自己写一个读取Arcgis Server切片的后台服务

概述：

Arcgis Server的切片得要有Arcgis Server的支持才能使用，这样就显得比较麻烦，如果对于已经切好的切片怎么样通过自己写的程序来调用展示呢，本文讲解的内容就是这些。

Arcgis 切片简介:

Arcgis Server的切片分为两种：松散型和紧凑型。松散型，就是以单个的jpg或者png文件形式存储；紧凑型，是将多个切片文件制作成一组bundle和bundlx文件，其中bundlx存储的是切片的索引，bundle存储的是切片本身。在10的版本之前，Arcgis只支持松散型的切片方式，紧凑型是在Arcgis10的版本之后才出现的。

实现方式：

1、后台读取

后台写了一个比较简单的servlet来实现切片的读取，其中实现参考了下两篇文章中的内容，最终的实现代码如下：

package com.lzugis.servlet;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.codec.binary.Base64;

import com.lzugis.tile.helper.CommonConfig;

/**
 * Servlet implementation class TileServlet
 */
@WebServlet(description = "get arcgis offline tile", urlPatterns =  {"/agstile"})
public class AgsOffTilesServiceServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	private String rootPath = "";
	private static String base64Blank = "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";
	
    /**
     * @see HttpServlet#HttpServlet()
     */
    public AgsOffTilesServiceServlet() {
        super();
        // TODO Auto-generated constructor stub
        try{
        	//切片存储路径
			rootPath = CommonConfig.getVal("tile.agspath")+File.separator;
        }
        catch(Exception e){
        	e.printStackTrace();
        }
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		this.doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	@SuppressWarnings("resource")
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String x= request.getParameter("x");
        String y= request.getParameter("y");
        String z= request.getParameter("z");
        String layer= request.getParameter("layer");
        String type= request.getParameter("type");//file为紧凑型，image为松散型
        String tilePath = rootPath+layer+"/Layers/_alllayers";
        int level = Integer.parseInt(z);
        int row = Integer.parseInt(x);
        int col = Integer.parseInt(y);
        try {
        	OutputStream os = response.getOutputStream();
        	byte[] output = null;
        	int outlength = 0;
        	if(type.equals("file")){//紧凑型
	            String l = "L" + getZero(2,z.length()) + level;
	
	            int rGroup = 128 * (row / 128);
	            String rTail = Integer.toHexString(rGroup);
	            String r = "R" + getZero(4,rTail.length()) +rTail ;
	
	            int cGroup = 128 * (col / 128);
	            String cTail = Integer.toHexString(cGroup);
	            String c = "C" + getZero(4,cTail.length()) + cTail;
	            String bundleBase = String.format("%s/%s/%s%s", tilePath, l, r, c);
	            String bundleFileName = bundleBase + ".bundle";
	            String bundlxFileName = bundleBase + ".bundlx";
	
	            File file = new File(bundleFileName);
	            
	            if(file.exists()){
		            int index = 128 * (col - cGroup) + (row - rGroup);
					FileInputStream isBundlx = new FileInputStream(bundlxFileName);
		            isBundlx.skip(16 + 5 * index);
		            byte[] buffer = new byte[5];
		            isBundlx.read(buffer);
		            long offset = (long)(buffer[0]&0xff) + (long)(buffer[1]&0xff)*256 + (long)(buffer[2]&0xff)*65536 + (long)(buffer[3]&0xff)*16777216+ (long)(buffer[4]&0xff)*4294967296L;
		            FileInputStream isBundle = new FileInputStream(bundleFileName);
		            isBundle.skip(offset);
		            byte[] lengthBytes = new byte[4];
		            isBundle.read(lengthBytes);
		            int length = (int)(lengthBytes[0]&0xff)+ (int)(lengthBytes[1]&0xff)*256	+ (int)(lengthBytes[2]&0xff)*65536+ (int)(lengthBytes[3]&0xff)*16777216;
		            byte [] result = new byte[length];
		            isBundle.read(result);
		            if(result.length>0){
		                output = result;
		                outlength = length;
		            }
	            }
	            else{
	            	byte[] blankImg = Base64.decodeBase64(base64Blank);
	            	InputStream is = new ByteArrayInputStream(blankImg); 
	            	int count=0;
	            	while ((count = is.read(blankImg)) != -1) {
	                    output = blankImg;
		                outlength = count;
	                }
	            }
        	}
        	else{//松散型
        		String l = "L" + getZero(2,z.length()) + level;
                
                String strRow = Integer.toHexString(row);        
                String r = "R" +getZero(8,strRow.length())+ strRow;
                
