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 {            
        }

}