最佳的线程联网类

以前自己打开Http连接，从未开启过线程，我自己对线程用的也不是很熟悉，今天去论坛求救，立马得到结果，结果来自亚日的一篇文章J2ME http连接的例子，他的代码写的很清晰，代码结构也不错，是用lcdui的高级UI写的。

但我用的是LWUIT的包，很多写法和lcdui不一样，我就对着它的代码研究了一下，自己写了一个LWUIT的版本，非常感谢亚日提供的这个例子。

 

首先看看亚日的例子，代码注释写的很清楚，看懂还是比较容易的。

import java.io.ByteArrayOutputStream;import java.io.DataOutputStream;import java.io.IOException;import java.io.InputStream;import javax.microedition.io.Connector;import javax.microedition.io.HttpConnection;import javax.microedition.lcdui.Alert;import javax.microedition.lcdui.AlertType;import javax.microedition.lcdui.Choice;import javax.microedition.lcdui.ChoiceGroup;import javax.microedition.lcdui.Command;import javax.microedition.lcdui.CommandListener;import javax.microedition.lcdui.Display;import javax.microedition.lcdui.Displayable;import javax.microedition.lcdui.Form;import javax.microedition.lcdui.Image;import javax.microedition.lcdui.TextField;import javax.microedition.midlet.MIDlet;/** * HttpDemo 增加网址输入以及取消功能 * * @author kf156(亚日) * */public class HttpTest extends MIDlet implements CommandListener {public static final byte WAIT = 0;// 等待public static final byte CONNECT = 1;// 连接中public static final byte SUCCESS = 2;// 成功public static final byte FAIL = 3;// 失败int state;// 当前状态Display display = Display.getDisplay(this);Form form = new Form("HttpTest");// StringBuffer sb = new StringBuffer("");// StringItem si = new StringItem(null, sb.toString());Command connect = new Command("联网", Command.OK, 1);Command cls = new Command("清除网址", Command.OK, 1);Command cancel = new Command("取消", Command.CANCEL, 1);Command exit = new Command("退出", Command.EXIT, 1);Command back = new Command("返回", Command.BACK, 1);ChoiceGroup cmwapCG;// 接入方式TextField urlTF;// 网址输入框String url;// 网址Http http;// 网络线程Form page;// 页面Alert waitPage;// 等待界面public HttpTest() {state = WAIT;// 等待状态// 初始化等待界面waitPage = new Alert("请等待", "网络连接中...", null, AlertType.INFO);waitPage.addCommand(cancel);waitPage.setCommandListener(this);waitPage.setTimeout(Alert.FOREVER);// 初始化页面page = new Form("访问的页面");page.addCommand(back);page.setCommandListener(this);// 初始化cmwapCG = new ChoiceGroup("网络接入方式：", Choice.MULTIPLE,new String[] { "CMWAP" }, null);urlTF = new TextField("请输入网址：","http://avatar.csdn.net/5/F/0/2_kf156.jpg", 100, TextField.URL);form.append(cmwapCG);form.append(urlTF);// form.append(si);form.addCommand(connect);form.addCommand(cls);// form.addCommand(cancel);form.addCommand(exit);form.setCommandListener(this);}protected void destroyApp(boolean b) {}protected void pauseApp() {}protected void startApp() {display.setCurrent(form);}public void commandAction(Command c, Displayable d) {if (c == connect) {// 联网if (checkError())return;// display.setCurrent(waitPage);http = new Http();new Thread(http).start();} else if (c == cancel) {// 取消http.cancel();http = null;display.setCurrent(form);} else if (c == back) {// 返回page.deleteAll();display.setCurrent(form);} else if (c == cls) {// 清除数据// cls();urlTF.setString("");} else if (c == exit) {// 退出destroyApp(true);notifyDestroyed();}}// private void cls() {// form.deleteAll();// 删除日志// sb.delete(0, sb.length());// si.setText(null);// form.append(cmwapCG);// form.append(urlTF);// form.append(si);// }/** * 判断是否正确 * * @return */private boolean checkError() {url = urlTF.getString();if (state == CONNECT) {addStr("当前已有网络连接，请稍候");return true;} else if (url == null || url.trim().equals("")) {addStr("url不能为空");return true;}if (!url.toLowerCase().startsWith("http://")) {// 添加http://url = "http://" + url;}System.out.println(url);return false;}/** * 添加文字 * * @param str * 要添加的文字 */private void addStr(String