使用filter解决项目编码问题
在开发JavaWeb项目时，前端的编码使用的时utf-8编码方式，服务器端使用的是ISO-8859-1编码方式，故在开发中会出现乱码。
解决方案（使用filter）
实现EncodingFilter来解决项目乱码问题
乱码情形举例：
- 写一个b.html文件
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<a href="/filtertest/demox?username=张三">向服务器发送请求</a>
</body>
</html>
- 再写一个servlet处理请求
package com.oracle.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DemoxServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
System.out.println(username);
response.getWriter().println("王五");
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
- servlet写到浏览器的内容和servlet从浏览器接收到的请求数据会出现乱码
EncodingFilter:
package com.oracle.filter;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
/**
* 统一编码
* @author Administrator
*
*/
public class EncodingFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
// TODO Auto-generated method stub
}
@Override
public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException {
//1.强转
HttpServletRequest request=(HttpServletRequest) req;
HttpServletResponse response=(HttpServletResponse) resp;
response.setContentType("text/html;charset=utf-8");
//2.放行
chain.doFilter(new MyRequest(request), response);
}
@Override
public void destroy() {
// TODO Auto-generated method stub
}
}
class MyRequest extends HttpServletRequestWrapper{
private HttpServletRequest request;
private boolean flag=true;
public MyRequest(HttpServletRequest request) {
super(request);
this.request=request;
}
@Override
public String getParameter(String name) {
if(name==null || name.trim().length()==0){
return null;
}
String[] values = getParameterValues(name);
if(values==null || values.length==0){
return null;
}
return values[0];
}
@Override
/**
* hobby=[eat,drink]
*/
public String[] getParameterValues(String name) {
if(name==null || name.trim().length()==0){
return null;
}
Map<String, String[]> map = getParameterMap();
if(map==null || map.size()==0){
return null;
}
return map.get(name);
}
@Override
/**
* map{ username=[tom],password=[123],hobby=[eat,drink]}
*/
public Map<String,String[]> getParameterMap() {
/**
* 首先判断请求方式
* 若为post request.setchar...(utf-8)
* 若为get 将map中的值遍历编码就可以了
*/
String method = request.getMethod();
if("post".equalsIgnoreCase(method)){
try {
request.setCharacterEncoding("utf-8");
return request.getParameterMap();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if("get".equalsIgnoreCase(method)){
Map<String,String[]> map = request.getParameterMap();
if(flag){
for (String key:map.keySet()) {
String[] arr = map.get(key);
//继续遍历数组
for(int i=0;i<arr.length;i++){
//编码
try {
arr[i]=new String(arr[i].getBytes("iso8859-1"),"utf-8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
}
flag=false;
}
//需要遍历map 修改value的每一个数据的编码
return map;
}
return super.getParameterMap();
}
}
配置web.xml文件:
<!-- 配置项目编码 -->
<filter>
<filter-name>EncodingFilter</filter-name>
<filter-class>com.oracle.filter.EncodingFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>EncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>