JavaEE_post乱码和乱码的解决方法

本文章讲解项目中 post 乱码与get 乱码的处理方法

1.post 乱码

解决方法在web.xml中加入以下代码

实质：servlet 中的拦截器 filter

<!-- post乱码过虑器 -->
<filter>
<filter-name>CharacterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

filter 处理类org.springframework.web.filter.CharacterEncodingFilter,

需要引入Spring的 jar包 spring-web-3.2.0 RELEASE.jar

该类的源码（见最下面）,有兴趣的同学可以参考下，比较简单（so easy）

2.get 乱码

对于get 请求中文参数出现乱码解决方法有两个

(1)修改tomcat 配置文件添加编码与工程编码一致;

<Connector URIEncoding="utf-8" connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/>

(2)另外一种方法对参数进行重新编码

String userName =  new String(request.getParamter("userName").getBytes("ISO8859-1"),"utf-8")
 

ISO8859-1是tomcat默认编码，需要将tomcat编码后的内容按utf-8编码

Post 拦截器源码：

CharacterEncodingFilter.java

/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0 *
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.springframework.web.filter;

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

/**
* Servlet 2.3/2.4 Filter that allows one to specify a character encoding for
* requests. This is useful because current browsers typically do not set a
* character encoding even if specified in the HTML page or form.
*
* <p>This filter can either apply its encoding if the request does not
* already specify an encoding, or enforce this filter's encoding in any case
* ("forceEncoding"="true"). In the latter case, the encoding will also be
* applied as default response encoding on Servlet 2.4+ containers (although
* this will usually be overridden by a full content type set in the view).
*
* @author Juergen Hoeller
* @since 15.03.2004
* @see #setEncoding
* @see #setForceEncoding
* @see javax.servlet.http.HttpServletRequest#setCharacterEncoding
* @see javax.servlet.http.HttpServletResponse#setCharacterEncoding
*/
public class CharacterEncodingFilter extends OncePerRequestFilter {

private String encoding;

private boolean forceEncoding = false;

/**
* Set the encoding to use for requests. This encoding will be passed into a
* {@link javax.servlet.http.HttpServletRequest#setCharacterEncoding} call.
* <p>Whether this encoding will override existing request encodings
* (and whether it will be applied as default response encoding as well)
* depends on the {@link #setForceEncoding "forceEncoding"} flag.
*/
public void setEncoding(String encoding) {
this.encoding = encoding;
}

/**
* Set whether the configured {@link #setEncoding encoding} of this filter
* is supposed to override existing request and response encodings.
* <p>Default is "false", i.e. do not modify the encoding if
* {@link javax.servlet.http.HttpServletRequest#getCharacterEncoding()}
* returns a non-null value. Switch this to "true" to enforce the specified
* encoding in any case, applying it as default response encoding as well.
* <p>Note that the response encoding will only be set on Servlet 2.4+
* containers, since Servlet 2.3 did not provide a facility for setting
* a default response encoding.
*/
public void setForceEncoding(boolean forceEncoding) {
this.forceEncoding = forceEncoding;
}

@Override
protected void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {

if (this.encoding != null && (this.forceEncoding || request.getCharacterEncoding() == null)) {
request.setCharacterEncoding(this.encoding);
if (this.forceEncoding) {
response.setCharacterEncoding(this.encoding);
}
}
filterChain.doFilter(request, response);
}

}

OncePerRequestFilter.java

/*
* Copyright 2002-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0 *
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.springframework.web.filter;

import java.io.IOException;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.context.request.async.WebAsyncManager;
import org.springframework.web.context.request.async.WebAsyncUtils;
import org.springframework.web.util.WebUtils;

