Java中的Http连接

使用http链接, 访问网站的json数据并转换成实体类对象

API接口官网: http://www.tngou.net/

    public static<T> T getDataFromHttp(String url, String method, Map<String, ?> parameter, Class<T> type){StringBuilder builder = new StringBuilder();Set<? extends Map.Entry<String, ?>> set = parameter.entrySet();for (Map.Entry<String, ?> stringEntry : set) {builder.append(stringEntry.getKey()).append("=").append(stringEntry.getValue()).append("&");}builder.deleteCharAt(builder.length() - 1);//删掉最后一个&符号if (method.equals("GET")) {url = url + "?" + builder.toString();}try {HttpURLConnection connection =  (HttpURLConnection) new URL(url).openConnection();connection.setRequestMethod(method);connection.setDoInput(true);if (method.equals("POST")) {connection.setDoOutput(true);OutputStream os = connection.getOutputStream();os.write(builder.toString().getBytes("UTF-8"));}int code = connection.getResponseCode();if (code == 200) {InputStream is = connection.getInputStream();byte[] buffer = new byte[102400];int length;ByteArrayOutputStream bos = new ByteArrayOutputStream();while ((length = is.read(buffer)) != -1) {bos.write(buffer, 0, length);}String json = bos.toString("UTF-8");Gson gson = new Gson();return gson.fromJson(json, type);}} catch (Exception e) {e.printStackTrace();}return null;}

文件下载, 支持断线续传, 显示进度条和下载

package org.lulu.learn;import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
/*** Project: Day17_HTTP* Created: Lulu* Date: 2016/8/18*/
public class DownloadTest {public static void main(String[] args) {try {File file = new File("res/NeoImaging_Setup.exe");HttpURLConnection connection = (HttpURLConnection) new URL("http://skycnxz2.wy119.com//4/NeoImaging_Setup.zip").openConnection();connection.setRequestMethod("GET");//进度条设置long sum = 0;if (file.exists()) {sum = file.length();//bytes=0- 表示起始位置到末尾connection.setRequestProperty("Range", "bytes=" + file.length() + "-" );}int code = connection.getResponseCode();
//            System.out.println("code=" + code);if (code == 200 || code == 206) {
//                //获取得到头部数据
//                Map<String, List<String>> fields = connection.getHeaderFields();
//                Set<Map.Entry<String, List<String>>> entries = fields.entrySet();
//                for (Map.Entry<String, List<String>> entry : entries) {//                    System.out.println(entry.getKey() + ":" + entry.getValue());
//                }/*Accept-Ranges [bytes]: (有该项)说明支持断点下载, 不一定从头部去下载Content-Length:[34493195]： 文件长度, 有长度不一定支持断点下载, 没有长度一定不支持断点下载*///获取文件长度int contentLength = connection.getContentLength();contentLength += sum;InputStream is = connection.getInputStream();FileOutputStream fos = new FileOutputStream(file, true);//apend将是否续写设置为truebyte[] buffer = new byte[102400];int length;long startTime = System.currentTimeMillis();while ((length = is.read(buffer)) != -1) {fos.write(buffer, 0, length);sum += length;float percent = sum * 100.0f / contentLength;System.out.print("\r[");int p = (int) (percent / 2);for (int i = 0; i < 50; i++) {if (i < p) {System.out.print("=");} else if (i == p) {System.out.print(">");} else {System.out.print(" ");}}System.out.print("]");System.out.printf("\t%.2f%%", percent);//速度显示long speed = sum * 1000 / (System.currentTimeMillis() - startTime);if (speed > (1 << 20)) {//1024 * 1024System.out.printf("\t%d MB/s", speed >> 20);} else if (speed > (1 << 10)){System.out.printf("\t%d KB/s", speed >> 10);} else {System.out.printf("\t%d B/s", speed);}}}} catch (Exception e) {e.printStackTrace();}}
}

执行效果

多线程下载

DownloadRunnable .java

package org.lulu.learn;import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;/*** Project: Day17_HTTP* Created: Lulu* Date: 2016/8/18*/
public class DownloadRunnable implements Runnable {private String url;//需要保存的文件private File file;//开始的位置和终止的位置private int start;private int end;public DownloadRunnable(String url, File file, int start, int end) {this.url = url;this.file = file;this.start = start;this.end = end;}@Overridepublic void run() {try {HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();connection.setRequestMethod("GET");connection.setRequestProperty("Range", "bytes=" + start + "-" + end);RandomAccessFile accessFile = new RandomAccessFile(file, "rw");//将位置移动到start位置accessFile.seek(start);int code = connection.getResponseCode();if (code == 206) {InputStream is = connection.getInputStream();byte[] buffer = new byte[102400];int length;while ((length = is.read(buffer)) != -1) {accessFile.write(buffer, 0, length);}}System.out.println("下载完成" + start);} catch (IOException e) {e.printStackTrace();}}
}

ThreadDownload.java

/*** Project: Day17_HTTP* Created: Lulu* Date: 2016/8/18* 多线程下载* 多线程下载*/
public class ThreadDownload {public static void main(String[] args) {try {String url = "http://skycnxz3.wy119.com/OrcsMustDie2Tr.zip";File file = new File("res/game.zip");HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();connection.setRequestMethod("GET");int contentLength = connection.getContentLength();int range = contentLength / 5;//分成5块. 最后一个线程下载完for (int i = 0; i < 5; i++) {int start = i * range;int end = start + range;if (i == 4) {//如果是最后一个end = contentLength-1;}new Thread(new DownloadRunnable(url, file, start, end)).start();}} catch (IOException e) {e.printStackTrace();}}
}

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