Spring MVC控制器：如何优雅地返回HTTP响应

无界猴

42天前更新

056871

在Spring MVC中，返回HTTP响应通常涉及控制器（Controller）的方法返回特定的视图名称或直接写入HTTP响应。以下是一些常见的实现方式：

1. 返回视图名称

最常见的方式是控制器方法返回一个字符串，该字符串表示视图的名称。Spring MVC会解析这个字符串并渲染相应的视图。


@Controller
public class MyController {
    @RequestMapping("/hello")
    public String sayHello(Model model) {
        model.addAttribute("message", "Hello, World!");
        return "hello"; // 返回视图名称，例如 hello.jsp 或 hello.html
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public String sayHello(Model model) {
        model.addAttribute("message", "Hello, World!");
        return "hello"; // 返回视图名称，例如 hello.jsp 或 hello.html
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public String sayHello(Model model) {
        model.addAttribute("message", "Hello, World!");
        return "hello"; // 返回视图名称，例如 hello.jsp 或 hello.html
    }
}

在这个例子中，Spring MVC会查找名为 hello 的视图模板（例如 hello.jsp 或 hello.html），并将模型数据传递给视图进行渲染。

2. 返回`ModelAndView`对象

ModelAndView对象封装了视图名称和模型数据，可以直接返回。


@Controller
public class MyController {
    @RequestMapping("/hello")
    public ModelAndView sayHello() {
        ModelAndView modelAndView = new ModelAndView("hello");
        modelAndView.addObject("message", "Hello, World!");
        return modelAndView;
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public ModelAndView sayHello() {
        ModelAndView modelAndView = new ModelAndView("hello");
        modelAndView.addObject("message", "Hello, World!");
        return modelAndView;
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public ModelAndView sayHello() {
        ModelAndView modelAndView = new ModelAndView("hello");
        modelAndView.addObject("message", "Hello, World!");
        return modelAndView;
    }
}

3. 返回`ResponseEntity`对象

ResponseEntity对象允许你完全控制HTTP响应，包括状态码、头部信息和响应体。


@Controller
public class MyController {
    @RequestMapping("/hello")
    public ResponseEntity<String> sayHello() {
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "text/plain");
        String responseBody = "Hello, World!";
        return new ResponseEntity<>(responseBody, headers, HttpStatus.OK);
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public ResponseEntity<String> sayHello() {
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "text/plain");
        String responseBody = "Hello, World!";
        return new ResponseEntity<>(responseBody, headers, HttpStatus.OK);
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public ResponseEntity<String> sayHello() {
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "text/plain");
        String responseBody = "Hello, World!";
        return new ResponseEntity<>(responseBody, headers, HttpStatus.OK);
    }
}

在这个例子中，返回的是一个纯文本响应，HTTP状态码为200（OK）。

4. 使用`@ResponseBody`注解

@ResponseBody注解告诉Spring MVC将方法的返回值作为响应体直接写入HTTP响应。


@Controller
public class MyController {
    @RequestMapping(value = "/hello", produces = MediaType.APPLICATION_JSON_VALUE)
    @ResponseBody
    public Map<String, String> sayHello() {
        Map<String, String> response = new HashMap<>();
        response.put("message", "Hello, World!");
        return response;
    }
}
@Controller
public class MyController {

    @RequestMapping(value = "/hello", produces = MediaType.APPLICATION_JSON_VALUE)
    @ResponseBody
    public Map<String, String> sayHello() {
        Map<String, String> response = new HashMap<>();
        response.put("message", "Hello, World!");
        return response;
    }
}
@Controller
public class MyController {

    @RequestMapping(value = "/hello", produces = MediaType.APPLICATION_JSON_VALUE)
    @ResponseBody
    public Map<String, String> sayHello() {
        Map<String, String> response = new HashMap<>();
        response.put("message", "Hello, World!");
        return response;
    }
}

在这个例子中，返回的是一个JSON格式的响应体。注意这里使用了produces = MediaType.APPLICATION_JSON_VALUE来指定响应的内容类型为JSON。

5. 使用`HttpServletResponse`对象

你也可以直接在控制器方法中访问HttpServletResponse对象，并手动写入响应。


@Controller
public class MyController {
    @RequestMapping("/hello")
    public void sayHello(HttpServletResponse response) throws IOException {
        response.setContentType("text/plain");
        response.getWriter().write("Hello, World!");
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public void sayHello(HttpServletResponse response) throws IOException {
        response.setContentType("text/plain");
        response.getWriter().write("Hello, World!");
    }
}
@Controller
public class MyController {

    @RequestMapping("/hello")
    public void sayHello(HttpServletResponse response) throws IOException {
        response.setContentType("text/plain");
        response.getWriter().write("Hello, World!");
    }
}