过滤器接口与实现字符编码过滤器实…

最新推荐文章于 2021-02-26 00:19:06 发布

原创最新推荐文章于 2021-02-26 00:19:06 发布 · 1k 阅读

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本文介绍了一个用于解决HTTP请求中字符编码问题的Java过滤器。该过滤器通过配置文件指定字符集，自动设置请求和响应的编码，有效避免了中文乱码问题。文中详细展示了过滤器的实现代码、配置步骤及应用示例。

[1]过滤器的原理

[2]过滤链

[3]Filter接口

*public void init(FilterConfig filterConfig)throws ServletException//过滤器初始化方法，此方法在过滤器初始化时被调用

*public void doilter(ServletRequest request , ServletResponse response,FilterChain chain)throws IOException, ServletException//对请求进行过滤处理

*public void destroy();//销毁方法，以便释放资源

[4]FilterConfig接口

*public Strng getFilterName();//用于获取过滤器的名字

*public ServletContext getServletContent();//获取Servlet上下文

*public String getInitParameter(String name);//获取过滤器的初始化参数值

*public Enumeration getInitParameterNames();//获取过滤器的所有初始化参数

[5]FilterChain接口

public void doFilter(ServletRequest request request, ServletResponse response)throws IOException , ServletException

[6]过滤器的配置

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<filter>
<filter-name>CharactorFilter</filter-name>
<filter-class>com.lyq.CharactorFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharactorFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

        
                
                CharactorFilter
                
                com.lyq.CharactorFilter
                
                
                        
                        encoding
                        
                        UTF-8
                
        
        
        
                
                CharactorFilter
                
                /*

[7]实现字符乱码过滤器处理实例

JSP文件

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<body>
<form action="AddServlet" method="post">
<table align="center" border="1" width="350">
<tr>
<td class="2" align="center" colspan="2">
<h2>添加图书信息</h2>
</td>
</tr>
<tr>
<td align="right">图书编号：</td>
<td>
<input type="text" name="id">
</td>
</tr>
<tr>
<td align="right">图书名称：</td>
<td>
<input type="text" name="name">
</td>
</tr>
<tr>
<td align="right">作　　者：</td>
<td>
<input type="text" name="author">
</td>
</tr>
<tr>
<td align="right">价　　格：</td>
<td>
<input type="text" name="price">
</td>
</tr>
<tr>
<td class="2" align="center" colspan="2">
<input type="submit" value="添　加">
</td>
</tr>
</table>
</form>
</body>

添加图书信息
图书编号：
图书名称：
作　　者：
价　　格：

servlet文件

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public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
//获取PrintWriter
PrintWriter out = response.getWriter();
//获取图书编号
String id = request.getParameter("id");
//获取图书名称
String name=request.getParameter("name");
//获取作者
String author =request.getParameter("author");
//获取价格
String price= request.getParameter("price");
//添加成功
out.print("<h2>图书信息添加成功</h2><hr>");
out.print("图书编号:"+id+"<br>");
out.print("图书名称:"+name+"<br>");
out.print(" 作者:"+author+"<br>");
out.print("体格:"+price+"<br>");
out.flush();//刷新流
out.close();//关闭流
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
                response.setContentType("text/html;charset=utf-8");
                //获取PrintWriter
                PrintWriter out = response.getWriter();
                //获取图书编号
                String id = request.getParameter("id");
                //获取图书名称
                String name=request.getParameter("name");
                //获取作者
                String author =request.getParameter("author");
                //获取价格
                String price= request.getParameter("price");
                //添加成功
                out.print("

图书信息添加成功

");
                out.print("图书编号:"+id+"

");
                out.print("图书名称:"+name+"

");
                out.print(" 作者:"+author+"

");
                out.print("体格:"+price+"

");
                out.flush();//刷新流
                out.close();//关闭流
        }

过滤器文件

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package com.lyq;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class CharactorFilter implements Filter {
// 字符编码
String encoding = null;
public void destroy() {
encoding = null;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// 判断字符编码是否为空
if(encoding != null){
// 设置request的编码格式
request.setCharacterEncoding(encoding);
// 设置response字符编码
response.setContentType("text/html; charset="+encoding);
}
// 传递给下一过滤器
chain.doFilter(request, response);
}
public void init(FilterConfig filterConfig) throws ServletException {
// 获取初始化参数
encoding = filterConfig.getInitParameter("encoding");
}
}

package com.lyq;
import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public class CharactorFilter implements Filter {
        // 字符编码
        String encoding = null;
        public void destroy() {
                encoding = null;
        }
        public void doFilter(ServletRequest request, ServletResponse response,
                        FilterChain chain) throws IOException, ServletException {
                // 判断字符编码是否为空
                if(encoding != null){
                        // 设置request的编码格式
                        request.setCharacterEncoding(encoding);
                        // 设置response字符编码
                response.setContentType("text/html; charset="+encoding);
                }
                // 传递给下一过滤器
                chain.doFilter(request, response);
        }
        public void init(FilterConfig filterConfig) throws ServletException {
                // 获取初始化参数
                encoding = filterConfig.getInitParameter("encoding");
        }
}

web配置文件

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