springmvc 参数绑定

@RequestParam 绑定单个请求

RequestMapping(value = "/form2")
    @ResponseBody
    public String form2(@RequestParam String name){
        logger.info("name=" + name );
        return "";
    }

@RequestParam 有required(是否必填),defaultValue(默认参数)参数
默认required=true,defaultValue为空
如果name参数不存在则返回400

使用下面这种写法则required默认为false

 @RequestMapping(value = "/form")
    @ResponseBody
    public String form(String name, Integer age) {
        logger.info("name=" + name + "," + "age=" + age);
        return "";
    }

@RequestParam还支持数组形式

@RequestMapping(value = "/names")
    @ResponseBody
    public String names(@RequestParam String[] name) {
        logger.info("name=" + Arrays.asList(name));
        return Arrays.asList(name).toString();
    }

对应请求/names.do?name=张三,李四
或者/names.do?name=张三&name=李四

@PathVariable 绑定uri变量值

@RequestMapping("/user/{id}")
    @ResponseBody
    public String getUser(@PathVariable Long id) {
        return String.valueOf(id);
    }

请求/user/1返回id为1

@CookieValue 绑定cookie的值

 @RequestMapping("/getCookie")
    @ResponseBody
    public String getCookie(@CookieValue("JSESSIONID") String sessionId) {
        return sessionId;
    }

@ModelAttribute绑定参数到命令对象

绑定请求参数到对象

先定义两个对象
Role

public class Role implements Serializable {

    private String id;
}

User

public class User implements Serializable {

    private String id;

    private Role role;
}

 @RequestMapping("/getUserByModel")
    @ResponseBody
    public String getUserByModel(@ModelAttribute("user") User user) {
        logger.info(user.toString());
        return "";
    }

对应请求/getUserByModel.do?id=123&role.id=1

暴露表单引用对象为模型数据

 @ModelAttribute("user")
    public User getUser(String userId) {
        User user = new User();
        user.setId("11");
        Role role=new Role();
        role.setId("123");
        user.setRole(role);
        return user;
    }
    
     @RequestMapping("/getUserModel")
    @ResponseBody
    public String getUserModel(@ModelAttribute User user) {
        return user.toString();
    }

请求/getUserModel?id=1
返回 User{id='1', role=Role{id='123'}}
使用@ModelAttribute注释的方法会在所有Controller方法前运行
因为先运行了@ModelAttribute注解的方法,生成了一个user对象,之后user对象的id属性被修改为1

@SessionAttributes绑定命令对象到session

springmvc提供了@SessionAttributes用来对会话数据的存取
添加session

 @RequestMapping("/setSession")
    @ResponseBody
    public String setSession(
            HttpSession session) {
        City city = new City();
        city.setCityName("shanghai");
        session.setAttribute("city", city);
        return city.toString();
    }

获取session数据

//在类头部添加需要的session属性
@Controller
@SessionAttributes(value = {"city"})
public class TestController {
 @RequestMapping("/getSession")
    @ResponseBody
    public String getSession(@ModelAttribute City city) {
        return city.toString();
    }
}

清除本次会话session

 @RequestMapping("/clearSession")
    @ResponseBody
    public String clearSession(SessionStatus status) {
        status.setComplete();
        return "success";
    }

@RequestBody绑定请求的内容区数据并能进行自动类型转换等

使用RequestBody可以将json转化为对象

 @RequestMapping("/getUserByJson")
    @ResponseBody
    public String getUserByJson(@RequestBody User user){
        return user.toString();
    }

发送json格式报文

{
    "id":"123"
}

返回结果User{id='123', role=null}

@RequestPart绑定“multipart/data”数据

 @RequestMapping("/getFile")
    @ResponseBody
    public String getFile(@RequestPart("image") MultipartFile file){
        System.out.println(file.getName()+","+file.getSize());
        return "success";
    }

源码地址:https://github.com/lialzmChina/javaeeLearn.git

拓展阅读
springmvc 参数绑定源码分析
springmvc 自定义参数转换器