                String strCol = Integer.toHexString(col);
                String c = "C"+getZero(8,strCol.length()) + strCol;
                
                String imgfile = tilePath+l+"/"+r+"/"+c+".png";
                
                InputStream is = null;
                
                File file = new File(imgfile);
                if(!file.exists()){
                	imgfile = tilePath+l+"/"+r+"/"+c+".jpg";
                	file = new File(imgfile);
                	 if(!file.exists()){
                		 byte[] blankImg = Base64.decodeBase64(base64Blank);
                		 is=new ByteArrayInputStream(blankImg); 
                	 }
                	 else{
                		 is = new FileInputStream(imgfile);
                	 }
                } 
                else{
                	is = new FileInputStream(imgfile);
                }
                int count = 0;
            	byte[] buffer = new byte[1024 * 1024];
            	while ((count = is.read(buffer)) != -1) {
                    output = buffer;
	                outlength = count;
                }
        	}
        	os.write(output, 0, outlength);
        	os.flush();
            os.close();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
	}
	private String getZero(int length,int strLength){
		int zeroLength = length-strLength;
		String strZero = "";
		for(int i=0;i<zeroLength;i++){
			strZero+="0";
		}
		return strZero;
	}
}

2、前台调用（Openlayers2）

为方便调用展示，扩展了一个Openlayers的图层类，代码如下：

OpenLayers.Layer.AgsTileLayer = OpenLayers.Class(OpenLayers.Layer.XYZ, {
    url: null,
    tileOrigin: null,
    tileSize: new OpenLayers.Size(256, 256),
    type: 'png',
    useScales: false,
    overrideDPI: false,
    useArcgisServer:false,
    cachetype:"file",//file为紧凑型，image为松散型
    initialize: function(name, url, options) { 
        OpenLayers.Layer.XYZ.prototype.initialize.apply(this, arguments);
    },
    getURL: function (bounds) {
        var res = this.getResolution();
        var originTileX = (this.tileOrigin.lon + (res * this.tileSize.w/2));
        var originTileY = (this.tileOrigin.lat - (res * this.tileSize.h/2));
        var center = bounds.getCenterLonLat();
        var y = (Math.round(Math.abs((center.lon - originTileX) / (res * this.tileSize.w))));
        var x = (Math.round(Math.abs((originTileY - center.lat) / (res * this.tileSize.h))));
        var z = this.map.getZoom();
        var url = this.url;
        var s = '' + x + y + z;
        if (OpenLayers.Util.isArray(url)) {
            url = this.selectUrl(s, url);
        }
        url = url + '?layer=${layer}&type=${type}&x=${x}&y=${y}&z=${z}';
        url = OpenLayers.String.format(url, {'layer': this.name,'type': this.cachetype,'x': x, 'y': y, 'z': z});
        return OpenLayers.Util.urlAppend(
            url, OpenLayers.Util.getParameterString(this.params)
        );
    },

    CLASS_NAME: 'OpenLayers.Layer.AgsTileLayer'
}); 

前台页面中的调用代码如下：

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title>openlayers map</title>
    <link rel="stylesheet" href="../../../plugin/OpenLayers-2.13.1/theme/default/style.css" type="text/css">
    <style>
        html, body,#map{
            padding:0;
            margin:0;
            height:100%;
             100%;
            overflow: hidden;
        }
    </style>
    <script src="../../../plugin/OpenLayers-2.13.1/OpenLayers.js"></script>
    <script src="../../../plugin/jquery/jquery-1.8.3.js"></script>
    <script src="extend/AgsOffTileLayer.js"></script>
    <script>
        var map;
        var tiled;
        $(window).load(function() {
            var bounds = new OpenLayers.Bounds(
                    73.45100463562233, 18.16324718764174,
                    134.97679764650596, 53.531943152223576
            );
            var options = {
                controls: [],
                maxExtent: bounds,
                maxResolution: 0.2403351289487642,
                projection: "EPSG:4326",
                units: 'degrees'
            };
            map = new OpenLayers.Map('map', options);
            OpenLayers.INCHES_PER_UNIT["千米"] = OpenLayers.INCHES_PER_UNIT["km"];
            OpenLayers.INCHES_PER_UNIT["米"] = OpenLayers.INCHES_PER_UNIT["m"];
            OpenLayers.INCHES_PER_UNIT["英里"] = OpenLayers.INCHES_PER_UNIT["mi"];
            OpenLayers.INCHES_PER_UNIT["英寸"] = OpenLayers.INCHES_PER_UNIT["ft"];
            //比例尺
            map.addControl(new OpenLayers.Control.ScaleLine({topOutUnits:"米",topOutUnits:"千米"}));
            $(".olControlScaleLineBottom").hide();
            map.addControl(new OpenLayers.Control.Zoom());
            map.addControl(new OpenLayers.Control.Navigation());
            tiled = new OpenLayers.Layer.AgsTileLayer( "chinashp",
                    "http://localhost:8081/tile/agstile", {
                        isBaseLayer: true,
                        tileSize: new OpenLayers.Size(256, 256),
                        resolutions: [
                            0.15228550437313793,
                            0.07614275218656896,
                            0.03807137609328448,
                            0.01903568804664224,
                            0.00951784402332112,
                            0.00475892201166056,
                            0.00237946100583028
                        ],
                        tileOrigin: new OpenLayers.LonLat(-400 , 400),
                        maxExtent: bounds,
                        projection: 'EPSG:4326'
                    });
            map.addLayers([tiled]);
            map.zoomToExtent(bounds);
        });
    </script>
</head>
<body>
<div id="map" style=" 100%;"></div>
</body>
</html>`

