springboot restTemplate 自定义消息转换器

爱被打了一巴掌 2023-02-21 09:31 14阅读 0赞

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### springboot restTemplate 自定义消息转换器 ###

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**相关类与接口**

**HttpMessageConverter**

public interface HttpMessageConverter<T> {
        boolean canRead(Class<?> var1, @Nullable MediaType var2);
    
        boolean canWrite(Class<?> var1, @Nullable MediaType var2);
    
        List<MediaType> getSupportedMediaTypes();
    
        T read(Class<? extends T> var1, HttpInputMessage var2) throws IOException, HttpMessageNotReadableException;
    
        void write(T var1, @Nullable MediaType var2, HttpOutputMessage var3) throws IOException, HttpMessageNotWritableException;
    }

**AbstractHttpMessageConverter**

public abstract class AbstractHttpMessageConverter<T> implements HttpMessageConverter<T> {
        protected final Log logger = HttpLogging.forLogName(this.getClass());
        private List<MediaType> supportedMediaTypes = Collections.emptyList();
        @Nullable
        private Charset defaultCharset;
    
    
    ***********
    构造方法
    
        protected AbstractHttpMessageConverter() {
        }
    
        protected AbstractHttpMessageConverter(MediaType supportedMediaType) {
            this.setSupportedMediaTypes(Collections.singletonList(supportedMediaType));
        }
    
        protected AbstractHttpMessageConverter(MediaType... supportedMediaTypes) {
            this.setSupportedMediaTypes(Arrays.asList(supportedMediaTypes));
        }
    
        protected AbstractHttpMessageConverter(Charset defaultCharset, MediaType... supportedMediaTypes) {
            this.defaultCharset = defaultCharset;
            this.setSupportedMediaTypes(Arrays.asList(supportedMediaTypes));
        }
    
    
    
    ***********
    普通方法
    
        public void setSupportedMediaTypes(List<MediaType> supportedMediaTypes) {
        public List<MediaType> getSupportedMediaTypes() {
    
        public void setDefaultCharset(@Nullable Charset defaultCharset) {
        public Charset getDefaultCharset() {
    
        public boolean canRead(Class<?> clazz, @Nullable MediaType mediaType) {
        protected boolean canRead(@Nullable MediaType mediaType) {
    
        public final T read(Class<? extends T> clazz, HttpInputMessage inputMessage) throws IOException, HttpMessageNotReadableException {
    
    
        public boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType) {
        protected boolean canWrite(@Nullable MediaType mediaType) {
    
        public final void write(T t, @Nullable MediaType contentType, HttpOutputMessage outputMessage) throws IOException, HttpMessageNotWritableException {
    
    
        protected void addDefaultHeaders(HttpHeaders headers, T t, @Nullable MediaType contentType) throws IOException {
    
        protected MediaType getDefaultContentType(T t) throws IOException {
        protected Long getContentLength(T t, @Nullable MediaType contentType) throws IOException {
    
    
        protected abstract boolean supports(Class<?> var1);
        protected abstract T readInternal(Class<? extends T> var1, HttpInputMessage var2) throws IOException, HttpMessageNotReadableException;
        protected abstract void writeInternal(T var1, HttpOutputMessage var2) throws IOException, HttpMessageNotWritableException;

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**示例**

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**config 层**

**CustomHttpMessageConverter：使用fastjson序列化、反序列化对象**

@Component
    public class CustomHttpMessageConverter extends AbstractHttpMessageConverter<Object> {
    
        public CustomHttpMessageConverter(){
            super(StandardCharsets.UTF_8,MediaType.ALL);
        }
    
        @Override
        protected boolean supports(Class<?> aClass) {
            return true;
        }
    
        @Override
        protected Object readInternal(Class<?> aClass, HttpInputMessage httpInputMessage) throws IOException, HttpMessageNotReadableException {
            return JSONObject.parseObject(StreamUtils.copyToString(httpInputMessage.getBody(), StandardCharsets.UTF_8),aClass);
        }
    
        @Override
        protected void writeInternal(Object o, HttpOutputMessage httpOutputMessage) throws IOException, HttpMessageNotWritableException {
            httpOutputMessage.getBody().write(JSONObject.toJSONBytes(o));
        }
    }

**WebConfig**

@Configuration
    public class WebConfig {
    
        @Resource
        private CustomHttpMessageConverter customHttpMessageConverter;
    
        @Bean
        public RestTemplate initRestTemplate(){
            RestTemplate restTemplate= new RestTemplate();
            restTemplate.getMessageConverters().set(5,customHttpMessageConverter);
                                                //使用自定义的消息转换器替换MappingJackson2HttpMessageConverter
    
            return restTemplate;
        }
    }

**restTemplate默认的消息转换器：restTemplate.getMessageConverters()**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70][]

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**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @RequestMapping("/hello")
        public Map<String,String> hello(){
            Map<String,String> params=new HashMap<>();
            params.put("name","瓜田李下");
            params.put("age","20");
    
            return params;
        }
    }

**Hello2Controller**

@RestController
    public class Hello2Controller {
    
        @Resource
        private RestTemplate restTemplate;
    
        @RequestMapping("/test")
        public Person test(){
            return restTemplate.getForObject("http://localhost:8080/hello",Person.class);
        }
    }

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**使用测试**

**localhost:8080/test**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70 1][]

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