利用线程池下载百度地图瓦片图

　　继上一文章,百度地图离线功能,这里主要讲述下载瓦片图具体方法。

　　1.利用全能电子地图下载带水印的瓦片图。其中文件夹路径为tile/层级/x/y.jpg，如下图所示，全能电子地图1.9下载的百度地图瓦片图是一个个黑点。

　　2.根据图片url下载图片，根据URL获取HttpURLConnection， 根据HttpURLConnection获取输入流InputStream ，在用输出流OutputStream out = new FileOutputStream(file);将字节写入文件即可。此方法为单线程下载，代码如下：

/**
 * 下载图片
 */
public class BaiDuMapDownload {
    static volatile Integer c = 0;//成功数
    static volatile Integer fail = 0;//失败数量

    public static void main(String[] args) throws Exception {
        String link = "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x={x}&y={y}&z={z}&styles=pl&udt=20170712&scaler=1&p=1";
        int z = 19;//层级
        int xmin = 103514;//x最小值
        int xmax = 104292;//x最大值
        int ymin = 29400;//y最小值
        int ymax = 30700;//y最大值
            for (int i = xmin; i <= xmax; i++) {   //循环X
                for (int j = ymin; j <= ymax; j++) {    //循环Y
                    try {

                        URL url = new URL(link.replace("{x}", i + "").replace("{y}", j + "").replace("{z}", z + ""));
                        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                        conn.setConnectTimeout(100);
                        conn.connect();
                        InputStream in = conn.getInputStream();
                        File dir = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i);
                        if (!dir.exists()) {
                            dir.mkdirs();
                        }
                        File file = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i + "/" + j + ".jpg");
                        if (!file.exists()) {
                            file.createNewFile();
                        }
                        OutputStream out = new FileOutputStream(file);
                        byte[] bytes = new byte[1024 * 20];
                        int len = 0;
                        while ((len = in.read(bytes)) != -1) {
                            out.write(bytes, 0, len);
                        }
                        out.close();
                        in.close();
                        //System.out.println("已成功下载:" + z + "_" + i + "_" + j + ".jpg");
                        c++;
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                        fail++;
                    }

                }    //循环Y结束
            }   //循环X结束
        Thread.sleep(1000);
        System.out.println("共下载:   " + c + "   张");
        System.out.println("失败:   " + fail + "   张");
    }
}

　　3.通过上面的代码就可以下载百度图片，但是很明显，上面代码是单线程，而且会IO阻塞，百度地图下载到第19级时有将近一百万的瓦片图。

线程池ThreadPoolExecutor优化下代码。本来两天才能下完的图时间缩减一天会感觉很棒。

/**
 * 线程池下载图片
 */
class BDTask implements Runnable{
    String link;
    int i;  //x坐标
    int j;  //y坐标
    int z;  //缩放级别

    static volatile Integer c = 0;//成功数
    static volatile Integer fail = 0;//失败数量

    public BDTask(String link, int i, int j, int z) {
        this.link = link;
        this.i = i;
        this.j = j;
        this.z = z;

    }
    public static void main(String[] args)
            throws Exception {
        String link = "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x={x}&y={y}&z={z}&styles=pl&udt=20170712&scaler=1&p=1";
        int z = 12;  //层级
        int xmin = 808; //x最小值
        int xmax = 814;  //x最大值
        int ymin = 230;  //y最小值
        int ymax = 239;  //y最大值
        //创建线程池,corePoolSize两条线程,最大存在四条线程,大于corePoolSize小于MaxmumPoolSize的线程等待空闲时间为500毫秒,任务队列LinkBlockingQueue不写时的默认值为Integer默认值.
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(2,4,500, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());
        for (int i = xmin; i <= xmax; i++) {   //循环X
            for (int j = ymin; j <= ymax; j++) {    //循环Y
                threadPoolExecutor.execute(new BDTask(link,i,j,z));
                //new Thread(new BDTask(link,i,j,z)).start();    //此种方法会一直创建线程导致死机
            }    //循环Y结束
        }   //循环X结束
        threadPoolExecutor.shutdown();   //关闭线程池
        while (!threadPoolExecutor.isTerminated()){}     //一直循环等到所有任务被执行完毕时继续往下执行
        System.out.println("共下载:   " + c + "   张");
        System.out.println("失败:   " + fail + "   张");
    }

    public void run() {
        try {
            URL url = new URL(link.replace("{x}", i + "").replace("{y}", j + "").replace("{z}", z + ""));
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(100);
            conn.connect();
            InputStream in = conn.getInputStream();
            File dir = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i);
            if (!dir.exists()) {
                dir.mkdirs();
            }
            File file = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i + "/" + j + ".jpg");
            if (!file.exists()) {
                file.createNewFile();
            }
            OutputStream out = new FileOutputStream(file);
            byte[] bytes = new byte[1024 * 20];
            int len = 0;
            while ((len = in.read(bytes)) != -1) {
                out.write(bytes, 0, len);
            }
            out.close();
            in.close();
            synchronized (fail) {
                c++;
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
            synchronized (c) {
                fail++;
            }
        }
    }
}

