問(wèn)題分析
不過(guò)在實(shí)際使用中, 還是發(fā)現按照最基本的方式調用 HttpClient 時(shí), 并不支持 UTF-8 編碼, 在網(wǎng)絡(luò )上找過(guò)一些文章, 也不得要領(lǐng), 于是查看了 commons-httpClient3.0.1 的一些代碼, 首先在 PostMethod 中找到了 generateRequestEntity() 方法:
/**
* Generates a request entity from the post parameters, if present. Calls
* {@link EntityEnclosingMethod#generateRequestBody()} if parameters have not been set.
*
* @since 3.0
*/
protected RequestEntity generateRequestEntity() {
if (!this.params.isEmpty()) {
// Use a ByteArrayRequestEntity instead of a StringRequestEntity.
// This is to avoid potential encoding issues. Form url encoded strings
// are ASCII by definition but the content type may not be. Treating the content
// as bytes allows us to keep the current charset without worrying about how
// this charset will effect the encoding of the form url encoded string.
String content = EncodingUtil.formUrlEncode(getParameters(), getRequestCharSet());
ByteArrayRequestEntity entity = new ByteArrayRequestEntity(
EncodingUtil.getAsciiBytes(content),
FORM_URL_ENCODED_CONTENT_TYPE
);
return entity;
} else {
return super.generateRequestEntity();
}
} |
原來(lái)使用 NameValuePair 加入的 HTTP 請求的參數最終都會(huì )轉化為 RequestEntity 提交到 HTTP 服務(wù)器, 接著(zhù)在 PostMethod 的父類(lèi) EntityEnclosingMethod 中找到了如下的代碼:
/**
* Returns the request's charset. The charset is parsed from the request entity's
* content type, unless the content type header has been set manually.
*
* @see RequestEntity#getContentType()
*
* @since 3.0
*/
public String getRequestCharSet() {
if (getRequestHeader("Content-Type") == null) {
// check the content type from request entity
// We can't call getRequestEntity() since it will probably call
// this method.
if (this.requestEntity != null) {
return getContentCharSet(
new Header("Content-Type", requestEntity.getContentType()));
} else {
return super.getRequestCharSet();
}
} else {
return super.getRequestCharSet();
}
} |
解決方案
從上面兩段代碼可以看出是 HttpClient 是如何依據 "Content-Type" 獲得請求的編碼(字符集), 而這個(gè)編碼又是如何應用到提交內容的編碼過(guò)程中去的. 按照這個(gè)原來(lái), 其實(shí)我們只需要重載 getRequestCharSet() 方法, 返回我們需要的編碼(字符集)名稱(chēng), 就可以解決 UTF-8 或者其它非默認編碼提交 POST 請求時(shí)的亂碼問(wèn)題了.
測試
首先在 Tomcat 的 ROOT WebApp 下部署一個(gè)頁(yè)面 test.jsp, 作為測試頁(yè)面, 主要代碼片段如下:
<%@ page contentType="text/html;charset=UTF-8"%>
<%@ page session="false" %>
<%
request.setCharacterEncoding("UTF-8");
String val = request.getParameter("TEXT");
System.out.println(">>>> The result is " + val);
%> |
接著(zhù)寫(xiě)一個(gè)測試類(lèi), 主要代碼如下:
public static void main(String[] args) throws Exception, IOException {
String url = "http://localhost:8080/test.jsp";
PostMethod postMethod = new UTF8PostMethod(url);
//填入各個(gè)表單域的值
NameValuePair[] data = {
new NameValuePair("TEXT", "中文"),
};
//將表單的值放入postMethod中
postMethod.setRequestBody(data);
//執行postMethod
HttpClient httpClient= new HttpClient();
httpClient.executeMethod(postMethod);
}
//Inner class for UTF-8 support
public static class UTF8PostMethod extends PostMethod{
public UTF8PostMethod(String url){
super(url);
}
@Override
public String getRequestCharSet() {
//return super.getRequestCharSet();
return "UTF-8";
}
} |
運行這個(gè)測試程序, 在 Tomcat 的后臺輸出中可以正確打印出 ">>>> The result is 中文" .
