OGNL学习笔记-属性访问实例

OGNL属性访问例子

作者：与风同行

前面是一些语法规则方面的东西，下面通过实际例子来看看：

例子来源于OGNL自带的测试用例，根据这些例子稍加改写而成，这些例子很经典，对属性访问的方方面面都有涉及

测试步骤：

1．建立下面的Root类，一个普通的javabean

package net.wide.ognl.bean;   import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map;   import ognl.DynamicSubscript;   import net.wide.test.MyMap; import net.wide.test.MyMapImpl;   public class Root {     public static final String      SIZE_STRING = "size";     public static final int         STATIC_INT = 23;       private int[]                   array = { 1, 2, 3, 4 };     private Map                     map = new HashMap(23);     private MyMap                   myMap = new MyMapImpl();     private List                    list = Arrays.asList(new Object[] { null, this, array });     private List                    settableList = new ArrayList(Arrays.asList(new Object[] { "foo", "bar", "baz" }));     private int                     index = 1;     private int                     intValue = 0;     private String                  stringValue;     private int                     yetAnotherIntValue = 46;     private boolean                 privateAccessorBooleanValue = true;     private int                     privateAccessorIntValue = 67;     private int                     privateAccessorIntValue2 = 67;     private int                     privateAccessorIntValue3 = 67;     public String                   anotherStringValue = "foo";     public int                      anotherIntValue = 123;     public int                      six = 6;     public Root(){          map.put( "test", this );          map.put( "array", array );          map.put( "list", list );          map.put( "size", new Integer(5000) );          map.put( DynamicSubscript.first, new Integer(99) );               /* make myMap identical */          myMap.putAll( map );     }     public int getAnotherIntValue() {         return anotherIntValue;     }     public void setAnotherIntValue(int anotherIntValue) {         this.anotherIntValue = anotherIntValue;     }     public String getAnotherStringValue() {         return anotherStringValue;     }     public void setAnotherStringValue(String anotherStringValue) {         this.anotherStringValue = anotherStringValue;     }     public int[] getArray() {         return array;     }     public void setArray(int[] array) {         this.array = array;     }     public int getIndex() {         return index;     }     public void setIndex(int index) {         this.index = index;     }     public int getIntValue() {         return intValue;     }     public void setIntValue(int intValue) {         this.intValue = intValue;     }     public List getList() {         return list;     }     public void setList(List list) {         this.list = list;     }     public Map getMap() {         return map;     }     public void setMap(Map map) {         this.map = map;     }     public MyMap getMyMap() {         return myMap;     }     public void setMyMap(MyMap myMap) {         this.myMap = myMap;     }     public boolean isPrivateAccessorBooleanValue() {         return privateAccessorBooleanValue;     }     public void setPrivateAccessorBooleanValue(boolean privateAccessorBooleanValue) {         this.privateAccessorBooleanValue = privateAccessorBooleanValue;     }     public int getPrivateAccessorIntValue() {         return privateAccessorIntValue;     }     public void setPrivateAccessorIntValue(int privateAccessorIntValue) {         this.privateAccessorIntValue = privateAccessorIntValue;     }     public int getPrivateAccessorIntValue2() {         return privateAccessorIntValue2;     }     public void setPrivateAccessorIntValue2(int privateAccessorIntValue2) {         this.privateAccessorIntValue2 = privateAccessorIntValue2;     }     public int getPrivateAccessorIntValue3() {         return privateAccessorIntValue3;     }     public void setPrivateAccessorIntValue3(int privateAccessorIntValue3) {         this.privateAccessorIntValue3 = privateAccessorIntValue3;     }     public List getSettableList() {         return settableList;     }     public void setSettableList(List settableList) {         this.settableList = settableList;     }     public int getSix() {         return six;     }     public void setSix(int six) {         this.six = six;     }     public String getStringValue() {         return stringValue;     }     public void setStringValue(String stringValue) {         this.stringValue = stringValue;     }     public int getYetAnotherIntValue() {         return yetAnotherIntValue;     }     public void setYetAnotherIntValue(int yetAnotherIntValue) {         this.yetAnotherIntValue = yetAnotherIntValue;     } }

