作者:cleverpig(作者的Blog:http://blog.matrix.org.cn/page/cleverpig)
原文:http://www.matrix.org.cn/resource/article/44/44154_j2me.html
关键字:j2me，页面，编码，乱码
一、摘要
根据xinshouj2me在j2me版提出的“httpconnection网络连接的问题”，本人分析了一下：由于www.163.com上的页面编码为gb2312，所以使用utf8读取由于编码方式不同会得到乱码。于是本人根据page的编码灵活进行编码转化，在此与大家共享、讨论。
二、代码分析
1.HttpConnectionHandler接口类
最好根据page的编码灵活进行编码转化，于是本人定义了一个HttpConnectionHandler接口类：
HttpConnectionHandler.java

				
package com.bjinfotech.practice.j2me.httpConnection;

import java.util.Hashtable;
import javax.microedition.io.HttpConnection;

/**
 * Http连接处理器接口
 * @author cleverpig
 *
 */
public interface HttpConnectionHandler {
        //http请求常量
        public static final String RQH_HOST="X-Online-Host";
        public static final String RQH_ACCEPT="Accept";
        public static final String RQH_CONTENT_LANGUAGE="Content-Language";
        public static final String RQH_CONTENT_TYPE="Content-Type";
        public static final String RQH_CONNECTION_OPTION="Connection";
        //http回应常量
        public static final String RSH_DATE="Date";
        public static final String RSH_SERVER="Server";
        public static final String RSH_MODIFIEDDATE="Last-Modified";
        public static final String RSH_CONTENT_ENCODING="Content-Encoding";
        public static final String RSH_CONTENT_LENGTH="Content-Length";
        public static final String RSH_CONTENT_TYPE="Content-Type";
        
        public boolean putRequestHeaderProperty(
                        HttpConnection conn,
                        String key,
                        String keyValue);
        
        public String getResponseHeaderProperty(
                        HttpConnection conn,
                        String key);
        
        public boolean setRequestMethod(
                        HttpConnection conn,
                        String methodName);
        
        public boolean putRequestHeader(
                        HttpConnection conn,
                        Hashtable propertiesPair);
        
        public Hashtable getResponseHeader(
                        HttpConnection conn,
                        String[] propertyNames);
        
        public boolean sendRequestData(
                        HttpConnection conn,
                        Object sendData);
        
        public Object getResponseData(HttpConnection conn);
        
}

2.HTML_HttpConnectionHandlerImpl类
根据HttpConnectionHandler接口规范实现了该接口——HTML_HttpConnectionHandlerImpl类。
HTML_HttpConnectionHandlerImpl.java

package com.bjinfotech.practice.j2me.httpConnection;

import java.io.DataOutputStream;
import java.io.DataInputStream;
import java.util.Hashtable;
import java.util.Vector;
import java.util.Enumeration;
import javax.microedition.io.HttpConnection;

/**
 * http连接处理器实现
 * @author cleverpig
 *
 */
public class HTML_HttpConnectionHandlerImpl implements HttpConnectionHandler{
        private String message="";
        
        public HTML_HttpConnectionHandlerImpl(){
        }
        
        public boolean putRequestHeaderProperty(
                        HttpConnection conn,
                        String key,
                        String keyValue){
                message="";
                try{
                        conn.setRequestProperty(key,keyValue);
                        return true;
                }
                catch(Exception ex){
                        message=ex.getMessage();
                }
                return false;
        }
        
        public String getResponseHeaderProperty(
                        HttpConnection conn,
                        String key){
                return conn.getRequestProperty(key);
        }
        
        public boolean putRequestHeader(
                        HttpConnection conn,
                        Hashtable propertiesPair){
                Enumeration keyEnumer=propertiesPair.keys();
                boolean result=true;
                while(keyEnumer.hasMoreElements()){
                        String keyName=(String)keyEnumer.nextElement();
                        String keyValue=(String)propertiesPair.get(keyName);
                        if (putRequestHeaderProperty(conn,keyName,keyValue)==false){
                                result=false;
                        }
                }
                return result;
        }
        
        public boolean setRequestMethod(
                        HttpConnection conn,
                        String methodName){
                message="";
                try{
                        conn.setRequestMethod(methodName);
                        return true;
                }
                catch(Exception ex){
                        message=ex.getMessage();
                        return false;
                }
        }
        
        public Hashtable getResponseHeader(
                        HttpConnection conn,
                        String[] propertyNames){
                Hashtable result=new Hashtable();
                for(int i=0;i<propertyNames.length;i++){
                        String keyValue=conn.getRequestProperty(propertyNames[i]);
                        result.put(propertyNames[i],keyValue);
                }
                return result;
        }
        
        public boolean sendRequestData(
                        HttpConnection conn,
                        Object sendData){
                message="";
                try{
                        DataOutputStream os=conn.openDataOutputStream();
                        os.writeUTF((String)(sendData));
                        os.flush();
                        return true;
                }
                catch(Exception ex){
                        message=ex.getMessage();
                        return false;
                }
        }
        