str) {// sb.append(str + "/n");// si.setText(sb.toString());System.out.println(str);}/** * 获取URL域名 * * @param srcUrl * @param domain * true为截域名，false为截地址 * @return */private String getURLhost(String srcUrl) {int k = srcUrl.toLowerCase().indexOf("/", 7);if (k == -1)return srcUrl.substring(7);return srcUrl.substring(7, k);}/** * * 字符串替换方法(字符串替换字符串) * * @author kf156 * * @param text * 文本 * @param oldStr * 旧字符串 * @param newStr * 新字符串 * @return */public static String replace(String text, String oldStr, String newStr) {int oldLen = oldStr.length();int k = 0;while (k + oldLen <= text.length()) {// 检测到字符串末尾k = text.indexOf(oldStr, k);// 从k处查找oldStr，并返回位置if (k == -1)// 若查不到，则跳出return text;// 若有，则将其替换为newStrtext = text.substring(0, k) + newStr+ text.substring(k += oldLen, text.length());}return text;}class Http implements Runnable {HttpConnection http;boolean cancel;// 是否取消public void cancel() {cancel = true;state = WAIT;// 等待状态}public void run() {// cls();state = CONNECT;addStr("网络连接中...");InputStream is = null;try {boolean cmwap = cmwapCG.isSelected(0);// 是否走CMWAPString host = getURLhost(url);System.out.println(host);String _url = cmwap ? replace(url, host, "10.0.0.172:80") : url;http = (HttpConnection) Connector.open(_url, Connector.READ,true);if (cmwap)http.setRequestProperty("X-Online-Host", host);http.setRequestMethod(HttpConnection.GET);cmwapCG.setSelectedIndex(0, true);String contentType = http.getHeaderField("Content-Type");// System.out.println(contentType);addStr("Content-Type=" + contentType);if (cancel) {// 中途结束addStr("已取消");return;}if (contentType != null&& contentType.indexOf("text/vnd.wap.wml") != -1) {// 过滤移动资费页面addStr("移动资费页面，过滤！");http.close();http = null;http = (HttpConnection) Connector.open(_url,Connector.READ, true);if (cmwap)http.setRequestProperty("X-Online-Host", host);http.setRequestMethod(HttpConnection.GET);contentType = http.getHeaderField("Content-Type");addStr("Content-Type=" + contentType);}int code = http.getResponseCode();addStr("HTTP Code :" + code);if (code == 200) {// 成功addStr("网络联网成功，接收数据...");is = http.openInputStream();byte[] b = new byte[1024];int len = 0;ByteArrayOutputStream baos = new ByteArrayOutputStream();DataOutputStream dos = new DataOutputStream(baos);while ((len = is.read(b)) != -1) {if (cancel) {// 中途结束addStr("已取消");return;}dos.write(b, 0, len);}byte[] data = baos.toByteArray();if (contentType != null&& contentType.toLowerCase().indexOf("image") != -1) {// 图片try {Image image = Image.createImage(data, 0,data.length);addStr("数据接收完毕，显示图片");// form.append(image);page.append(image);} catch (Exception e) {addStr("生成图片失败 " + e.toString());page.append("生成图片失败 " + e.toString());}} else { // 文字addStr("数据接收完毕，显示内容");String s = null;if (contentType != null&& contentType.toLowerCase().indexOf("utf-8") != -1)s = new String(data, "UTF-8");elses = new String(data);// form.append(s);page.append(s);}data = null;dos.close();dos = null;baos.close();baos = null;is.close();is = null;state = SUCCESS;} else {addStr("访问页面失败");page.append("访问页面失败: " + code);state = FAIL;}} catch (IOException e) {addStr("联网发生异常：" + e.toString());e.printStackTrace();if (!cancel)page.append("网络异常：" + e.toString());state = FAIL;} catch (Exception e) {addStr("发生异常：" + e.toString());e.printStackTrace();if (!cancel)page.append("异常：" + e.toString());state = FAIL;} finally {if (is != null) {// 关闭istry {is.close();} catch (IOException e) {e.printStackTrace();}is = null;}if (http != null) {// 关闭httptry {http.close();} catch (IOException e) {e.printStackTrace();}http = null;}}if (!cancel)display.setCurrent(page);// 显示页面}}}  
 看看效果图，是从网络读取图片的效果

