(1)系統(tǒng)的復(fù)雜性。
(2)程序員的差異因素。
(3)代碼的維護工作。
(4)缺乏天才程序員的參與。
(5)項目管理方面的問題。
2009年2月16日 #
曲:顧嘉輝 詞:黃沾
浪奔浪流
萬里滔滔江水永不休
淘盡了世間事
混作滔滔一片潮流
是喜是愁
浪里分不清歡笑悲憂
成功失敗
浪里看不出有未有
愛你恨你
問君知否
似大江一發(fā)不收轉(zhuǎn)千彎轉(zhuǎn)千灘
亦未平復(fù)此中爭斗
又有喜又有愁
就算分不清歡笑悲憂仍愿翻百千浪
在我心中起伏夠
這是一個關(guān)于鷹的故事。
鷹是世界上壽命最長的鳥類,它一生的年齡可達70歲。
要活那么長的壽命,它在40歲時必須做出困難卻重要的決定。這時,它的喙變得又長又彎,幾乎碰到胸脯;它的爪子開始老化,無法有效地捕捉獵物;它的羽毛長得又濃又厚,翅膀變得十分沉重,使得飛翔十分吃力。
此時的鷹只有兩種選擇:要么等死,要么經(jīng)過一個十分痛苦的更新過程——150天漫長的蛻變。它必須很努力地飛到山頂,在懸崖上筑巢,并停留在那里,不得飛翔。
鷹首先用它的喙擊打巖石,直到其完全脫落,然后靜靜地等待新的喙長出來。鷹會用新長出的喙把爪子上老化的趾甲一根一根拔掉,鮮血一滴滴灑落。當(dāng)新的趾甲長出來后,鷹便用新的趾甲把身上的羽毛一根一根拔掉。
5個月以后,新的羽毛長出來了,鷹重新開始飛翔,重新再度過30年的歲月!
We also introduced some core JBI concepts:
SLD(Style Layer Descriptor)樣式層描述符
基于XML語言
創(chuàng)建樣式,相對比較簡單。
1. SLD Hello World
1.1 Create the SLD File----OK
1.2 Load Your New SLD ----OK
1.3 Give a FeatureType Your New SLD---OK
View the Style---OK
2. SLD Text Symbolizers 文本符號----OK 存在問題:使用中國地圖顯示異常,請求樣式不適用于圖層,進一步操作??????
Modify the SLD File to Include Text Symbolizers
<Label>: What label to give each rendered object. Here we use an attribute of the object, "TYPE". The property name is case sensitive. 標(biāo)簽
<Font>: The font and size the label will have. 字體
<Fill>: The color that we will fill the font with 填充
3. Outlines and Filters -----OK
<ogc:Filter>
<ogc:Not>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>TYPE</ogc:PropertyName>
<ogc:Literal>highway</ogc:Literal>
</ogc:PropertyIsEqualTo>
</ogc:Not>
</ogc:Filter>
<ogc:PropertyIsLessThan>
<ogc:PropertyIsGreaterThan>
The halo is essentially a buffer outline of the text. halo文本的暈環(huán)
4. What SLDs are, a text approach
SLD (Styled Layer Descriptor) is a specification put out by the OGC, that defines an XML language to allow users to define symbolization of their feature data. It was written to be a complement to their Web Map Service (WMS) specification, by extending it to allow users a way to define how they want to visualize their features.
Then there are 5 types of symbolizers you can use to actually portray the features,
(1)line, 線
(2)polygon, 多邊形
A Polygon Symbolizer has a geometry and a stroke, just like a line symbolizer, but also has a 'fill', defining what color to put in the center. Can be straight color, or a graphic, of varying opacity and the like.
(3)point, 點
A point symbolizer is made up of a geometry and a Graphic. A graphic is made of either an External Graphic, or a Mark, and has an opacity, a size, and a rotation. Opacity is the same as for the other symbolizers, Size is the absolute size of the graphic in pixels (default is to be dynamic), and rotation defines the rotation of the graphic in the clockwise dimension in decimal degrees. A Mark has a well known name (like square, circle, star, ect.), and a fill and a stroke. An External Graphic uses an xlink to refer to the location of an resource on the web to use to represent the point.
(4)text, 文本
A text symbolizer is made up of a Geometry, a Label, a Font, a LabelPlacement, a Halo, and a Fill.
(5)and raster. 光柵
A raster symbolizer consists of a Geometry(幾何學(xué)), opacity(透明度), channel selection(路線選擇), overlap behavior(交疊事件), color map(顏色地圖), contrast enhancement(對照增強), shaded relief(陰影浮雕) and image outline(圖像輪廓).
STEP 1. Start GeoServer and Login---- OK
用戶名:amdin
密 碼:geoserver
STEP 2. Create a DataStore -------OK
STEP 3. Create The FeatureType---- OK
3415 PROJCS["WGS 72BE / South China Sea Lambert",
GEOGCS["WGS 72BE",
DATUM["WGS 72 Transit Broadcast Ephemeris",
SPHEROID["WGS 72", 6378135.0, 298.26, AUTHORITY["EPSG","7043"]],
TOWGS84[0.0, 0.0, 1.9, 0.0, 0.0, 0.814, -0.07838062637389662],
AUTHORITY["EPSG","6324"]],
PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],
UNIT["degree", 0.017453292519943295],
AXIS["Geodetic longitude", EAST],
AXIS["Geodetic latitude", NORTH],
AUTHORITY["EPSG","4324"]],
PROJECTION["Lambert Conic Conformal (2SP)", AUTHORITY["EPSG","9802"]],
PARAMETER["central_meridian", 114.0],
PARAMETER["latitude_of_origin", 21.0],
PARAMETER["standard_parallel_1", 18.0],
PARAMETER["false_easting", 500000.0],
PARAMETER["false_northing", 500000.0],
PARAMETER["standard_parallel_2", 24.0],
UNIT["m", 1.0],
AXIS["Easting", EAST],
AXIS["Northing", NORTH],
AUTHORITY["EPSG","3415"]]
STEP 4. Try It Out----Exception
出現(xiàn)問題,出現(xiàn)異常
java.lang.reflect.UndeclaredThrowableException
繼續(xù)努力===========|||||||||
嘗試變化地圖的文件-----
嘗試修改樣式----失敗
(1)The requested Style can not be used with this layer. The style specifies an attribute of PERSONS and the layer is: topp:world_adm0
提示樣式不正確。
(2)重新新增樣式
樣式表的問題-----修改為系統(tǒng)原有樣式。系統(tǒng)正常。
Geoserver 下載后運行有比較弱智的問題:
在運行startup.bat后,系統(tǒng)沒有正常運行起來。原因是因為java_home的放在Program Files下,郁悶了小半天,移動了一下位置,終于運行起來了。