/**
* Filter base class that aims to guarantee a single execution per request
* dispatch, on any servlet container. It provides a {@link #doFilterInternal}
* method with HttpServletRequest and HttpServletResponse arguments.
*
* <p>As of Servlet 3.0, a filter may be invoked as part of a
* {@link javax.servlet.DispatcherType.REQUEST REQUEST} or
* {@link javax.servlet.DispatcherType.ASYNC ASYNC} dispatches that occur in
* separate threads. A filter can be configured in {@code web.xml} whether it
* should be involved in async dispatches. However, in some cases servlet
* containers assume different default configuration. Therefore sub-classes can
* override the method {@link #shouldNotFilterAsyncDispatch()} to declare
* statically if they shouuld indeed be invoked, <em>once</em>, during both types
* of dispatches in order to provide thread initialization, logging, security,
* and so on. This mechanism complements and does not replace the need to
* configure a filter in {@code web.xml} with dispatcher types.
*
* <p>Sub-classes may use {@link #isAsyncDispatch(HttpServletRequest)} to
* determine when a filter is invoked as part of an async dispatch, and
* use {@link #isAsyncStarted(HttpServletRequest)} to determine when the
* request has been placed in async mode and therefore the current dispatch
* won't be the last one.
*
* <p>Yet another dispatch type that also occurs in its own thread is
* {@link javax.servlet.DispatcherType.ERROR ERROR}. Sub-classes can override
* {@link #shouldNotFilterErrorDispatch()} if they wish to declare statically
* if they should be invoked <em>once</em> during error dispatches.
*
* <p>The {@link #getAlreadyFilteredAttributeName} method determines how to
* identify that a request is already filtered. The default implementation is
* based on the configured name of the concrete filter instance.
*
* @author Juergen Hoeller
* @author Rossen Stoyanchev
* @since 06.12.2003
*/
public abstract class OncePerRequestFilter extends GenericFilterBean {

/**
* Suffix that gets appended to the filter name for the
* "already filtered" request attribute.
* @see #getAlreadyFilteredAttributeName
*/
public static final String ALREADY_FILTERED_SUFFIX = ".FILTERED";

/**
* This <code>doFilter</code> implementation stores a request attribute for
* "already filtered", proceeding without filtering again if the
* attribute is already there.
* @see #getAlreadyFilteredAttributeName
* @see #shouldNotFilter
* @see #doFilterInternal
*/
public final void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
throws ServletException, IOException {

if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
throw new ServletException("OncePerRequestFilter just supports HTTP requests");
}
HttpServletRequest httpRequest = (HttpServletRequest) request;
HttpServletResponse httpResponse = (HttpServletResponse) response;

String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();
boolean hasAlreadyFilteredAttribute = request.getAttribute(alreadyFilteredAttributeName) != null;

if (hasAlreadyFilteredAttribute || skipDispatch(httpRequest) || shouldNotFilter(httpRequest)) {

// Proceed without invoking this filter...
filterChain.doFilter(request, response);
}
else {
// Do invoke this filter...
request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);
try {
doFilterInternal(httpRequest, httpResponse, filterChain);
}
finally {
// Remove the "already filtered" request attribute for this request.
request.removeAttribute(alreadyFilteredAttributeName);
}
}
}

private boolean skipDispatch(HttpServletRequest request) {
if (isAsyncDispatch(request) && shouldNotFilterAsyncDispatch()) {
return true;
}
if ((request.getAttribute(WebUtils.ERROR_REQUEST_URI_ATTRIBUTE) != null) && shouldNotFilterErrorDispatch()) {
return true;
}
return false;
}

/**
* The dispatcher type {@code javax.servlet.DispatcherType.ASYNC} introduced
* in Servlet 3.0 means a filter can be invoked in more than one thread over
* the course of a single request. This method returns {@code true} if the
* filter is currently executing within an asynchronous dispatch.
*
* @param request the current request
* @see WebAsyncManager#hasConcurrentResult()
*/
protected boolean isAsyncDispatch(HttpServletRequest request) {
return WebAsyncUtils.getAsyncManager(request).hasConcurrentResult();
}

