web访问经常会莫名其妙的出现各种乱码问题。按照我自己的理解，设置一个charSet的过滤器，代码如下：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;import java.io.ByteArrayOutputStream;
import java.io.OutputStreamWriter;
public class Charset implements Filter {
@Override//过滤器销毁
public void destroy() {
// TODO Auto-generated method stub
}
@Override//chain我感觉是对request的一次转发
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
//设置字符编码，解决乱码问题
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("chatset=utf-8");
chain.doFilter(request, response);//让目标执行，放行
}
@Override//过滤器初始化
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
}
private static String getDefaultCharSet() {
OutputStreamWriter writer = new OutputStreamWriter(new ByteArrayOutputStream());
String enc = writer.getEncoding();
return enc;
}
}
然后在tomcat的conf目录下server.xml添加那么一句 URIEncoding="UTF-8"
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" URIEncoding="UTF-8" />
最后记得每个jsp的开头都要记得 pageEncoding="utf-8"
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
基本上javaWeb的开发就不会出现什么乱码问题了。
然后想得深入些，String类里面有个方法 String.getBytes() ，这个方法JDK的源码是这样子的
@Deprecated
public void getBytes(int srcBegin, int srcEnd, byte dst[], int dstBegin) {
if (srcBegin < 0) {
throw new StringIndexOutOfBoundsException(srcBegin);
}
if (srcEnd > value.length) {
throw new StringIndexOutOfBoundsException(srcEnd);
}
if (srcBegin > srcEnd) {
throw new StringIndexOutOfBoundsException(srcEnd - srcBegin);
}
int j = dstBegin;
int n = srcEnd;
int i = srcBegin;
char[] val = value; /* avoid getfield opcode */
while (i < n) {
dst[j++] = (byte)val[i++];
}
}
/**
* Encodes this {@code String} into a sequence of bytes using the named
* charset, storing the result into a new byte array.
*
* <p> The behavior of this method when this string cannot be encoded in
* the given charset is unspecified. The {@link
* java.nio.charset.CharsetEncoder} class should be used when more control
* over the encoding process is required.
*
* @param charsetName
* The name of a supported {@linkplain java.nio.charset.Charset
* charset}
*
* @return The resultant byte array
*
* @throws UnsupportedEncodingException
* If the named charset is not supported
*
* @since JDK1.1
*/
public byte[] getBytes(String charsetName)
throws UnsupportedEncodingException {
if (charsetName == null) throw new NullPointerException();
return StringCoding.encode(charsetName, value, 0, value.length);
}
/**
* Encodes this {@code String} into a sequence of bytes using the given
* {@linkplain java.nio.charset.Charset charset}, storing the result into a
* new byte array.
*
* <p> This method always replaces malformed-input and unmappable-character
* sequences with this charset's default replacement byte array. The
* {@link java.nio.charset.CharsetEncoder} class should be used when more
* control over the encoding process is required.
*
* @param charset
* The {@linkplain java.nio.charset.Charset} to be used to encode
* the {@code String}
*
* @return The resultant byte array
*
* @since 1.6
*/
public byte[] getBytes(Charset charset) {
if (charset == null) throw new NullPointerException();
return StringCoding.encode(charset, value, 0, value.length);
}
/**
* Encodes this {@code String} into a sequence of bytes using the
* platform's default charset, storing the result into a new byte array.
*
* <p> The behavior of this method when this string cannot be encoded in
* the default charset is unspecified. The {@link
* java.nio.charset.CharsetEncoder} class should be used when more control
* over the encoding process is required.
*
* @return The resultant byte array
*
* @since JDK1.1
*/
public byte[] getBytes() {
return StringCoding.encode(value, 0, value.length);
}
如果不指定String.getBytes()里面的参数，它会调用系统默认的参数，也就是java虚拟机的默认参数，查看这个参数的方法如下所示
System.out.println("Default Charset=" + java.nio.charset.Charset.defaultCharset());
System.out.println("file.encoding=" + System.getProperty("file.encoding"));
System.out.println("Default Charset=" + java.nio.charset.Charset.defaultCharset());
System.out.println("Default Charset in Use=" + getDefaultCharSet());
值得一提的是，当你使用sftp工具上传文件至服务器时，如果没有指定sftp协议的文件名格式，sftp工具会以你默认系统的编码（大部分windows的编码都是GBK）传送中文文件名给服务器，这时候如果服务器默认的编码方式不是GBK，那么你上传的文件名在服务器端显示都是乱码。
在tomcat7中，用get方式访问中文名的文件，如uploads/%E6%B5%8B%E8%AF%95.mp3
浏览器本身会借助url.enCode()把中文名，空格等等转化为%E8等等的web地址传输编码格式，然后servlet接收到这个地址后会先url.unCode换成普通的编码，然后再根据request.setContentType="UTF-8"来换成中文名，但是这样子设置tomcat的 URIEncoding="UTF-8" 又是闹得哪样？
更多Tomcat相关教程见以下内容：