2．测试代码

package net.wide.ognl;   import net.wide.test.Root; import ognl.DynamicSubscript; import ognl.Ognl; import ognl.OgnlContext; import ognl.SimpleNode; import junit.framework.TestCase;   public class RootTest extends TestCase {     private OgnlContext context;     private static Root             ROOT = new Root();       private static Object[][]       TESTS = {                  { ROOT, "map", ROOT.getMap() },                  { ROOT, "map.test", ROOT },                  { ROOT, "map[/"test/"]", ROOT },                  { ROOT, "map[/"te/" + /"st/"]", ROOT }, { ROOT, "map[(/"s/" + /"i/") + /"ze/"]", ROOT.getMap().get(Root.SIZE_STRING) },                                         { ROOT, "map[/"size/"]", ROOT.getMap().get(Root.SIZE_STRING) },                                         { ROOT, "map[@net.wide.ognl.bean.Root@SIZE_STRING]", ROOT.getMap().get(Root.SIZE_STRING) },                                         { ROOT.getMap(), "list", ROOT.getList() },                                         { ROOT, "map.array[0]", new Integer(ROOT.getArray()[0]) },                                         { ROOT, "map.list[1]", ROOT.getList().get(1) },                                         { ROOT, "map[^]", new Integer(99) },                                         { ROOT, "map[$]", null },                                         { ROOT.getMap(), "array[$]", new Integer(ROOT.getArray()[ROOT.getArray().length-1]) },                                         { ROOT, "[/"map/"]", ROOT.getMap() },                                         { ROOT.getArray(), "length", new Integer(ROOT.getArray().length) },                                         { ROOT, "getMap().list[|]", ROOT.getList().get(ROOT.getList().size()/2) },                                         { ROOT, "map.(array[2] + size()).doubleValue()", new Double(ROOT.getArray()[2] + ROOT.getMap().size()) },                                         { ROOT, "map.(#this)", ROOT.getMap() },                                         { ROOT, "map.(#this != null ? #this['size'] : null)", ROOT.getMap().get(Root.SIZE_STRING) },                                         { ROOT, "map[^].(#this == null ? 'empty' : #this)", new Integer(99) },                                         { ROOT, "map[$].(#this == null ? 'empty' : #this)", "empty" },                                         { ROOT, "map[$].(#root == null ? 'empty' : #root)", ROOT }                                     };     protected void setUp() throws Exception {         super.setUp();         context = (OgnlContext)Ognl.createDefaultContext(null);     }       protected void tearDown() throws Exception {         super.tearDown();     }     public void testProperties()throws Exception{         SimpleNode expression;         //直接用Root中map属性的名字来访问         expression = (SimpleNode) Ognl.parseExpression((String) TESTS[0][1]);         assertTrue(Ognl.getValue(expression, context, ROOT) == ROOT.getMap());         //访问Root中map属性的test属性         expression = (SimpleNode) Ognl.parseExpression((String) TESTS[1][1]);         assertTrue(Ognl.getValue(expression, context, ROOT).equals(ROOT));         //上面用map.test来访问，现在用下标形式访问         expression = (SimpleNode) Ognl.parseExpression((String) TESTS[2][1]);         assertTrue(Ognl.getValue(expression, context, ROOT).equals(ROOT));         //跟上面的是一样的，这里演示了下标计算之后，访问到的值         expression = (SimpleNode) Ognl.parseExpression((String) TESTS[3][1]);         assertTrue(Ognl.getValue(expression, context, ROOT).equals(ROOT));         /*来看看对size的访问，这里有看头，在初始化的时候是map.put( "size", new Integer(5000) );          *很自然我们会想到用map.size或者map["size"]来访问，显然没有问题          *这里要演示的是，怎样访问静态变量，在Root中定义了：          *public static final String      SIZE_STRING = "size";          *我们不可以用map[Root.SIZE_STRING]的形式访问吗？写成下面的形式：          *expression = (SimpleNode) Ognl.parseExpression("map[Root.SIZE_STRING]");          *OGNL就会认为有Root.SIZE_STRING这样一个对象是map的属性，而不是先去解释Root.SIZE_STRING为字符串size的          *看看下面是怎么办的,@做为静态导航          */         expression = (SimpleNode) Ognl.parseExpression("map[@net.wide.ognl.bean.Root@SIZE_STRING]");         System.out.println(Ognl.getValue(expression, context, ROOT));         //下面通过下标访问List或者数组         expression = (SimpleNode) Ognl.parseExpression("map.array[0]");//map.list[1]         System.out.println(Ognl.getValue(expression, context, ROOT));         /*对DynamicSubscript的测试          * 先看看它的代码：          * switch (flag)           {             case FIRST: return "^";             case MID:   return "|";             case LAST:  return "$";             case ALL:   return "*";             default:    return "?"; // Won't happen           }           很清楚了！下面来试试           在Root中有这么一个初始化的地方：           map.put( DynamicSubscript.first, new Integer(99) );           我们通过OGNL表达式怎么访问呢？           对于一个数组或List应用上面的表达式，则是取出在这个列表中对应位置的元素           在Map中我们需要显示地使用DynamicSubscript.first等做为key才能取得到值          */         expression = (SimpleNode) Ognl.parseExpression("map[^]");         System.out.println("first-^:" + Ognl.getValue(expression, context, ROOT));         expression = (SimpleNode) Ognl.parseExpression("map.array[|]");         System.out.println("middle-|:" + Ognl.getValue(expression, context, ROOT));         expression = (SimpleNode) Ognl.parseExpression("map.array[$]");         System.out.println("last-$:" + Ognl.getValue(expression, context, ROOT));         expression = (SimpleNode) Ognl.parseExpression("map.array[*]");         System.out.println("all-*:" + Ognl.getValue(expression, context, ROOT));         //测试数组或列表的伪属性         expression = (SimpleNode) Ognl.parseExpression("map.array.length");         System.out.println("array length:" + Ognl.getValue(expression, context, ROOT));                 /* 看看上面有这么一个东东：          * map.(array[2] + size()).doubleValue()          * 在前面的学习中，我们了解了OGNL的导航链，解析链中的属性或方法都是基于当前解释出来的结果的          * 因此array[2]就是map.array[2]          * size()就是map.size()          * 他们相加转换成Double型。          * 看看结果是:8.0          */         expression = (SimpleNode) Ognl.parseExpression("map.(array[2] + size()).doubleValue()");         System.out.println("map.(array[2] + size()).doubleValue():" + Ognl.getValue(expression, context, ROOT));         //map.(#this),this是对自身的引用，另外注意在变量名前加#符号，这个变量在这个表达式里面是全局的         expression = (SimpleNode) Ognl.parseExpression("map.(#this)");         System.out.println("map.(#this):" + Ognl.getValue(expression, context, ROOT));         //几个OGNL表达式，下面的意思是，测试map的第一个元素是否为空，如果为空则返回empty否则返回该对象         //这个写法我们非常熟悉，无论是java还是c都有这种写法         expression = (SimpleNode) Ognl.parseExpression("map[^].(#this == null ? 'empty' : #this)");         System.out.println("map[^].(#this == null ? 'empty' : #this):" + Ognl.getValue(expression, context, ROOT));     } }