        public Object getResponseData(HttpConnection conn){
                DataInputStream is=null;
                message="";
                try{
                        is=conn.openDataInputStream();
                }
                catch(Exception ex){
                        message=ex.getMessage();
                        return null;
                }
                
                byte[] data=null;
                String type=getResponseHeaderProperty(conn,RSH_CONTENT_TYPE);
                int len = 0;
                try{
                        len=Integer.parseInt(getResponseHeaderProperty(conn,RSH_CONTENT_LENGTH));
                }
                catch(Exception ex){
                        len=0;
                }
                if (len > 0) {
             int actual = 0;
             int bytesread = 0 ;
             data = new byte[len];
             while ((bytesread != len) && (actual != -1)) {
                     try{
                             actual = is.read(data, bytesread, len - bytesread);
                             bytesread += actual;
                     }
                     catch(Exception ex){
                             message=ex.getMessage();
                             return null;
                     }
             }
        } else {
            int ch;
            Vector vbuffer=new Vector();
            try{
                    while ((ch = is.read()) != -1) {
                            vbuffer.addElement(new Integer(ch));
                    }
            }
                       catch(Exception ex){
                                message=ex.getMessage();
                                return null;
                       }
            len=vbuffer.size();
            data = new byte[len];
            for(int i=0;i<len;i++){
                    data[i]=((Integer)vbuffer.elementAt(i)).byteValue();
            }
        }
        
        String result=new String(data);
        int flagBeginPosition=result.indexOf("charset=");
        int flagEndPosition=result.indexOf("\">",flagBeginPosition);
        if (flagEndPosition>flagBeginPosition){
                type=result.substring(flagBeginPosition+"charset=".length(),flagEndPosition);
        }
        System.out.println("获得html字符集:"+type);
        if (type!=null){
                
                try{
                        result=new String(data,type);
                }
                catch(Exception ex){
                        message=ex.getMessage();
                }
        }
        return result;
        }
        
        public String getMessage(){
                return message;
        }
        
        
}

上面实现类中根据page中的实际编码类型对html字符串进行了编码转化，这样就实现了page编码的灵活转化。
虽然灵活性加强了，但是对于内存的占用也随之增加了一倍。
三.测试代码

package com.bjinfotech.practice.j2me.httpConnection;

import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
import javax.microedition.io.HttpConnection;
import javax.microedition.io.Connector;
import java.util.Hashtable;

public class HttpConnectionMIDlet extends MIDlet {

        public HttpConnectionMIDlet() {
                super();
        }

        
        protected void startApp() throws MIDletStateChangeException {
                HTML_HttpConnectionHandlerImpl handler=new HTML_HttpConnectionHandlerImpl();
                try{
                        String host="10.11.3.99";
                        String url="http://10.11.3.99:8080/test_gbk.html";
//                        String url="http://10.11.3.99:8080/test_gb2312.html";
//                        String url="http://10.11.3.99:8080/test_utf8.html";
                        
                        HttpConnection conn=(HttpConnection)Connector.open(url);
                        if (conn.getResponseCode()==HttpConnection.HTTP_OK){
                                System.out.println("建立连接成功");
                                
                                Hashtable requestHeaderPair=new Hashtable();
                                requestHeaderPair.put(
                                                HTML_HttpConnectionHandlerImpl.RQH_HOST,
                                                host);
                                requestHeaderPair.put(
                                                HTML_HttpConnectionHandlerImpl.RQH_CONTENT_TYPE,
                                                "application/octet-stream");
                                requestHeaderPair.put(
                                                HTML_HttpConnectionHandlerImpl.RQH_CONTENT_LANGUAGE,
                                                "en-US");
                                requestHeaderPair.put(
                                                HTML_HttpConnectionHandlerImpl.RQH_ACCEPT,
                                                "application/octet-stream");
                                requestHeaderPair.put(
                                                HTML_HttpConnectionHandlerImpl.RQH_CONNECTION_OPTION,
                                                "Keep-Alive");
                                handler.putRequestHeader(conn,requestHeaderPair);
                                handler.setRequestMethod(conn,HttpConnection.GET);
                                handler.sendRequestData(conn,"GET / HTTP/1.1");
                                if (conn.getResponseCode()==HttpConnection.HTTP_OK){
                                        System.out.println("发送请求成功");
                                        
                                        System.out.println("获得回应数据");
                                        String reponseData=(String)handler.getResponseData(conn);
                                        System.out.println(reponseData);
                                }
                                else{
                                        System.out.println("发送请求失败");
                                        System.out.println("错误信息:"+handler.getMessage());
                                }
                        }
                        else{
                                System.out.println("建立连接失败");
                        }
                }
                catch(Exception ex){
                        System.out.println("错误信息:"+handler.getMessage());
                        ex.printStackTrace();
                }
                

        }
        
        protected void pauseApp() {
                

        }

        protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
                

        }

}

更多问题，请到Matrix J2me版讨论