注意：在前台页面调用的时候，有两个参数：分辨率组（resolutions）和切片原点（tileOrigin）。这两个参数是从服务的配置中获取的，你可以从服务配置文件Conf.xml中读取，Conf.xml文件位于“切片路径Layers”文件夹下，内容如下：

<?xml version="1.0" encoding="utf-8"?>

<CacheInfo xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:typens="http://www.esri.com/schemas/ArcGIS/10.1" xsi:type="typens:CacheInfo">
  <TileCacheInfo xsi:type="typens:TileCacheInfo">
    <SpatialReference xsi:type="typens:GeographicCoordinateSystem">
      <WKT>GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433],AUTHORITY["EPSG",4326]]</WKT>
      <XOrigin>-400</XOrigin>
      <YOrigin>-400</YOrigin>
      <XYScale>11258999068426.24</XYScale>
      <ZOrigin>-100000</ZOrigin>
      <ZScale>10000</ZScale>
      <MOrigin>-100000</MOrigin>
      <MScale>10000</MScale>
      <XYTolerance>8.983152841195215e-009</XYTolerance>
      <ZTolerance>0.001</ZTolerance>
      <MTolerance>0.001</MTolerance>
      <HighPrecision>true</HighPrecision>
      <LeftLongitude>-180</LeftLongitude>
      <WKID>4326</WKID>
      <LatestWKID>4326</LatestWKID>
    </SpatialReference>
    <TileOrigin xsi:type="typens:PointN">
      <X>-400</X>
      <Y>399.99999999999977</Y>
    </TileOrigin>
    <TileCols>256</TileCols>
    <TileRows>256</TileRows>
    <DPI>96</DPI>
    <PreciseDPI>96</PreciseDPI>
    <LODInfos xsi:type="typens:ArrayOfLODInfo">
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>0</LevelID>
        <Scale>64000000</Scale>
        <Resolution>0.15228550437313793</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>1</LevelID>
        <Scale>32000000</Scale>
        <Resolution>0.076142752186568963</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>2</LevelID>
        <Scale>16000000</Scale>
        <Resolution>0.038071376093284481</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>3</LevelID>
        <Scale>8000000</Scale>
        <Resolution>0.019035688046642241</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>4</LevelID>
        <Scale>4000000</Scale>
        <Resolution>0.0095178440233211203</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>5</LevelID>
        <Scale>2000000</Scale>
        <Resolution>0.0047589220116605602</Resolution>
      </LODInfo>
      <LODInfo xsi:type="typens:LODInfo">
        <LevelID>6</LevelID>
        <Scale>1000000</Scale>
        <Resolution>0.0023794610058302801</Resolution>
      </LODInfo>
    </LODInfos>
  </TileCacheInfo>
  <TileImageInfo xsi:type="typens:TileImageInfo">
    <CacheTileFormat>PNG</CacheTileFormat>
    <CompressionQuality>0</CompressionQuality>
    <Antialiasing>false</Antialiasing>
  </TileImageInfo>
  <CacheStorageInfo xsi:type="typens:CacheStorageInfo">
    <StorageFormat>esriMapCacheStorageModeCompact</StorageFormat>
    <PacketSize>128</PacketSize>
  </CacheStorageInfo>
</CacheInfo>

实现效果：

参考文献：

http://www.cnblogs.com/yuantf/p/3320876.html

http://blog.csdn.net/wankehui165/article/details/49489703

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