/**
* Whether request processing is in asynchronous mode meaning that the
* response will not be committed after the current thread is exited.
*
* @param request the current request
* @see WebAsyncManager#isConcurrentHandlingStarted()
*/
protected boolean isAsyncStarted(HttpServletRequest request) {
return WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted();
}

/**
* Return the name of the request attribute that identifies that a request
* is already filtered.
* <p>Default implementation takes the configured name of the concrete filter
* instance and appends ".FILTERED". If the filter is not fully initialized,
* it falls back to its class name.
* @see #getFilterName
* @see #ALREADY_FILTERED_SUFFIX
*/
protected String getAlreadyFilteredAttributeName() {
String name = getFilterName();
if (name == null) {
name = getClass().getName();
}
return name + ALREADY_FILTERED_SUFFIX;
}

/**
* Can be overridden in subclasses for custom filtering control,
* returning <code>true</code> to avoid filtering of the given request.
* <p>The default implementation always returns <code>false</code>.
* @param request current HTTP request
* @return whether the given request should <i>not</i> be filtered
* @throws ServletException in case of errors
*/
protected boolean shouldNotFilter(HttpServletRequest request) throws ServletException {
return false;
}

/**
* The dispatcher type {@code javax.servlet.DispatcherType.ASYNC} introduced
* in Servlet 3.0 means a filter can be invoked in more than one thread
* over the course of a single request. Some filters only need to filter
* the initial thread (e.g. request wrapping) while others may need
* to be invoked at least once in each additional thread for example for
* setting up thread locals or to perform final processing at the very end.
* <p>Note that although a filter can be mapped to handle specific dispatcher
* types via {@code web.xml} or in Java through the {@code ServletContext},
* servlet containers may enforce different defaults with regards to
* dispatcher types. This flag enforces the design intent of the filter.
*
* <p>The default return value is "true", which means the filter will not be
* invoked during subsequent async dispatches. If "false", the filter will
* be invoked during async dispatches with the same guarantees of being
* invoked only once during a request within a single thread.
*/
protected boolean shouldNotFilterAsyncDispatch() {
return true;
}

/**
* Whether to filter error dispatches such as when the servlet container
* processes and error mapped in {@code web.xml}. The default return value
* is "true", which means the filter will not be invoked in case of an error
* dispatch.
*/
protected boolean shouldNotFilterErrorDispatch() {
return true;
}

/**
* Same contract as for <code>doFilter</code>, but guaranteed to be
* just invoked once per request within a single request thread.
* See {@link #shouldNotFilterAsyncDispatch()} for details.
* <p>Provides HttpServletRequest and HttpServletResponse arguments instead of the
* default ServletRequest and ServletResponse ones.
*/
protected abstract void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException;

}

GenericFilterBean.java

/*
* Copyright 2002-2011 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0 *
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.springframework.web.filter;

import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.Environment;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceEditor;
import org.springframework.core.io.ResourceLoader;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.context.support.StandardServletEnvironment;
import org.springframework.web.context.support.ServletContextResourceLoader;
import org.springframework.web.util.NestedServletException;

/**
* Simple base implementation of {@link javax.servlet.Filter} which treats
* its config parameters (<code>init-param</code> entries within the
* <code>filter</code> tag in <code>web.xml</code>) as bean properties.
*
* <p>A handy superclass for any type of filter. Type conversion of config
* parameters is automatic, with the corresponding setter method getting
* invoked with the converted value. It is also possible for subclasses to
* specify required properties. Parameters without matching bean property
* setter will simply be ignored.
*
* <p>This filter leaves actual filtering to subclasses, which have to
* implement the {@link javax.servlet.Filter#doFilter} method.
*
* <p>This generic filter base class has no dependency on the Spring
* {@link org.springframework.context.ApplicationContext} concept.
* Filters usually don't load their own context but rather access service
* beans from the Spring root application context, accessible via the
* filter's {@link #getServletContext() ServletContext} (see
* {@link org.springframework.web.context.support.WebApplicationContextUtils}).
*
* @author Juergen Hoeller
* @since 06.12.2003
* @see #addRequiredProperty
* @see #initFilterBean
* @see #doFilter
*/
public abstract class GenericFilterBean implements
Filter, BeanNameAware, EnvironmentAware, ServletContextAware, InitializingBean, DisposableBean {