包装一下方便使用

　　其中，baiduMap.properties的link为下载地址，rootDir为存储地址

　　BaiDuMapDownloadByThreadPool.java代码如下

 

package com.autumn.dao;

import java.io.File;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Properties;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 * 下载图片
 */
public class BaiDuMapDownloadByThreadPool {
    public static void main(String[] args)
            throws Exception {

        //根据properties文件配置url和存储路径
        Properties properties = new Properties();
        File file = new File("classpath:baiduMap.properties");
        InputStream inputStream = BaiDuMapDownloadByThreadPool.class.getResourceAsStream("baiduMap.properties");
        //判断是否有此文件
        if (inputStream!=null) {
            properties.load(inputStream);
            String link = properties.getProperty("link");
            if (link!=null&&!link.isEmpty()){
                BDTask.link=link;
            }
            String rootDir = properties.getProperty("rootDir");
            if (rootDir!=null&&!rootDir.isEmpty()){
                BDTask.rootDir=rootDir;
            }
        }

        BDTask.startDownload();
    }
}

/**
 * 线程池下载图片
 */
class BDTask implements Runnable {
    //正常百度地图String link = "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x={x}&y={y}&z={z}&styles=pl&udt=20170712&scaler=1&p=1";
    //午夜蓝版
    static String link ="http://api0.map.bdimg.com/customimage/tile?&x={x}&y={y}&z={z}&udt=20180711&scale=1&ak=0F7691e465f5d7d161a4771f48ee38ff&styles=t%3Awater%7Ce%3Aall%7Cc%3A%23021019%2Ct%3Ahighway%7Ce%3Ag.f%7Cc%3A%23000000%2Ct%3Ahighway%7Ce%3Ag.s%7Cc%3A%23147a92%2Ct%3Aarterial%7Ce%3Ag.f%7Cc%3A%23000000%2Ct%3Aarterial%7Ce%3Ag.s%7Cc%3A%230b3d51%2Ct%3Alocal%7Ce%3Ag%7Cc%3A%23000000%2Ct%3Aland%7Ce%3Aall%7Cc%3A%2308304b%2Ct%3Arailway%7Ce%3Ag.f%7Cc%3A%23000000%2Ct%3Arailway%7Ce%3Ag.s%7Cc%3A%2308304b%2Ct%3Asubway%7Ce%3Ag%7Cl%3A-70%2Ct%3Abuilding%7Ce%3Ag.f%7Cc%3A%23000000%2Ct%3Aall%7Ce%3Al.t.f%7Cc%3A%23857f7f%2Ct%3Aall%7Ce%3Al.t.s%7Cc%3A%23000000%2Ct%3Abuilding%7Ce%3Ag%7Cc%3A%23022338%2Ct%3Agreen%7Ce%3Ag%7Cc%3A%23062032%2Ct%3Aboundary%7Ce%3Aall%7Cc%3A%231e1c1c%2Ct%3Amanmade%7Ce%3Ag%7Cc%3A%23022338%2Ct%3Apoi%7Ce%3Aall%7Cv%3Aoff%2Ct%3Aall%7Ce%3Al.i%7Cv%3Aoff%2Ct%3Aall%7Ce%3Al.t.f%7Cv%3Aon%7Cc%3A%232da0c6";;
    static String rootDir = "d:/mybaidumapdownload1";

    int i;  //x坐标
    int j;  //y坐标
    int z;  //缩放级别

    static volatile Integer c = 0;//成功数
    static volatile Integer fail = 0;//失败数量

    public BDTask(String link, int i, int j, int z) {
        this.link = link;
        this.i = i;
        this.j = j;
        this.z = z;

