和API返回数据时如何处理。

一、API返回时：返回的json数据

使用spring mvc默认配置就可以返回json了，不过需要jackson的jar包

APIResponse是一个实体类，配合@ResponseBody就会自动转成Json

@RequestMapping("user")@Controllerpublic class UserController {    @Resource    private UserService userService;    @RequestMapping(value = "/login", method = RequestMethod.POST, headers = "api-version=1")    public @ResponseBody    APIResponse login(HttpServletRequest request) {        return userService.login(new APIRequest(request));    }    @RequestMapping(value = "/query", method = RequestMethod.GET, headers = "api-version=1")    public @ResponseBody    APIResponse query() {        return userService.allUsers();    }}

二、API请求时：提取和解析参数

springMVC后台控制层提取和解析请求参数的方式主要有两种

request.getParameter("name")；

通过注解@RequestParam直接获取；

1.注解方式：@ResponseBody

// 必传且参数名为`userName`@RequestParam String userName// 必传且指定参数为 user_name@RequestParam(value="user_name") String userName// 标识是否为必传，required=false 会给参数赋值为null@RequestParam(value="aa", required=true)

完整的如下：

@RequestMapping(method = RequestMethod.GET)public String setupForm(@RequestParam("user_name") String userName) {  APIResponse api = new APIResponse();  api.setUserName(userName);  ...   }

value用来指定要传入值的id名称

String userName, ModelMap model 是接受 value 传给的值

2.HttpServletRequest 方式

如果参较多的时候，注解方式可能显得比较臃肿，这时候也可以使用HttpServletRequest提取参数，request.getParameter("username")也比较简单。

这里着重Controller中接收的HttpServletRequest做进一步封装。

APIRequest对HttpServletRequest进一步封装，提供常用的属性包括请求的URL、请求参数等。如果提供的属性不能满足需求，还提供了原 HttpServletRequest 对象属性 request。

创建 API 请求的实体类

package com.lugq.web.tools.api;import javax.servlet.http.HttpServletRequest;import java.util.Enumeration;import java.util.HashMap;import java.util.Iterator;import java.util.Map;/** * API请求实体类 */public class APIRequest {    /**     * Raw Request, 单元测试时为null     */    private HttpServletRequest request;    /**     * 请求头     */    private Map
     
       header;    /**     * 请求参数     */    private Map
      
        params;    /**     * 客户端发出请求时的完整URL     */    private String url;    /**     * 请求行中的资源名部分     */    private String uri;    /**     * 请求行中的参数部分     */    private String queryString;    /**     * 请求方法     */    private String method;    /**     * 发出请求的客户机的IP地址     */    private String remoteAddr;    /**     * 发出请求的客户机的完整主机名     */    private String remoteHost;    /**     * 发出请求的客户机的网络端口号     */    private int remotePort;    /**     * WEB服务器的IP地址     */    private String localAddr;    /**     * WEB服务器的主机名     */    private String localName;    /**     * WEB服务器的网络端口号     */    private int localPort;    /**     * 编码格式     */    private String characterEncoding;    /**     * 上下文     */    private String contextPath;    public APIRequest() {        super();    }    public APIRequest(HttpServletRequest request) {        this.request = request;        header = new HashMap
       
        ();        Enumeration e = request.getHeaderNames();        while (e.hasMoreElements()) {            String name = (String) e.nextElement();            Object value = request.getHeader(name);            header.put(name, value);        }        params = getParamesMap(request.getParameterMap());        url = request.getRequestURL().toString();        uri = request.getRequestURI();        remoteAddr = request.getRemoteAddr();        remoteHost = request.getRemoteHost();        remotePort = request.getRemotePort();        contextPath = request.getContextPath();        localAddr = request.getLocalAddr();        characterEncoding = request.getCharacterEncoding();        localName = request.getLocalName();        localPort = request.getLocalPort();        method = request.getMethod();        queryString = request.getQueryString();    }    private Map
        
          getParamesMap(Map properties) {        Map
         
           returnMap = new HashMap
          
           (); Iterator entries = properties.entrySet().iterator(); Map.Entry entry; String name; String value = ""; while (entries.hasNext()) { entry = (Map.Entry) entries.next(); name = (String) entry.getKey(); Object valueObj = entry.getValue(); if (null == valueObj) { value = ""; } else if (valueObj instanceof String[]) { String[] values = (String[]) valueObj; for (String v : values) { value = v + ","; } value = value.substring(0, value.length() - 1); } else { value = valueObj.toString(); } returnMap.put(name, value); } return returnMap; } public Object getParameter(String s) { return params.get(s); } public void setAttribute(String s, Object o) { if (params == null) params = new HashMap
           
            (); params.put(s, o.toString()); } // 省略 get set method. 自行补充 ......}

在控制层controller中实现栗子：

@RequestMapping("user")@Controllerpublic class UserController {    @Resource    private UserService userService;    @RequestMapping(value = "/login", method = RequestMethod.POST, headers = "api-version=1")    public @ResponseBody    APIResponse login(HttpServletRequest request) {        // 将HttpServletRequest实例赋值到APIRequest对其进一步封装        return userService.login(new APIRequest(request));    }}

Service 层的逻辑处理如下

@Servicepublic class UserServiceImpl implements UserService {    @Resource    private UserMapper mapper;    public APIResponse login(APIRequest request) {        // 获取请求参数        String username = (String) request.getParameter("username");        String password = (String) request.getParameter("password");        // 处理业务逻辑        User user = mapper.selectUserByUsername(username);        APIStatus status = API_SUCCESS;        if (user == null) {            status = API_USER_NOT_EXIST;        } else {            if (!MD5Util.md5(password).equals(user.getPassword()))                status = API_USER_PASSWORD_ERROR;        }        // 返回APIResponse对象，配合@ResponseBody转为Json        return APIUtil.getResponse(status, user);    }    public APIResponse allUsers() {        List
     
       users = mapper.selectAllUser();        return APIUtil.getResponse(API_SUCCESS, users);    }}