SpringBoot___自定義消息轉換器、MVC配置

1. 自動配置的消息轉換器 
 在SptingBoot的源碼中的spring-boot-autoconfig的Jar包下，咱們能夠找到org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration.class文件，這個類就是自動配置消息轉換器：

@Configuration
@ConditionalOnClass(HttpMessageConverter.class)
@AutoConfigureAfter({GsonAutoConfiguration.class,
                          JacksonAutoConfiguration.class})
@Improt({JacksonHttpMessageConvertersConfiguration.class, 
            GsonHttpMessageConvertersConfiguration.class})
public class HttpMessageConverterAutoConfiguration{
    static final String PREFERRED_MAPPER_PROPERTY = 
            "spring.http.converters.preferred-json-mapper";
    private final List<HttpMessageConverter<?>> converters;
}
1
2
3
4
5
6
7
8
9
10
11
 在這個類中定義了一個String類的轉換器，其源碼以下：

@Configuration
@ConditionalOnClass(StringHttpMessageConverter.class)
@EnableConfigurationProperties(HttpEncodingProperties.class)
protected static class StringHttpMessageConverterConfiguration{
    private final HttpEncodingProperties encodingProperties;

    protected StringHttpMessageConverterConfiguration(
                        HttpEncodingProperties encodingProperties){
        this.encodingProperties = encodingProperties;
    }

    @Bean
    @ConfigurationOnMissingBean
    public StringHttpMessageConverter StringHttpMessageConverter(){
        StringHttpMessageConverter converter = new StringHttpMessageConverter(
                    this.encodingProperties.getCharset());
        converter.setWriterAccpetCharset(false);
        return converter;
    }
}


 注意：在默認的消息轉換器中，使用的編碼爲UTF-8。

2. 自定義消息轉換器 
 自定義消息換換器，咱們只須要在配置類@Configuration的類中添加消息轉換器的@Bean加入spring容器，就會被SpringBoot自動加入到容器中。 
例如：

@Bean
public StringHttpMessageConverter stringHttpMessageConverter(){
    StringHttpMessageConverter converter = new StringHttpMessageConverter(
                Charset.forName("UTF-8"));
    return converter;
}






3.自定義 MVC配置 
 有些時候咱們須要自已配置SpringMVC而不是採用默認，好比說增長一個攔截器，這個時候就得經過繼承WebMvcConfigurerAdapter而後重寫父類中的方法進行擴展。 
 其代碼以下：

import java.nio.charset.Charset;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration //申明這是一個配置
public class MySrpingMVCConfig extends WebMvcConfigurerAdapter{

    // 自定義攔截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        HandlerInterceptor handlerInterceptor = new HandlerInterceptor() {
            @Override
            public boolean preHandle(HttpServletRequest request, 
                           HttpServletResponse response, Object handler)
                           throws Exception {
                System.out.println("自定義攔截器............");
                return true;
            }

            @Override
            public void postHandle(HttpServletRequest request, 
                        HttpServletResponse response, Object handler,
                    ModelAndView modelAndView) throws Exception {

            }

            @Override
            public void afterCompletion(HttpServletRequest request, 
                       HttpServletResponse response, Object handler,
                       Exception ex) throws Exception {
            }
        };
        registry.addInterceptor(handlerInterceptor).addPathPatterns("/**");
    }

    // 自定義消息轉化器的第二種方法
    @Override
    public void configureMessageConverters(
                    List<HttpMessageConverter<?>> converters) {
        StringHttpMessageConverter converter  = 
                    new StringHttpMessageConverter(Charset.forName("UTF-8"));
        converters.add(converter);
    }

}