/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());

/**
* Set of required properties (Strings) that must be supplied as
* config parameters to this filter.
*/
private final Set<String> requiredProperties = new HashSet<String>();

private FilterConfig filterConfig;

private String beanName;

private Environment environment = new StandardServletEnvironment();

private ServletContext servletContext;

/**
* Stores the bean name as defined in the Spring bean factory.
* <p>Only relevant in case of initialization as bean, to have a name as
* fallback to the filter name usually provided by a FilterConfig instance.
* @see org.springframework.beans.factory.BeanNameAware
* @see #getFilterName()
*/
public final void setBeanName(String beanName) {
this.beanName = beanName;
}

/**
* {@inheritDoc}
* <p>Any environment set here overrides the {@link StandardServletEnvironment}
* provided by default.
* <p>This {@code Environment} object is used only for resolving placeholders in
* resource paths passed into init-parameters for this filter. If no init-params are
* used, this {@code Environment} can be essentially ignored.
* @see #init(FilterConfig)
*/
public void setEnvironment(Environment environment) {
this.environment = environment;
}

/**
* Stores the ServletContext that the bean factory runs in.
* <p>Only relevant in case of initialization as bean, to have a ServletContext
* as fallback to the context usually provided by a FilterConfig instance.
* @see org.springframework.web.context.ServletContextAware
* @see #getServletContext()
*/
public final void setServletContext(ServletContext servletContext) {
this.servletContext = servletContext;
}

/**
* Calls the <code>initFilterBean()</code> method that might
* contain custom initialization of a subclass.
* <p>Only relevant in case of initialization as bean, where the
* standard <code>init(FilterConfig)</code> method won't be called.
* @see #initFilterBean()
* @see #init(javax.servlet.FilterConfig)
*/
public void afterPropertiesSet() throws ServletException {
initFilterBean();
}

/**
* Subclasses can invoke this method to specify that this property
* (which must match a JavaBean property they expose) is mandatory,
* and must be supplied as a config parameter. This should be called
* from the constructor of a subclass.
* <p>This method is only relevant in case of traditional initialization
* driven by a FilterConfig instance.
* @param property name of the required property
*/
protected final void addRequiredProperty(String property) {
this.requiredProperties.add(property);
}

/**
* Standard way of initializing this filter.
* Map config parameters onto bean properties of this filter, and
* invoke subclass initialization.
* @param filterConfig the configuration for this filter
* @throws ServletException if bean properties are invalid (or required
* properties are missing), or if subclass initialization fails.
* @see #initFilterBean
*/
public final void init(FilterConfig filterConfig) throws ServletException {
Assert.notNull(filterConfig, "FilterConfig must not be null");
if (logger.isDebugEnabled()) {
logger.debug("Initializing filter '" + filterConfig.getFilterName() + "'");
}

this.filterConfig = filterConfig;

// Set bean properties from init parameters.
try {
PropertyValues pvs = new FilterConfigPropertyValues(filterConfig, this.requiredProperties);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
ResourceLoader resourceLoader = new ServletContextResourceLoader(filterConfig.getServletContext());
bw.registerCustomEditor(Resource.class, new ResourceEditor(resourceLoader, this.environment));
initBeanWrapper(bw);
bw.setPropertyValues(pvs, true);
}
catch (BeansException ex) {
String msg = "Failed to set bean properties on filter '" +
filterConfig.getFilterName() + "': " + ex.getMessage();
logger.error(msg, ex);
throw new NestedServletException(msg, ex);
}

// Let subclasses do whatever initialization they like.
initFilterBean();

if (logger.isDebugEnabled()) {
logger.debug("Filter '" + filterConfig.getFilterName() + "' configured successfully");
}
}