 

下面的代码是我用LWUIT改造的代码，代码可以自己修改一下，让代码结构更良好，可以把Http类抽出来。

import com.sun.lwuit.CheckBox;import com.sun.lwuit.Command;import com.sun.lwuit.Display;import com.sun.lwuit.Form;import com.sun.lwuit.Image;import com.sun.lwuit.Label;import com.sun.lwuit.TextField;import com.sun.lwuit.events.ActionEvent;import com.sun.lwuit.events.ActionListener;import java.io.ByteArrayOutputStream;import java.io.DataOutputStream;import java.io.IOException;import java.io.InputStream;import javax.microedition.io.Connector;import javax.microedition.io.HttpConnection;import javax.microedition.midlet.*;/** * @author 水货程序员 * Demo作为学习交流使用 */public class HttpTest extends MIDlet implements ActionListener { public static final byte WAIT = 0;//等待 public static final byte CONNECT = 1;//连接中 public static final byte SUCCESS = 2;//成功 public static final byte FAIL = 3;//失败 int state; Command connect = new Command("联网", 1); Command cls = new Command("清除网址", 2); Command cancel = new Command("取消", 3); Command exit = new Command("退出", 4); Command back = new Command("返回", 5); CheckBox cmwapCG;//接入方式 TextField urlTF;//网址输入框 String url;//网址 Http http;//网络线程 Form page;//页面 Form waitPage;//等待界面 public void actionPerformed(ActionEvent evt) { int cmdId = evt.getCommand().getId(); switch (cmdId) { case 1://连接 if (checkError()) { return; } http = new Http(); new Thread(http).start(); break; case 2://清除网址 urlTF.setText(""); break; case 3://取消 http.cancel(); http = null; showTestForm(); break; case 4://退出 destroyApp(true); notifyDestroyed(); break; case 5://返回 showTestForm(); break; } } /** * 在LWUIT的主类里面，Form不能声明为属性，否则会出现NullPointerException。 * 取得图片后，再返回时，重新new一下cmwapCB，urlTF，否则会报 * Component is already contained in Container的异常。 */ public void showTestForm() { Form form = new Form("HttpTest"); cmwapCG = new CheckBox("CMWAP"); urlTF = new TextField("http://avatar.csdn.net/5/F/0/2_kf156.jpg"); form.addComponent(cmwapCG); form.addComponent(urlTF); form.addCommand(connect); form.addCommand(cls); form.addCommand(exit); form.addCommandListener(this); form.show(); } public void startApp() { Display.init(this); state = WAIT;//等待 //waitPage = new Form() page = new Form("访问的页面"); page.addCommand(back); page.addCommandListener(this); cmwapCG = new CheckBox("CMWAP"); urlTF = new TextField("http://avatar.csdn.net/5/F/0/2_kf156.jpg"); url = urlTF.getText(); showTestForm(); } public void pauseApp() { } public void destroyApp(boolean unconditional) { } /** * 检验URL正确性 * @return */ private boolean checkError() { url = urlTF.getText(); if (state == CONNECT) { System.out.println("当前已有网络连接，请稍后"); return true; } else if (url == null || url.trim().equals("")) { return true; } if (!url.toLowerCase().startsWith("http://")) { // 添加http:// url = "http://" + http; } System.out.println(url); return false; } /** * 获取URL域名 * 例如http://www.google.cn，域名为www.google.cn * http://blog.csdn.net/pjw100,域名为blog.csdn.net，会把/pjw100截掉。 * @param srcUrl * @return */ private String getURLhost(String srcUrl) { int k = srcUrl.toLowerCase().indexOf("/", 7); if (k == -1) { return srcUrl.substring(7); } return srcUrl.substring(7, k); } public static String replace(String text, String oldStr, String newStr) { int oldLen = oldStr.length(); int k = 0; while (k + oldLen < text.length()) {//检测到字符串末尾 k = text.indexOf(oldStr, k);//查找字符串 if (k == -1) {//若查不到，跳出 return text; } //有则替换 text = text.substring(0, k) + newStr + text.substring(k += oldLen, text.length()); } return text; } class Http implements Runnable { HttpConnection http; boolean cancel;//是否取消 public void cancel() { cancel = true; state = WAIT;//等待状态 } public void run() { state = CONNECT; System.out.println("网络连接中..."); InputStream is = null; try { boolean cmwap = cmwapCG.isSelected(); String host = getURLhost(url); System.out.println(host); String _url = cmwap ? replace(url, host, "10.0.0.172:80") : url; http = (HttpConnection) Connector.open(_url, Connector.READ, true); if (cmwap) { http.setRequestProperty("X-Online-Host", host); } http.setRequestMethod(HttpConnection.GET); String contentType = http.getHeaderField("Content-Type"); if (cancel) {//中途取消 return; } if (contentType != null && contentType.indexOf("text/vnd.wap.wml") != -1) { //过滤移动资费 http.close(); http = null; http = (HttpConnection) Connector.open(_url, Connector.READ, true); if (cmwap) { http.setRequestProperty("X-Online-Host", host); } http.setRequestMethod(HttpConnection.GET); contentType = http.getHeaderField("Content-Type"); } int code = http.getResponseCode(); if (code == 200) {//联网成功 is = http.openInputStream(); byte[] b = new byte[1024]; int len = 0; ByteArrayOutputStream baos = new ByteArrayOutputStream(); DataOutputStream dos = new DataOutputStream(baos); while ((len = is.read(b)) != -1) { if (cancel) { //取消 return; } dos.write(b, 0, len); } byte[] data = baos.toByteArray(); if (contentType != null && contentType.toLowerCase().indexOf("image") != -1) { try { Image image = Image.createImage(data, 0, data.length); System.out.println("数据接收完毕，显示图片"); Label l = new Label(image); page.addComponent(l); } catch (Exception ex) { System.out.println("生成图片失败" + ex.toString()); Label err = new Label("生成图片失败" + ex.toString()); page.addComponent(err); } } else {//文字 System.out.println("数据接收完毕，显示内容"); String s = null; if (contentType != null && contentType.toLowerCase().indexOf("utf-8") != -1) { s = new String(data, "UTF-8"); } else { s = new String(data); } page.addComponent(new Label(s)); } data = null; dos.close(); dos = null; baos.close(); baos = null; is.close(); is = null; state = SUCCESS; } else { page.addComponent(new Label("访问页面失败：" + code)); state = FAIL; } } catch (IOException ex) { System.out.println("联网发生异常:" + ex.toString()); ex.printStackTrace(); if (!cancel) { page.addComponent(new Label("网络异常：" + ex.toString())); } state = FAIL; } catch (Exception ex) { System.out.println("发生异常" + ex.toString()); ex.printStackTrace(); if (!cancel) { page.addComponent(new Label("异常：" + ex.toString())); } state = FAIL; } finally { if (is != null) {//关闭is try { is.close(); } catch (IOException ex) { ex.printStackTrace(); } is = null; } if (http != null) {//关闭http try { http.close(); } catch (IOException ex) { ex.printStackTrace(); } http = null; } } if (!cancel) { page.show(); } } }}