当我使用角度发布数据时，我在弹簧控制器中得到空值

Question

我使用 Angularjs 将数据发布到 spring 控制器。

像这样。

var user ={
    "userID" : "1",
    "username" : "hello",
    "password" : "123456"
};
console.log(user);
var response = $http.post("/login/signup",user);
response.success(function (data) {
    alert("success");
    alert(data);
});
response.error(function (data) {
    alert("error");
    alert(data);
});

我的模型

public class User {
    private long userID;
    private String username;
    private String password;

    public User(){

    }

    public User(long userID, String username, String password) {
        this.userID = userID;
        this.username = username;
        this.password = password;
    }


    public long getUserID() {
        return userID;
    }

    public void setUserID(long userID) {
        this.userID = userID;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

还有我的控制器。

@Controller
@RequestMapping(value = "/login")
public class LoginController {

    @RequestMapping(value = "/signup",method = RequestMethod.POST)
    public String signUp(User user){
        String username = user.getUsername();// NULL!!
        System.out.println(username);
        return "login";
    }

}

我得到这样的空用户。

如果我将@RequestBody 添加到我的控制器。我什至无法进入控制器并获得异常。

@RequestMapping(value = "/signup",method = RequestMethod.POST,produces = {MediaType.APPLICATION_JSON_VALUE})
    public String signUp(@RequestBody User user){
        String username = user.getUsername();
        System.out.println(username);
        return "login";
    }

异常

The server refused this request because the request entity is in a format not supported by the requested resource for the requested method.

Answer 1

当您将数据发布到服务器时，您可能需要在请求标头中设置Content-Type: application/json。

同时使用：

@RequestMapping(value = "/signup",method = RequestMethod.POST,consumes = MediaType.APPLICATION_JSON_VALUE)

安装于：

@RequestMapping(value = "/signup",method = RequestMethod.POST,produces = {MediaType.APPLICATION_JSON_VALUE})

编辑

有时（我不确定何时），MappingJackson2HttpMessageConverter 没有注册到负责将请求参数转换为模型 bean 的 spring 上下文。如果未注册，手动注册可能会解决问题。

Answer 2

首先在你的模型中你应该有

public class User {
    private long id;
    private String username;
    private String password;
...
}

而不是

public class User {
    private long userID;
    private String username;
    private String password;

...
}

因为你发布了这样的 json

 {
       "id" : "1",
       "username" : "hello",
       "password" : "123456"                        
}

而不是

{
       "userID" : "1",
       "username" : "hello",
       "password" : "123456"                        
}

那么在你的控制器中应该有

@Controller
@RequestMapping(value = "/login")
public class LoginController {

@RequestMapping(value = "/signup",method = RequestMethod.POST,consumes = {MediaType.APPLICATION_JSON_VALUE})
    public String signUp(@RequestBoby User user){
        String username = user.getUsername();
        System.out.println(username);
        return "login";
    }

}

请记住，在这种情况下，spring 并没有为您更改页面，我认为更好的选择是使用 @RestController 和 ResponseEntity 作为您的方法的结果，以便对响应进行细粒度控制，如下所示。

@RestController
@RequestMapping(value = "/login")
public class LoginController {

@RequestMapping(value = "/signup",method = RequestMethod.POST,consumes = {MediaType.APPLICATION_JSON_VALUE})
    public ResponseEntity signUp(@RequestBoby User user){
        String username = user.getUsername();
        System.out.println(username);
    return ResponseEntity.ok().build();
    }

}

希望对你有帮助

Answer 3

我终于通过添加MappingJackson2HttpMessageConverter bean来解决这个问题。

首先在pom.xml中添加依赖

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.7.3</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.7.3</version>
        </dependency>

其次，在您的配置中添加 Bean 定义。

    @Bean
    public MappingJackson2HttpMessageConverter jsonConverter() {
        MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        jsonConverter.setObjectMapper(objectMapper);
        return jsonConverter;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(jsonConverter());
        super.configureMessageConverters(converters);
    }

    @Override
    public void configureContentNegotiation(ContentNegotiationConfigurer configurer) {
        configurer.defaultContentType(MediaType.APPLICATION_JSON);
    }