httpthread.java

J2ME图像处理演示程序,演示图像转换个效果

/**
 * 
 * @author Sam Huang
 *
 */

import java.io.IOException;
import java.io.InputStream;

import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;

/**
 * 
 * 下载图片的线程类
 * 
 */
public class HttpThread extends Thread {

	private static final int MAX_LENGTH = 30 * 1024; // 30K

	private boolean userInterrupted = false;

	private String url;

	private byte[] buffer = null;

	private IHttpListener listener;

	public HttpThread(String url, IHttpListener listener) {
		this.url = url;
		this.listener = listener;
	}

	public void setUserInterrupted() {
		this.userInterrupted = true;
	}

	public void run() {
		getDataFromUrl(url);
	}

	private void getDataFromUrl(String url) {

		InputStream is = null;
		HttpConnection c = null;
		try {
			listener.onProgress(0);
			// 使用代理
			//System.out.println(ImageAlbum.getConnectionMethod());
			if (ImageAlbum.getConnectionMethod().equals("cmwap")) {
				c = (HttpConnection) Connector.open(url);
				c.setRequestProperty("X-Online-Host", "www.the3gwireless.com");
			} else {
				// 不使用代理
				StringBuffer sb = new StringBuffer(url.substring(0, url
						.indexOf("10.0.0.172")));
				sb.append("www.the3gwireless.com");
				sb.append(url.substring(sb.length()
						- "www.the3gwireless.com".length()
						+ "10.0.0.172".length(), url.length()));
				url = sb.toString();
				c = (HttpConnection) Connector.open(url);
			}
			// 默认即为GET
			c.setRequestMethod(HttpConnection.GET);

			// 获得响应码, 200表示成功
			int code = c.getResponseCode();
			if (code > HttpConnection.HTTP_OK) {
				listener.onError(code, c.getResponseMessage());
				return;
			}
			// 返回响应大小，或者-1如果大小无法确定，我是在WTK上测试通过的，每次都返回正确的尺寸，因此返回-1的代码我不知道是否正确,如有错请帮助改正
			int size = (int) c.getLength();
			int leftSize = 0;
			int loopCount = 0;
			if (size != -1) {
				leftSize = size;
				listener.onSetSize(size);
			} else {
				// 不知道大小,只好什么也不做,
			}
			// 开始读响应：
			is = c.openInputStream();
			int percent = 0; // 百分比
			int tmp_percent = 0;
			int index = 0; // 缓冲区索引
			int reads; // 读取的字节数
			if (size != -1) {
				// 响应大小已知，确定缓冲区大小
				buffer = new byte[size];
			} else {// 响应大小未知，设定一个固定大小的缓冲区
				buffer = new byte[MAX_LENGTH];
			}
			while (!userInterrupted) {
				int len = buffer.length - index;
				// 每次读取128个字节
				len = len > 128 ? 128 : len;
				try {
					reads = is.read(buffer, index, len);
				} catch (Exception e) {
					break;
				}
				// reads<0表示已经读完所有数据,退出循环
				if (reads <= 0)
					break;
				index += reads;
				// 更新进度
				if (size != -1) {
					leftSize = size - index;
					tmp_percent = index * 100 / size;
					if (tmp_percent != percent) {
						percent = tmp_percent;
						listener.onProgress(percent);
					}
					// 设置已经读取的尺寸
					listener.onSetSize(leftSize);
				} else {
					// 由于尺寸未知,所以是假的进度条,不过至少表示正在下载数据
					percent = loopCount++ / 3;
					listener.onProgress(percent);
				}
			}
			if (!userInterrupted && is.available() > 0) // 缓冲区已满，无法继续读取
				listener.onError(-1, "缓冲区溢出");
			if (!userInterrupted) {
				if (size != -1 && index != size)
					listener.onError(-2, "内容不匹配");
				else
					listener.onFinish(buffer, index);
			}
		} catch (IOException ioe) {
			listener.onError(-3, "发生 IOException" + ioe.getMessage());
		} finally { // 清理资源
			if (is != null)
				try {
					is.close();
				} catch (IOException ioe) {
				}
			if (c != null)
				try {
					c.close();
				} catch (IOException ioe) {
				}
		}
	}
}