Springboot from getting started to getting started (2) getting request parameters

origin：https://www.cnblogs.com/xiaoxi/p/5695783.html

1.Controller Method parameter receiving parameter

 @RequestMapping("/index1")
public String index1(String name, String age){
return name + age;
}

2. Use HttpServletRequest Receiving parameters

 @RequestMapping("/index2")
public String index2(HttpServletRequest request){
String name = request.getParameter("name");
String age = request.getParameter("age");
return name + age;
}

3. Use bean Receiving parameters

Create a corresponding to the request parameter bean

 public class UserModel {
private String name;
private String age;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
}

Use bean Receiving parameters

@RequestMapping("/index3")
public UserModel index3(UserModel userModel){
String name = userModel.getName();
String age = userModel.getAge();
return userModel;
}

4. Use PathVariable Receiving parameters , Parameters in the receive path 

 @RequestMapping(value="/index4/{name}/{age}")
public String index4(@PathVariable String name,@PathVariable String age){
return name+age;
}

5. Use RequestParam Receiving parameters , Similar to the first way , If parameters are missing , There will be abnormal

You can use @RequestParam(required = false) Avoid exceptions

Missing parameters will cause exceptions , The lack of name or age All parameters have exceptions

 @RequestMapping(value="/index5")
public String index5(@RequestParam String name,@RequestParam String age){
return name+age;
}

The lack of name There will be no exception in the parameter , The lack of age There will be exceptions to the parameter

 @RequestMapping(value="/index5")
public String index5(@RequestParam(value = "name",required = false) String name,@RequestParam String age){
return name+age;
}