/**
* Initialize the BeanWrapper for this GenericFilterBean,
* possibly with custom editors.
* <p>This default implementation is empty.
* @param bw the BeanWrapper to initialize
* @throws BeansException if thrown by BeanWrapper methods
* @see org.springframework.beans.BeanWrapper#registerCustomEditor
*/
protected void initBeanWrapper(BeanWrapper bw) throws BeansException {
}

/**
* Make the FilterConfig of this filter available, if any.
* Analogous to GenericServlet's <code>getServletConfig()</code>.
* <p>Public to resemble the <code>getFilterConfig()</code> method
* of the Servlet Filter version that shipped with WebLogic 6.1.
* @return the FilterConfig instance, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletConfig()
*/
public final FilterConfig getFilterConfig() {
return this.filterConfig;
}

/**
* Make the name of this filter available to subclasses.
* Analogous to GenericServlet's <code>getServletName()</code>.
* <p>Takes the FilterConfig's filter name by default.
* If initialized as bean in a Spring application context,
* it falls back to the bean name as defined in the bean factory.
* @return the filter name, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletName()
* @see javax.servlet.FilterConfig#getFilterName()
* @see #setBeanName
*/
protected final String getFilterName() {
return (this.filterConfig != null ? this.filterConfig.getFilterName() : this.beanName);
}

/**
* Make the ServletContext of this filter available to subclasses.
* Analogous to GenericServlet's <code>getServletContext()</code>.
* <p>Takes the FilterConfig's ServletContext by default.
* If initialized as bean in a Spring application context,
* it falls back to the ServletContext that the bean factory runs in.
* @return the ServletContext instance, or <code>null</code> if none available
* @see javax.servlet.GenericServlet#getServletContext()
* @see javax.servlet.FilterConfig#getServletContext()
* @see #setServletContext
*/
protected final ServletContext getServletContext() {
return (this.filterConfig != null ? this.filterConfig.getServletContext() : this.servletContext);
}

/**
* Subclasses may override this to perform custom initialization.
* All bean properties of this filter will have been set before this
* method is invoked.
* <p>Note: This method will be called from standard filter initialization
* as well as filter bean initialization in a Spring application context.
* Filter name and ServletContext will be available in both cases.
* <p>This default implementation is empty.
* @throws ServletException if subclass initialization fails
* @see #getFilterName()
* @see #getServletContext()
*/
protected void initFilterBean() throws ServletException {
}

/**
* Subclasses may override this to perform custom filter shutdown.
* <p>Note: This method will be called from standard filter destruction
* as well as filter bean destruction in a Spring application context.
* <p>This default implementation is empty.
*/
public void destroy() {
}

/**
* PropertyValues implementation created from FilterConfig init parameters.
*/
@SuppressWarnings("serial")
private static class FilterConfigPropertyValues extends MutablePropertyValues {

/**
* Create new FilterConfigPropertyValues.
* @param config FilterConfig we'll use to take PropertyValues from
* @param requiredProperties set of property names we need, where
* we can't accept default values
* @throws ServletException if any required properties are missing
*/
public FilterConfigPropertyValues(FilterConfig config, Set<String> requiredProperties)
throws ServletException {

Set<String> missingProps = (requiredProperties != null && !requiredProperties.isEmpty()) ?
new HashSet<String>(requiredProperties) : null;

Enumeration<?> en = config.getInitParameterNames();
while (en.hasMoreElements()) {
String property = (String) en.nextElement();
Object value = config.getInitParameter(property);
addPropertyValue(new PropertyValue(property, value));
if (missingProps != null) {
missingProps.remove(property);
}
}

// Fail if we are still missing properties.
if (missingProps != null && missingProps.size() > 0) {
throw new ServletException(
"Initialization from FilterConfig for filter '" + config.getFilterName() +
"' failed; the following required properties were missing: " +
StringUtils.collectionToDelimitedString(missingProps, ", "));
}
}
}

}