1.浏览器向服务器发送消息：request,使用过滤器为所有请求：设置 request.setCharacterEncoding(“utf-8”);

此时不修改编码格式的话，tomcat默认是按照编码的，不是utf-8，这样的数据写进数据库就是乱码啦呱~

//浏览器发来服务器消息进行重新编码的编码。
request.setCharacterEncoding("utf-8");

1.1EncodingFilter.java代码

@WebFilter("/*")
public class EncodingFilter  implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request =(HttpServletRequest) servletRequest;
        request.setCharacterEncoding("utf-8");
        filterChain.doFilter(request,servletResponse);
    }

    @Override
    public void destroy() {

    }
}

2.服务器向浏览器发送消息：response，使用BaseController进行判断方法是否被自定义注解修饰：设置resp.setContentType(“text/html;charset=utf-8”);

//对服务器发送浏览器消息：用于定义网络文件bai的类型和网页的编码，决定浏览器du将以什么zhi形式、什么编码读取这个文件
resp.setContentType("text/html;charset=utf-8");

2.1自定义注解ContentType 代码

//详情请见：
https://blog.csdn.net/qq_39773004/article/details/108661464?ops_request_misc=%257B%2522request%255Fid%2522%253A%2522160048748919725247415269%2522%252C%2522scm%2522%253A%252220140713.130102334.pc%255Fblog.%2522%257D&request_id=160048748919725247415269&biz_id=0&utm_medium=distribute.pc_search_result.none-task-blog-2~blog~first_rank_v2~rank_blog_default-1-108661464.pc_v2_rank_blog_default&utm_term=%E8%87%AA%E5%AE%9A%E4%B9%89%E6%B3%A8%E8%A7%A3&spm=1018.2118.3001.4187

@Retention(RetentionPolicy.RUNTIME)  //被反射读取到  class
@Target(ElementType.METHOD)   //应用到方法上

public @interface ContentType {
    String  value();
    int id() default 1;
    String name() default  "Ellie";
}

2.2BaseController代码

public class BaseController extends HttpServlet {
 @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

if (method.isAnnotationPresent(ContentType.class)){
                ContentType contentType =   method.getAnnotation(ContentType.class);
                String type = contentType.value();//image/jpeg  application/json;charset=utf-8

                resp.setContentType(type);
            }else{
                resp.setContentType("text/html;charset=utf-8");
            }
       }
}

请求(doFilter)与响应乱码(BaseController+自定义注解@ContentType(““))集中处理

1.浏览器向服务器发送消息：request,使用过滤器为所有请求：设置 request.setCharacterEncoding(“utf-8”);

1.1EncodingFilter.java代码

2.服务器向浏览器发送消息：response，使用BaseController进行判断方法是否被自定义注解修饰：设置resp.setContentType(“text/html;charset=utf-8”);

2.1自定义注解ContentType 代码

2.2BaseController代码