实现中文UTF8的过滤器

1.过滤器代码：

package com.yin;

import javax.servlet.*;
import java.io.IOException;

public class filter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {
        //初始化
        System.out.println("初始化");
    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("UTF-8");
        servletResponse.setCharacterEncoding("UTF-8");
        servletResponse.setContentType("text/html;charset=UTF-8");

        System.out.println("CharacterEncodingFilter执行前...");
        filterChain.doFilter(servletRequest,servletResponse);//让请求继续走，不写程序就停了
        System.out.println("CharacterEncodingFilter执行后...");
    }

    public void destroy() {
        //销毁
        System.out.println("销毁");
    }
}

　　2.被转译原文件代码（showsevlet.jsp）

package com.yin;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class ShowServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().write("你好");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }
}

　　3.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>image</servlet-name>
        <servlet-class>com.yin.ShowServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>image</servlet-name>
        <url-pattern>/i</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>filter1</filter-name>
        <filter-class>com.yin.filter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>filter1</filter-name>
        <!--只要是servlet的任何请求都会走过滤器-->
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

　　4.pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>javaweb</artifactId>
    <version>1.0-SNAPSHOT</version>
<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>javax.servlet.jsp-api</artifactId>
        <version>2.3.3</version>
    </dependency>

    <!-- JSTL表达式依赖 -->
    <dependency>
        <groupId>javax.servlet.jsp.jstl</groupId>
        <artifactId>jstl-api</artifactId>
        <version>1.2</version>
    </dependency>

    <!--  standard标签库-->
    <dependency>
        <groupId>taglibs</groupId>
        <artifactId>standard</artifactId>
        <version>1.1.2</version>
    </dependency>

    <!-- 连接数据库 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.16</version>
    </dependency>


</dependencies>

    <!--在build中配置resources，来防止我们资源导出失败的问题-->
    <build>
        <resources>

            <resource>
                <directory>src/main/java</directory><!--设置java目录下的指定文件也会被导出-->
                <includes>
                    <include>**/*.properties</include><!--自己指定的文件类型-->
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>

            <!--系统会自动导出resources中的文件，这个一般不写，如果你的resources中资源也不无法导出，可以试一下把这个加上-->
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>

        </resources>
    </build>
</project>