    }

    public static void startDownload() {
        ThreadPoolExecutor threadPoolExecutor = null;
        long start = 0L;
        for(Level c : Level.values()){
            int z = c.getLevel();
            int xmin = c.getX_min();
            int xmax = c.getX_max();
            int ymin = c.getY_min();
            int ymax = c.getY_max();
            start = System.currentTimeMillis();    //开始时间
            threadPoolExecutor = new ThreadPoolExecutor(2, 4, 500, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>());
            for (int i = xmin; i <= xmax; i++) {   //循环X
                for (int j = ymin; j <= ymax; j++) {    //循环Y
                    threadPoolExecutor.execute(new BDTask(link, i, j, z));  //下载图片
                    //new Thread(new BDTask(link,i,j,z)).start();    //此种方法会一直创建线程导致死机
                        /*try {
                            URL url = new URL(link.replace("{x}", i + "").replace("{y}", j + "").replace("{z}", z + ""));
                            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                            conn.setConnectTimeout(100);
                            conn.connect();
                            InputStream in = conn.getInputStream();
                            File dir = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i);
                            if (!dir.exists()) {
                                dir.mkdirs();
                            }
                            File file = new File("d:/mybaidumapdownload1/tiles/" + z + "/" + i + "/" + j + ".jpg");
                            if (!file.exists()) {
                                file.createNewFile();
                            }
                            OutputStream out = new FileOutputStream(file);
                            byte[] bytes = new byte[1024 * 20];
                            int len = 0;
                            while ((len = in.read(bytes)) != -1) {
                                out.write(bytes, 0, len);
                            }
                            out.close();
                            in.close();
                            //System.out.println("已成功下载:" + z + "_" + i + "_" + j + ".jpg");
                            c++;
                        } catch (Exception e) {
                            System.out.println(e.getMessage());
                            fail++;
                        }*/
                }    //循环Y结束
            }   //循环X结束
        }

        threadPoolExecutor.shutdown();   //关闭线程池
        while (!threadPoolExecutor.isTerminated()) {
        }     //所有任务被执行完毕时继续往下执行
        System.out.println("-------用时-------:" + (System.currentTimeMillis() - start));
        System.out.println("共下载:   " + c + "   张");
        System.out.println("失败:   " + fail + "   张");
    }

    public void run() {
        try {
            URL url = new URL(link.replace("{x}", i + "").replace("{y}", j + "").replace("{z}", z + ""));
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setConnectTimeout(100);
            conn.connect();
            InputStream in = conn.getInputStream();

            File file = new File(rootDir+"/tiles/" + z + "/" + i + "/" + j + ".jpg");
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            file.createNewFile();

            OutputStream out = new FileOutputStream(file);
            byte[] bytes = new byte[1024 * 20];
            int len = 0;
            while ((len = in.read(bytes)) != -1) {
                out.write(bytes, 0, len);
            }
            out.close();
            in.close();
            synchronized (fail) {
                c++;
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
            synchronized (c) {
                fail++;
            }
        }
    }
}

/**
 * 枚举类型，这里所有的等级和xy轴数据为扬州的地图
 * 等级 x最小 x最大 y最小 y最大
 */
enum Level {
    Level_3(3, 1, 1, 0, 0),
    Level_4(4, 3, 3, 0, 0),
    Level_5(5, 6, 6, 1, 3),
    Level_6(6, 12, 12, 3, 3),
    Level_7(7, 25, 25, 7, 7),
    Level_8(8, 50, 50, 14, 14),
    Level_9(9, 101, 101, 28, 29),
    Level_10(10, 202, 203, 57, 59),
    Level_11(11, 404, 407, 115, 119),
    Level_12(12, 808, 814, 230,239),
    Level_13(13, 1617, 1629, 460, 480),
    Level_14(14, 3234, 3259, 920, 960),
    Level_15(15, 6469, 6518, 1840, 1920),
    Level_16(16, 12939, 13036, 3680, 3850),
    Level_17(17, 25878, 26073, 7360, 7670),
    Level_18(18, 51757, 52146, 14720,15400),
    Level_19(19, 103514, 104292, 29400,30700);

    private int level;
    private int x_min;
    private int x_max;
    private int y_min;
    private int y_max;

    Level(int level, int x_min, int x_max, int y_min, int y_max) {
        this.level = level;
        this.x_min = x_min;
        this.x_max = x_max;
        this.y_min = y_min;
        this.y_max = y_max;
    }

    public int getLevel() {
        return level;
    }

    public int getX_min() {
        return x_min;
    }

    public int getX_max() {
        return x_max;
    }

    public int getY_min() {
        return y_min;
    }

    public int getY_max() {
        return y_max;
    }
}

源码