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
關鍵字:j2me，頁面，編碼，亂碼
一、摘要
根據xinshouj2me在j2me版提出的“httpconnection網絡連接的問題”，本人分析了一下：由于www.163.com上的頁面編碼為gb2312，所以使用utf8讀取由于編碼方式不同會得到亂碼。于是本人根據page的編碼靈活進行編碼轉化，在此與大家共享、討論。
二、代碼分析
1.HttpConnectionHandler接口類
最好根據page的編碼靈活進行編碼轉化，于是本人定義了一個HttpConnectionHandler接口類：
HttpConnectionHandler.java

				
package com.bjinfotech.practice.j2me.httpConnection;

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

/**
 * Http連接處理器接口
 * @author cleverpig
 *
 */
public interface HttpConnectionHandler {
????????//http請求常量
????????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回應常量
????????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類
根據HttpConnectionHandler接口規范實現了該接口——HTML_HttpConnectionHandlerImpl類。
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連接處理器實現
 * @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("獲得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;
????????}
????????
????????
}

上面實現類中根據page中的實際編碼類型對html字符串進行了編碼轉化，這樣就實現了page編碼的靈活轉化。
雖然靈活性加強了，但是對于內存的占用也隨之增加了一倍。
三.測試代碼

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("建立連接成功");
????????????????????????????????
????????????????????????????????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("發送請求成功");
????????????????????????????????????????
????????????????????????????????????????System.out.println("獲得回應數據");
????????????????????????????????????????String reponseData=(String)handler.getResponseData(conn);
????????????????????????????????????????System.out.println(reponseData);
????????????????????????????????}
????????????????????????????????else{
????????????????????????????????????????System.out.println("發送請求失敗");
????????????????????????????????????????System.out.println("錯誤信息:"+handler.getMessage());
????????????????????????????????}
????????????????????????}
????????????????????????else{
????????????????????????????????System.out.println("建立連接失敗");
????????????????????????}
????????????????}
????????????????catch(Exception ex){
????????????????????????System.out.println("錯誤信息:"+handler.getMessage());
????????????????????????ex.printStackTrace();
????????????????}
????????????????

????????}
????????
????????protected void pauseApp() {
????????????????

????????}

????????protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
????????????????

????????}

}

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