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使用filter解决request.getParameter的中文乱码问题

2014-01-11 17:29 471 查看

注意：一般一个站点的所有页面的编码，包括数据库编码都要保持一致，下面默认的编码都是UTF-8

----------------------------------例1：直接提交到jsp页面----------------------------------

input_info.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="display_info.jsp" method="post">
<!-- 输入中文来测试 -->
请输入要显示的内容：<input type="text" name="info">
<input type="submit" value="显示">
</form>
</body>
</html>

display_info.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<!--
注意这里并没有调用request.setCharacterEncoding()，
你把CharacterEncodingFilter关闭了试试，看看结果有什么
不一样
-->
<%
String str = (String) request.getParameter("info");
%>
<h1><%=str%></h1>
</body>
</html>

CharacterEncodingFilter.java

　　charset参数是从web.xml中配置好的，这里读取进来

public final class CharacterEncodingFilter implements Filter {
private String encoding = null;
private boolean enable = false;
public void destroy() {
this.encoding = null;
}
/**
* 完成request.setCharacterEncoding(encoding);
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
if (this.enable) {
String encoding = this.selectEncoding(request);
if (encoding != null && !encoding.equals("")) {
request.setCharacterEncoding(encoding);
}
}
// Pass control on to the next filter
chain.doFilter(request, response);
// After other filters are done:
if (this.enable) {
String encoding = this.selectEncoding(request);
if (encoding != null && !encoding.equals("")) {
// response.setCharacterEncoding(encoding); // 实验证明这货没起什么作用，所以，不要也行
}
}
}
/**
* 读取encoding参数以及enable参数，enable参数与encoding的功能无关，只是用来启用或者停用这个filter的
*/
public void init(FilterConfig filterConfig) throws ServletException {
this.encoding = filterConfig.getInitParameter("encoding");
if (!Charset.isSupported(encoding)) {
encoding = null; // 如果不支持的话，只能选择默认的encoding了，这个filter就不起作用
}
// 读取enable参数
String enableString = filterConfig.getInitParameter("enable");
if (enableString.equalsIgnoreCase("true")) {
this.enable = true;
} else {
this.enable = false;
}
}
}

web.xml

<filter>
<filter-name>charset-encoding</filter-name>
<filter-class>org.foo.filterdemo.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
<init-param>
<param-name>enable</param-name>
<param-value>true</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>charset-encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

--------例2：提交到Servlet，Serlvet再设置为request的attribute，再提交到jsp页面--------

AttributeSetterServlet.java

public class AttributeSetterServlet extends HttpServlet {
/**
* Generated serialVersionUID
*/
private static final long serialVersionUID = 8458482445490259121L;

@Override
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 在这里也没有调用request.setCharacterEncoding()，
// 你把CharacterEncodingFilter关闭了试试，看看结果有什么
// 不一样
String attr = req.getParameter("attr");
if (attr != null) {
// System.out.println(this + ", " + attr); // @Debug
attr += " -- 这是一个小尾巴";
req.setAttribute("attr", attr);
req.getRequestDispatcher("display_attribute.jsp").forward(req, resp);
}
}
@Override
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doGet(req, resp);
}
}

input_attribute.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="AttributeSetterServlet" method="post">
<!-- 输入中文来测试 -->
请输入要设置的attribute：<input type="text" name="attr">
<input type="submit" value="显示">
</form>
</body>
</html>

display_attribute.jsp

<%@ page language="java" contentType="text/html"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Insert title here</title>
</head>
<body>
<h1>设置的attribute是：<%=request.getAttribute("attr")%></h1>
</body>
</html>

web.xml中添加如下代码：

<servlet>
<servlet-name>attribute-setter-servlet</servlet-name>
<servlet-class>
org.foo.servletdemo.AttributeSetterServlet
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>attribute-setter-servlet</servlet-name>
<url-pattern>/AttributeSetterServlet</url-pattern>
</servlet-mapping>

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