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newStr
            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() {
            // cls();
            state = CONNECT;
            addStr("网络连接中...");
            InputStream is = null;
            try {
                boolean cmwap = cmwapCG.isSelected(0);// 是否走CMWAP
                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);
                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");
                        else
                            s = 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is
                    try {
                        is.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    is = null;
                }
                if (http != null) {// 关闭http
                    try {
                        http.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                    http = null;
                }
            }
            if (!cancel)
                display.setCurrent(page);// 显示页面
        }
    }
}

 

 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();
            }
        }
    }
}